     1                                  ; ****************************************************************************
     2                                  ; UNIX386.ASM (RETRO UNIX 386 Kernel) - v0.2.1.6
     3                                  ; ----------------------------------------------------------------------------
     4                                  ; NASM version 2.15 (unix386.s)
     5                                  ;
     6                                  ; RETRO UNIX 386 (Retro Unix == Turkish Rational Unix)
     7                                  ; Operating System Project (v0.2) by ERDOGAN TAN (Beginning: 24/12/2013)
     8                                  ;
     9                                  ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
    10                                  ; (v0.1 - Beginning: 11/07/2012)
    11                                  ;
    12                                  ; [ Last Modification: 18/07/2022 (v0.2.1.6) ]
    13                                  ;	 04/02/2016 - Retro UNIX 386 v1.1 (Retro UNIX Kernel v0.2.1.0)	
    14                                  ;	 31/12/2021 - BugFix and Code Optimization (v0.2.1.1)
    15                                  ;	 03/03/2022 - Code Optimization and BugFix (v0.2.1.2) - 02/01/2022
    16                                  ;	 04/04/2022 - Inode Table/List Address Modification (v0.2.1.2) -u5.s-
    17                                  ;	 22/04/2022 - BugFix ('mget' -u5.s-)
    18                                  ;	 29/04/2022 - BugFix ('syschmod' -u2.s-) (v0.2.1.2)
    19                                  ;	 ; (v0.2.1.3)
    20                                  ;	 09/05/2022 - u2.s (sysstat), u7.s (sysumount), diskinit.inc  
    21                                  ;	 15/05/2022 - u2.s (namei), u7.s (sysumount)
    22                                  ;	 01/06/2022 - BugFix ('set_date_time' -u0.s-) (v0.2.1.3)
    23                                  ;	 ; (v0.2.1.4)
    24                                  ;	 13/06/2022 - LPT1 (/dev/lpr) printing modification (v0.2.1.4)
    25                                  ;	 14/06/2022 - BugFix (video.inc,'set_cpos' <- u9.s 'putc' carry flg)
    26                                  ;	 ; (v0.2.1.5)
    27                                  ;	 08/07/2022 - diskio.s (diskio simplified by removing the unused code) 
    28                                  ;	 ; (v0.2.1.6) 
    29                                  ;	 15/07/2022 - Simplified and Improved Buffer Handling -u8.s-
    30                                  ;	 16/07/2022 - Code Optimization
    31                                  ;	 17/07/2022 - Code Optimization
    32                                  ;
    33                                  ; Derived from UNIX Operating System (v1.0 for PDP-11) 
    34                                  ; (Original) Source Code by Ken Thompson (1971-1972)
    35                                  ; <Bell Laboratories (17/3/1972)>
    36                                  ; <Preliminary Release of UNIX Implementation Document>
    37                                  ;
    38                                  ; Derived from 'UNIX v7/x86' source code by Robert Nordier (1999)
    39                                  ; UNIX V7/x86 source code: see www.nordier.com/v7x86 for details.
    40                                  ;
    41                                  ; ****************************************************************************
    42                                  ; 31/12/2021 - 15/07/2022
    43                                  ; nasm unix386.s -l unix386.txt -o unix386 -Z error.txt
    44                                  ; ('unixcopy' utility is used for updating retro unix kernel on runix fs disk)
    45                                  
    46                                  ; 02/01/2022 - Code Optimization
    47                                  ; Runix Kernel v0.2.1.2
    48                                  ; 24/12/2021 - BugFix and Code Optimization
    49                                  ; Runix Kernel v0.2.1.1 
    50                                  
    51                                  ; 24/12/2013
    52                                  
    53                                  ; Entering protected mode:
    54                                  ; Derived from 'simple_asm.txt' source code file and 
    55                                  ; 'The world of Protected mode' tutorial/article by Gregor Brunmar (2003)
    56                                  ; (gregor.brunmar@home.se)
    57                                  ; http://www.osdever.net/tutorials/view/the-world-of-protected-mode
    58                                  ;
    59                                  
    60                                  ; "The Real, Protected, Long mode assembly tutorial for PCs" 
    61                                  ; by Michael Chourdakis (2009) 
    62                                  ; http://www.codeproject.com/Articles/45788/
    63                                  ; http://www.michaelchourdakis.com
    64                                  ;
    65                                  
    66                                  ; Global Descriptor Table:
    67                                  ; Derived from 'head.s" source code of Linux v1.0 kernel
    68                                  ; by Linus Torvalds (1991-1992)
    69                                  ;
    70                                  
    71                                  KLOAD	equ 10000h ; Kernel loading address
    72                                  	; NOTE: Retro UNIX 8086 v1 /boot code loads kernel at 1000h:0000h
    73                                  KCODE	equ 08h	; Code segment descriptor (ring 0)
    74                                  KDATA	equ 10h	; Data segment descriptor (ring 0)
    75                                  ; 19/03/2015
    76                                  UCODE	equ 1Bh ; 18h + 3h  (ring 3)
    77                                  UDATA	equ 23h ; 20h + 3h  (ring 3)
    78                                  ; 24/03/2015
    79                                  TSS	equ 28h	; Task state segment descriptor (ring 0)
    80                                  ; 19/03/2015
    81                                  CORE	equ 400000h  ; Start of USER's virtual/linear address space 
    82                                  		     ; (at the end of the 1st 4MB)
    83                                  ECORE	equ 0FFC00000h ; End of USER's virtual address space (4GB - 4MB)
    84                                  		     ; ULIMIT = (ECORE/4096) - 1 = 0FFBFFh (in GDT)
    85                                  
    86                                  ; 02/01/2022 (Retro UNIX 386 v1.1, Runix Kernel v0.2.1.2)
    87                                  ;; 27/12/2013
    88                                  ;KEND	equ KLOAD + 65536 ; (28/12/2013) (end of kernel space)
    89                                  
    90                                  ; IBM PC/AT BIOS ----- 10/06/85 (postequ.inc)
    91                                  ;--------- CMOS TABLE LOCATION ADDRESS'S -------------------------------------
    92                                  CMOS_SECONDS	EQU	00H		; SECONDS (BCD)
    93                                  CMOS_MINUTES	EQU	02H		; MINUTES (BCD)	
    94                                  CMOS_HOURS	EQU	04H		; HOURS (BCD)
    95                                  CMOS_DAY_WEEK	EQU	06H		; DAY OF THE WEEK  (BCD)
    96                                  CMOS_DAY_MONTH	EQU	07H		; DAY OF THE MONTH (BCD) 
    97                                  CMOS_MONTH	EQU	08H		; MONTH (BCD)
    98                                  CMOS_YEAR	EQU	09H		; YEAR (TWO DIGITS) (BCD)
    99                                  CMOS_CENTURY	EQU	32H		; DATE CENTURY BYTE (BCD)
   100                                  CMOS_REG_A	EQU	0AH		; STATUS REGISTER A
   101                                  CMOS_REG_B	EQU	00BH		; STATUS REGISTER B  ALARM
   102                                  CMOS_REG_C	EQU	00CH		; STATUS REGISTER C  FLAGS
   103                                  CMOS_REG_D	EQU	0DH		; STATUS REGISTER D  BATTERY
   104                                  CMOS_SHUT_DOWN	EQU	0FH		; SHUTDOWN STATUS COMMAND BYTE
   105                                  ;----------------------------------------
   106                                  ;	CMOS EQUATES FOR THIS SYSTEM	;
   107                                  ;-----------------------------------------------------------------------------
   108                                  CMOS_PORT	EQU	070H		; I/O ADDRESS OF CMOS ADDRESS PORT
   109                                  CMOS_DATA	EQU	071H		; I/O ADDRESS OF CMOS DATA PORT
   110                                  NMI		EQU	10000000B	; DISABLE NMI INTERRUPTS MASK -
   111                                  					; HIGH BIT OF CMOS LOCATION ADDRESS
   112                                  
   113                                  ; Memory Allocation Table Address
   114                                  ; 05/11/2014
   115                                  ; 31/10/2014
   116                                  MEM_ALLOC_TBL	equ	100000h		; Memory Allocation Table at the end of
   117                                  					; the 1st 1 MB memory space.
   118                                  					; (This address must be aligned
   119                                  					;  on 128 KB boundary, if it will be
   120                                  					;  changed later.)
   121                                  					; ((lower 17 bits of 32 bit M.A.T.
   122                                  					;   address must be ZERO)).
   123                                  					; ((((Reason: 32 bit allocation 
   124                                  					;     instructions, dword steps)))
   125                                  					; (((byte >> 12 --> page >> 5)))  
   126                                  ;04/11/2014	
   127                                  PDE_A_PRESENT	equ	1		; Present flag for PDE
   128                                  PDE_A_WRITE	equ 	2		; Writable (write permission) flag
   129                                  PDE_A_USER	equ	4		; User (non-system/kernel) page flag
   130                                  ;
   131                                  PTE_A_PRESENT	equ	1		; Present flag for PTE (bit 0)
   132                                  PTE_A_WRITE	equ 	2		; Writable (write permission) flag (bit 1)
   133                                  PTE_A_USER	equ	4		; User (non-system/kernel) page flag (bit 2)
   134                                  PTE_A_ACCESS    equ	32		; Accessed flag (bit 5) ; 09/03/2015
   135                                  
   136                                  ; 17/02/2015 (unix386.s)
   137                                  ; 10/12/2014 - 30/12/2014 (0B000h -> 9000h) (dsectrm2.s)
   138                                  DPT_SEGM equ 09000h  ; FDPT segment (EDD v1.1, EDD v3)
   139                                  ;
   140                                  HD0_DPT	 equ 0	    ; Disk parameter table address for hd0
   141                                  HD1_DPT	 equ 32	    ; Disk parameter table address for hd1
   142                                  HD2_DPT	 equ 64	    ; Disk parameter table address for hd2
   143                                  HD3_DPT	 equ 96	    ; Disk parameter table address for hd3
   144                                  
   145                                  
   146                                  ; FDPT (Phoenix, Enhanced Disk Drive Specification v1.1, v3.0)
   147                                  ;      (HDPT: Programmer's Guide to the AMIBIOS, 1993)
   148                                  ;
   149                                  FDPT_CYLS	equ 0 ; 1 word, number of cylinders
   150                                  FDPT_HDS	equ 2 ; 1 byte, number of heads
   151                                  FDPT_TT		equ 3 ; 1 byte, A0h = translated FDPT with logical values
   152                                  		      ; otherwise it is standard FDPT with physical values 	
   153                                  FDPT_PCMP	equ 5 ; 1 word, starting write precompensation cylinder
   154                                  		      ; (obsolete for IDE/ATA drives)
   155                                  FDPT_CB		equ 8 ; 1 byte, drive control byte
   156                                  			; Bits 7-6 : Enable or disable retries (00h = enable)
   157                                  			; Bit 5	: 1 = Defect map is located at last cyl. + 1
   158                                  			; Bit 4 : Reserved. Always 0
   159                                  			; Bit 3 : Set to 1 if more than 8 heads
   160                                  			; Bit 2-0 : Reserved. Alsways 0
   161                                  FDPT_LZ		equ 12 ; 1 word, landing zone (obsolete for IDE/ATA drives)
   162                                  FDPT_SPT	equ 14 ; 1 byte, sectors per track
   163                                  
   164                                  ; Floppy Drive Parameters Table (Programmer's Guide to the AMIBIOS, 1993)
   165                                  ; (11 bytes long) will be used by diskette handler/bios
   166                                  ; which is derived from IBM PC-AT BIOS (DISKETTE.ASM, 21/04/1986).						 	  		 	  
   167                                  
   168                                  [BITS 16]       ; We need 16-bit intructions for Real mode
   169                                  
   170                                  [ORG 0]
   171                                  
   172                                  KSTART: ; 01/01/2022
   173                                   
   174                                  	; 12/11/2014
   175                                  	; Save boot drive number (that is default root drive)
   176 00000000 8816[385D]              	mov	[boot_drv], dl ; physical drv number
   177                                  
   178                                  	; Determine installed memory
   179                                  	; 31/10/2014
   180                                  	;
   181 00000004 B801E8                  	mov	ax, 0E801h ; Get memory size 
   182 00000007 CD15                    	int	15h	   ; for large configurations
   183 00000009 7308                    	jnc	short chk_ms
   184 0000000B B488                    	mov	ah, 88h    ; Get extended memory size 
   185 0000000D CD15                    	int	15h
   186                                  	;	   
   187                                  	;mov	al, 17h	; Extended memory (1K blocks) low byte
   188                                  	;out	70h, al ; select CMOS register
   189                                  	;in	al, 71h ; read data (1 byte)
   190                                  	;mov	cl, al
   191                                  	;mov	al, 18h ; Extended memory (1K blocks) high byte
   192                                  	;out	70h, al ; select CMOS register
   193                                  	;in	al, 71h ; read data (1 byte)
   194                                  	;mov	ch, al
   195                                   	;      
   196 0000000F 89C1                    	mov	cx, ax
   197 00000011 31D2                    	xor	dx, dx
   198                                  chk_ms:
   199 00000013 890E[A45F]              	mov	[mem_1m_1k], cx
   200 00000017 8916[A85F]              	mov	[mem_16m_64k], dx
   201                                  	; 05/11/2014
   202                                  	;and	dx, dx
   203                                  	;jz	short L2
   204 0000001B 81F90004                        cmp     cx, 1024
   205 0000001F 7351                    	jnb	short L0
   206                                  		 ; insufficient memory_error	
   207                                  		 ; Minimum 2 MB memory is needed... 
   208                                  	; 05/11/2014
   209                                  	; (real mode error printing)
   210 00000021 FB                      	sti
   211 00000022 BE[3600]                	mov	si, msg_out_of_memory
   212 00000025 BB0700                  	mov	bx, 7
   213 00000028 B40E                    	mov	ah, 0Eh	; write tty
   214                                  oom_1:
   215 0000002A AC                      	lodsb
   216 0000002B 08C0                    	or	al, al
   217 0000002D 7404                    	jz	short oom_2
   218 0000002F CD10                    	int	10h
   219 00000031 EBF7                    	jmp	short oom_1
   220                                  oom_2:
   221 00000033 F4                              hlt
   222 00000034 EBFD                    	jmp	short oom_2
   223                                  
   224                                  ; 02/01/2022
   225                                  ; 05/11/2014
   226                                  msg_out_of_memory:
   227 00000036 070D0A                  	db 	07h, 0Dh, 0Ah
   228 00000039 496E73756666696369-             db      'Insufficient memory !'
   228 00000042 656E74206D656D6F72-
   228 0000004B 792021             
   229 0000004E 0D0A                    	db	0Dh, 0Ah
   230                                  _int13h_48h_buffer: ; 02/01/2022 (Runix Kernel v0.2.1.2, 'diskinit.inc')
   231 00000050 284D696E696D756D20-     	db	'(Minimum 2MB memory is needed.)'
   231 00000059 324D42206D656D6F72-
   231 00000062 79206973206E656564-
   231 0000006B 65642E29           
   232 0000006F 0D0A00                   	db	0Dh, 0Ah, 0
   233                                  
   234                                  L0:
   235                                  %include 'diskinit.inc' ; 07/03/2015
   236                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.5) - DISKINIT.INC
   237                              <1> ; Last Modification: 12/07/2022
   238                              <1> 
   239                              <1> ; DISK I/O SYSTEM INITIALIZATION - Erdogan Tan (Retro UNIX 386 v1 project)
   240                              <1> 
   241                              <1> ; ///////// DISK I/O SYSTEM STRUCTURE INITIALIZATION ///////////////
   242                              <1> 
   243                              <1> 	; 02/01/2022 (Retro UNIX 386 v1.1, Runix Kernel v0.2.1.2)
   244                              <1> 	; 10/12/2014 - 02/02/2015 - dsectrm2.s
   245                              <1> ;L0:
   246                              <1> 	; 12/11/2014 (Retro UNIX 386 v1 - beginning)
   247                              <1> 	; Detecting disk drives... (by help of ROM-BIOS)
   248 00000072 BA7F00              <1> 	mov	dx, 7Fh
   249                              <1> L1:	
   250 00000075 FEC2                <1> 	inc	dl
   251 00000077 B441                <1> 	mov	ah, 41h ; Check extensions present
   252                              <1> 			; Phoenix EDD v1.1 - EDD v3
   253 00000079 BBAA55              <1> 	mov	bx, 55AAh
   254 0000007C CD13                <1> 	int 	13h
   255 0000007E 721A                <1> 	jc	short L2
   256                              <1> 
   257 00000080 81FB55AA            <1> 	cmp	bx, 0AA55h
   258 00000084 7514                <1> 	jne	short L2
   259 00000086 FE06[3B5D]          <1> 	inc	byte [hdc]	; count of hard disks (EDD present)
   260 0000008A 8816[3A5D]          <1>         mov     [last_drv], dl  ; last hard disk number
   261 0000008E BB[BE5C]            <1> 	mov	bx, hd0_type - 80h
   262 00000091 01D3                <1> 	add	bx, dx	 
   263 00000093 880F                <1> 	mov	[bx], cl ; Interface support bit map in CX
   264                              <1> 			 ; Bit 0 - 1, Fixed disk access subset ready
   265                              <1> 			 ; Bit 1 - 1, Drv locking and ejecting ready
   266                              <1> 			 ; Bit 2 - 1, Enhanced Disk Drive Support
   267                              <1>                          ;            (EDD) ready (DPTE ready)
   268                              <1> 			 ; Bit 3 - 1, 64bit extensions are present
   269                              <1>                          ;            (EDD-3)
   270                              <1> 			 ; Bit 4 to 15 - 0, Reserved
   271 00000095 80FA83              <1> 	cmp	dl, 83h	 ; drive number < 83h
   272 00000098 72DB                <1> 	jb	short L1
   273                              <1> L2:
   274                              <1> 	; 23/11/2014
   275                              <1> 	; 19/11/2014
   276 0000009A 30D2                <1> 	xor	dl, dl  ; 0
   277                              <1> 	; 04/02/2016 (esi -> si)
   278 0000009C BE[3C5D]            <1> 	mov	si, fd0_type
   279                              <1> L3:
   280                              <1> 	; 14/01/2015
   281 0000009F 8816[395D]          <1> 	mov	[drv], dl
   282                              <1> 	;
   283 000000A3 B408                <1> 	mov 	ah, 08h ; Return drive parameters
   284 000000A5 CD13                <1> 	int	13h	
   285 000000A7 7210                <1> 	jc	short L4
   286                              <1> 		; BL = drive type (for floppy drives)
   287                              <1> 		; DL = number of floppy drives
   288                              <1> 		;		
   289                              <1> 		; ES:DI = Address of DPT from BIOS
   290                              <1> 		;
   291 000000A9 881C                <1> 	mov	[si], bl ;  Drive type
   292                              <1> 			; 4 = 1.44 MB, 80 track, 3 1/2"
   293                              <1> 	; 14/01/2015
   294 000000AB E8BB01              <1> 	call	set_disk_parms
   295                              <1> 	; 10/12/2014
   296 000000AE 81FE[3C5D]          <1> 	cmp	si, fd0_type
   297 000000B2 7705                <1> 	ja	short L4
   298 000000B4 46                  <1> 	inc	si ; fd1_type
   299 000000B5 B201                <1> 	mov	dl, 1
   300 000000B7 EBE6                <1> 	jmp	short L3
   301                              <1> L4:
   302                              <1> 	; Older BIOS (INT 13h, AH = 48h is not available)
   303 000000B9 B27F                <1> 	mov	dl, 7Fh
   304                              <1> 	; 24/12/2014 (Temporary)
   305 000000BB 803E[3B5D]00        <1> 	cmp	byte [hdc], 0 ; EDD present or not ?	
   306                              <1> 	;ja	L10       ; yes, all fixed disk operations
   307                              <1> 			  ; will be performed according to
   308                              <1> 			  ; present EDD specification
   309                              <1> 	; 02/01/2022
   310 000000C0 7603                <1> 	jna	short L5
   311 000000C2 E99100              <1> 	jmp	L10
   312                              <1> L5:
   313 000000C5 FEC2                <1> 	inc 	dl
   314 000000C7 8816[395D]          <1>         mov     [drv], dl
   315 000000CB 8816[3A5D]          <1>         mov     [last_drv], dl ; 14/01/2015
   316 000000CF B408                <1> 	mov 	ah, 08h ; Return drive parameters
   317 000000D1 CD13                <1> 	int	13h	; (conventional function)
   318                              <1> 	;jc	L13	; fixed disk drive not ready
   319                              <1> 	; 02/01/2022
   320 000000D3 7303                <1> 	jnc	short L6
   321 000000D5 E98301              <1> 	jmp	L13
   322                              <1> L6:
   323 000000D8 8816[3B5D]          <1>         mov     [hdc], dl ; number of drives
   324                              <1> 	;; 14/01/2013
   325                              <1> 	;;push	cx
   326 000000DC E88A01              <1> 	call	set_disk_parms
   327                              <1> 	;;pop	cx
   328                              <1> 	;
   329                              <1> 	;;and	cl, 3Fh	 ; sectors per track (bits 0-6)
   330 000000DF 8A16[395D]          <1>         mov     dl, [drv]
   331 000000E3 BB0401              <1> 	mov	bx, 65*4 ; hd0 parameters table (INT 41h)	
   332 000000E6 80FA80              <1> 	cmp	dl, 80h
   333 000000E9 7603                <1> 	jna	short L7
   334 000000EB 83C314              <1> 	add	bx, 5*4	 ; hd1 parameters table (INT 46h)
   335                              <1> L7:	
   336 000000EE 31C0                <1> 	xor	ax, ax
   337 000000F0 8ED8                <1> 	mov	ds, ax
   338 000000F2 8B37                <1>         mov     si, [bx]
   339 000000F4 8B4702              <1>         mov     ax, [bx+2] 
   340 000000F7 8ED8                <1> 	mov	ds, ax
   341 000000F9 3A4C0E              <1>         cmp     cl, [si+FDPT_SPT] ; sectors per track 
   342                              <1> 	;jne	L12 ; invalid FDPT
   343                              <1> 	; 02/01/2022
   344 000000FC 7403                <1> 	je	short L7_8
   345 000000FE E95601              <1> 	jmp	L12
   346                              <1> L7_8:
   347 00000101 BF0000              <1> 	mov	di, HD0_DPT
   348 00000104 80FA80              <1> 	cmp	dl, 80h
   349 00000107 7603                <1> 	jna	short L8
   350 00000109 BF2000              <1> 	mov	di, HD1_DPT 
   351                              <1> L8:
   352                              <1> 	; 30/12/2014
   353 0000010C B80090              <1> 	mov	ax, DPT_SEGM
   354 0000010F 8EC0                <1> 	mov	es, ax
   355                              <1> 	; 24/12/2014
   356 00000111 B90800              <1> 	mov	cx, 8
   357 00000114 F3A5                <1> 	rep	movsw  ; copy 16 bytes to the kernel's DPT location
   358 00000116 8CC8                <1> 	mov	ax, cs
   359 00000118 8ED8                <1> 	mov	ds, ax
   360                              <1> 	; 02/02/2015
   361 0000011A 8A0E[395D]          <1>         mov     cl, [drv]
   362 0000011E 88CB                <1> 	mov	bl, cl
   363 00000120 B8F001              <1> 	mov	ax, 1F0h
   364 00000123 80E301              <1> 	and	bl, 1
   365 00000126 7406                <1> 	jz	short L9
   366 00000128 C0E304              <1> 	shl	bl, 4
   367 0000012B 2D8000              <1> 	sub	ax, 1F0h-170h
   368                              <1> L9:
   369 0000012E AB                  <1> 	stosw	; I/O PORT Base Address (1F0h, 170h)
   370 0000012F 050602              <1> 	add	ax, 206h
   371 00000132 AB                  <1> 	stosw	; CONTROL PORT Address (3F6h, 376h)	
   372 00000133 88D8                <1> 	mov	al, bl
   373 00000135 04A0                <1> 	add	al, 0A0h
   374 00000137 AA                  <1> 	stosb	; Device/Head Register upper nibble
   375                              <1> 	;
   376 00000138 FE06[395D]          <1> 	inc	byte [drv]
   377 0000013C BB[BE5C]            <1> 	mov	bx, hd0_type - 80h
   378 0000013F 01CB                <1> 	add	bx, cx
   379 00000141 800F80              <1>         or      byte [bx], 80h  ; present sign (when lower nibble is 0)
   380 00000144 A0[3B5D]            <1> 	mov	al, [hdc]
   381 00000147 FEC8                <1> 	dec	al
   382                              <1> 	;jz	L13
   383                              <1> 	; 02/01/2022
   384 00000149 7408                <1> 	jz	short L9_10
   385 0000014B 80FA80              <1> 	cmp	dl, 80h
   386                              <1>         ;jna	L5
   387                              <1> 	;jmp	L13
   388                              <1> 	; 02/01/2022
   389 0000014E 7703                <1> 	ja	short L9_10
   390 00000150 E972FF              <1> 	jmp	L5
   391                              <1> L9_10:
   392 00000153 E90501              <1>         jmp     L13
   393                              <1> L10:
   394 00000156 FEC2                <1> 	inc 	dl
   395                              <1> 	; 25/12/2014
   396 00000158 8816[395D]          <1> 	mov	[drv], dl
   397 0000015C B408                <1> 	mov 	ah, 08h ; Return drive parameters
   398 0000015E CD13                <1> 	int	13h	; (conventional function)
   399                              <1> 	;jc	L13
   400                              <1> 	; 02/01/2022
   401 00000160 72F1                <1> 	jc	short L9_10
   402                              <1> 	; 14/01/2015
   403 00000162 8A16[395D]          <1> 	mov	dl, [drv]
   404 00000166 52                  <1> 	push	dx
   405 00000167 51                  <1> 	push	cx
   406 00000168 E8FE00              <1> 	call	set_disk_parms
   407 0000016B 59                  <1> 	pop	cx
   408 0000016C 5A                  <1> 	pop	dx
   409                              <1> 	; 02/01/2022 - Retro UNIX 386 v1.1 (Runix Kernel v0.2.1.2)
   410                              <1> 	; 04/02/2016 (esi -> si)
   411                              <1> 	;mov	si, _end ; 30 byte temporary buffer address
   412                              <1> 	;		 ; at the '_end' of kernel.
   413                              <1> 	;mov	word [si], 30
   414                              <1> 	; 06/07/2016
   415 0000016D BE[5000]            <1> 	mov	si, _int13h_48h_buffer
   416                              <1> 	; 09/07/2016
   417 00000170 B81E00              <1> 	mov	ax, 001Eh
   418 00000173 8824                <1> 	mov	[si], ah ; 0
   419 00000175 46                  <1> 	inc	si
   420 00000176 8904                <1> 	mov	word [si], ax
   421                              <1>  	; word [si] = 30
   422                              <1> 	;
   423 00000178 B448                <1> 	mov	ah, 48h	 ; Get drive parameters (EDD function)
   424 0000017A CD13                <1> 	int	13h
   425                              <1>         ;jc	L13
   426                              <1> 	; 02/01/2022
   427 0000017C 72D5                <1> 	jc	short L9_10
   428                              <1> 	; 04/02/2016 (ebx -> bx)
   429                              <1> 	; 14/01/2015
   430                              <1> 	;sub	bx, bx
   431 0000017E 28FF                <1> 	sub	bh, bh ; 02/01/2022
   432 00000180 88D3                <1> 	mov	bl, dl
   433 00000182 80EB80              <1> 	sub	bl, 80h
   434 00000185 81C3[3E5D]          <1> 	add	bx, hd0_type
   435 00000189 8A07                <1> 	mov 	al, [bx]
   436 0000018B 0C80                <1> 	or	al, 80h
   437 0000018D 8807                <1> 	mov 	[bx], al	
   438 0000018F 81EB[3C5D]          <1> 	sub	bx, hd0_type - 2 ; 15/01/2015
   439 00000193 81C3[5E5D]          <1> 	add	bx, drv.status
   440 00000197 8807                <1> 	mov	[bx], al
   441                              <1> 	; 04/02/2016 (eax -> ax)
   442 00000199 8B4410              <1> 	mov	ax, [si+16]
   443 0000019C 854412              <1> 	test	ax, [si+18]
   444 0000019F 7413                <1> 	jz	short L10_A0h 
   445                              <1> 			; 'CHS only' disks on EDD system 
   446                              <1> 			;  are reported with ZERO disk size
   447 000001A1 81EB[5E5D]          <1> 	sub	bx, drv.status
   448 000001A5 C1E302              <1> 	shl	bx, 2
   449 000001A8 81C3[425D]          <1> 	add	bx, drv.size ; disk size (in sectors)
   450 000001AC 8907                <1> 	mov	[bx], ax
   451 000001AE 8B4412              <1> 	mov	ax, [si+18]
   452                              <1> 	;mov	[bx], ax
   453                              <1> 	; 02/01/2022 (BugFix)
   454 000001B1 894702              <1> 	mov	[bx+2], ax
   455                              <1> 
   456                              <1> L10_A0h: ; Jump here to fix a ZERO (LBA) disk size problem 
   457                              <1> 	 ; for CHS disks (28/02/2015)
   458                              <1> 	; 30/12/2014
   459 000001B4 BF0000              <1> 	mov	di, HD0_DPT
   460 000001B7 88D0                <1> 	mov	al, dl
   461 000001B9 83E003              <1> 	and 	ax, 3
   462 000001BC C0E005              <1> 	shl	al, 5 ; *32
   463 000001BF 01C7                <1> 	add 	di, ax
   464 000001C1 B80090              <1> 	mov	ax, DPT_SEGM
   465 000001C4 8EC0                <1> 	mov	es, ax
   466                              <1> 	;
   467 000001C6 88E8                <1> 	mov	al, ch	; max. cylinder number (bits 0-7)
   468 000001C8 88CC                <1> 	mov	ah, cl	
   469 000001CA C0EC06              <1> 	shr	ah, 6	; max. cylinder number (bits 8-9)
   470 000001CD 40                  <1>  	inc	ax	; logical cylinders (limit 1024)
   471 000001CE AB                  <1> 	stosw		
   472 000001CF 88F0                <1> 	mov	al, dh	; max. head number
   473 000001D1 FEC0                <1> 	inc	al
   474 000001D3 AA                  <1> 	stosb		; logical heads (limits 256)
   475 000001D4 B0A0                <1> 	mov	al, 0A0h ; Indicates translated table
   476 000001D6 AA                  <1> 	stosb
   477 000001D7 8A440C              <1> 	mov	al, [si+12]
   478 000001DA AA                  <1> 	stosb		 ; physical sectors per track
   479 000001DB 31C0                <1>  	xor	ax, ax
   480                              <1> 	;dec	ax	 ; 02/01/2015 
   481 000001DD AB                  <1> 	stosw		 ; precompensation (obsolete)
   482                              <1> 	;xor	al, al	 ; 02/01/2015	
   483 000001DE AA                  <1> 	stosb		 ; reserved
   484 000001DF B008                <1> 	mov	al, 8	 ; drive control byte
   485                              <1> 		         ; (do not disable retries, 
   486                              <1> 			 ; more than 8 heads)
   487 000001E1 AA                  <1> 	stosb
   488 000001E2 8B4404              <1> 	mov	ax, [si+4]
   489 000001E5 AB                  <1> 	stosw		 ; physical number of cylinders	
   490                              <1> 	;push	ax	 ; 02/01/2015
   491 000001E6 8A4408              <1> 	mov	al, [si+8]
   492 000001E9 AA                  <1> 	stosb		 ; physical num. of heads (limit 16)
   493 000001EA 29C0                <1> 	sub 	ax, ax
   494                              <1> 	;pop	ax	 ; 02/01/2015	
   495 000001EC AB                  <1> 	stosw		 ; landing zone (obsolete)
   496 000001ED 88C8                <1> 	mov	al, cl	 ; logical sectors per track (limit 63)
   497 000001EF 243F                <1> 	and 	al, 3Fh	
   498 000001F1 AA                  <1> 	stosb
   499                              <1> 	;sub	al, al	 ; checksum
   500                              <1> 	;stosb
   501                              <1> 	;
   502 000001F2 83C61A              <1> 	add	si, 26   ; (BIOS) DPTE address pointer
   503 000001F5 AD                  <1> 	lodsw
   504 000001F6 50                  <1> 	push	ax	 ; (BIOS) DPTE offset
   505 000001F7 AD                  <1> 	lodsw
   506 000001F8 50                  <1> 	push	ax	 ; (BIOS) DPTE segment
   507                              <1> 	;
   508                              <1> 	; checksum calculation
   509 000001F9 89FE                <1> 	mov	si, di
   510 000001FB 06                  <1> 	push	es
   511 000001FC 1F                  <1> 	pop	ds
   512                              <1> 	;mov	cx, 16
   513 000001FD B90F00              <1> 	mov 	cx, 15
   514 00000200 29CE                <1> 	sub	si, cx
   515 00000202 30E4                <1> 	xor	ah, ah
   516                              <1> 	;del	cl
   517                              <1> L11:		
   518 00000204 AC                  <1> 	lodsb
   519 00000205 00C4                <1> 	add	ah, al
   520 00000207 E2FB                <1> 	loop	L11
   521                              <1> 	;
   522 00000209 88E0                <1> 	mov	al, ah
   523 0000020B F6D8                <1> 	neg	al	; -x+x = 0
   524 0000020D AA                  <1> 	stosb		; put checksum in byte 15 of the tbl
   525                              <1> 	;
   526 0000020E 1F                  <1> 	pop	ds	; (BIOS) DPTE segment
   527 0000020F 5E                  <1> 	pop	si	; (BIOS) DPTE offset	
   528                              <1> 	;
   529                              <1> 	; 23/02/2015
   530 00000210 57                  <1> 	push	di
   531                              <1> 	; ES:DI points to DPTE (FDPTE) location
   532                              <1> 	;mov	cx, 8
   533 00000211 B108                <1> 	mov	cl, 8
   534 00000213 F3A5                <1> 	rep	movsw	
   535                              <1> 	;
   536                              <1> 	; 23/02/2015
   537                              <1> 	; (P)ATA drive and LBA validation
   538                              <1> 	; (invalidating SATA drives and setting
   539                              <1> 	; CHS type I/O for old type fixed disks)
   540 00000215 5B                  <1> 	pop	bx
   541 00000216 8CC8                <1> 	mov	ax, cs
   542 00000218 8ED8                <1> 	mov	ds, ax
   543 0000021A 268B07              <1> 	mov	ax, [es:bx]
   544 0000021D 3DF001              <1> 	cmp	ax, 1F0h
   545 00000220 7418                <1> 	je	short L11a
   546 00000222 3D7001              <1> 	cmp	ax, 170h
   547 00000225 7413                <1> 	je	short L11a
   548                              <1> 	; invalidation 
   549                              <1> 	; (because base port address is not 1F0h or 170h)
   550 00000227 30FF                <1> 	xor	bh, bh
   551 00000229 88D3                <1> 	mov	bl, dl
   552 0000022B 80EB80              <1> 	sub	bl, 80h
   553 0000022E C687[3E5D]00        <1> 	mov	byte [bx+hd0_type], 0 ; not a valid disk drive !		
   554 00000233 808F[605D]F0        <1>         or      byte [bx+drv.status+2], 0F0h ; (failure sign)
   555 00000238 EB14                <1> 	jmp	short L11b
   556                              <1> L11a:	
   557                              <1> 	; LBA validation
   558 0000023A 268A4704            <1> 	mov	al, [es:bx+4] ; Head register upper nibble
   559 0000023E A840                <1> 	test	al, 40h ; LBA bit (bit 6)
   560 00000240 750C                <1> 	jnz	short L11b ; LBA type I/O is OK! (E0h or F0h)
   561                              <1> 	; force CHS type I/O for this drive (A0h or B0h)
   562 00000242 28FF                <1> 	sub	bh, bh
   563 00000244 88D3                <1> 	mov	bl, dl
   564 00000246 80EB80              <1> 	sub	bl, 80h ; 26/02/2015
   565 00000249 80A7[605D]FE        <1>         and     byte [bx+drv.status+2], 0FEh ; clear bit 0
   566                              <1> 				; bit 0 = LBA ready bit
   567                              <1> 	; 'diskio' procedure will check this bit !
   568                              <1> L11b:
   569 0000024E 3A16[3A5D]          <1> 	cmp	dl, [last_drv] ; 25/12/2014
   570 00000252 7307                <1>         jnb     short L13
   571 00000254 E9FFFE              <1>         jmp     L10
   572                              <1> L12:
   573                              <1> 	; Restore data registers
   574 00000257 8CC8                <1> 	mov	ax, cs
   575 00000259 8ED8                <1> 	mov	ds, ax	
   576                              <1> L13:
   577                              <1> 	; 13/12/2014
   578 0000025B 0E                  <1> 	push	cs
   579 0000025C 07                  <1> 	pop	es
   580                              <1> L14:
   581 0000025D B411                <1> 	mov 	ah, 11h
   582 0000025F CD16                <1> 	int 	16h
   583                              <1> 	;jz 	short L15 ; no keys in keyboard buffer
   584                              <1> 	; 02/01/2022
   585 00000261 7447                <1> 	jz	short L16
   586 00000263 B010                <1> 	mov	al, 10h
   587 00000265 CD16                <1> 	int 	16h
   588 00000267 EBF4                <1> 	jmp 	short L14
   589                              <1> L15:
   590                              <1> 
   591                              <1> ; //////
   592                              <1> 
   593                              <1> ; 02/01/2022 - Retro UNIX 386 v1.1 (Runix Kernel v0.2.1.2)
   594                              <1> %if 0
   595                              <1> 	; 24/11/2014
   596                              <1> 	; 19/11/2014
   597                              <1> 	; 14/11/2014
   598                              <1> 	; Temporary code for disk searching code check
   599                              <1> 	;
   600                              <1> 	; This code will show existing (usable) drives and also
   601                              <1> 	; will show EDD interface support status for hard disks		
   602                              <1> 	; (If status bit 7 is 1, Identify Device info is ready,
   603                              <1> 	; no need to get it again in protected mode...) 
   604                              <1> 	;	
   605                              <1> 	; 13/11/2014
   606                              <1> 	mov	bx, 7
   607                              <1> 	mov	ah, 0Eh
   608                              <1> 	mov	al, [fd0_type]
   609                              <1> 	and	al, al
   610                              <1> 	jz	short L15a
   611                              <1> 	mov	dl, al
   612                              <1> 	mov	al, 'F'
   613                              <1> 	int 	10h
   614                              <1> 	mov	al, 'D'
   615                              <1> 	int 	10h
   616                              <1> 	mov	al, '0'
   617                              <1> 	int 	10h
   618                              <1> 	mov	al, ' '
   619                              <1> 	int	10h
   620                              <1> 	call	L15c
   621                              <1> 	mov	al, ' '
   622                              <1> 	int	10h
   623                              <1> 	;
   624                              <1> 	mov	al, [fd1_type]
   625                              <1> 	and	al, al
   626                              <1> 	jz	short L15a
   627                              <1> 	mov	dl, al
   628                              <1> 	mov	al, 'F'
   629                              <1> 	int 	10h
   630                              <1> 	mov	al, 'D'
   631                              <1> 	int 	10h
   632                              <1> 	mov	al, '1'
   633                              <1> 	int 	10h
   634                              <1> 	mov	al, ' '
   635                              <1> 	int	10h
   636                              <1> 	call	L15c
   637                              <1> 	mov	al, ' '
   638                              <1> 	int	10h
   639                              <1> 	mov	al, ' '
   640                              <1> 	int	10h
   641                              <1> L15a:
   642                              <1> 	mov	al, [hd0_type]
   643                              <1> 	and	al, al
   644                              <1> 	jz	short L15b
   645                              <1> 	mov	dl, al
   646                              <1> 	mov	al, 'H'
   647                              <1> 	int 	10h
   648                              <1> 	mov	al, 'D'
   649                              <1> 	int 	10h
   650                              <1> 	mov	al, '0'
   651                              <1> 	int 	10h
   652                              <1> 	mov	al, ' '
   653                              <1> 	int 	10h
   654                              <1> 	call	L15c
   655                              <1> 	mov	al, ' '
   656                              <1> 	int	10h
   657                              <1> 	;
   658                              <1> 	mov	al, [hd1_type]
   659                              <1> 	and	al, al
   660                              <1> 	jz	short L15b
   661                              <1> 	mov	dl, al
   662                              <1> 	mov	al, 'H'
   663                              <1> 	int 	10h
   664                              <1> 	mov	al, 'D'
   665                              <1> 	int 	10h
   666                              <1> 	mov	al, '1'
   667                              <1> 	int 	10h
   668                              <1> 	mov	al, ' '
   669                              <1> 	int 	10h
   670                              <1> 	call	L15c
   671                              <1> 	mov	al, ' '
   672                              <1> 	int	10h
   673                              <1> 	;
   674                              <1> 	mov	al, [hd2_type]
   675                              <1> 	and	al, al
   676                              <1> 	jz	short L15b
   677                              <1> 	mov	dl, al
   678                              <1> 	mov	al, 'H'
   679                              <1> 	int 	10h
   680                              <1> 	mov	al, 'D'
   681                              <1> 	int 	10h
   682                              <1> 	mov	al, '2'
   683                              <1> 	int 	10h
   684                              <1> 	mov	al, ' '
   685                              <1> 	int 	10h
   686                              <1> 	call	L15c
   687                              <1> 	mov	al, ' '
   688                              <1> 	int	10h
   689                              <1> 	;
   690                              <1> 	mov	al, [hd3_type]
   691                              <1> 	and	al, al
   692                              <1> 	jz	short L15b
   693                              <1> 	mov	dl, al
   694                              <1> 	mov	al, 'H'
   695                              <1> 	int 	10h
   696                              <1> 	mov	al, 'D'
   697                              <1> 	int 	10h
   698                              <1> 	mov	al, '3'
   699                              <1> 	int 	10h
   700                              <1> 	mov	al, ' '
   701                              <1> 	int 	10h
   702                              <1> 	call	L15c
   703                              <1> 	mov	al, ' '
   704                              <1> 	int	10h
   705                              <1> 	;
   706                              <1> L15b:
   707                              <1> 	mov	al, 0Dh
   708                              <1> 	int 	10h	
   709                              <1> 	mov	al, 0Ah
   710                              <1> 	int 	10h
   711                              <1> 	;;xor	ah, ah
   712                              <1> 	;;int 	16h	
   713                              <1> 	;
   714                              <1>         ;jmp	L16  ; jmp short L16
   715                              <1>         ; 02/01/2022
   716                              <1> 	jmp	short L16
   717                              <1> 	;
   718                              <1> L15c:
   719                              <1> 	mov	dh, dl
   720                              <1> 	shr	dh, 4
   721                              <1> 	add	dh, 30h
   722                              <1> 	and	dl, 15
   723                              <1> 	add	dl, 30h
   724                              <1> 	mov	al, dh
   725                              <1> 	int	10h
   726                              <1> 	mov	al, dl
   727                              <1> 	int	10h
   728                              <1> 	retn
   729                              <1> 	;
   730                              <1> 	; end of temporary code for disk searching code check
   731                              <1> 
   732                              <1> %endif
   733                              <1> 
   734                              <1> ; //////
   735                              <1> 
   736                              <1> set_disk_parms:
   737                              <1> 	; 12/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
   738                              <1> 	; 09/05/2022
   739                              <1> 	;	disksize = cylinders*spt*heads (*)
   740                              <1> 	; (fd0&fd1 drv.size is calculated with total cylinders)
   741                              <1> 	;
   742                              <1> 	; 04/02/2016 (ebx -> bx)
   743                              <1> 	; 10/07/2015
   744                              <1> 	; 14/01/2015
   745                              <1> 	;push	bx
   746 00000269 28FF                <1> 	sub	bh, bh
   747 0000026B 8A1E[395D]          <1> 	mov	bl, [drv]
   748 0000026F 80FB80              <1> 	cmp	bl, 80h
   749 00000272 7203                <1> 	jb	short sdp0
   750 00000274 80EB7E              <1> 	sub	bl, 7Eh
   751                              <1> sdp0:	
   752 00000277 81C3[5E5D]          <1> 	add	bx, drv.status
   753 0000027B C60780              <1>   	mov	byte [bx], 80h ; 'Present' flag
   754                              <1> 	;
   755 0000027E 88E8                <1> 	mov	al, ch ; last cylinder (bits 0-7)
   756 00000280 88CC                <1> 	mov	ah, cl ; 
   757 00000282 C0EC06              <1> 	shr	ah, 6  ; last cylinder (bits 8-9)
   758 00000285 81EB[5E5D]          <1> 	sub	bx, drv.status
   759 00000289 D0E3                <1> 	shl	bl, 1
   760                              <1> 	; 12/07/2022
   761                              <1> 	;add	bx, drv.cylinders
   762 0000028B 40                  <1> 	inc	ax  ; convert max. cyl number to cyl count
   763                              <1> 	;mov	[bx], ax
   764 0000028C 50                  <1> 	push	ax ; ** cylinders
   765                              <1> 	;sub	bx, drv.cylinders
   766                              <1> 	;add	bx, drv.heads
   767 0000028D 30E4                <1> 	xor	ah, ah
   768 0000028F 88F0                <1> 	mov	al, dh ; heads
   769 00000291 40                  <1> 	inc	ax
   770                              <1> 	;mov	[bx], ax
   771                              <1>         ;sub	bx, drv.heads
   772                              <1>         ;add	bx, drv.spt
   773 00000292 30ED                <1> 	xor	ch, ch
   774 00000294 80E13F              <1> 	and	cl, 3Fh	; sectors (bits 0-6)
   775                              <1> 	;mov	[bx], cx
   776                              <1>         ;sub	bx, drv.spt
   777 00000297 D1E3                <1> 	shl	bx, 1
   778 00000299 81C3[425D]          <1> 	add	bx, drv.size ; disk size (in sectors)
   779                              <1> 	; LBA size = cylinders * heads * secpertrack
   780 0000029D F7E1                <1> 	mul	cx 
   781 0000029F 89C2                <1> 	mov	dx, ax	; heads*spt
   782 000002A1 58                  <1> 	pop	ax ; ** cylinders
   783                              <1> 	; 09/05/2022 (fd0&fd1 drv.size = cyls*spt*heads)
   784                              <1> 	;dec	ax ; 1 cylinder reserved (!?) ; (*)
   785 000002A2 F7E2                <1> 	mul	dx ; cylinders * (heads*spt)
   786 000002A4 8907                <1> 	mov	[bx], ax
   787 000002A6 895702              <1> 	mov	[bx+2], dx
   788                              <1> 	;
   789                              <1> 	;pop	bx
   790 000002A9 C3                  <1> 	retn
   791                              <1> 
   792                              <1> ;align 2
   793                              <1> 
   794                              <1> ;cylinders :  dw 0, 0, 0, 0, 0, 0
   795                              <1> ;heads     :  dw 0, 0, 0, 0, 0, 0
   796                              <1> ;spt       :  dw 0, 0, 0, 0, 0, 0
   797                              <1> ;disk_size :  dd 0, 0, 0, 0, 0, 0
   798                              <1> 
   799                              <1> ;last_drv:
   800                              <1> ;	db  0
   801                              <1> ;drv_status:
   802                              <1> ;	db  0,0,0,0,0,0
   803                              <1> ;	db 0
   804                              <1> 
   805                              <1> ; End Of DISK I/O SYSTEM STRUCTURE INITIALIZATION /// 06/02/2015
   806                              <1> 
   807                              <1> L16:
   236                                  
   237                                  	; 10/11/2014
   238 000002AA FA                           	cli	; Disable interrupts (clear interrupt flag)
   239                                  		; Reset Interrupt MASK Registers (Master&Slave)
   240                                  	;mov	al, 0FFh	; mask off all interrupts
   241                                  	;out	21h, al		; on master PIC (8259)
   242                                  	;jmp 	$+2  ; (delay)
   243                                  	;out	0A1h, al	; on slave PIC (8259)
   244                                  	;
   245                                  	; Disable NMI 
   246 000002AB B080                    	mov   	al, 80h 
   247 000002AD E670                    	out   	70h, al		; set bit 7 to 1 for disabling NMI
   248                                  	;23/02/2015
   249 000002AF 90                      	nop			;
   250                                  	;in	al, 71h		; read in 71h just after writing out to 70h
   251                                  				; for preventing unknown state (!?)
   252                                  
   253                                  	; 02/01/2022
   254                                  	%define KERNELFSIZE KEND-KSTART 
   255                                  	;
   256                                   	; 20/08/2014
   257                                  	; Moving the kernel 64 KB back (to physical address 0)
   258                                  	; DS = CS = 1000h
   259                                  	; 05/11/2014
   260 000002B0 31C0                    	xor	ax, ax
   261 000002B2 8EC0                    	mov	es, ax ; ES = 0
   262                                  	;
   263                                  	;;mov	cx, (KEND - KLOAD)/4
   264                                  	;mov	cx, (KERNELFSIZE+3)/4 ; 02/01/2022
   265 000002B4 B9D62F                  	mov	cx, (KERNELFSIZE+1)/2 ; 02/01/2022
   266 000002B7 31F6                    	xor	si, si
   267 000002B9 31FF                    	xor	di, di
   268                                  	;rep	movsd
   269 000002BB F3A5                    	rep	movsw ; 02/01/2022
   270                                  	;
   271 000002BD 06                      	push	es ; 0
   272 000002BE 68[C202]                	push	L17
   273 000002C1 CB                      	retf
   274                                  	;
   275                                  L17:
   276                                  	; Turn off the floppy drive motor
   277 000002C2 BAF203                          mov     dx, 3F2h
   278 000002C5 EE                              out     dx, al ; 0 ; 31/12/2013
   279                                  
   280                                  	; Enable access to memory above one megabyte
   281                                  L18:
   282 000002C6 E464                    	in	al, 64h
   283 000002C8 A802                    	test	al, 2
   284 000002CA 75FA                            jnz     short L18
   285 000002CC B0D1                    	mov	al, 0D1h	; Write output port
   286 000002CE E664                    	out	64h, al
   287                                  L19:
   288 000002D0 E464                    	in	al, 64h
   289 000002D2 A802                    	test	al, 2
   290 000002D4 75FA                            jnz     short L19
   291 000002D6 B0DF                    	mov	al, 0DFh	; Enable A20 line
   292 000002D8 E660                    	out	60h, al
   293                                  ;L20:
   294                                  	;
   295                                  	; Load global descriptor table register
   296                                  
   297                                          ;mov     ax, cs
   298                                          ;mov     ds, ax
   299                                  
   300 000002DA 2E0F0116[605A]                  lgdt    [cs:gdtd]
   301                                  
   302 000002E0 0F20C0                          mov     eax, cr0
   303                                  	; or 	eax, 1
   304 000002E3 40                      	inc     ax
   305 000002E4 0F22C0                  	mov     cr0, eax
   306                                  
   307                                  	; Jump to 32 bit code
   308                                  	
   309 000002E7 66                      	db 66h 			; Prefix for 32-bit
   310 000002E8 EA                      	db 0EAh 		; Opcode for far jump
   311 000002E9 [EF020000]              	dd StartPM 		; Offset to start, 32-bit
   312                                  				; (1000h:StartPM = StartPM + 10000h)
   313 000002ED 0800                    	dw KCODE		; This is the selector for CODE32_DESCRIPTOR,
   314                                  				; assuming that StartPM resides in code32
   315                                  
   316                                  [BITS 32] 
   317                                  
   318                                  StartPM:
   319                                  	; Kernel Base Address = 0 ; 30/12/2013
   320 000002EF 66B81000                	mov ax, KDATA           ; Save data segment identifier
   321 000002F3 8ED8                            mov ds, ax              ; Move a valid data segment into DS register
   322 000002F5 8EC0                           	mov es, ax              ; Move data segment into ES register
   323 000002F7 8EE0                           	mov fs, ax              ; Move data segment into FS register
   324 000002F9 8EE8                          	mov gs, ax              ; Move data segment into GS register
   325 000002FB 8ED0                            mov ss, ax              ; Move data segment into SS register
   326 000002FD BC00000900                      mov esp, 90000h         ; Move the stack pointer to 090000h
   327                                  
   328                                  clear_bss: ; Clear uninitialized data area
   329                                  	; 11/03/2015
   330 00000302 31C0                    	xor	eax, eax ; 0
   331                                  	;mov	ecx, (bss_end - bss_start)/4
   332                                  	;;shr	ecx, 2 ; bss section is already aligned for double words
   333                                  	; 02/01/2022
   334 00000304 B9C1060000              	mov	ecx, BSS_SIZE/4
   335 00000309 BF[B05F0000]            	mov	edi, bss_start
   336 0000030E F3AB                    	rep	stosd  		
   337                                  
   338                                  memory_init:
   339                                  	; Initialize memory allocation table and page tables
   340                                  	;
   341                                  	; 02/01/2022 (Retro UNIX 386 v1.1, Runix Kernel v0.2.1.2)
   342                                  	; 16/11/2014
   343                                  	; 15/11/2014
   344                                  	; 07/11/2014
   345                                  	; 06/11/2014
   346                                  	; 05/11/2014
   347                                  	; 04/11/2014
   348                                  	; 31/10/2014 (Retro UNIX 386 v1 - Beginning) 
   349                                  	;
   350                                  ;	xor	eax, eax
   351                                  ;	xor 	ecx, ecx
   352 00000310 B108                    	mov	cl, 8
   353 00000312 BF00001000              	mov	edi, MEM_ALLOC_TBL	
   354 00000317 F3AB                    	rep	stosd		   ; clear Memory Allocation Table
   355                                  				   ; for the first 1 MB memory
   356                                  	;
   357 00000319 8B0D[A45F0000]          	mov	ecx, [mem_1m_1k]   ; 02/01/2022	
   358                                  	;mov	cx, [mem_1m_1k]	   ; Number of contiguous KB between
   359                                  				   ; 1 and 16 MB, max. 3C00h = 15 MB.
   360                                  	;shr	cx, 2		   ; convert 1 KB count to 4 KB count
   361 0000031F C1E902                  	shr	ecx, 2	; 02/01/2022
   362 00000322 890D[20620000]          	mov	[free_pages], ecx
   363 00000328 8B15[A85F0000]          	mov	edx, [mem_16m_64k] ; 02/01/2022
   364                                  	;mov	dx, [mem_16m_64k]  ; Number of contiguous 64 KB blocks
   365                                  				   ; between 16 MB and 4 GB.
   366                                  	;or	dx, dx
   367 0000032E 09D2                    	or	edx, edx ; 02/01/2022
   368 00000330 7412                    	jz	short mi_0
   369                                  	;
   370                                  	;mov	ax, dx
   371 00000332 89D0                    	mov	eax, edx ; 02/01/2022
   372 00000334 C1E004                  	shl	eax, 4		   ; 64 KB -> 4 KB (page count)
   373 00000337 0105[20620000]          	add	[free_pages], eax
   374 0000033D 0500100000              	add	eax, 4096	   ; 16 MB = 4096 pages
   375 00000342 EB06                    	jmp	short mi_1
   376                                  mi_0:
   377                                  	;mov	ax, cx
   378 00000344 89C8                    	mov	eax, ecx ; 02/01/2022	 
   379 00000346 66050001                	add	ax, 256		   ; add 256 pages for the first 1 MB
   380                                  mi_1:
   381 0000034A A3[1C620000]            	mov	[memory_size], eax ; Total available memory in pages
   382                                  				   ; 1 alloc. tbl. bit = 1 memory page
   383                                  				   ; 32 allocation bits = 32 mem. pages
   384                                  	;
   385 0000034F 05FF7F0000              	add	eax, 32767	   ; 32768 memory pages per 1 M.A.T. page
   386 00000354 C1E80F                  	shr	eax, 15		   ; ((32768 * x) + y) pages (y < 32768)
   387                                  				   ;  --> x + 1 M.A.T. pages, if y > 0
   388                                  				   ;  --> x M.A.T. pages, if y = 0
   389                                  	;mov	[mat_size], ax	   ; Memory Alloc. Table Size in pages
   390 00000357 A3[30620000]            	mov	[mat_size], eax ; 02/01/2022
   391 0000035C C1E00C                  	shl	eax, 12		   ; 1 M.A.T. page = 4096 bytes
   392                                  	;			   ; Max. 32 M.A.T. pages (4 GB memory)
   393 0000035F 89C3                    	mov	ebx, eax	   ; M.A.T. size in bytes
   394                                  	; Set/Calculate Kernel's Page Directory Address
   395 00000361 81C300001000            	add	ebx, MEM_ALLOC_TBL
   396 00000367 891D[18620000]          	mov	[k_page_dir], ebx  ; Kernel's Page Directory address
   397                                  				   ; just after the last M.A.T. page
   398                                  	;
   399 0000036D 83E804                  	sub	eax, 4		   ; convert M.A.T. size to offset value
   400 00000370 A3[28620000]            	mov	[last_page], eax   ; last page ofset in the M.A.T.
   401                                  	;			   ; (allocation status search must be
   402                                  				   ; stopped after here)
   403 00000375 31C0                    	xor	eax, eax
   404 00000377 48                      	dec	eax		   ; FFFFFFFFh (set all bits to 1)
   405                                  	;push	cx
   406 00000378 51                      	push	ecx ; 02/01/2022 
   407 00000379 C1E905                  	shr	ecx, 5		   ; convert 1 - 16 MB page count to
   408                                  				   ; count of 32 allocation bits
   409 0000037C F3AB                    	rep	stosd
   410                                  	;pop	cx
   411 0000037E 59                      	pop	ecx ; 02/01/2022
   412 0000037F 40                      	inc	eax		   ; 0
   413 00000380 80E11F                  	and	cl, 31		   ; remain bits
   414 00000383 7412                    	jz	short mi_4
   415 00000385 8907                    	mov	[edi], eax	   ; reset
   416                                  mi_2:
   417 00000387 0FAB07                  	bts	[edi], eax	   ; 06/11/2014
   418 0000038A FEC9                    	dec	cl
   419 0000038C 7404                    	jz	short mi_3
   420 0000038E FEC0                    	inc	al
   421 00000390 EBF5                    	jmp	short mi_2
   422                                  mi_3:
   423 00000392 28C0                    	sub	al, al	   	   ; 0
   424 00000394 83C704                  	add	edi, 4		   ; 15/11/2014
   425                                  mi_4:
   426 00000397 09D2                    	or	edx, edx ; 02/01/2022
   427                                  	;or	dx, dx		  ; check 16M to 4G memory space
   428 00000399 741F                    	jz	short mi_6	  ; max. 16 MB memory, no more...
   429                                  	;	
   430 0000039B B900021000              	mov	ecx, MEM_ALLOC_TBL + 512 ; End of first 16 MB memory
   431                                  	;	
   432 000003A0 29F9                    	sub	ecx, edi	  ; displacement (to end of 16 MB)
   433 000003A2 7405                    	jz	short mi_5	  ; jump if EDI points to 
   434                                  				  ;         end of first 16 MB	
   435                                  	;shr	ecx, 1		  ; convert to dword count
   436                                  	;shr	ecx, 1		  ; (shift 2 bits right) 
   437 000003A4 C1E902                  	shr	ecx, 2	; 02/01/2022
   438 000003A7 F3AB                    	rep 	stosd		  ; reset all bits for reserved pages
   439                                  				  ; (memory hole under 16 MB)
   440                                  mi_5:
   441 000003A9 89D1                    	mov	ecx, edx ; 02/01/2022
   442                                  	;mov	cx, dx		  ; count of 64 KB memory blocks
   443 000003AB D1E9                    	shr	ecx, 1		  ; 1 alloc. dword per 128 KB memory
   444 000003AD 9C                      	pushf			  ; 16/11/2014		
   445 000003AE 48                      	dec	eax		  ; FFFFFFFFh (set all bits to 1)
   446 000003AF F3AB                    	rep	stosd
   447 000003B1 40                      	inc	eax		  ; 0
   448 000003B2 9D                      	popf			  ; 16/11/2014
   449 000003B3 7305                    	jnc	short mi_6
   450 000003B5 6648                    	dec	ax		  ; eax = 0000FFFFh
   451 000003B7 AB                      	stosd
   452 000003B8 6640                    	inc	ax		  ; 0		
   453                                  mi_6:
   454 000003BA 39DF                    	cmp	edi, ebx	  ; check if EDI points to 	
   455 000003BC 7309                    	jnb	short mi_7	  ; end of memory allocation table
   456                                  	;			  ; (>= MEM_ALLOC_TBL + 4906) 
   457 000003BE 89D9                    	mov	ecx, ebx	  ; end of memory allocation table
   458 000003C0 29F9                    	sub	ecx, edi	  ; convert displacement/offset
   459                                  	;shr	ecx, 1		  ; to dword count
   460                                  	;shr	ecx, 1		  ; (shift 2 bits right) 
   461 000003C2 C1E902                  	shr	ecx, 2 ; 02/01/2022	
   462 000003C5 F3AB                    	rep 	stosd		  ; reset all remain M.A.T. bits
   463                                  mi_7:
   464                                  	; Reset M.A.T. bits in M.A.T. (allocate M.A.T. pages)
   465 000003C7 BA00001000              	mov	edx, MEM_ALLOC_TBL
   466                                  	;sub	ebx, edx	  ; Mem. Alloc. Tbl. size in bytes
   467                                  	;shr	ebx, 12		  ; Mem. Alloc. Tbl. size in pages	
   468 000003CC 8B0D[30620000]          	mov	ecx, [mat_size] ; 02/01/2022
   469                                  	;mov	cx, [mat_size]	  ; Mem. Alloc. Tbl. size in pages
   470 000003D2 89D7                    	mov	edi, edx
   471 000003D4 C1EF0F                  	shr	edi, 15		  ; convert M.A.T. address to
   472                                  				  ; byte offset in M.A.T.
   473                                  				  ; (1 M.A.T. byte points to 
   474                                  				  ;	      32768 bytes)
   475                                  				  ; Note: MEM_ALLOC_TBL address 
   476                                  				  ; must be aligned on 128 KB 
   477                                  				  ; boundary!
   478 000003D7 01D7                    	add	edi, edx	  ; points to M.A.T.'s itself	
   479                                  	; eax = 0
   480 000003D9 290D[20620000]          	sub	[free_pages], ecx ; 07/11/2014
   481                                  mi_8:
   482 000003DF 0FB307                  	btr	[edi], eax	  ; clear bit 0 to bit x (1 to 31)
   483                                  	;dec	bl
   484 000003E2 FEC9                    	dec	cl
   485 000003E4 7404                    	jz	short mi_9
   486 000003E6 FEC0                    	inc	al
   487 000003E8 EBF5                    	jmp	short mi_8
   488                                  mi_9:
   489                                  	;
   490                                  	; Reset Kernel's Page Dir. and Page Table bits in M.A.T.
   491                                  	;		(allocate pages for system page tables)
   492                                  
   493                                  	; edx = MEM_ALLOC_TBL
   494 000003EA 8B0D[1C620000]          	mov	ecx, [memory_size] ; memory size in pages (PTEs)
   495 000003F0 81C1FF030000            	add	ecx, 1023	 ; round up (1024 PTEs per table)
   496 000003F6 C1E90A                  	shr	ecx, 10		 ; convert memory page count to 
   497                                  				 ; page table count (PDE count)
   498                                  	;
   499 000003F9 51                      	push	ecx		 ; (**) PDE count (<= 1024)
   500                                  	;
   501 000003FA 41                      	inc	ecx		 ; +1 for kernel page directory	
   502                                  	;
   503 000003FB 290D[20620000]          	sub	[free_pages], ecx ; 07/11/2014
   504                                  	;
   505 00000401 8B35[18620000]          	mov	esi, [k_page_dir] ; Kernel's Page Directory address
   506 00000407 C1EE0C                  	shr	esi, 12		 ; convert to page number
   507                                  mi_10:
   508 0000040A 89F0                    	mov	eax, esi	 ; allocation bit offset
   509 0000040C 89C3                    	mov	ebx, eax
   510 0000040E C1EB03                  	shr	ebx, 3		 ; convert to alloc. byte offset
   511 00000411 80E3FC                  	and	bl,  0FCh	 ; clear bit 0 and bit 1
   512                                  				 ;   to align on dword boundary
   513 00000414 83E01F                  	and	eax, 31		 ; set allocation bit position 
   514                                  				 ;  (bit 0 to bit 31)
   515                                  	;
   516 00000417 01D3                    	add	ebx, edx	 ; offset in M.A.T. + M.A.T. address 
   517                                  	;
   518 00000419 0FB303                  	btr 	[ebx], eax	 ; reset relevant bit (0 to 31)
   519                                  	;
   520 0000041C 46                      	inc	esi		 ; next page table
   521 0000041D E2EB                    	loop	mi_10		 ; allocate next kernel page table 
   522                                  				 ; (ecx = page table count + 1)
   523                                  	;
   524 0000041F 59                      	pop	ecx		 ; (**) PDE count (= pg. tbl. count)
   525                                  	;
   526                                  	; Initialize Kernel Page Directory and Kernel Page Tables
   527                                  	;
   528                                  	; Initialize Kernel's Page Directory
   529 00000420 8B3D[18620000]          	mov	edi, [k_page_dir]
   530 00000426 89F8                    	mov	eax, edi
   531 00000428 0C03                    	or	al, PDE_A_PRESENT + PDE_A_WRITE
   532                                  		     	      ; supervisor + read&write + present
   533 0000042A 89CA                    	mov	edx, ecx 	; (**) PDE count (= pg. tbl. count)
   534                                  mi_11:
   535 0000042C 0500100000              	add	eax, 4096	; Add page size (PGSZ)
   536                                  			        ; EAX points to next page table
   537 00000431 AB                      	stosd
   538 00000432 E2F8                    	loop	mi_11
   539 00000434 29C0                    	sub	eax, eax	; Empty PDE
   540                                  	;mov	cx, 1024	; Entry count (PGSZ/4)
   541                                  	; 02/01/2022
   542 00000436 B504                    	mov	ch, 4 ; cx = 4*256 = 1024
   543 00000438 29D1                    	sub	ecx, edx
   544 0000043A 7402                    	jz	short mi_12
   545 0000043C F3AB                    	rep	stosd 		; clear remain (empty) PDEs
   546                                  	;
   547                                  	; Initialization of Kernel's Page Directory is OK, here.
   548                                  mi_12:
   549                                  	; Initialize Kernel's Page Tables
   550                                  	;
   551                                  	; (EDI points to address of page table 0)
   552                                  	; eax = 0
   553 0000043E 8B0D[1C620000]          	mov	ecx, [memory_size] ; memory size in pages
   554 00000444 89CA                    	mov	edx, ecx	; (***)
   555 00000446 B003                    	mov	al, PTE_A_PRESENT + PTE_A_WRITE
   556                                  			     ; supervisor + read&write + present
   557                                  mi_13:
   558 00000448 AB                      	stosd
   559 00000449 0500100000              	add	eax, 4096	
   560 0000044E E2F8                    	loop	mi_13
   561                                  	; 02/01/2022
   562 00000450 66B9FF03                	mov	cx, 1023
   563 00000454 21CA                    	and	edx, ecx
   564                                  	;and	dx, 1023	; (***)
   565 00000456 7407                    	jz	short mi_14
   566                                  	;mov	cx, 1024	
   567                                  	; 02/01/2022
   568                                  	;mov	ch, 4 ; cx = 4*256 = 1024
   569 00000458 41                      	inc	ecx ; ecx = 1024
   570 00000459 29D1                    	sub	ecx, edx
   571                                  	;sub	cx, dx		; from dx (<= 1023) to 1024
   572 0000045B 31C0                    	xor	eax, eax
   573 0000045D F3AB                    	rep	stosd		; clear remain (empty) PTEs 
   574                                  				; of the last page table
   575                                  mi_14:
   576                                  	;  Initialization of Kernel's Page Tables is OK, here.
   577                                  	;
   578 0000045F 89F8                    	mov	eax, edi	; end of the last page table page
   579                                  			        ; (beginging of user space pages)
   580 00000461 C1E80F                  	shr	eax, 15		; convert to M.A.T. byte offset
   581 00000464 24FC                    	and	al, 0FCh	; clear bit 0 and bit 1 for
   582                                  				; aligning on dword boundary
   583                                  	 
   584 00000466 A3[2C620000]            	mov	[first_page], eax
   585 0000046B A3[24620000]            	mov	[next_page], eax ; The first free page pointer
   586                                  				 ; for user programs
   587                                  				 ; (Offset in Mem. Alloc. Tbl.)	
   588                                  	;
   589                                  	; Linear/FLAT (1 to 1) memory paging for the kernel is OK, here.
   590                                  	;
   591                                  	
   592                                  	; Enable paging
   593                                  	;
   594 00000470 A1[18620000]                    mov     eax, [k_page_dir]
   595 00000475 0F22D8                  	mov	cr3, eax
   596 00000478 0F20C0                  	mov	eax, cr0
   597 0000047B 0D00000080              	or	eax, 80000000h	; set paging bit (bit 31)
   598 00000480 0F22C0                  	mov	cr0, eax
   599                                          ;jmp    KCODE:StartPMP
   600                                  
   601 00000483 EA                      	db 0EAh 		; Opcode for far jump
   602 00000484 [8A040000]                      dd StartPMP		; 32 bit offset
   603 00000488 0800                    	dw KCODE		; kernel code segment descriptor
   604                                  
   605                                  StartPMP:
   606                                  	; 06/11//2014
   607                                  	; Clear video page 0
   608                                  	;
   609                                  	; Temporary Code
   610                                  	;
   611                                  	;mov	ecx, 80*25/2
   612 0000048A 66B9E803                	mov	cx, (80*25)/2 ; 02/01/2022
   613 0000048E BF00800B00              	mov	edi, 0B8000h
   614 00000493 57                      	push	edi ; * ; 02/01/2022
   615 00000494 31C0                    	xor	eax, eax	; black background, black fore color
   616 00000496 F3AB                    	rep	stosd
   617                                  	
   618                                  	; 19/08/2014
   619                                  	; Kernel Base Address = 0
   620                                  	; It is mapped to (physically) 0 in the page table.
   621                                  	; So, here is exactly 'StartPMP' address.
   622                                  	;
   623                                  	;;mov	ah, 4Eh	; Red background, yellow forecolor
   624                                  	;;mov	esi, msgPM
   625                                  	;; 14/08/2015 (kernel version message will appear
   626                                  	;;	       when protected mode and paging is enabled)
   627 00000498 B40B                    	mov	ah, 0Bh ; Black background, light cyan forecolor
   628 0000049A BE[745D0000]            	mov	esi, msgKVER
   629 0000049F 5F                      	pop	edi ; * ; 02/01/2022
   630                                  	;mov	edi, 0B8000h ; 27/08/2014
   631                                  	; 20/08/2014
   632 000004A0 E891010000              	call	printk
   633                                  
   634                                  	; 'UNIX v7/x86' source code by Robert Nordier (1999)
   635                                  	; // Set IRQ offsets
   636                                  	;
   637                                  	;  Linux (v0.12) source code by Linus Torvalds (1991)
   638                                  	;
   639                                  					;; ICW1
   640 000004A5 B011                    	mov	al, 11h			; Initialization sequence
   641 000004A7 E620                    	out	20h, al			; 	8259A-1
   642                                  	; jmp 	$+2
   643 000004A9 E6A0                    	out	0A0h, al		; 	8259A-2
   644                                  					;; ICW2
   645 000004AB B020                    	mov	al, 20h			; Start of hardware ints (20h)
   646 000004AD E621                    	out	21h, al			;	for 8259A-1
   647                                  	; jmp 	$+2
   648 000004AF B028                    	mov	al, 28h			; Start of hardware ints (28h)
   649 000004B1 E6A1                    	out	0A1h, al		; 	for 8259A-2
   650                                  					;
   651 000004B3 B004                    	mov	al, 04h			;; ICW3
   652 000004B5 E621                    	out	21h, al			; 	IRQ2 of 8259A-1 (master)
   653                                  	; jmp 	$+2
   654 000004B7 B002                    	mov	al, 02h			; 	is 8259A-2 (slave)
   655 000004B9 E6A1                    	out	0A1h, al		;
   656                                  					;; ICW4
   657 000004BB B001                    	mov	al, 01h	 		;
   658 000004BD E621                    	out	21h, al			; 	8086 mode, normal EOI	
   659                                  	; jmp 	$+2
   660 000004BF E6A1                    	out	0A1h, al		;	for both chips.
   661                                  
   662                                  	;mov	al, 0FFh	; mask off all interrupts for now
   663                                  	;out	21h, al
   664                                  	;; jmp 	$+2
   665                                  	;out	0A1h, al
   666                                  
   667                                  	; 02/04/2015
   668                                  	; 26/03/2015 System call (INT 30h) modification
   669                                  	;  DPL = 3 (Interrupt service routine can be called from user mode)			
   670                                  	;
   671                                  	;; Linux (v0.12) source code by Linus Torvalds (1991)
   672                                  	;  setup_idt:
   673                                  	;
   674                                          ;; 16/02/2015
   675                                  	;;mov	dword [DISKETTE_INT], fdc_int ; IRQ 6 handler
   676                                  	; 21/08/2014 (timer_int)
   677 000004C1 BE[6C5A0000]            	mov	esi, ilist
   678 000004C6 8D3D[B05F0000]          	lea	edi, [idt]
   679                                  	; 26/03/2015
   680 000004CC B930000000              	mov	ecx, 48		; 48 hardware interrupts (INT 0 to INT 2Fh)
   681                                  	; 02/04/2015
   682 000004D1 BB00000800              	mov	ebx,  80000h
   683                                  rp_sidt1:
   684 000004D6 AD                      	lodsd
   685 000004D7 89C2                    	mov	edx, eax
   686 000004D9 66BA008E                	mov	dx, 8E00h
   687 000004DD 6689C3                  	mov	bx, ax
   688 000004E0 89D8                    	mov	eax, ebx	; /* selector = 0x0008 = cs */
   689                                         			        ; /* interrupt gate - dpl=0, present */
   690 000004E2 AB                      	stosd	; selector & offset bits 0-15 	
   691 000004E3 89D0                    	mov	eax, edx
   692 000004E5 AB                      	stosd	; attributes & offset bits 16-23
   693 000004E6 E2EE                    	loop	rp_sidt1
   694 000004E8 B110                    	mov	cl, 16        ; 16 software interrupts (INT 30h to INT 3Fh)
   695                                  rp_sidt2:
   696 000004EA AD                      	lodsd
   697 000004EB 21C0                    	and	eax, eax
   698 000004ED 7413                    	jz	short rp_sidt3
   699 000004EF 89C2                    	mov	edx, eax
   700 000004F1 66BA00EE                	mov	dx, 0EE00h	; P=1b/DPL=11b/01110b
   701 000004F5 6689C3                  	mov	bx, ax
   702 000004F8 89D8                    	mov	eax, ebx	; selector & offset bits 0-15 	
   703 000004FA AB                      	stosd
   704 000004FB 89D0                    	mov	eax, edx
   705 000004FD AB                      	stosd
   706 000004FE E2EA                    	loop	rp_sidt2
   707 00000500 EB16                    	jmp	short sidt_OK
   708                                  rp_sidt3:
   709 00000502 B8[5A090000]            	mov	eax, ignore_int
   710 00000507 89C2                    	mov	edx, eax
   711 00000509 66BA00EE                	mov	dx, 0EE00h	; P=1b/DPL=11b/01110b
   712 0000050D 6689C3                  	mov	bx, ax
   713 00000510 89D8                    	mov	eax, ebx	; selector & offset bits 0-15 	
   714                                  rp_sidt4:
   715 00000512 AB                      	stosd
   716 00000513 92                      	xchg	eax, edx
   717 00000514 AB                      	stosd
   718 00000515 92                      	xchg	edx, eax
   719 00000516 E2FA                    	loop	rp_sidt4
   720                                  sidt_OK: 
   721 00000518 0F011D[665A0000]        	lidt 	[idtd]
   722                                  	;
   723                                  	; TSS descriptor setup ; 24/03/2015
   724 0000051F B8[B0610000]            	mov	eax, task_state_segment
   725 00000524 66A3[5A5A0000]          	mov	[gdt_tss0], ax
   726 0000052A C1C010                  	rol	eax, 16
   727 0000052D A2[5C5A0000]            	mov	[gdt_tss1], al
   728 00000532 8825[5F5A0000]          	mov	[gdt_tss2], ah
   729 00000538 66C705[16620000]68-     	mov	word [tss.IOPB], tss_end - task_state_segment
   729 00000540 00                 
   730                                  		; 
   731                                  		; IO Map Base address (When this address points
   732                                  		; to end of the TSS, CPU does not use IO port 
   733                                  		; permission bit map for RING 3 IO permissions, 
   734                                  		; access to any IO ports in ring 3 will be forbidden.)
   735                                   		;
   736                                  	;mov	[tss.esp0], esp ; TSS offset 4
   737                                  	;mov	word [tss.ss0], KDATA ; TSS offset 8 (SS)
   738 00000541 66B82800                   	mov	ax, TSS  ; It is needed when an interrupt 
   739                                  			 ; occurs (or a system call -software INT- is requested)
   740                                  			 ; while cpu running in ring 3 (in user mode).				
   741                                  			 ; (Kernel stack pointer and segment will be loaded
   742                                  			 ; from offset 4 and 8 of the TSS, by the CPU.)	 
   743 00000545 0F00D8                  	ltr	ax  ; Load task register
   744                                  	;
   745                                  esp0_set0:
   746                                  	; 30/07/2015
   747 00000548 8B0D[1C620000]          	mov 	ecx, [memory_size] ; memory size in pages
   748 0000054E C1E10C                  	shl 	ecx, 12 ; convert page count to byte count
   749 00000551 81F900004000            	cmp	ecx, CORE ; beginning of user's memory space (400000h)
   750                                  			  ; (kernel mode virtual address)
   751 00000557 7605                    	jna	short esp0_set1
   752                                  	;
   753                                  	; If available memory > CORE (end of the 1st 4 MB)
   754                                  	; set stack pointer to CORE
   755                                  	;(Because, PDE 0 is reserved for kernel space in user's page directory)
   756                                  	;(PDE 0 points to page table of the 1st 4 MB virtual address space)
   757 00000559 B900004000              	mov	ecx, CORE
   758                                  esp0_set1:
   759 0000055E 89CC                    	mov	esp, ecx ; top of kernel stack (**tss.esp0**)
   760                                  esp0_set_ok:
   761                                  	; 30/07/2015 (**tss.esp0**) 
   762 00000560 8925[B4610000]          	mov	[tss.esp0], esp
   763 00000566 66C705[B8610000]10-             mov     word [tss.ss0], KDATA
   763 0000056E 00                 
   764                                  	; 14/08/2015
   765                                  	; 10/11/2014 (Retro UNIX 386 v1 - Erdogan Tan)
   766                                  	;
   767                                  	;cli	; Disable interrupts (for CPU)
   768                                  	;    (CPU will not handle hardware interrupts, except NMI!)
   769                                  	;
   770 0000056F 30C0                    	xor	al, al		; Enable all hardware interrupts!
   771 00000571 E621                    	out	21h, al		; (IBM PC-AT compatibility)
   772 00000573 EB00                    	jmp 	$+2		; (All conventional PC-AT hardware
   773 00000575 E6A1                    	out	0A1h, al	;  interrupts will be in use.)	
   774                                  				; (Even if related hardware component
   775                                  				;  does not exist!)
   776                                  	; Enable NMI 
   777 00000577 B07F                    	mov	al, 7Fh		; Clear bit 7 to enable NMI (again)
   778 00000579 E670                    	out  	70h, al
   779                                  	; 23/02/2015
   780 0000057B 90                      	nop
   781 0000057C E471                    	in	al, 71h		; read in 71h just after writing out to 70h
   782                                  				; for preventing unknown state (!?)
   783                                  	;
   784                                  	; Only a NMI can occur here... (Before a 'STI' instruction)
   785                                  	;
   786                                  	; 02/09/2014
   787                                  	;xor	bx, bx
   788                                  	;mov	dx, 0200h	; Row 2, column 0  ; 07/03/2015
   789                                  	; 27/02/2022	
   790 0000057E 31DB                    	xor	ebx, ebx
   791 00000580 31D2                    	xor	edx, edx
   792 00000582 B602                    	mov	dh, 2
   793 00000584 E8230F0000              	call	set_cpos
   794                                  	;
   795                                  	; 06/11/2014
   796                                  	; Temporary Code
   797                                  	;
   798 00000589 E898100000              	call	memory_info
   799                                  	; 14/08/2015
   800                                  	;call getch ; 28/02/2015
   801                                  drv_init:
   802 0000058E FB                      	sti	; Enable Interrupts 
   803                                  	; 06/02/2015
   804 0000058F 8B15[3E5D0000]          	mov	edx, [hd0_type] ; hd0, hd1, hd2, hd3
   805 00000595 668B1D[3C5D0000]        	mov	bx, [fd0_type] ; fd0, fd1
   806                                  	; 22/02/2015
   807 0000059C 6621DB                  	and	bx, bx
   808 0000059F 751B                    	jnz	short di1
   809                                  	;
   810 000005A1 09D2                    	or 	edx, edx
   811 000005A3 7529                    	jnz	short di2
   812                                  	;
   813                                  setup_error:
   814 000005A5 BE[5D5E0000]            	mov 	esi, setup_error_msg
   815                                  psem:	
   816 000005AA AC                      	lodsb
   817 000005AB 08C0                    	or	al, al
   818                                  	;jz	short haltx ; 22/02/2015
   819 000005AD 7426                    	jz	short di3
   820 000005AF 56                      	push	esi
   821 000005B0 31DB                    	xor	ebx, ebx ; 0
   822                                  			; Video page 0 (bl=0)
   823 000005B2 B407                    	mov	ah, 07h ; Black background, 
   824                                  			; light gray forecolor
   825 000005B4 E8E90D0000              	call	write_tty
   826 000005B9 5E                      	pop	esi
   827 000005BA EBEE                    	jmp	short psem
   828                                  
   829                                  di1:
   830                                  	; supress 'jmp short T6'
   831                                  	;  (activate fdc motor control code)
   832 000005BC 66C705[B7060000]90-     	mov	word [T5], 9090h ; nop
   832 000005C4 90                 
   833                                  	;
   834                                  	;mov	ax, int_0Eh	; IRQ 6 handler
   835                                  	;mov	di, 0Eh*4	; IRQ 6 vector
   836                                  	;stosw
   837                                  	;mov 	ax, cs
   838                                  	;stosw
   839                                  	;; 16/02/2015
   840                                          ;;mov	dword [DISKETTE_INT], fdc_int ; IRQ 6 handler
   841                                  	;
   842 000005C5 E8021A0000              	CALL	DSKETTE_SETUP	; Initialize Floppy Disks
   843                                  	;
   844 000005CA 09D2                    	or	edx, edx
   845 000005CC 7407                            jz      short di3
   846                                  di2:
   847 000005CE E82B1A0000              	call   	DISK_SETUP	; Initialize Fixed Disks
   848 000005D3 72D0                            jc      short setup_error
   849                                  di3:
   850 000005D5 E820100000              	call	setup_rtc_int	; 22/05/2015 (dsectrpm.s)
   851                                  	;
   852 000005DA E8AE530000              	call	display_disks ; 07/03/2015  (Temporary)
   853                                  ;haltx:
   854                                  	; 14/08/2015
   855                                  	;call	getch ; 22/02/2015
   856 000005DF FB                      	sti	; Enable interrupts (for CPU)
   857                                  	; 14/08/2015
   858                                  	;mov 	ecx, 0FFFFFFFh
   859                                  	; 24/12/2021
   860 000005E0 B9FFFF2F00              	mov 	ecx, 02FFFFFh
   861                                  md_info_msg_wait:
   862 000005E5 51                      	push 	ecx
   863 000005E6 B001                    	mov	al, 1
   864 000005E8 8A25[46620000]          	mov 	ah, [ptty] ; active (current) video page
   865 000005EE E885500000              	call	getc_n
   866 000005F3 59                      	pop	ecx
   867 000005F4 7502                    	jnz	short md_info_msg_ok
   868 000005F6 E2ED                    	loop	md_info_msg_wait
   869                                  md_info_msg_ok:
   870                                  	; 30/06/2015
   871 000005F8 E8BF230000              	call	sys_init
   872                                  	;
   873                                  	;jmp 	cpu_reset ; 22/02/2015
   874                                  hang:
   875                                  	; 24/12/2021
   876 000005FD 29C0                    	sub	eax, eax
   877                                  _hang:	
   878                                  	; 23/02/2015
   879                                  	;sti			; Enable interrupts
   880 000005FF F4                      	hlt
   881                                  	;
   882                                  	;nop
   883                                  	;; 03/12/2014
   884                                  	;; 28/08/2014
   885                                  	;mov	ah, 11h
   886                                  	;call	getc
   887                                  	;jz      _c8
   888                                  	;
   889                                  	; 23/02/2015
   890                                  	; 06/02/2015
   891                                  	; 07/09/2014
   892 00000600 31DB                    	xor	ebx, ebx
   893 00000602 8A1D[46620000]          	mov	bl, [ptty]	; active_page
   894 00000608 89DE                    	mov	esi, ebx
   895                                  	;shl 	si, 1
   896                                  	; 17/07/2022
   897 0000060A D1E6                    	shl	esi, 1
   898 0000060C 81C6[48620000]          	add	esi, ttychr
   899 00000612 668B06                  	mov	ax, [esi]
   900                                  	;and	ax, ax
   901                                  	;;jz	short _c8
   902                                  	;jz	short hang
   903                                  	; 24/12/2021
   904 00000615 21C0                    	and	eax, eax
   905 00000617 74E6                    	jz	short _hang
   906 00000619 66C7060000              	mov	word [esi], 0
   907 0000061E 80FB03                  	cmp	bl, 3		; Video page 3
   908                                  	;jb	short _c8
   909 00000621 72DA                    	jb	short hang
   910                                  	;	
   911                                  	; 02/09/2014
   912 00000623 B40E                    	mov	ah, 0Eh		; Yellow character 
   913                                  				; on black background
   914                                  	; 24/12/2021 (32 bit reg push-pop)
   915                                  	; 07/09/2014
   916                                  nxtl:
   917 00000625 53                      	push	ebx
   918                                  	;
   919                                  	;xor	ebx, ebx	; bl = 0 (video page 0)
   920                                  				; bh = 0 (video mode)
   921                                  				; Retro UNIX 386 v1 - Video Mode 0
   922                                  				; (PC/AT Video Mode 3 - 80x25 Alpha.)
   923 00000626 50                      	push	eax
   924 00000627 E8760D0000              	call 	write_tty
   925 0000062C 58                      	pop	eax
   926                                  	;pop	bx
   927 0000062D 5B                      	pop	ebx
   928 0000062E 3C0D                    	cmp	al, 0Dh		; carriage return (enter)
   929                                  	;jne	short _c8
   930 00000630 75CB                    	jne	short hang
   931 00000632 B00A                    	mov	al, 0Ah		; next line
   932 00000634 EBEF                    	jmp	short nxtl
   933                                  	
   934                                  ;_c8:
   935                                  ;	; 25/08/2014
   936                                  ;	cli			; Disable interrupts
   937                                  ;	mov	al, [scounter + 1]
   938                                  ;	and	al, al
   939                                  ;	jnz	hang
   940                                  ;	call	rtc_p
   941                                  ;	jmp     hang
   942                                  
   943                                  
   944                                  	; 27/08/2014
   945                                  	; 20/08/2014
   946                                  printk:
   947                                          ;mov    edi, [scr_row]
   948                                  pkl:
   949 00000636 AC                      	lodsb
   950 00000637 08C0                    	or 	al, al
   951 00000639 7404                    	jz	short pkr
   952 0000063B 66AB                    	stosw
   953 0000063D EBF7                    	jmp	short pkl
   954                                  pkr:
   955 0000063F C3                      	retn
   956                                  
   957                                  ; 25/07/2015
   958                                  ; 14/05/2015 (multi tasking -time sharing- 'clock', x_timer)
   959                                  ; 17/02/2015
   960                                  ; 06/02/2015 (unix386.s)
   961                                  ; 11/12/2014 - 22/12/2014 (dsectrm2.s) 
   962                                  ;
   963                                  ; IBM PC-XT Model 286 Source Code - BIOS2.ASM (06/10/85)
   964                                  ;
   965                                  ;-- HARDWARE INT  08 H - ( IRQ LEVEL 0 ) ---------------------------------------
   966                                  ;	THIS ROUTINE HANDLES THE TIMER INTERRUPT FROM FROM CHANNEL 0 OF        :
   967                                  ;	THE 8254 TIMER.  INPUT FREQUENCY IS 1.19318 MHZ AND THE DIVISOR        :
   968                                  ;	IS 65536, RESULTING IN APPROXIMATELY 18.2 INTERRUPTS EVERY SECOND.     :
   969                                  ;									       :
   970                                  ;	THE INTERRUPT HANDLER MAINTAINS A COUNT (40:6C) OF INTERRUPTS SINCE    :
   971                                  ;	POWER ON TIME, WHICH MAY BE USED TO ESTABLISH TIME OF DAY.	       :
   972                                  ;	THE INTERRUPT HANDLER ALSO DECREMENTS THE MOTOR CONTROL COUNT (40:40)  :
   973                                  ;	OF THE DISKETTE, AND WHEN IT EXPIRES, WILL TURN OFF THE 	       :
   974                                  ;	DISKETTE MOTOR(s), AND RESET THE MOTOR RUNNING FLAGS.		       :
   975                                  ;	THE INTERRUPT HANDLER WILL ALSO INVOKE A USER ROUTINE THROUGH	       :
   976                                  ;	INTERRUPT 1CH AT EVERY TIME TICK.  THE USER MUST CODE A 	       :
   977                                  ;	ROUTINE AND PLACE THE CORRECT ADDRESS IN THE VECTOR TABLE.	       :
   978                                  ;-------------------------------------------------------------------------------
   979                                  ;
   980                                  
   981                                  timer_int:	; IRQ 0
   982                                  ;int_08h:	; Timer
   983                                  	; 14/10/2015
   984                                  	; Here, we are simulating system call entry (for task switch)
   985                                  	; (If multitasking is enabled, 
   986                                  	; 'clock' procedure may jump to 'sysrelease')
   987 00000640 1E                      	push	ds
   988 00000641 06                      	push	es
   989 00000642 0FA0                    	push	fs
   990 00000644 0FA8                    	push	gs
   991 00000646 60                      	pushad  ; eax, ecx, edx, ebx, esp -before pushad-, ebp, esi, edi
   992 00000647 66B91000                	mov     cx, KDATA
   993 0000064B 8ED9                            mov     ds, cx
   994 0000064D 8EC1                            mov     es, cx
   995 0000064F 8EE1                            mov     fs, cx
   996 00000651 8EE9                            mov     gs, cx
   997                                  	;
   998 00000653 0F20D9                  	mov	ecx, cr3
   999 00000656 890D[F9060000]          	mov	[cr3reg], ecx ; save current cr3 register value/content
  1000                                  	;
  1001 0000065C 3B0D[18620000]          	cmp 	ecx, [k_page_dir]
  1002 00000662 741F                    	je	short T3
  1003                                  	;
  1004                                  	; timer interrupt has been occurred while OS is in user mode
  1005 00000664 A3[DC650000]            	mov 	[u.r0], eax
  1006 00000669 89E1                    	mov	ecx, esp
  1007 0000066B 83C130                  	add	ecx, ESPACE ; 4 * 12 (stack frame)	
  1008 0000066E 890D[D4650000]          	mov	[u.sp], ecx ; kernel stack pointer at the start of interrupt
  1009 00000674 8925[D8650000]          	mov	[u.usp], esp ; kernel stack points to user's registers   
  1010                                  	;
  1011 0000067A 8B0D[18620000]          	mov	ecx, [k_page_dir]
  1012 00000680 0F22D9                  	mov	cr3, ecx
  1013                                  T3:
  1014 00000683 FB                      	sti				; INTERRUPTS BACK ON
  1015 00000684 66FF05[94620000]        	INC	word [TIMER_LOW]	; INCREMENT TIME
  1016 0000068B 7507                    	JNZ	short T4		; GO TO TEST_DAY
  1017 0000068D 66FF05[96620000]        	INC	word [TIMER_HIGH]	; INCREMENT HIGH WORD OF TIME
  1018                                  T4:					; TEST_DAY
  1019 00000694 66833D[96620000]18      	CMP	word [TIMER_HIGH],018H	; TEST FOR COUNT EQUALING 24 HOURS
  1020 0000069C 7519                    	JNZ	short T5		; GO TO DISKETTE_CTL
  1021 0000069E 66813D[94620000]B0-     	CMP	word [TIMER_LOW],0B0H
  1021 000006A6 00                 
  1022 000006A7 750E                    	JNZ	short T5		; GO TO DISKETTE_CTL
  1023                                  
  1024                                  ;-----	TIMER HAS GONE 24 HOURS
  1025                                  	;;SUB	AX,AX
  1026                                  	;MOV	[TIMER_HIGH],AX
  1027                                  	;MOV	[TIMER_LOW],AX
  1028 000006A9 29C0                    	sub	eax, eax
  1029 000006AB A3[94620000]            	mov	[TIMER_LH], eax
  1030                                  	;	
  1031 000006B0 C605[98620000]01        	MOV	byte [TIMER_OFL],1
  1032                                  
  1033                                  ;-----	TEST FOR DISKETTE TIME OUT
  1034                                  
  1035                                  T5:
  1036                                  	; 23/12/2014
  1037 000006B7 EB1D                    	jmp	short T6		; will be replaced with nop, nop
  1038                                  					; (9090h) if a floppy disk
  1039                                  					; is detected.
  1040                                  	;mov	al,[CS:MOTOR_COUNT]
  1041 000006B9 A0[9B620000]            	mov	al, [MOTOR_COUNT]
  1042 000006BE FEC8                    	dec	al
  1043                                  	;mov	[CS:MOTOR_COUNT], al	; DECREMENT DISKETTE MOTOR CONTROL
  1044 000006C0 A2[9B620000]            	mov	[MOTOR_COUNT], al
  1045                                  	;mov	[ORG_MOTOR_COUNT], al
  1046 000006C5 750F                    	JNZ	short T6		; RETURN IF COUNT NOT OUT
  1047 000006C7 B0F0                    	mov 	al,0F0h
  1048                                  	;AND	[CS:MOTOR_STATUS],al 	; TURN OFF MOTOR RUNNING BITS
  1049 000006C9 2005[9A620000]          	and	[MOTOR_STATUS], al
  1050                                  	;and	[ORG_MOTOR_STATUS], al
  1051 000006CF B00C                    	MOV	AL,0CH			; bit 3 = enable IRQ & DMA, 
  1052                                  					; bit 2 = enable controller
  1053                                  					;	1 = normal operation
  1054                                  					;	0 = reset	
  1055                                  					; bit 0, 1 = drive select
  1056                                  					; bit 4-7 = motor running bits 
  1057 000006D1 66BAF203                	MOV	DX,03F2H		; FDC CTL PORT
  1058 000006D5 EE                      	OUT	DX,AL			; TURN OFF THE MOTOR
  1059                                  T6:	
  1060                                  	;inc	word [CS:wait_count]	; 22/12/2014 (byte -> word)
  1061                                  					; TIMER TICK INTERRUPT
  1062                                  	;;inc	word [wait_count] ;;27/02/2015
  1063                                  	;INT	1CH			; TRANSFER CONTROL TO A USER ROUTINE
  1064                                  	;;;;cli
  1065                                  	;call 	u_timer			; TRANSFER CONTROL TO A USER ROUTINE
  1066 000006D6 FF15[F1060000]          	call	[x_timer] ; 14/05/2015
  1067                                  T7:
  1068                                  	; 14/10/2015
  1069 000006DC B020                    	MOV	AL,EOI			; GET END OF INTERRUPT MASK
  1070 000006DE FA                      	CLI				; DISABLE INTERRUPTS TILL STACK CLEARED
  1071 000006DF E620                    	OUT	INTA00,AL		; END OF INTERRUPT TO 8259 - 1	
  1072                                  	;
  1073 000006E1 A1[F9060000]            	mov 	eax, [cr3reg] 		; previous value/content of cr3 register
  1074 000006E6 0F22D8                   	mov	cr3, eax  ; restore cr3 register content
  1075                                  	;
  1076 000006E9 61                      	popad ; edi, esi, ebp, temp (icrement esp by 4), ebx, edx, ecx, eax
  1077                                  	;
  1078 000006EA 0FA9                    	pop	gs
  1079 000006EC 0FA1                    	pop	fs
  1080 000006EE 07                      	pop	es
  1081 000006EF 1F                      	pop	ds
  1082 000006F0 CF                      	iretd	; return from interrupt
  1083                                  
  1084                                  
  1085                                  ; ////////////////
  1086                                  
  1087                                  ; 14/05/2015 - Multi tasking 'clock' procedure (sys emt)
  1088                                  x_timer:
  1089 000006F1 [FD060000]              	dd 	u_timer			; 14/05/2015
  1090                                  	;dd	clock
  1091                                  
  1092                                  ; 26/02/2022 - Real time clock (digital) output demo (sys emt)
  1093                                  x_rtci:
  1094 000006F5 [330A0000]              	dd	rtc_p	; (temporary demo code)	; 26/02/2022
  1095                                  
  1096                                  ; 14/10/2015
  1097 000006F9 00000000                cr3reg: dd 0
  1098                                  
  1099                                  	; 24/12/2021 - Retro UNIX 386 v1.1
  1100                                  	; 06/02/2015
  1101                                  	; 07/09/2014
  1102                                  	; 21/08/2014
  1103                                  u_timer:
  1104                                  ;timer_int:	; IRQ 0
  1105                                  	; 06/02/2015
  1106                                  	;push	eax
  1107                                  	;push	edx
  1108                                  	;push	ecx
  1109                                  	;push	ebx
  1110                                  	;push	ds
  1111                                  	;push	es
  1112                                  	;mov	eax, KDATA
  1113                                  	;mov	ds, ax
  1114                                  	;mov	es, ax
  1115 000006FD FF05[5C620000]          	inc	dword [tcount]
  1116 00000703 BB[E65D0000]            	mov	ebx, tcountstr + 4
  1117                                  	;mov	ax, [tcount]
  1118                                  	; 24/12/2021
  1119 00000708 A1[5C620000]            	mov	eax, [tcount]
  1120 0000070D B90A000000              	mov	ecx, 10
  1121                                  rp_divtcnt:
  1122 00000712 31D2                    	xor	edx, edx
  1123 00000714 F7F1                    	div	ecx
  1124 00000716 80C230                  	add	dl, 30h
  1125 00000719 8813                    	mov	[ebx], dl
  1126                                  	;or	ax, ax
  1127                                  	; 24/12/2021
  1128 0000071B 09C0                    	or	eax, eax
  1129 0000071D 7403                    	jz	short print_lzero
  1130 0000071F 4B                      	dec	ebx
  1131 00000720 EBF0                    	jmp	short rp_divtcnt
  1132                                  print_lzero:
  1133 00000722 81FB[E25D0000]          	cmp	ebx, tcountstr
  1134 00000728 7606                    	jna	short print_tcount
  1135 0000072A 4B                      	dec	ebx
  1136 0000072B C60330                   	mov	byte [ebx], 30h
  1137 0000072E EBF2                    	jmp	short print_lzero
  1138                                  print_tcount:
  1139 00000730 56                      	push	esi
  1140 00000731 57                      	push	edi
  1141 00000732 BE[BE5D0000]            	mov	esi, timer_msg ; Timer interrupt message
  1142                                  	; 07/09/2014
  1143                                  	;mov	bx, 1	; Video page 1
  1144                                  	; 24/12/2021
  1145 00000737 29DB                    	sub	ebx, ebx
  1146                                  	;inc	bl ; ebx = 1
  1147                                  	; 02/01/2022
  1148 00000739 B306                    	mov	bl, 6	; Video page 6
  1149                                  ptmsg:
  1150 0000073B AC                      	lodsb
  1151 0000073C 08C0                    	or	al, al
  1152 0000073E 740D                    	jz	short ptmsg_ok
  1153 00000740 56                      	push	esi
  1154                                  	;push	bx
  1155                                  	; 24/12/2021
  1156 00000741 53                              push	ebx
  1157 00000742 B42F                    	mov     ah, 2Fh ; Green background, white forecolor
  1158 00000744 E8590C0000              	call 	write_tty
  1159                                  	;pop	bx
  1160                                  	; 24/12/2021
  1161 00000749 5B                      	pop	ebx
  1162 0000074A 5E                      	pop	esi
  1163 0000074B EBEE                    	jmp	short ptmsg
  1164                                  	;; 27/08/2014
  1165                                  	;mov	edi, 0B8000h + 0A0h ; Row 1
  1166                                  	;call	printk
  1167                                  	;
  1168                                  ptmsg_ok:
  1169                                  	; 07/09/2014
  1170                                  	;xor	dx, dx		; column 0, row 0
  1171                                  	; 24/12/2021
  1172 0000074D 31D2                    	xor	edx, edx
  1173 0000074F E8580D0000              	call	set_cpos	; set cursor position to 0,0 
  1174                                  	; 23/02/2015
  1175                                  	; 25/08/2014
  1176                                  	;mov	ebx, scounter		; (seconds counter)
  1177                                  	;dec	byte [ebx+1]		; (for reading real time clock)
  1178                                  ;	dec	byte [scounter+1]
  1179                                  ;;	jns	short timer_eoi		; 0 -> 0FFh ?
  1180                                  ;	jns	short u_timer_retn
  1181                                  	; 26/02/2015
  1182                                  ;	call	rtc_p
  1183                                  ;	mov	ebx, scounter		; (seconds counter)
  1184                                  ;	mov	byte [ebx+1], 18	; (18.2 timer ticks per second)
  1185                                  ;	dec 	byte [ebx]		; 19+18+18+18+18 (5)	
  1186                                  ;	jnz	short timer_eoi		; (109 timer ticks in 5 seconds)
  1187                                  ;	jnz	short u_timer_retn ; 06/02/2015
  1188                                  ;	mov	byte [ebx], 5
  1189                                  ;	inc	byte [ebx+1] ; 19
  1190                                  ;;timer_eoi:
  1191                                  ;;	mov	al, 20h ; END OF INTERRUPT COMMAND TO 8259
  1192                                  ;;	out	20h, al	; 8259 PORT
  1193                                  	;
  1194                                  ;u_timer_retn:  ; 06/02/2015
  1195 00000754 5F                      	pop	edi
  1196 00000755 5E                      	pop	esi
  1197                                  	;pop	es
  1198                                  	;pop	ds
  1199                                  	;pop	ebx
  1200                                  	;pop	ecx
  1201                                  	;pop	edx
  1202                                  	;pop	eax
  1203                                  	;iret
  1204 00000756 C3                      	retn	; 06/02/2015
  1205                                  
  1206                                  	; 28/08/2014
  1207                                  irq0:
  1208 00000757 6A00                            push 	dword 0
  1209 00000759 EB48                    	jmp	short which_irq
  1210                                  irq1:
  1211 0000075B 6A01                            push 	dword 1
  1212 0000075D EB44                    	jmp	short which_irq
  1213                                  irq2:
  1214 0000075F 6A02                            push 	dword 2
  1215 00000761 EB40                    	jmp	short which_irq
  1216                                  irq3:
  1217                                  	; 20/11/2015
  1218                                  	; 24/10/2015
  1219 00000763 2EFF15[D4300000]        	call	dword [cs:com2_irq3]
  1220 0000076A 6A03                    	push 	dword 3
  1221 0000076C EB35                    	jmp	short which_irq
  1222                                  irq4:
  1223                                  	; 20/11/2015
  1224                                  	; 24/10/2015
  1225 0000076E 2EFF15[D0300000]        	call	dword [cs:com1_irq4]
  1226 00000775 6A04                            push 	dword 4
  1227 00000777 EB2A                    	jmp	short which_irq
  1228                                  irq5:
  1229 00000779 6A05                            push 	dword 5
  1230 0000077B EB26                    	jmp	short which_irq
  1231                                  irq6:
  1232 0000077D 6A06                            push 	dword 6
  1233 0000077F EB22                    	jmp	short which_irq
  1234                                  irq7:
  1235 00000781 6A07                            push 	dword 7
  1236 00000783 EB1E                    	jmp	short which_irq
  1237                                  irq8:
  1238 00000785 6A08                            push 	dword 8
  1239 00000787 EB1A                    	jmp	short which_irq
  1240                                  irq9:
  1241 00000789 6A09                            push 	dword 9
  1242 0000078B EB16                    	jmp	short which_irq
  1243                                  irq10:
  1244 0000078D 6A0A                            push 	dword 10
  1245 0000078F EB12                    	jmp	short which_irq
  1246                                  irq11:
  1247 00000791 6A0B                            push 	dword 11
  1248 00000793 EB0E                    	jmp	short which_irq
  1249                                  irq12:
  1250 00000795 6A0C                            push 	dword 12
  1251 00000797 EB0A                    	jmp	short which_irq
  1252                                  irq13:
  1253 00000799 6A0D                            push 	dword 13
  1254 0000079B EB06                    	jmp	short which_irq
  1255                                  irq14:
  1256 0000079D 6A0E                            push 	dword 14
  1257 0000079F EB02                    	jmp	short which_irq
  1258                                  irq15:
  1259 000007A1 6A0F                            push 	dword 15
  1260                                  	;jmp	short which_irq
  1261                                  
  1262                                  	; 19/10/2015
  1263                                  	; 29/08/2014
  1264                                  	; 21/08/2014
  1265                                  which_irq:
  1266 000007A3 870424                  	xchg	eax, [esp]  ; 28/08/2014
  1267 000007A6 53                      	push	ebx
  1268 000007A7 56                      	push	esi
  1269 000007A8 57                      	push	edi
  1270 000007A9 1E                      	push 	ds
  1271 000007AA 06                      	push 	es
  1272                                  	;
  1273 000007AB 88C3                    	mov	bl, al
  1274                                  	;
  1275 000007AD B810000000              	mov	eax, KDATA
  1276 000007B2 8ED8                    	mov	ds, ax
  1277 000007B4 8EC0                    	mov	es, ax
  1278                                  	; 19/10/2015
  1279 000007B6 FC                      	cld
  1280                                          ; 27/08/2014
  1281 000007B7 8105[6C5D0000]A000-             add     dword [scr_row], 0A0h
  1281 000007BF 0000               
  1282                                  	;
  1283 000007C1 B417                    	mov	ah, 17h	; blue (1) background, 
  1284                                  			; light gray (7) forecolor
  1285 000007C3 8B3D[6C5D0000]                  mov     edi, [scr_row]
  1286 000007C9 B049                    	mov	al, 'I'
  1287 000007CB 66AB                    	stosw
  1288 000007CD B052                    	mov	al, 'R'
  1289 000007CF 66AB                    	stosw
  1290 000007D1 B051                    	mov	al, 'Q'
  1291 000007D3 66AB                    	stosw
  1292 000007D5 B020                    	mov	al, ' '
  1293 000007D7 66AB                    	stosw
  1294 000007D9 88D8                    	mov	al, bl
  1295 000007DB 3C0A                    	cmp	al, 10
  1296 000007DD 7208                    	jb	short iix
  1297 000007DF B031                    	mov	al, '1'
  1298 000007E1 66AB                    	stosw
  1299 000007E3 88D8                    	mov	al, bl
  1300 000007E5 2C0A                    	sub	al, 10
  1301                                  iix:
  1302 000007E7 0430                    	add	al, '0'
  1303 000007E9 66AB                    	stosw
  1304 000007EB B020                    	mov	al, ' '
  1305 000007ED 66AB                    	stosw
  1306 000007EF B021                    	mov	al, '!'
  1307 000007F1 66AB                    	stosw
  1308 000007F3 B020                    	mov	al, ' '
  1309 000007F5 66AB                    	stosw
  1310                                  	; 23/02/2015
  1311 000007F7 80FB07                  	cmp	bl, 7 ; check for IRQ 8 to IRQ 15 
  1312                                  	;jna	iiret
  1313                                  	; 02/01/2022
  1314 000007FA 7604                    	jna	short iiz
  1315                                  iiy:
  1316 000007FC B020                    	mov	al, 20h  ; END OF INTERRUPT COMMAND TO
  1317 000007FE E6A0                    	out	0A0h, al ; the 2nd 8259
  1318                                  iiz:
  1319 00000800 E983010000              	jmp     iiret
  1320                                  	;
  1321                                  	; 22/08/2014
  1322                                  	;mov	al, 20h ; END OF INTERRUPT COMMAND TO 8259
  1323                                  	;out	20h, al	; 8259 PORT
  1324                                  	;
  1325                                  	;pop	es
  1326                                  	;pop	ds
  1327                                  	;pop	edi
  1328                                  	;pop	esi
  1329                                  	;pop	ebx
  1330                                  	;pop 	eax
  1331                                  	;iret
  1332                                  
  1333                                  	; 02/04/2015
  1334                                  	; 25/08/2014
  1335                                  exc0:
  1336 00000805 6A00                            push 	dword 0
  1337 00000807 E990000000                      jmp     cpu_except
  1338                                  exc1:
  1339 0000080C 6A01                            push 	dword 1
  1340 0000080E E989000000                      jmp     cpu_except
  1341                                  exc2:
  1342 00000813 6A02                            push 	dword 2
  1343 00000815 E982000000                      jmp     cpu_except
  1344                                  exc3:
  1345 0000081A 6A03                            push 	dword 3
  1346 0000081C EB7E                            jmp     cpu_except
  1347                                  exc4:
  1348 0000081E 6A04                            push 	dword 4
  1349 00000820 EB7A                            jmp     cpu_except
  1350                                  exc5:
  1351 00000822 6A05                            push 	dword 5
  1352 00000824 EB76                            jmp     cpu_except
  1353                                  exc6:
  1354 00000826 6A06                            push 	dword 6
  1355 00000828 EB72                            jmp     cpu_except
  1356                                  exc7:
  1357 0000082A 6A07                            push 	dword 7
  1358 0000082C EB6E                            jmp     cpu_except
  1359                                  exc8:
  1360                                  	; [esp] = Error code
  1361 0000082E 6A08                            push 	dword 8
  1362 00000830 EB5C                            jmp     cpu_except_en
  1363                                  exc9:
  1364 00000832 6A09                            push 	dword 9
  1365 00000834 EB66                            jmp     cpu_except
  1366                                  exc10:
  1367                                  	; [esp] = Error code
  1368 00000836 6A0A                            push 	dword 10
  1369 00000838 EB54                            jmp     cpu_except_en
  1370                                  exc11:
  1371                                  	; [esp] = Error code
  1372 0000083A 6A0B                            push 	dword 11
  1373 0000083C EB50                            jmp     cpu_except_en
  1374                                  exc12:
  1375                                  	; [esp] = Error code
  1376 0000083E 6A0C                            push 	dword 12
  1377 00000840 EB4C                            jmp     cpu_except_en
  1378                                  exc13:
  1379                                  	; [esp] = Error code
  1380 00000842 6A0D                            push 	dword 13
  1381 00000844 EB48                            jmp     cpu_except_en
  1382                                  exc14:
  1383                                  	; [esp] = Error code
  1384 00000846 6A0E                            push 	dword 14
  1385 00000848 EB44                    	jmp	short cpu_except_en
  1386                                  exc15:
  1387 0000084A 6A0F                            push 	dword 15
  1388 0000084C EB4E                            jmp     cpu_except
  1389                                  exc16:
  1390 0000084E 6A10                            push 	dword 16
  1391 00000850 EB4A                            jmp     cpu_except
  1392                                  exc17:
  1393                                  	; [esp] = Error code
  1394 00000852 6A11                            push 	dword 17
  1395 00000854 EB38                    	jmp	short cpu_except_en
  1396                                  exc18:
  1397 00000856 6A12                            push 	dword 18
  1398 00000858 EB42                    	jmp	short cpu_except
  1399                                  exc19:
  1400 0000085A 6A13                            push 	dword 19
  1401 0000085C EB3E                    	jmp	short cpu_except
  1402                                  exc20:
  1403 0000085E 6A14                            push 	dword 20
  1404 00000860 EB3A                    	jmp	short cpu_except
  1405                                  exc21:
  1406 00000862 6A15                            push 	dword 21
  1407 00000864 EB36                    	jmp	short cpu_except
  1408                                  exc22:
  1409 00000866 6A16                            push 	dword 22
  1410 00000868 EB32                    	jmp	short cpu_except
  1411                                  exc23:
  1412 0000086A 6A17                            push 	dword 23
  1413 0000086C EB2E                    	jmp	short cpu_except
  1414                                  exc24:
  1415 0000086E 6A18                            push 	dword 24
  1416 00000870 EB2A                    	jmp	short cpu_except
  1417                                  exc25:
  1418 00000872 6A19                            push 	dword 25
  1419 00000874 EB26                    	jmp	short cpu_except
  1420                                  exc26:
  1421 00000876 6A1A                            push 	dword 26
  1422 00000878 EB22                    	jmp	short cpu_except
  1423                                  exc27:
  1424 0000087A 6A1B                            push 	dword 27
  1425 0000087C EB1E                    	jmp	short cpu_except
  1426                                  exc28:
  1427 0000087E 6A1C                            push 	dword 28
  1428 00000880 EB1A                    	jmp	short cpu_except
  1429                                  exc29:
  1430 00000882 6A1D                            push 	dword 29
  1431 00000884 EB16                    	jmp	short cpu_except
  1432                                  exc30:
  1433 00000886 6A1E                            push 	dword 30
  1434 00000888 EB04                    	jmp	short cpu_except_en
  1435                                  exc31:
  1436 0000088A 6A1F                            push 	dword 31
  1437 0000088C EB0E                            jmp     short cpu_except
  1438                                  
  1439                                  	; 02/01/2022
  1440                                  	; 19/10/2015
  1441                                  	; 19/09/2015
  1442                                  	; 01/09/2015
  1443                                  	; 28/08/2015
  1444                                  	; 28/08/2014
  1445                                  cpu_except_en:
  1446 0000088E 87442404                	xchg	eax, [esp+4] ; Error code
  1447 00000892 36A3[C4620000]          	mov	[ss:error_code], eax
  1448 00000898 58                      	pop	eax  ; Exception number
  1449 00000899 870424                  	xchg	eax, [esp]
  1450                                  		; eax = eax before exception
  1451                                  		; [esp] -> exception number
  1452                                  		; [esp+4] -> EIP to return
  1453                                  	; 19/10/2015
  1454                                  	; 19/09/2015
  1455                                  	; 01/09/2015
  1456                                  	; 28/08/2015
  1457                                  	; 29/08/2014
  1458                                  	; 28/08/2014
  1459                                  	; 25/08/2014
  1460                                  	; 21/08/2014
  1461                                  cpu_except:	; CPU Exceptions
  1462 0000089C FC                      	cld
  1463 0000089D 870424                  	xchg	eax, [esp] 
  1464                                  		; eax = Exception number
  1465                                  		; [esp] = eax (before exception)
  1466 000008A0 53                      	push	ebx
  1467 000008A1 56                      	push	esi
  1468 000008A2 57                      	push	edi
  1469 000008A3 1E                      	push 	ds
  1470 000008A4 06                      	push 	es
  1471                                  	; 28/08/2015
  1472 000008A5 66BB1000                	mov	bx, KDATA
  1473 000008A9 8EDB                    	mov	ds, bx
  1474 000008AB 8EC3                    	mov	es, bx
  1475 000008AD 0F20DB                  	mov	ebx, cr3
  1476 000008B0 53                      	push	ebx ; (*) page directory
  1477                                  	; 19/10/2015
  1478 000008B1 FC                      	cld
  1479                                  	; 25/03/2015
  1480 000008B2 8B1D[18620000]          	mov	ebx, [k_page_dir]
  1481 000008B8 0F22DB                  	mov	cr3, ebx
  1482                                  	; 28/08/2015
  1483 000008BB 83F80E                  	cmp	eax, 0Eh ; 14, PAGE FAULT
  1484 000008BE 7513                    	jne	short cpu_except_nfp
  1485 000008C0 E8B31E0000              	call	page_fault_handler
  1486 000008C5 21C0                    	and 	eax, eax
  1487                                  	;jz	iiretp ; 01/09/2015
  1488                                  	; 02/01/2022
  1489 000008C7 7505                    	jnz	short cpu_except_pf
  1490 000008C9 E9B6000000              	jmp	iiretp
  1491                                  cpu_except_pf:
  1492 000008CE B80E000000              	mov	eax, 0Eh ; 14
  1493                                  cpu_except_nfp:
  1494                                  	; 02/04/2015
  1495 000008D3 BB[FD050000]            	mov	ebx, hang
  1496 000008D8 875C241C                	xchg	ebx, [esp+28]
  1497                                  		; EIP (points to instruction which faults)
  1498                                  	  	; New EIP (hang)
  1499 000008DC 891D[C8620000]          	mov	[FaultOffset], ebx
  1500 000008E2 C744242008000000        	mov	dword [esp+32], KCODE ; kernel's code segment
  1501 000008EA 814C242400020000        	or	dword [esp+36], 200h ; enable interrupts (set IF)
  1502                                  	;
  1503 000008F2 88C4                    	mov	ah, al
  1504 000008F4 240F                    	and	al, 0Fh
  1505 000008F6 3C09                    	cmp	al, 9
  1506 000008F8 7602                    	jna	short h1ok
  1507 000008FA 0407                    	add	al, 'A'-':'
  1508                                  h1ok:
  1509 000008FC D0EC                    	shr	ah, 1
  1510 000008FE D0EC                    	shr	ah, 1
  1511 00000900 D0EC                    	shr	ah, 1
  1512 00000902 D0EC                    	shr	ah, 1
  1513 00000904 80FC09                  	cmp	ah, 9
  1514 00000907 7603                    	jna	short h2ok
  1515 00000909 80C407                  	add	ah, 'A'-':'
  1516                                  h2ok:	
  1517 0000090C 86E0                    	xchg 	ah, al	
  1518 0000090E 66053030                	add	ax, '00'
  1519 00000912 66A3[FA5D0000]          	mov	[excnstr], ax
  1520                                  	;
  1521                                  	; 29/08/2014
  1522 00000918 A1[C8620000]            	mov	eax, [FaultOffset]
  1523 0000091D 51                      	push	ecx
  1524 0000091E 52                      	push	edx
  1525 0000091F 89E3                    	mov	ebx, esp
  1526                                  	; 28/08/2015
  1527 00000921 B910000000              	mov	ecx, 16	  ; divisor value to convert binary number
  1528                                  			  ; to hexadecimal string
  1529                                  	;mov	ecx, 10	    ; divisor to convert
  1530                                  			    ; binary number to decimal string
  1531                                  b2d1:
  1532 00000926 31D2                    	xor	edx, edx
  1533 00000928 F7F1                    	div	ecx
  1534                                  	;push	dx
  1535                                  	; 02/01/2022
  1536 0000092A 52                      	push	edx
  1537 0000092B 39C8                    	cmp	eax, ecx
  1538 0000092D 73F7                    	jnb	short b2d1
  1539 0000092F BF[055E0000]            	mov	edi, EIPstr ; EIP value
  1540                                  			    ; points to instruction which faults
  1541                                  	; 28/08/2015
  1542 00000934 89C2                    	mov	edx, eax
  1543                                  b2d2:
  1544                                  	;add	al, '0'
  1545 00000936 8A82[DE160000]          	mov	al, [edx+hexchrs]
  1546 0000093C AA                      	stosb		    ; write hexadecimal digit to its place
  1547 0000093D 39E3                    	cmp	ebx, esp
  1548 0000093F 7605                    	jna	short b2d3
  1549                                  	; 02/01/2022
  1550 00000941 58                      	pop	eax
  1551                                  	;pop	ax
  1552 00000942 88C2                    	mov	dl, al
  1553 00000944 EBF0                    	jmp	short b2d2
  1554                                  b2d3:
  1555 00000946 B068                    	mov 	al, 'h' ; 28/08/2015
  1556 00000948 AA                      	stosb
  1557 00000949 B020                    	mov	al, 20h	    ; space
  1558 0000094B AA                      	stosb
  1559 0000094C 30C0                    	xor	al, al	    ; to do it an ASCIIZ string	
  1560 0000094E AA                      	stosb
  1561                                  	;
  1562 0000094F 5A                      	pop	edx
  1563 00000950 59                      	pop	ecx
  1564                                  	;
  1565 00000951 B44F                    	mov	ah, 4Fh	; red (4) background, 
  1566                                  			; white (F) forecolor
  1567 00000953 BE[EA5D0000]            	mov	esi, exc_msg ; message offset
  1568                                  	;
  1569 00000958 EB11                    	jmp	short piemsg
  1570                                  	;
  1571                                          ;add    dword [scr_row], 0A0h
  1572                                          ;mov    edi, [scr_row]
  1573                                          ;
  1574                                  	;call 	printk
  1575                                  	;
  1576                                  	;mov	al, 20h ; END OF INTERRUPT COMMAND TO 8259
  1577                                  	;out	20h, al	; 8259 PORT
  1578                                  	;
  1579                                  	;pop	es
  1580                                  	;pop	ds
  1581                                  	;pop	edi
  1582                                  	;pop	esi
  1583                                  	;pop 	eax
  1584                                  	;iret
  1585                                  	
  1586                                  	; 28/08/2015
  1587                                  	; 23/02/2015
  1588                                  	; 20/08/2014
  1589                                  ignore_int:
  1590 0000095A 50                      	push	eax
  1591 0000095B 53                      	push	ebx ; 23/02/2015
  1592 0000095C 56                      	push	esi
  1593 0000095D 57                      	push	edi
  1594 0000095E 1E                      	push 	ds
  1595 0000095F 06                      	push 	es
  1596                                  	; 28/08/2015
  1597 00000960 0F20D8                  	mov	eax, cr3
  1598 00000963 50                      	push	eax ; (*) page directory
  1599                                  	;
  1600 00000964 B467                    	mov	ah, 67h	; brown (6) background, 
  1601                                  			; light gray (7) forecolor
  1602 00000966 BE[A85D0000]            	mov	esi, int_msg ; message offset
  1603                                  piemsg:
  1604                                          ; 27/08/2014
  1605 0000096B 8105[6C5D0000]A000-             add     dword [scr_row], 0A0h
  1605 00000973 0000               
  1606 00000975 8B3D[6C5D0000]                  mov     edi, [scr_row]
  1607                                          ;
  1608 0000097B E8B6FCFFFF              	call 	printk
  1609                                  	;
  1610                                  	; 23/02/2015
  1611 00000980 B020                    	mov	al, 20h  ; END OF INTERRUPT COMMAND TO
  1612 00000982 E6A0                    	out	0A0h, al ; the 2nd 8259
  1613                                  iiretp: ; 01/09/2015
  1614                                  	; 28/08/2015
  1615 00000984 58                      	pop	eax ; (*) page directory
  1616 00000985 0F22D8                  	mov	cr3, eax
  1617                                  	;
  1618                                  iiret:
  1619                                  	; 22/08/2014
  1620 00000988 B020                    	mov	al, 20h ; END OF INTERRUPT COMMAND TO 8259
  1621 0000098A E620                    	out	20h, al	; 8259 PORT
  1622                                  	;
  1623 0000098C 07                      	pop	es
  1624 0000098D 1F                      	pop	ds
  1625 0000098E 5F                      	pop	edi
  1626 0000098F 5E                      	pop	esi
  1627 00000990 5B                      	pop	ebx ; 29/08/2014
  1628 00000991 58                      	pop 	eax
  1629 00000992 CF                      	iretd
  1630                                  
  1631                                  	; 26/02/2022
  1632                                  	; 26/02/2015
  1633                                  	; 07/09/2014
  1634                                  	; 25/08/2014
  1635                                  rtc_int:       ; Real Time Clock Interrupt (IRQ 8)
  1636                                  	; 22/08/2014
  1637 00000993 50                      	push	eax
  1638 00000994 53                      	push	ebx ; 29/08/2014
  1639 00000995 56                      	push	esi
  1640 00000996 57                      	push	edi
  1641 00000997 1E                      	push 	ds
  1642 00000998 06                      	push 	es
  1643                                  	;
  1644 00000999 B810000000              	mov	eax, KDATA
  1645 0000099E 8ED8                    	mov	ds, ax
  1646 000009A0 8EC0                    	mov	es, ax
  1647                                  	;
  1648                                  	; 25/08/2014
  1649                                  	;call	rtc_p
  1650                                  	; 26/02/2022
  1651 000009A2 FF15[F5060000]          	call	[x_rtci]
  1652                                  	;
  1653                                  	; 22/02/2015 - dsectpm.s
  1654                                  	; [ source: http://wiki.osdev.org/RTC ]
  1655                                  	; read status register C to complete procedure
  1656                                  	;(it is needed to get a next IRQ 8) 
  1657 000009A8 B00C                    	mov	al, 0Ch ; 
  1658 000009AA E670                    	out	70h, al ; select register C
  1659 000009AC 90                      	nop
  1660 000009AD E471                    	in	al, 71h ; just throw away contents
  1661                                  	; 22/02/2015
  1662 000009AF B020                    	MOV	AL,EOI		; END OF INTERRUPT
  1663 000009B1 E6A0                    	OUT	INTB00,AL	; FOR CONTROLLER #2
  1664                                  	;
  1665 000009B3 EBD3                    	jmp	short iiret	
  1666                                  
  1667                                  	; 22/08/2014
  1668                                  	; IBM PC/AT BIOS source code ----- 10/06/85 (bios.asm)
  1669                                  	; (INT 1Ah)
  1670                                  	;; Linux (v0.12) source code (main.c) by Linus Torvalds (1991)
  1671                                  time_of_day:
  1672 000009B5 E866010000              	call	UPD_IPR		; WAIT TILL UPDATE NOT IN PROGRESS
  1673 000009BA 726F                            jc      short rtc_retn 
  1674 000009BC B000                    	mov	al, CMOS_SECONDS
  1675 000009BE E847010000              	call	CMOS_READ
  1676 000009C3 A2[8C620000]            	mov	[time_seconds], al 
  1677 000009C8 B002                    	mov	al, CMOS_MINUTES
  1678 000009CA E83B010000              	call	CMOS_READ
  1679 000009CF A2[8D620000]            	mov	[time_minutes], al 
  1680 000009D4 B004                    	mov	al, CMOS_HOURS
  1681 000009D6 E82F010000              	call	CMOS_READ
  1682 000009DB A2[8E620000]                    mov     [time_hours], al
  1683 000009E0 B006                    	mov	al, CMOS_DAY_WEEK 
  1684 000009E2 E823010000              	call	CMOS_READ
  1685 000009E7 A2[8F620000]            	mov	[date_wday], al
  1686 000009EC B007                     	mov	al, CMOS_DAY_MONTH
  1687 000009EE E817010000              	call	CMOS_READ
  1688 000009F3 A2[90620000]            	mov	[date_day], al
  1689 000009F8 B008                    	mov	al, CMOS_MONTH
  1690 000009FA E80B010000              	call	CMOS_READ
  1691 000009FF A2[91620000]            	mov	[date_month], al
  1692 00000A04 B009                    	mov	al, CMOS_YEAR
  1693 00000A06 E8FF000000              	call	CMOS_READ
  1694 00000A0B A2[92620000]            	mov	[date_year], al
  1695 00000A10 B032                    	mov	al, CMOS_CENTURY
  1696 00000A12 E8F3000000              	call	CMOS_READ
  1697 00000A17 A2[93620000]            	mov	[date_century], al
  1698                                  	;
  1699 00000A1C B000                    	mov	al, CMOS_SECONDS
  1700 00000A1E E8E7000000              	call 	CMOS_READ
  1701 00000A23 3A05[8C620000]          	cmp	al, [time_seconds]
  1702 00000A29 758A                    	jne	short time_of_day
  1703                                  
  1704                                  rtc_retn:
  1705 00000A2B C3                      	retn
  1706                                  
  1707                                  rtci_default:
  1708                                  	; 26/02/2022 (Temporary!)
  1709                                  	; (default real time clock handler in multitasking mode)
  1710                                  	; ((2 rtc ticks per second after 'setup_rtc_int'))
  1711 00000A2C FF05[D0620000]          	inc	dword [rtc_ticks] ; real time clock counter
  1712                                  			; (not used in anywhere of kernel for now!)
  1713 00000A32 C3                      	retn
  1714                                  
  1715                                  rtc_p:	
  1716                                  	; 07/09/2014
  1717                                  	; 29/08/2014
  1718                                  	; 27/08/2014
  1719                                  	; 25/08/2014
  1720                                   	; Print Real Time Clock content
  1721                                  	;
  1722                                  	;
  1723 00000A33 E87DFFFFFF              	call	time_of_day
  1724 00000A38 72F1                    	jc	short rtc_retn
  1725                                  	;
  1726 00000A3A 3A05[5C5E0000]          	cmp	al, [ptime_seconds]
  1727 00000A40 74E9                            je      short rtc_retn ; 29/08/2014
  1728                                  	;
  1729 00000A42 A2[5C5E0000]            	mov	[ptime_seconds], al
  1730                                  	;
  1731 00000A47 A0[93620000]            	mov	al, [date_century]
  1732 00000A4C E8EA000000              	call	bcd_to_ascii
  1733 00000A51 66A3[295E0000]          	mov	[datestr+6], ax
  1734 00000A57 A0[92620000]            	mov	al, [date_year]
  1735 00000A5C E8DA000000              	call	bcd_to_ascii
  1736 00000A61 66A3[2B5E0000]          	mov	[datestr+8], ax
  1737 00000A67 A0[91620000]            	mov	al, [date_month]
  1738 00000A6C E8CA000000              	call	bcd_to_ascii
  1739 00000A71 66A3[265E0000]          	mov	[datestr+3], ax
  1740 00000A77 A0[90620000]            	mov	al, [date_day]
  1741 00000A7C E8BA000000              	call	bcd_to_ascii
  1742 00000A81 66A3[235E0000]          	mov	[datestr], ax
  1743                                  	;
  1744 00000A87 0FB61D[8F620000]        	movzx	ebx, byte [date_wday]
  1745 00000A8E C0E302                  	shl 	bl, 2
  1746 00000A91 81C3[3C5E0000]          	add	ebx, daytmp
  1747 00000A97 8B03                    	mov	eax, [ebx]
  1748 00000A99 A3[2E5E0000]            	mov	[daystr], eax
  1749                                  	;
  1750 00000A9E A0[8E620000]            	mov	al, [time_hours]
  1751 00000AA3 E893000000              	call	bcd_to_ascii
  1752 00000AA8 66A3[325E0000]          	mov	[timestr], ax
  1753 00000AAE A0[8D620000]            	mov	al, [time_minutes]
  1754 00000AB3 E883000000              	call	bcd_to_ascii
  1755 00000AB8 66A3[355E0000]          	mov	[timestr+3], ax
  1756 00000ABE A0[8C620000]            	mov	al, [time_seconds]
  1757 00000AC3 E873000000              	call	bcd_to_ascii
  1758 00000AC8 66A3[385E0000]          	mov	[timestr+6], ax
  1759                                  	;		
  1760 00000ACE BE[115E0000]            	mov	esi, rtc_msg ; message offset
  1761                                  	; 23/02/2015
  1762 00000AD3 52                      	push	edx
  1763 00000AD4 51                      	push	ecx
  1764                                  	; 07/09/2014
  1765                                  	;mov	bx, 2	; Video page 2
  1766                                  	; 02/01/2022
  1767 00000AD5 29DB                    	sub	ebx, ebx
  1768 00000AD7 B307                    	mov	bl, 7	; Video page 7 
  1769                                  prtmsg:
  1770 00000AD9 AC                      	lodsb
  1771 00000ADA 08C0                    	or	al, al
  1772 00000ADC 740D                    	jz	short prtmsg_ok
  1773 00000ADE 56                      	push	esi
  1774                                  	; 02/01/2022
  1775 00000ADF 53                      	push	ebx
  1776                                  	;push	bx
  1777 00000AE0 B43F                            mov	ah, 3Fh	; cyan (6) background, 
  1778                                  			; white (F) forecolor
  1779 00000AE2 E8BB080000              	call 	write_tty
  1780                                  	;pop	bx
  1781                                  	; 02/01/2022
  1782 00000AE7 5B                      	pop	ebx
  1783 00000AE8 5E                      	pop	esi
  1784 00000AE9 EBEE                    	jmp	short prtmsg
  1785                                  	;
  1786                                  	;mov	edi, 0B8000h+0A0h+0A0h ; Row 2
  1787                                  	;call	printk
  1788                                  prtmsg_ok:
  1789                                  	; 07/09/2014
  1790                                  	;xor	dx, dx		; column 0, row 0
  1791                                  	; 02/01/2022
  1792 00000AEB 31D2                    	xor	edx, edx
  1793 00000AED E8BA090000              	call	set_cpos	; set curspor position to 0,0 
  1794                                  	; 23/02/2015
  1795 00000AF2 59                      	pop	ecx
  1796 00000AF3 5A                      	pop	edx
  1797 00000AF4 C3                      	retn
  1798                                  
  1799                                  ; Default IRQ 7 handler against spurious IRQs (from master PIC)
  1800                                  ; 25/02/2015 (source: http://wiki.osdev.org/8259_PIC)
  1801                                  default_irq7:
  1802                                  	; 24/12/2021
  1803                                  	;push	ax
  1804 00000AF5 50                      	push	eax
  1805 00000AF6 B00B                    	mov	al, 0Bh  ; In-Service register
  1806 00000AF8 E620                    	out	20h, al
  1807 00000AFA EB00                            jmp short $+2
  1808 00000AFC EB00                    	jmp short $+2
  1809 00000AFE E420                    	in	al, 20h
  1810 00000B00 2480                    	and 	al, 80h ; bit 7 (is it real IRQ 7 or fake?)
  1811 00000B02 7404                            jz      short irq7_iret ; Fake (spurious) IRQ, do not send EOI 
  1812 00000B04 B020                            mov     al, 20h ; EOI
  1813 00000B06 E620                    	out	20h, al 
  1814                                  irq7_iret:
  1815                                  	;pop	ax
  1816                                  	; 24/12/2021
  1817 00000B08 58                      	pop	eax
  1818 00000B09 CF                      	iretd	
  1819                                  	
  1820                                  	; 24/12/2021
  1821                                  	; 22/08/2014
  1822                                  	; IBM PC/AT BIOS source code ----- 10/06/85 (test4.asm)
  1823                                  CMOS_READ:
  1824 00000B0A 9C                      	pushf		; SAVE INTERRUPT ENABLE STATUS AND FLAGS
  1825 00000B0B D0C0                    	rol	al, 1	; MOVE NMI BIT TO LOW POSITION
  1826 00000B0D F9                      	stc		; FORCE NMI BIT ON IN CARRY FLAG
  1827 00000B0E D0D8                    	rcr	al, 1	; HIGH BIT ON TO DISABLE NMI - OLD IN CY
  1828 00000B10 FA                      	cli		; DISABLE INTERRUPTS
  1829 00000B11 E670                    	out	CMOS_PORT, al	; ADDRESS LOCATION AND DISABLE NMI
  1830 00000B13 90                      	nop		; I/O DELAY
  1831 00000B14 E471                    	in	al, CMOS_DATA	; READ THE REQUESTED CMOS LOCATION
  1832                                  	;push	ax	; SAVE (AH) REGISTER VALUE AND CMOS BYTE
  1833                                  	; 24/12/2021
  1834 00000B16 50                      	push	eax
  1835                                  	; 15/03/2015 ; IBM PC/XT Model 286 BIOS source code 
  1836                                  		     ; ----- 10/06/85 (test4.asm)
  1837 00000B17 B01E                    	mov	al, CMOS_SHUT_DOWN*2 ; GET ADDRESS OF DEFAULT LOCATION
  1838                                  	;mov	al, CMOS_REG_D*2 ; GET ADDRESS OF DEFAULT LOCATION
  1839 00000B19 D0D8                    	rcr	al, 1	; PUT ORIGINAL NMI MASK BIT INTO ADDRESS
  1840 00000B1B E670                    	out	CMOS_PORT, al	; SET DEFAULT TO READ ONLY REGISTER
  1841                                  	;pop	ax	; RESTORE (AH) AND (AL), CMOS BYTE
  1842                                  	; 24/12/2021
  1843 00000B1D 58                      	pop	eax
  1844 00000B1E 9D                      	popf	
  1845 00000B1F C3                      	retn		; RETURN WITH FLAGS RESTORED
  1846                                  
  1847                                  	; 22/08/2014
  1848                                  	; IBM PC/AT BIOS source code ----- 10/06/85 (bios2.asm)
  1849                                  UPD_IPR:				; WAIT TILL UPDATE NOT IN PROGRESS
  1850 00000B20 51                      	push	ecx
  1851 00000B21 B9FFFF0000              	mov	ecx, 65535		; SET TIMEOUT LOOP COUNT (= 800)
  1852                                  		; mov cx, 800	
  1853                                  UPD_10:
  1854 00000B26 B00A                    	mov	al, CMOS_REG_A		; ADDRESS STATUS REGISTER A
  1855 00000B28 FA                      	cli				; NO TIMER INTERRUPTS DURING UPDATES
  1856 00000B29 E8DCFFFFFF              	call	CMOS_READ		; READ UPDATE IN PROCESS FLAG
  1857 00000B2E A880                    	test	al, 80h			; IF UIP BIT IS ON ( CANNOT READ TIME )
  1858 00000B30 7406                    	jz	short UPD_90		; EXIT WITH CY= 0 IF CAN READ CLOCK NOW
  1859 00000B32 FB                      	sti				; ALLOW INTERRUPTS WHILE WAITING
  1860 00000B33 E2F1                    	loop	UPD_10			; LOOP TILL READY OR TIMEOUT
  1861 00000B35 31C0                    	xor	eax, eax		; CLEAR RESULTS IF ERROR
  1862                                  		; xor ax, ax
  1863 00000B37 F9                      	stc				; SET CARRY FOR ERROR
  1864                                  UPD_90:
  1865 00000B38 59                      	pop	ecx			; RESTORE CALLERS REGISTER
  1866 00000B39 FA                      	cli				; INTERRUPTS OFF DURING SET
  1867 00000B3A C3                      	retn				; RETURN WITH CY FLAG SET
  1868                                  
  1869                                  bcd_to_ascii:
  1870                                  	; 25/08/2014
  1871                                  	; INPUT ->
  1872                                  	;	al = Packed BCD number
  1873                                  	; OUTPUT ->
  1874                                  	;	ax  = ASCII word/number
  1875                                  	;
  1876                                  	; Erdogan Tan - 1998 (proc_hex) - TRDOS.ASM (2004-2011)
  1877                                  	;
  1878 00000B3B D410                    	db 0D4h,10h                     ; Undocumented inst. AAM
  1879                                  					; AH = AL / 10h
  1880                                  					; AL = AL MOD 10h
  1881 00000B3D 660D3030                	or ax,'00'                      ; Make it ASCII based
  1882                                  
  1883 00000B41 86E0                            xchg ah, al 
  1884                                  	
  1885 00000B43 C3                      	retn	
  1886                                  	
  1887                                  
  1888                                  %include 'keyboard.inc' ; 07/03/2015
  1889                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.4) - KEYBOARD.INC
  1890                              <1> ; Last Modification: 13/06/2022
  1891                              <1> ;		    (Keyboard Data is in 'KYBDATA.INC')	
  1892                              <1> ;
  1893                              <1> ; ///////// KEYBOARD FUNCTIONS (PROCEDURES) ///////////////
  1894                              <1> 
  1895                              <1> ; 23/02/2022
  1896                              <1> ; 04/02/2022 (Retro UNIX 386 v1, Kernel v0.2.0.18)
  1897                              <1> ; 24/12/2021 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  1898                              <1> ; 30/06/2015
  1899                              <1> ; 11/03/2015
  1900                              <1> ; 28/02/2015
  1901                              <1> ; 25/02/2015
  1902                              <1> ; 20/02/2015
  1903                              <1> ; 18/02/2015
  1904                              <1> ; 03/12/2014
  1905                              <1> ; 07/09/2014
  1906                              <1> ; KEYBOARD INTERRUPT HANDLER
  1907                              <1> ; (kb_int - Retro UNIX 8086 v1 - U0.ASM, 30/06/2014)
  1908                              <1> 
  1909                              <1> ;getch:
  1910                              <1> ;	; 18/02/2015
  1911                              <1> ;	; This routine will be replaced with Retro UNIX 386
  1912                              <1> ;	; version of Retro UNIX 8086 getch (tty input)
  1913                              <1> ;	; routine, later... (multi tasking ability)
  1914                              <1> ;	; 28/02/2015
  1915                              <1> ;	sti	; enable interrupts
  1916                              <1> ;	;
  1917                              <1> ;	;push	esi
  1918                              <1> ;	;push	ebx
  1919                              <1> ;	;xor	ebx, ebx
  1920                              <1> ;	;mov	bl, [ptty]  ; active_page
  1921                              <1> ;	;mov	esi, ebx
  1922                              <1> ;	;shl 	si, 1
  1923                              <1> ;	;add	esi, ttychr
  1924                              <1> ;getch_1:
  1925                              <1> ;	;mov	ax, [esi]
  1926                              <1> ;	mov	ax, [ttychr] ; video page 0 (tty0)
  1927                              <1> ;	and	ax, ax
  1928                              <1> ;	jz	short getch_2
  1929                              <1> ;	mov	word [ttychr], 0
  1930                              <1> ;	;mov	word [esi], 0
  1931                              <1> ;	;pop	ebx
  1932                              <1> ;	;pop	esi
  1933                              <1> ;	retn
  1934                              <1> ;getch_2:
  1935                              <1> ;	hlt	; not proper for multi tasking!
  1936                              <1> ;		; (temporary halt for now)
  1937                              <1> ;		; 'sleep' on tty 
  1938                              <1> ;		; will (must) be located here		
  1939                              <1> ;	nop
  1940                              <1> ;	jmp	short getch_1
  1941                              <1> 
  1942                              <1> keyb_int:
  1943                              <1> 	; 23/02/2022
  1944                              <1> 	; 30/06/2015
  1945                              <1> 	; 25/02/2015
  1946                              <1> 	; 20/02/2015
  1947                              <1> 	; 03/12/2014 (getc_int - INT 16h modifications)
  1948                              <1> 	; 07/09/2014 - Retro UNIX 386 v1
  1949                              <1> 	; 30/06/2014
  1950                              <1> 	; 10/05/2013	
  1951                              <1>       	; Retro Unix 8086 v1 feature only!
  1952                              <1> 	; 03/03/2014
  1953                              <1> 	
  1954 00000B44 1E                  <1> 	push	ds
  1955 00000B45 53                  <1> 	push	ebx
  1956 00000B46 50                  <1> 	push	eax
  1957                              <1> 	;
  1958                              <1> 	; 23/02/2022
  1959 00000B47 9C                  <1> 	pushfd
  1960 00000B48 0E                  <1> 	push	cs
  1961                              <1> 	;mov	ax, KDATA
  1962 00000B49 31C0                <1> 	xor	eax, eax
  1963 00000B4B B010                <1> 	mov	al, KDATA
  1964 00000B4D 8ED8                <1> 	mov	ds, ax
  1965                              <1> 	;
  1966                              <1> 	;pushfd
  1967                              <1> 	;push	cs
  1968 00000B4F E810020000          <1> 	call	kb_int   ; int_09h
  1969                              <1> 	;
  1970 00000B54 B411                <1> 	mov	ah, 11h	 ; 03/12/2014	
  1971                              <1> 	;call	getc
  1972 00000B56 E854000000          <1> 	call	int_16h  ; 30/06/2015
  1973 00000B5B 744E                <1> 	jz	short keyb_int4
  1974                              <1> 	;
  1975 00000B5D B410                <1> 	mov	ah, 10h	 ; 03/12/2014
  1976                              <1> 	;call	getc
  1977 00000B5F E84B000000          <1> 	call	int_16h  ; 30/06/2015
  1978                              <1> 	;
  1979                              <1> 	; 20/02/2015
  1980 00000B64 0FB61D[46620000]    <1>         movzx   ebx, byte [ptty]  ; active_page
  1981                              <1> 	;
  1982 00000B6B 20C0                <1> 	and 	al, al
  1983 00000B6D 751D                <1> 	jnz	short keyb_int1
  1984                              <1> 	;
  1985 00000B6F 80FC68              <1> 	cmp	ah, 68h	 ; ALT + F1 key
  1986 00000B72 7218                <1> 	jb	short keyb_int1
  1987 00000B74 80FC6F              <1> 	cmp	ah, 6Fh  ; ALT + F8 key	
  1988 00000B77 7713                <1> 	ja	short keyb_int1
  1989                              <1> 	;
  1990 00000B79 88D8                <1> 	mov	al, bl
  1991 00000B7B 0468                <1> 	add	al, 68h
  1992 00000B7D 38E0                <1> 	cmp	al, ah
  1993 00000B7F 7409                <1> 	je	short keyb_int0
  1994 00000B81 88E0                <1> 	mov	al, ah
  1995 00000B83 2C68                <1> 	sub	al, 68h
  1996 00000B85 E8370A0000          <1> 	call	tty_sw
  1997                              <1> 	;movzx	ebx, [ptty]  ; active_page
  1998                              <1> keyb_int0: ; 30/06/2015
  1999                              <1> 	;xor	ax, ax
  2000                              <1> 	; 23/02/2022
  2001 00000B8A 31C0                <1> 	xor	eax, eax
  2002                              <1> keyb_int1:
  2003 00000B8C D0E3                <1> 	shl	bl, 1
  2004 00000B8E 81C3[48620000]      <1> 	add	ebx, ttychr
  2005                              <1> 	;
  2006                              <1> 	;23/02/2022
  2007 00000B94 09C0                <1> 	or	eax, eax
  2008                              <1> 	;or	ax, ax
  2009 00000B96 7406                <1> 	jz	short keyb_int2
  2010                              <1> 	;
  2011 00000B98 66833B00            <1> 	cmp 	word [ebx], 0
  2012 00000B9C 7703                <1>         ja      short keyb_int3 
  2013                              <1> keyb_int2:
  2014 00000B9E 668903              <1>         mov	[ebx], ax  ; Save ascii code
  2015                              <1> 			   ; and scan code of the character
  2016                              <1> 			   ; for current tty (or last tty
  2017                              <1> 			   ; just before tty switch).
  2018                              <1> keyb_int3:
  2019 00000BA1 A0[46620000]        <1>         mov     al, [ptty]
  2020 00000BA6 E8333B0000          <1> 	call	wakeup
  2021                              <1> 	;
  2022                              <1> keyb_int4:
  2023 00000BAB 58                  <1> 	pop	eax
  2024 00000BAC 5B                  <1> 	pop	ebx
  2025 00000BAD 1F                  <1> 	pop	ds
  2026 00000BAE CF                  <1> 	iret
  2027                              <1> 
  2028                              <1> ; 18/02/2015
  2029                              <1> ; REMINDER: Only 'keyb_int' (IRQ 9) must call getc.
  2030                              <1> ; 'keyb_int' always handles 'getc' at 1st and puts the
  2031                              <1> ; scancode and ascii code of the character 
  2032                              <1> ; in the tty input (ttychr) buffer. 
  2033                              <1> ; Test procedures must call 'getch' for tty input
  2034                              <1> ; otherwise, 'getc' will not be able to return to the caller
  2035                              <1> ; due to infinite (key press) waiting loop.
  2036                              <1> ; 
  2037                              <1> ; 03/12/2014
  2038                              <1> ; 26/08/2014
  2039                              <1> ; KEYBOARD I/O
  2040                              <1> ; (INT_16h - Retro UNIX 8086 v1 - U9.ASM, 30/06/2014)
  2041                              <1> 
  2042                              <1> ;NOTE: 'k0' to 'k7' are name of OPMASK registers.
  2043                              <1> ;	(The reason of using '_k' labels!!!) (27/08/2014)    
  2044                              <1> ;NOTE: 'NOT' keyword is '~' unary operator in NASM.
  2045                              <1> ;	('NOT LC_HC' --> '~LC_HC') (bit reversing operator)
  2046                              <1> 
  2047                              <1> int_16h: ; 30/06/2015
  2048                              <1> ;getc:
  2049 00000BAF 9C                  <1> 	pushfd	; 28/08/2014
  2050 00000BB0 0E                  <1> 	push 	cs
  2051 00000BB1 E826000000          <1> 	call 	getc_int
  2052 00000BB6 C3                  <1> 	retn
  2053                              <1> 
  2054                              <1> ; 24/12/2021
  2055                              <1> 
  2056                              <1> 	;-----	SHIFT STATUS
  2057                              <1> _K3E:                                   ; GET THE EXTENDED SHIFT STATUS FLAGS
  2058 00000BB7 8A25[745C0000]      <1> 	mov	ah, [KB_FLAG_1]		; GET SYSTEM SHIFT KEY STATUS
  2059 00000BBD 80E404              <1> 	and	ah, SYS_SHIFT		; MASK ALL BUT SYS KEY BIT
  2060                              <1> 	;mov	cl, 5			; SHIFT THEW SYSTEMKEY BIT OVER TO
  2061                              <1> 	;shl	ah, cl			; BIT 7 POSITION
  2062 00000BC0 C0E405              <1>         shl	ah, 5
  2063 00000BC3 A0[745C0000]        <1> 	mov	al, [KB_FLAG_1]		; GET SYSTEM SHIFT STATES BACK
  2064 00000BC8 2473                <1> 	and	al, 01110011b		; ELIMINATE SYS SHIFT, HOLD_STATE AND INS_SHIFT
  2065 00000BCA 08C4                <1> 	or	ah, al                  ; MERGE REMAINING BITS INTO AH
  2066 00000BCC A0[765C0000]        <1> 	mov	al, [KB_FLAG_3]		; GET RIGHT CTL AND ALT
  2067 00000BD1 240C                <1> 	and	al, 00001100b		; ELIMINATE LC_E0 AND LC_E1
  2068 00000BD3 08C4                <1> 	or	ah, al			; OR THE SHIFT FLAGS TOGETHER
  2069                              <1> _K3:
  2070 00000BD5 A0[735C0000]        <1> 	mov	al, [KB_FLAG]		; GET THE SHIFT STATUS FLAGS
  2071 00000BDA EB2B                <1> 	jmp	short _KIO_EXIT		; RETURN TO CALLER
  2072                              <1> 
  2073                              <1> getc_int:
  2074                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2075                              <1> 	; 28/02/2015
  2076                              <1> 	; 03/12/2014 (derivation from pc-xt-286 bios source code -1986-, 
  2077                              <1> 	;	      instead of pc-at bios - 1985-)
  2078                              <1> 	; 28/08/2014 (_k1d)
  2079                              <1> 	; 30/06/2014
  2080                              <1> 	; 03/03/2014
  2081                              <1> 	; 28/02/2014
  2082                              <1> 	; Derived from "KEYBOARD_IO_1" procedure of IBM "pc-xt-286" 
  2083                              <1> 	; rombios source code (21/04/1986)
  2084                              <1> 	;	 'keybd.asm', INT 16H, KEYBOARD_IO
  2085                              <1> 	;
  2086                              <1> 	; KYBD --- 03/06/86  KEYBOARD BIOS
  2087                              <1> 	;
  2088                              <1> 	;--- INT 16 H -----------------------------------------------------------------
  2089                              <1> 	; KEYBOARD I/O								      :
  2090                              <1> 	;	THESE ROUTINES PROVIDE READ KEYBOARD SUPPORT			      :
  2091                              <1> 	; INPUT									      :
  2092                              <1> 	;	(AH)= 00H  READ THE NEXT ASCII CHARACTER ENTERED FROM THE KEYBOARD,   :
  2093                              <1> 	;		   RETURN THE RESULT IN (AL), SCAN CODE IN (AH).              :
  2094                              <1> 	;		   THIS IS THE COMPATIBLE READ INTERFACE, EQUIVALENT TO THE   :
  2095                              <1> 	;                  STANDARD PC OR PCAT KEYBOARD				      :	
  2096                              <1> 	;-----------------------------------------------------------------------------:
  2097                              <1> 	;	(AH)= 01H  SET THE ZERO FLAG TO INDICATE IF AN ASCII CHARACTER IS     :
  2098                              <1> 	;		   AVAILABLE TO BE READ FROM THE KEYBOARD BUFFER.	      :
  2099                              <1> 	;		   (ZF)= 1 -- NO CODE AVAILABLE			              :
  2100                              <1> 	;		   (ZF)= 0 -- CODE IS AVAILABLE  (AX)= CHARACTER              :
  2101                              <1> 	;		   IF (ZF)= 0, THE NEXT CHARACTER IN THE BUFFER TO BE READ IS :
  2102                              <1> 	;		   IN (AX), AND THE ENTRY REMAINS IN THE BUFFER.              :
  2103                              <1> 	;		   THIS WILL RETURN ONLY PC/PCAT KEYBOARD COMPATIBLE CODES    :
  2104                              <1> 	;-----------------------------------------------------------------------------:	
  2105                              <1> 	;	(AH)= 02H  RETURN THE CURRENT SHIFT STATUS IN AL REGISTER             :
  2106                              <1> 	;		   THE BIT SETTINGS FOR THIS CODE ARE INDICATED IN THE        :
  2107                              <1> 	;		   EQUATES FOR @KB_FLAG		                              :
  2108                              <1> 	;-----------------------------------------------------------------------------:	
  2109                              <1> 	;	(AH)= 03H  SET TYPAMATIC RATE AND DELAY                               :
  2110                              <1> 	;	      (AL) = 05H                                                      :
  2111                              <1> 	;	      (BL) = TYPAMATIC RATE (BITS 5 - 7 MUST BE RESET TO 0)           :
  2112                              <1> 	;		       							      :
  2113                              <1> 	;                     REGISTER     RATE      REGISTER     RATE                :
  2114                              <1> 	;                      VALUE     SELECTED     VALUE     SELECTED              :
  2115                              <1> 	;                     --------------------------------------------            :
  2116                              <1> 	;			00H        30.0        10H        7.5                 :
  2117                              <1> 	;			01H        26.7        11H        6.7                 :
  2118                              <1> 	;			02H        24.0        12H        6.0                 :
  2119                              <1> 	;			03H        21.8        13H        5.5                 :
  2120                              <1> 	;			04H        20.0        14H        5.0                 :
  2121                              <1> 	;			05H        18.5        15H        4.6                 :
  2122                              <1> 	;			06H        17.1        16H        4.3                 :
  2123                              <1> 	;			07H        16.0        17H        4.0                 :
  2124                              <1> 	;			08H        15.0        18H        3.7                 :
  2125                              <1> 	;			09H        13.3        19H        3.3                 :
  2126                              <1> 	;			0AH        12.0        1AH        3.0                 :
  2127                              <1> 	;			0BH        10.9        1BH        2.7                 :
  2128                              <1>         ;			0CH        10.0        1CH        2.5                 :
  2129                              <1> 	;			0DH         9.2        1DH        2.3                 :
  2130                              <1> 	;			0EH         8.6        1EH        2.1                 :
  2131                              <1> 	;			0FH         8.0        1FH        2.0                 :
  2132                              <1> 	;									      :
  2133                              <1> 	;	      (BH) = TYPAMATIC DELAY  (BITS 2 - 7 MUST BE RESET TO 0)         :
  2134                              <1> 	;		       							      :
  2135                              <1> 	;                     REGISTER     DELAY                                      :
  2136                              <1> 	;                      VALUE       VALUE                                      :
  2137                              <1> 	;                     ------------------                                      :
  2138                              <1> 	;			00H        250 ms                                     :
  2139                              <1> 	;			01H        500 ms                                     :
  2140                              <1> 	;			02H        750 ms                                     :
  2141                              <1> 	;			03H       1000 ms                                     :
  2142                              <1> 	;-----------------------------------------------------------------------------:
  2143                              <1> 	;	(AH)= 05H  PLACE ASCII CHARACTER/SCAN CODE COMBINATION IN KEYBOARD    :
  2144                              <1> 	;		   BUFFER AS IF STRUCK FROM KEYBOARD                          :
  2145                              <1> 	;		   ENTRY:  (CL) = ASCII CHARACTER		              :
  2146                              <1> 	;		           (CH) = SCAN CODE                                   :
  2147                              <1> 	;		   EXIT:   (AH) = 00H = SUCCESSFUL OPERATION                  :
  2148                              <1> 	;		           (AL) = 01H = UNSUCCESSFUL - BUFFER FULL            :
  2149                              <1> 	;		   FLAGS:  CARRY IF ERROR                                     :
  2150                              <1> 	;-----------------------------------------------------------------------------:		
  2151                              <1> 	;	(AH)= 10H  EXTENDED READ INTERFACE FOR THE ENHANCED KEYBOARD,         :
  2152                              <1> 	;		   OTHERWISE SAME AS FUNCTION AH=0                            :
  2153                              <1> 	;-----------------------------------------------------------------------------:
  2154                              <1> 	;	(AH)= 11H  EXTENDED ASCII STATUS FOR THE ENHANCED KEYBOARD,           :
  2155                              <1> 	;		   OTHERWISE SAME AS FUNCTION AH=1                            :
  2156                              <1> 	;-----------------------------------------------------------------------------:	
  2157                              <1> 	;	(AH)= 12H  RETURN THE EXTENDED SHIFT STATUS IN AX REGISTER            :
  2158                              <1> 	;		   AL = BITS FROM KB_FLAG, AH = BITS FOR LEFT AND RIGHT       :
  2159                              <1> 	;		   CTL AND ALT KEYS FROM KB_FLAG_1 AND KB_FLAG_3              :
  2160                              <1> 	; OUTPUT					                              :
  2161                              <1> 	;	AS NOTED ABOVE, ONLY (AX) AND FLAGS CHANGED	                      :
  2162                              <1> 	;	ALL REGISTERS RETAINED		                                      :
  2163                              <1> 	;------------------------------------------------------------------------------
  2164                              <1> 	
  2165 00000BDC FB                  <1> 	sti				; INTERRUPTS BACK ON
  2166 00000BDD 1E                  <1> 	push	ds			; SAVE CURRENT DS
  2167 00000BDE 53                  <1> 	push	ebx			; SAVE BX TEMPORARILY
  2168                              <1> 	;push	ecx			; SAVE CX TEMPORARILY
  2169 00000BDF 66BB1000            <1>         mov     bx, KDATA 
  2170 00000BE3 8EDB                <1> 	mov	ds, bx			; PUT SEGMENT VALUE OF DATA AREA INTO DS
  2171 00000BE5 08E4                <1> 	or	ah, ah			; CHECK FOR (AH)= 00H
  2172 00000BE7 742D                <1> 	jz	short _K1		; ASCII_READ
  2173 00000BE9 FECC                <1> 	dec	ah                      ; CHECK FOR (AH)= 01H
  2174 00000BEB 7446                <1>         jz      short _K2               ; ASCII_STATUS
  2175 00000BED FECC                <1> 	dec	ah			; CHECK FOR (AH)= 02H
  2176 00000BEF 74E4                <1>         jz      short _K3               ; SHIFT STATUS
  2177 00000BF1 FECC                <1> 	dec	ah			; CHECK FOR (AH)= 03H	
  2178 00000BF3 745B                <1>         jz      short _K300             ; SET TYPAMATIC RATE/DELAY
  2179 00000BF5 80EC02              <1> 	sub	ah, 2			; CHECK FOR (AH)= 05H	
  2180 00000BF8 7479                <1>         jz      short _K500             ; KEYBOARD WRITE         
  2181                              <1> _KIO1:	
  2182 00000BFA 80EC0B              <1> 	sub	ah, 11			; AH =  10H
  2183 00000BFD 740B                <1> 	jz	short _K1E		; EXTENDED ASCII READ
  2184 00000BFF FECC                <1> 	dec	ah			; CHECK FOR (AH)= 11H
  2185 00000C01 7421                <1> 	jz	short _K2E		; EXTENDED_ASCII_STATUS
  2186 00000C03 FECC                <1> 	dec	ah			; CHECK FOR (AH)= 12H
  2187 00000C05 74B0                <1> 	jz	short _K3E		; EXTENDED_SHIFT_STATUS
  2188                              <1> _KIO_EXIT:
  2189                              <1> 	;pop	ecx			; RECOVER REGISTER
  2190 00000C07 5B                  <1> 	pop	ebx			; RECOVER REGISTER
  2191 00000C08 1F                  <1> 	pop	ds			; RECOVER SEGMENT
  2192 00000C09 CF                  <1> 	iretd				; INVALID COMMAND, EXIT
  2193                              <1> 
  2194                              <1> 	;-----	ASCII CHARACTER
  2195                              <1> _K1E:	
  2196 00000C0A E891000000          <1> 	call	_K1S			; GET A CHARACTER FROM THE BUFFER (EXTENDED)
  2197 00000C0F E804010000          <1> 	call	_KIO_E_XLAT		; ROUTINE TO XLATE FOR EXTENDED CALLS
  2198 00000C14 EBF1                <1> 	jmp	short _KIO_EXIT         ; GIVE IT TO THE CALLER
  2199                              <1> _K1:	
  2200 00000C16 E885000000          <1> 	call	_K1S			; GET A CHARACTER FROM THE BUFFER
  2201 00000C1B E803010000          <1> 	call	_KIO_S_XLAT		; ROUTINE TO XLATE FOR STANDARD CALLS
  2202 00000C20 72F4                <1> 	jc	short _K1		; CARRY SET MEANS TROW CODE AWAY
  2203                              <1> _K1A:
  2204 00000C22 EBE3                <1> 	jmp	short _KIO_EXIT         ; RETURN TO CALLER
  2205                              <1> 
  2206                              <1> 	;-----	ASCII STATUS
  2207                              <1> _K2E:	
  2208 00000C24 E8C2000000          <1> 	call	_K2S			; TEST FOR CHARACTER IN BUFFER (EXTENDED)
  2209 00000C29 7420                <1> 	jz	short _K2B		; RETURN IF BUFFER EMPTY
  2210 00000C2B 9C                  <1> 	pushf				; SAVE ZF FROM TEST
  2211 00000C2C E8E7000000          <1> 	call	_KIO_E_XLAT		; ROUTINE TO XLATE FOR EXTENDED CALLS
  2212 00000C31 EB17                <1> 	jmp	short _K2A	        ; GIVE IT TO THE CALLER
  2213                              <1> _K2:	
  2214 00000C33 E8B3000000          <1> 	call	_K2S			; TEST FOR CHARACTER IN BUFFER
  2215 00000C38 7411                <1> 	jz	short _K2B		; RETURN IF BUFFER EMPTY
  2216 00000C3A 9C                  <1> 	pushf				; SAVE ZF FROM TEST
  2217 00000C3B E8E3000000          <1> 	call	_KIO_S_XLAT		; ROUTINE TO XLATE FOR STANDARD CALLS
  2218 00000C40 7308                <1> 	jnc	short _K2A	        ; CARRY CLEAR MEANS PASS VALID CODE
  2219 00000C42 9D                  <1> 	popf				; INVALID CODE FOR THIS TYPE OF CALL
  2220 00000C43 E858000000          <1> 	call	_K1S			; THROW THE CHARACTER AWAY
  2221 00000C48 EBE9                <1> 	jmp	short _K2		; GO LOOK FOR NEXT CHAR, IF ANY
  2222                              <1> _K2A:
  2223 00000C4A 9D                  <1> 	popf				; RESTORE ZF FROM TEST
  2224                              <1> _K2B:
  2225                              <1> 	;pop	ecx			; RECOVER REGISTER
  2226 00000C4B 5B                  <1> 	pop	ebx			; RECOVER REGISTER
  2227 00000C4C 1F                  <1> 	pop	ds			; RECOVER SEGMENT
  2228 00000C4D CA0400              <1> 	retf	4			; THROW AWAY (e)FLAGS
  2229                              <1> 
  2230                              <1> ; 24/12/2021
  2231                              <1> ;	;-----	SHIFT STATUS
  2232                              <1> ;_K3E:                                  ; GET THE EXTENDED SHIFT STATUS FLAGS
  2233                              <1> ;	mov	ah, [KB_FLAG_1]		; GET SYSTEM SHIFT KEY STATUS
  2234                              <1> ;	and	ah, SYS_SHIFT		; MASK ALL BUT SYS KEY BIT
  2235                              <1> ;	;mov	cl, 5			; SHIFT THEW SYSTEMKEY BIT OVER TO
  2236                              <1> ;	;shl	ah, cl			; BIT 7 POSITION
  2237                              <1> ;       shl	ah, 5
  2238                              <1> ;	mov	al, [KB_FLAG_1]		; GET SYSTEM SHIFT STATES BACK
  2239                              <1> ;	and	al, 01110011b		; ELIMINATE SYS SHIFT, HOLD_STATE AND INS_SHIFT
  2240                              <1> ;	or	ah, al                  ; MERGE REMAINING BITS INTO AH
  2241                              <1> ;	mov	al, [KB_FLAG_3]		; GET RIGHT CTL AND ALT
  2242                              <1> ;	and	al, 00001100b		; ELIMINATE LC_E0 AND LC_E1
  2243                              <1> ;	or	ah, al			; OR THE SHIFT FLAGS TOGETHER
  2244                              <1> ;_K3:
  2245                              <1> ;	mov	al, [KB_FLAG]		; GET THE SHIFT STATUS FLAGS
  2246                              <1> ;	jmp	short _KIO_EXIT		; RETURN TO CALLER
  2247                              <1> 
  2248                              <1> 	;-----	SET TYPAMATIC RATE AND DELAY
  2249                              <1> _K300:
  2250 00000C50 3C05                <1> 	cmp	al, 5			; CORRECT FUNCTION CALL?
  2251 00000C52 75B3                <1> 	jne	short _KIO_EXIT		; NO, RETURN
  2252 00000C54 F6C3E0              <1>      	test	bl, 0E0h		; TEST FOR OUT-OF-RANGE RATE
  2253 00000C57 75AE                <1> 	jnz	short _KIO_EXIT		; RETURN IF SO
  2254 00000C59 F6C7FC              <1> 	test	BH, 0FCh		; TEST FOR OUT-OF-RANGE DELAY
  2255 00000C5C 75A9                <1> 	jnz	short _KIO_EXIT		; RETURN IF SO
  2256 00000C5E B0F3                <1> 	mov	al, KB_TYPA_RD		; COMMAND FOR TYPAMATIC RATE/DELAY		
  2257 00000C60 E87C060000          <1> 	call	SND_DATA		; SEND TO KEYBOARD	
  2258                              <1> 	;mov	cx, 5			; SHIFT COUNT
  2259                              <1> 	;shl	bh, cl			; SHIFT DELAY OVER
  2260 00000C65 C0E705              <1> 	shl	bh, 5
  2261 00000C68 88D8                <1> 	mov	al, bl			; PUT IN RATE
  2262 00000C6A 08F8                <1> 	or	al, bh			; AND DELAY
  2263 00000C6C E870060000          <1> 	call	SND_DATA		; SEND TO KEYBOARD	
  2264 00000C71 EB94                <1>         jmp     _KIO_EXIT               ; RETURN TO CALLER
  2265                              <1> 
  2266                              <1> 	;-----	WRITE TO KEYBOARD BUFFER
  2267                              <1> _K500:
  2268 00000C73 56                  <1> 	push	esi			; SAVE SI (esi)
  2269 00000C74 FA                  <1> 	cli				; 
  2270 00000C75 8B1D[845C0000]      <1>      	mov	ebx, [BUFFER_TAIL]	; GET THE 'IN TO' POINTER TO THE BUFFER
  2271 00000C7B 89DE                <1> 	mov	esi, ebx		; SAVE A COPY IN CASE BUFFER NOT FULL
  2272 00000C7D E8D1000000          <1> 	call	_K4			; BUMP THE POINTER TO SEE IF BUFFER IS FULL
  2273 00000C82 3B1D[805C0000]      <1> 	cmp	ebx, [BUFFER_HEAD]	; WILL THE BUFFER OVERRUN IF WE STORE THIS?
  2274 00000C88 740D                <1> 	je	short _K502		; YES - INFORM CALLER OF ERROR		
  2275 00000C8A 66890E              <1> 	mov	[esi], cx		; NO - PUT ASCII/SCAN CODE INTO BUFFER	
  2276 00000C8D 891D[845C0000]      <1> 	mov	[BUFFER_TAIL], ebx	; ADJUST 'IN TO' POINTER TO REFLECT CHANGE
  2277 00000C93 28C0                <1> 	sub	al, al			; TELL CALLER THAT OPERATION WAS SUCCESSFUL
  2278 00000C95 EB02                <1> 	jmp	short _K504		; SUB INSTRUCTION ALSO RESETS CARRY FLAG
  2279                              <1> _K502:
  2280 00000C97 B001                <1> 	mov	al, 01h			; BUFFER FULL INDICATION
  2281                              <1> _K504:
  2282 00000C99 FB                  <1> 	sti				
  2283 00000C9A 5E                  <1> 	pop	esi			; RECOVER SI (esi)
  2284 00000C9B E967FFFFFF          <1>         jmp     _KIO_EXIT               ; RETURN TO CALLER WITH STATUS IN AL
  2285                              <1> 
  2286                              <1> 	;-----	READ THE KEY TO FIGURE OUT WHAT TO DO -----
  2287                              <1> _K1S:
  2288 00000CA0 FA                  <1> 	cli	; 03/12/2014
  2289 00000CA1 8B1D[805C0000]      <1>         mov     ebx, [BUFFER_HEAD] 	; GET POINTER TO HEAD OF BUFFER
  2290 00000CA7 3B1D[845C0000]      <1>         cmp     ebx, [BUFFER_TAIL] 	; TEST END OF BUFFER
  2291                              <1> 	;jne	short _K1U		; IF ANYTHING IN BUFFER SKIP INTERRUPT
  2292 00000CAD 750F                <1> 	jne	short _k1x ; 03/12/2014
  2293                              <1> 	;
  2294                              <1> 	; 03/12/2014
  2295                              <1> 	; 28/08/2014
  2296                              <1> 	; PERFORM OTHER FUNCTION ?? here !
  2297                              <1> 	;; MOV	AX, 9002h		; MOVE IN WAIT CODE & TYPE
  2298                              <1> 	;; INT 	15H			; PERFORM OTHER FUNCTION
  2299                              <1> _K1T:                                   ; ASCII READ
  2300 00000CAF FB                  <1> 	sti				; INTERRUPTS BACK ON DURING LOOP
  2301 00000CB0 90                  <1> 	nop				; ALLOW AN INTERRUPT TO OCCUR
  2302                              <1> _K1U:	
  2303 00000CB1 FA                  <1> 	cli				; INTERRUPTS BACK OFF
  2304 00000CB2 8B1D[805C0000]      <1>         mov    	ebx, [BUFFER_HEAD] 	; GET POINTER TO HEAD OF BUFFER
  2305 00000CB8 3B1D[845C0000]      <1>         cmp     ebx, [BUFFER_TAIL] 	; TEST END OF BUFFER
  2306                              <1> _k1x:
  2307 00000CBE 53                  <1> 	push	ebx			; SAVE ADDRESS		
  2308 00000CBF 9C                  <1> 	pushf				; SAVE FLAGS
  2309 00000CC0 E8D0060000          <1> 	call	MAKE_LED		; GO GET MODE INDICATOR DATA BYTE
  2310 00000CC5 8A1D[755C0000]      <1> 	mov	bl, [KB_FLAG_2] 	; GET PREVIOUS BITS
  2311 00000CCB 30C3                <1> 	xor	bl, al			; SEE IF ANY DIFFERENT
  2312 00000CCD 80E307              <1> 	and	bl, 07h	; KB_LEDS	; ISOLATE INDICATOR BITS
  2313 00000CD0 7406                <1> 	jz	short _K1V		; IF NO CHANGE BYPASS UPDATE
  2314 00000CD2 E86A060000          <1> 	call	SND_LED1
  2315 00000CD7 FA                  <1> 	cli				; DISABLE INTERRUPTS
  2316                              <1> _K1V:
  2317 00000CD8 9D                  <1> 	popf				; RESTORE FLAGS
  2318 00000CD9 5B                  <1> 	pop	ebx			; RESTORE ADDRESS
  2319 00000CDA 74D3                <1>         je      short _K1T              ; LOOP UNTIL SOMETHING IN BUFFER
  2320                              <1> 	;
  2321 00000CDC 668B03              <1> 	mov	ax, [ebx] 		; GET SCAN CODE AND ASCII CODE
  2322 00000CDF E86F000000          <1>         call    _K4                     ; MOVE POINTER TO NEXT POSITION
  2323 00000CE4 891D[805C0000]      <1>         mov     [BUFFER_HEAD], ebx      ; STORE VALUE IN VARIABLE
  2324 00000CEA C3                  <1> 	retn				; RETURN
  2325                              <1> 
  2326                              <1> 	;-----	READ THE KEY TO SEE IF ONE IS PRESENT -----
  2327                              <1> _K2S:
  2328 00000CEB FA                  <1> 	cli				; INTERRUPTS OFF
  2329 00000CEC 8B1D[805C0000]      <1>         mov     ebx, [BUFFER_HEAD]      ; GET HEAD POINTER
  2330 00000CF2 3B1D[845C0000]      <1>         cmp     ebx, [BUFFER_TAIL]      ; IF EQUAL (Z=1) THEN NOTHING THERE
  2331 00000CF8 668B03              <1> 	mov	ax, [ebx]
  2332 00000CFB 9C                  <1> 	pushf				; SAVE FLAGS
  2333                              <1> 	;push	ax			; SAVE CODE
  2334                              <1> 	; 24/12/2021
  2335 00000CFC 50                  <1> 	push	eax
  2336 00000CFD E893060000          <1> 	call	MAKE_LED		; GO GET MODE INDICATOR DATA BYTE
  2337 00000D02 8A1D[755C0000]      <1> 	mov	bl, [KB_FLAG_2] 	; GET PREVIOUS BITS
  2338 00000D08 30C3                <1> 	xor	bl, al			; SEE IF ANY DIFFERENT
  2339 00000D0A 80E307              <1> 	and	bl, 07h ; KB_LEDS	; ISOLATE INDICATOR BITS
  2340 00000D0D 7405                <1> 	jz	short _K2T		; IF NO CHANGE BYPASS UPDATE
  2341 00000D0F E816060000          <1> 	call	SND_LED			; GO TURN ON MODE INDICATORS
  2342                              <1> _K2T:
  2343                              <1> 	;pop	ax			; RESTORE CODE
  2344                              <1> 	; 24/12/2021
  2345 00000D14 58                  <1> 	pop	eax
  2346 00000D15 9D                  <1> 	popf				; RESTORE FLAGS
  2347 00000D16 FB                  <1> 	sti				; INTERRUPTS BACK ON
  2348 00000D17 C3                  <1> 	retn				; RETURN
  2349                              <1> 
  2350                              <1> 	;-----	ROUTINE TO TRANSLATE SCAN CODE PAIRS FOR EXTENDED CALLS -----
  2351                              <1> _KIO_E_XLAT:
  2352 00000D18 3CF0                <1> 	cmp	al, 0F0h		; IS IT ONE OF THE FILL-INs?
  2353 00000D1A 7506                <1> 	jne	short _KIO_E_RET	; NO, PASS IT ON
  2354 00000D1C 08E4                <1>         or 	ah, ah			; AH = 0 IS SPECIAL CASE
  2355 00000D1E 7402                <1>         jz	short _KIO_E_RET        ; PASS THIS ON UNCHANGED
  2356 00000D20 30C0                <1> 	xor	al, al			; OTHERWISE SET AL = 0
  2357                              <1> _KIO_E_RET:				
  2358 00000D22 C3                  <1> 	retn				; GO BACK
  2359                              <1> 
  2360                              <1> 	;-----	ROUTINE TO TRANSLATE SCAN CODE PAIRS FOR STANDARD CALLS -----
  2361                              <1> _KIO_S_XLAT:
  2362 00000D23 80FCE0              <1> 	cmp	ah, 0E0h		; IS IT KEYPAD ENTER OR / ?
  2363 00000D26 750F                <1> 	jne	short _KIO_S2		; NO, CONTINUE
  2364 00000D28 3C0D                <1> 	cmp	al, 0Dh			; KEYPAD ENTER CODE?
  2365 00000D2A 7408                <1>         je	short _KIO_S1		; YES, MASSAGE A BIT
  2366 00000D2C 3C0A                <1> 	cmp	al, 0Ah			; CTRL KEYPAD ENTER CODE?
  2367 00000D2E 7404                <1>         je	short _KIO_S1		; YES, MASSAGE THE SAME
  2368 00000D30 B435                <1> 	mov	ah, 35h			; NO, MUST BE KEYPAD /
  2369                              <1> _kio_ret: ; 03/12/2014
  2370 00000D32 F8                  <1> 	clc
  2371 00000D33 C3                  <1> 	retn
  2372                              <1> 	;jmp	short _KIO_USE		; GIVE TO CALLER
  2373                              <1> _KIO_S1:				
  2374 00000D34 B41C                <1> 	mov	ah, 1Ch			; CONVERT TO COMPATIBLE OUTPUT
  2375                              <1> 	;jmp	short _KIO_USE		; GIVE TO CALLER
  2376 00000D36 C3                  <1> 	retn
  2377                              <1> _KIO_S2:		
  2378 00000D37 80FC84              <1> 	cmp	ah, 84h			; IS IT ONE OF EXTENDED ONES?
  2379 00000D3A 7715                <1> 	ja	short _KIO_DIS		; YES, THROW AWAY AND GET ANOTHER CHAR
  2380 00000D3C 3CF0                <1> 	cmp	al, 0F0h		; IS IT ONE OF THE FILL-INs?
  2381 00000D3E 7506                <1>         jne	short _KIO_S3		; NO, TRY LAST TEST
  2382 00000D40 08E4                <1> 	or	ah, ah			; AH = 0 IS SPECIAL CASE
  2383 00000D42 740C                <1>         jz	short _KIO_USE		; PASS THIS ON UNCHANGED
  2384 00000D44 EB0B                <1> 	jmp	short _KIO_DIS		; THROW AWAY THE REST
  2385                              <1> _KIO_S3:
  2386 00000D46 3CE0                <1> 	cmp	al, 0E0h		; IS IT AN EXTENSION OF A PREVIOUS ONE?
  2387                              <1> 	;jne	short _KIO_USE		; NO, MUST BE A STANDARD CODE
  2388 00000D48 75E8                <1> 	jne	short _kio_ret
  2389 00000D4A 08E4                <1> 	or	ah, ah			; AH = 0 IS SPECIAL CASE
  2390 00000D4C 7402                <1>         jz	short _KIO_USE		; JUMP IF AH = 0
  2391 00000D4E 30C0                <1> 	xor	al, al			; CONVERT TO COMPATIBLE OUTPUT
  2392                              <1> 	;jmp	short _KIO_USE		; PASS IT ON TO CALLER
  2393                              <1> _KIO_USE:
  2394                              <1> 	;clc				; CLEAR CARRY TO INDICATE GOOD CODE
  2395 00000D50 C3                  <1> 	retn				; RETURN	
  2396                              <1> _KIO_DIS:
  2397 00000D51 F9                  <1> 	stc				; SET CARRY TO INDICATE DISCARD CODE
  2398 00000D52 C3                  <1> 	retn				; RETURN
  2399                              <1> 
  2400                              <1> 	;-----	INCREMENT BUFFER POINTER ROUTINE -----
  2401                              <1> _K4:    
  2402 00000D53 43                  <1> 	inc     ebx
  2403 00000D54 43                  <1> 	inc	ebx			; MOVE TO NEXT WORD IN LIST
  2404 00000D55 3B1D[7C5C0000]      <1>         cmp     ebx, [BUFFER_END] 	; AT END OF BUFFER?
  2405                              <1>         ;jne    short _K5               ; NO, CONTINUE
  2406 00000D5B 7206                <1> 	jb	short _K5
  2407 00000D5D 8B1D[785C0000]      <1>         mov     ebx, [BUFFER_START]     ; YES, RESET TO BUFFER BEGINNING
  2408                              <1> _K5:
  2409 00000D63 C3                  <1> 	retn
  2410                              <1> 
  2411                              <1> ; 20/02/2015
  2412                              <1> ; 05/12/2014
  2413                              <1> ; 26/08/2014
  2414                              <1> ; KEYBOARD (HARDWARE) INTERRUPT -  IRQ LEVEL 1
  2415                              <1> ; (INT_09h - Retro UNIX 8086 v1 - U9.ASM, 07/03/2014)
  2416                              <1> ;
  2417                              <1> ; Derived from "KB_INT_1" procedure of IBM "pc-at" 
  2418                              <1> ; rombios source code (06/10/1985)
  2419                              <1> ; 'keybd.asm', HARDWARE INT 09h - (IRQ Level 1)
  2420                              <1> 
  2421                              <1> ;--------- 8042 COMMANDS -------------------------------------------------------
  2422                              <1> ENA_KBD		equ	0AEh	; ENABLE KEYBOARD COMMAND
  2423                              <1> DIS_KBD		equ	0ADh	; DISABLE KEYBOARD COMMAND
  2424                              <1> SHUT_CMD	equ	0FEh	; CAUSE A SHUTDOWN COMMAND
  2425                              <1> ;--------- 8042 KEYBOARD INTERFACE AND DIAGNOSTIC CONTROL REGISTERS ------------
  2426                              <1> STATUS_PORT	equ	064h	; 8042 STATUS PORT
  2427                              <1> INPT_BUF_FULL	equ	00000010b ; 1 = +INPUT BUFFER FULL
  2428                              <1> PORT_A		equ	060h	; 8042 KEYBOARD SCAN CODE/CONTROL PORT
  2429                              <1> ;---------- 8042 KEYBOARD RESPONSE ---------------------------------------------
  2430                              <1> KB_ACK		equ	0FAh	; ACKNOWLEDGE PROM TRANSMISSION
  2431                              <1> KB_RESEND	equ	0FEh	; RESEND REQUEST
  2432                              <1> KB_OVER_RUN	equ	0FFh	; OVER RUN SCAN CODE
  2433                              <1> ;---------- KEYBOARD/LED COMMANDS ----------------------------------------------
  2434                              <1> KB_ENABLE	equ	0F4h		; KEYBOARD ENABLE
  2435                              <1> LED_CMD		equ	0EDh		; LED WRITE COMMAND
  2436                              <1> KB_TYPA_RD	equ	0F3h		; TYPAMATIC RATE/DELAY COMMAND
  2437                              <1> ;---------- KEYBOARD SCAN CODES ------------------------------------------------
  2438                              <1> NUM_KEY		equ	69		; SCAN CODE FOR	 NUMBER LOCK KEY
  2439                              <1> SCROLL_KEY	equ	70		; SCAN CODE FOR	 SCROLL LOCK KEY
  2440                              <1> ALT_KEY		equ	56		; SCAN CODE FOR	 ALTERNATE SHIFT KEY
  2441                              <1> CTL_KEY		equ	29		; SCAN CODE FOR	 CONTROL KEY
  2442                              <1> CAPS_KEY	equ	58		; SCAN CODE FOR	 SHIFT LOCK KEY
  2443                              <1> DEL_KEY		equ	83		; SCAN CODE FOR	 DELETE KEY
  2444                              <1> INS_KEY		equ	82		; SCAN CODE FOR	 INSERT KEY
  2445                              <1> LEFT_KEY	equ	42		; SCAN CODE FOR	 LEFT SHIFT
  2446                              <1> RIGHT_KEY	equ	54		; SCAN CODE FOR	 RIGHT SHIFT
  2447                              <1> SYS_KEY		equ	84		; SCAN CODE FOR	 SYSTEM KEY
  2448                              <1> ;---------- ENHANCED KEYBOARD SCAN CODES ---------------------------------------
  2449                              <1> ID_1		equ	0ABh		; 1ST ID CHARACTER FOR KBX
  2450                              <1> ID_2		equ	041h		; 2ND ID CHARACTER FOR KBX
  2451                              <1> ID_2A		equ	054h		; ALTERNATE 2ND ID CHARACTER FOR KBX
  2452                              <1> F11_M		equ	87		; F11 KEY MAKE
  2453                              <1> F12_M		equ	88		; F12 KEY MAKE
  2454                              <1> MC_E0		equ	224		; GENERAL MARKER CODE
  2455                              <1> MC_E1		equ	225		; PAUSE KEY MARKER CODE
  2456                              <1> ;---------- FLAG EQUATES WITHIN @KB_FLAG----------------------------------------
  2457                              <1> RIGHT_SHIFT	equ	00000001b	; RIGHT SHIFT KEY DEPRESSED
  2458                              <1> LEFT_SHIFT	equ	00000010b	; LEFT SHIFT KEY DEPRESSED
  2459                              <1> CTL_SHIFT	equ	00000100b	; CONTROL SHIFT KEY DEPRESSED
  2460                              <1> ALT_SHIFT	equ	00001000b	; ALTERNATE SHIFT KEY DEPRESSED
  2461                              <1> SCROLL_STATE	equ	00010000b	; SCROLL LOCK STATE IS ACTIVE
  2462                              <1> NUM_STATE	equ	00100000b	; NUM LOCK STATE IS ACTIVE
  2463                              <1> CAPS_STATE	equ	01000000b	; CAPS LOCK STATE IS ACTIVE
  2464                              <1> INS_STATE	equ	10000000b	; INSERT STATE IS ACTIVE
  2465                              <1> ;---------- FLAG EQUATES WITHIN	@KB_FLAG_1 -------------------------------------
  2466                              <1> L_CTL_SHIFT	equ	00000001b	; LEFT CTL KEY DOWN
  2467                              <1> L_ALT_SHIFT	equ	00000010b	; LEFT ALT KEY DOWN
  2468                              <1> SYS_SHIFT	equ	00000100b	; SYSTEM KEY DEPRESSED AND HELD
  2469                              <1> HOLD_STATE	equ	00001000b	; SUSPEND KEY HAS BEEN TOGGLED
  2470                              <1> SCROLL_SHIFT	equ	00010000b	; SCROLL LOCK KEY IS DEPRESSED
  2471                              <1> NUM_SHIFT	equ	00100000b	; NUM LOCK KEY IS DEPRESSED
  2472                              <1> CAPS_SHIFT	equ	01000000b	; CAPS LOCK KEY IS DEPRE55ED
  2473                              <1> INS_SHIFT	equ	10000000b	; INSERT KEY IS DEPRESSED
  2474                              <1> ;---------- FLAGS EQUATES WITHIN @KB_FLAG_2 -----------------------------------
  2475                              <1> KB_LEDS		equ	00000111b	; KEYBOARD LED STATE BITS
  2476                              <1> ;		equ	00000001b	; SCROLL LOCK INDICATOR
  2477                              <1> ;		equ	00000010b	; NUM LOCK INDICATOR
  2478                              <1> ;		equ	00000100b	; CAPS LOCK INDICATOR
  2479                              <1> ;		equ	00001000b	; RESERVED (MUST BE ZERO)
  2480                              <1> KB_FA		equ	00010000b	; ACKNOWLEDGMENT RECEIVED
  2481                              <1> KB_FE		equ	00100000b	; RESEND RECEIVED FLAG
  2482                              <1> KB_PR_LED	equ	01000000b	; MODE INDICATOR UPDATE
  2483                              <1> KB_ERR		equ	10000000b	; KEYBOARD TRANSMIT ERROR FLAG
  2484                              <1> ;----------- FLAGS EQUATES WITHIN @KB_FLAG_3 -----------------------------------
  2485                              <1> LC_E1		equ	00000001b	; LAST CODE WAS THE E1 HIDDEN CODE
  2486                              <1> LC_E0		equ	00000010b	; LAST CODE WAS THE E0 HIDDEN CODE
  2487                              <1> R_CTL_SHIFT	equ	00000100b	; RIGHT CTL KEY DOWN
  2488                              <1> R_ALT_SHIFT	equ	00001000b	; RIGHT ALT KEY DOWN
  2489                              <1> GRAPH_ON	equ	00001000b	; ALT GRAPHICS KEY DOWN (WT ONLY)	
  2490                              <1> KBX		equ	00010000b	; ENHANCED KEYBOARD INSTALLED
  2491                              <1> SET_NUM_LK	equ	00100000b	; FORCE NUM LOCK IF READ ID AND KBX
  2492                              <1> LC_AB		equ	01000000b	; LAST CHARACTER WAS FIRST ID CHARACTER
  2493                              <1> RD_ID		equ	10000000b	; DOING A READ ID (MUST BE BIT0)
  2494                              <1> ;
  2495                              <1> ;----------- INTERRUPT EQUATES -------------------------------------------------
  2496                              <1> EOI		equ	020h		; END OF INTERRUPT COMMAND TO 8259
  2497                              <1> INTA00		equ	020h		; 8259 PORT
  2498                              <1> 
  2499                              <1> 
  2500                              <1> kb_int:
  2501                              <1> 
  2502                              <1> ; 13/06/2022
  2503                              <1> ; 24/12/2021 (Retro UNIX 386 v1.1)
  2504                              <1> ; 17/10/2015 ('ctrlbrk') 
  2505                              <1> ; 05/12/2014
  2506                              <1> ; 04/12/2014 (derivation from pc-xt-286 bios source code -1986-, 
  2507                              <1> 	;	      instead of pc-at bios - 1985-)
  2508                              <1> ; 26/08/2014
  2509                              <1> ;
  2510                              <1> ; 03/06/86  KEYBOARD BIOS
  2511                              <1> ;
  2512                              <1> ;--- HARDWARE INT 09H -- (IRQ LEVEL 1) ------------------------------------------
  2513                              <1> ;										;
  2514                              <1> ;	KEYBOARD INTERRUPT ROUTINE						;
  2515                              <1> ;										;
  2516                              <1> ;--------------------------------------------------------------------------------
  2517                              <1> 
  2518                              <1> KB_INT_1:
  2519 00000D64 FB                  <1> 	sti				; ENABLE INTERRUPTS
  2520                              <1> 	;push	ebp
  2521 00000D65 50                  <1> 	push	eax
  2522 00000D66 53                  <1> 	push	ebx
  2523 00000D67 51                  <1> 	push	ecx
  2524 00000D68 52                  <1> 	push	edx
  2525 00000D69 56                  <1> 	push	esi
  2526 00000D6A 57                  <1> 	push	edi
  2527 00000D6B 1E                  <1> 	push	ds
  2528 00000D6C 06                  <1> 	push	es
  2529 00000D6D FC                  <1> 	cld				; FORWARD DIRECTION
  2530 00000D6E 66B81000            <1> 	mov	ax, KDATA
  2531 00000D72 8ED8                <1> 	mov	ds, ax
  2532 00000D74 8EC0                <1> 	mov	es, ax
  2533                              <1> 	;
  2534                              <1> 	;-----	WAIT FOR KEYBOARD DISABLE COMMAND TO BE ACCEPTED
  2535 00000D76 B0AD                <1> 	mov	al, DIS_KBD		; DISABLE THE KEYBOARD COMMAND
  2536 00000D78 E852050000          <1> 	call	SHIP_IT			; EXECUTE DISABLE
  2537 00000D7D FA                  <1> 	cli				; DISABLE INTERRUPTS
  2538 00000D7E B900000100          <1> 	mov	ecx, 10000h		; SET MAXIMUM TIMEOUT
  2539                              <1> KB_INT_01:
  2540 00000D83 E464                <1> 	in	al, STATUS_PORT		; READ ADAPTER STATUS
  2541 00000D85 A802                <1> 	test	al, INPT_BUF_FULL	; CHECK INPUT BUFFER FULL STATUS BIT
  2542 00000D87 E0FA                <1> 	loopnz	KB_INT_01		; WAIT FOR COMMAND TO BE ACCEPTED
  2543                              <1> 	;
  2544                              <1> 	;-----	READ CHARACTER FROM KEYBOARD INTERFACE
  2545 00000D89 E460                <1> 	in	al, PORT_A		; READ IN THE CHARACTER
  2546                              <1> 	;
  2547                              <1> 	;-----	SYSTEM HOOK INT 15H - FUNCTION 4FH (ON HARDWARE INT LEVEL 9H) 	
  2548                              <1> 	;MOV	AH, 04FH		; SYSTEM INTERCEPT - KEY CODE FUNCTION
  2549                              <1> 	;STC				; SET CY=1 (IN CASE OF IRET)
  2550                              <1> 	;INT	15H			; CASETTE CALL (AL)=KEY SCAN CODE
  2551                              <1> 	;				; RETURNS CY=1 FOR INVALID FUNCTION
  2552                              <1> 	;JC	KB_INT_02		; CONTINUE IF CARRY FLAG SET ((AL)=CODE)
  2553                              <1> 	;JMP	K26			; EXIT IF SYSTEM HANDLES SCAN CODE
  2554                              <1> 	;				; EXT HANDLES HARDWARE EOI AND ENABLE		
  2555                              <1> 	;
  2556                              <1> 	;-----	CHECK FOR A RESEND COMMAND TO KEYBOARD
  2557                              <1> KB_INT_02:				; 	  (AL)= SCAN CODE
  2558 00000D8B FB                  <1> 	sti				; ENABLE INTERRUPTS AGAIN
  2559 00000D8C 3CFE                <1> 	cmp	al, KB_RESEND		; IS THE INPUT A RESEND
  2560 00000D8E 7411                <1>         je      short KB_INT_4          ; GO IF RESEND
  2561                              <1> 	;
  2562                              <1> 	;-----	CHECK FOR RESPONSE TO A COMMAND TO KEYBOARD
  2563 00000D90 3CFA                <1> 	cmp	al, KB_ACK		; IS THE INPUT AN ACKNOWLEDGE
  2564 00000D92 751A                <1>         jne     short KB_INT_2          ; GO IF NOT
  2565                              <1> 	;
  2566                              <1> 	;-----	A COMMAND TO THE KEYBOARD WAS ISSUED
  2567 00000D94 FA                  <1> 	cli				; DISABLE INTERRUPTS
  2568 00000D95 800D[755C0000]10    <1> 	or	byte [KB_FLAG_2], KB_FA ; INDICATE ACK RECEIVED
  2569 00000D9C E963020000          <1>         jmp     K26                     ; RETURN IF NOT (ACK RETURNED FOR DATA)
  2570                              <1> 	;
  2571                              <1> 	;-----	RESEND THE LAST BYTE
  2572                              <1> KB_INT_4:
  2573 00000DA1 FA                  <1> 	cli				; DISABLE INTERRUPTS
  2574 00000DA2 800D[755C0000]20    <1> 	or	byte [KB_FLAG_2], KB_FE ; INDICATE RESEND RECEIVED
  2575 00000DA9 E956020000          <1>         jmp     K26                     ; RETURN IF NOT ACK RETURNED FOR DATA)
  2576                              <1> 	;
  2577                              <1> ;-----	UPDATE MODE INDICATORS IF CHANGE IN STATE
  2578                              <1> KB_INT_2:
  2579                              <1> 	;push 	ax			; SAVE DATA IN
  2580                              <1> 	; 24/12/2021
  2581 00000DAE 50                  <1> 	push	eax
  2582 00000DAF E8E1050000          <1> 	call	MAKE_LED		; GO GET MODE INDICATOR DATA BYTE
  2583 00000DB4 8A1D[755C0000]      <1> 	mov	bl, [KB_FLAG_2] 	; GET PREVIOUS BITS
  2584 00000DBA 30C3                <1> 	xor	bl, al			; SEE IF ANY DIFFERENT
  2585 00000DBC 80E307              <1> 	and	bl, KB_LEDS		; ISOLATE INDICATOR BITS
  2586 00000DBF 7405                <1> 	jz	short UP0		; IF NO CHANGE BYPASS UPDATE
  2587 00000DC1 E864050000          <1> 	call	SND_LED			; GO TURN ON MODE INDICATORS
  2588                              <1> UP0:
  2589                              <1> 	;pop	ax			; RESTORE DATA IN
  2590                              <1> 	; 24/12/2021
  2591 00000DC6 58                  <1> 	pop	eax
  2592                              <1> ;------------------------------------------------------------------------
  2593                              <1> ;	START OF KEY PROCESSING						;
  2594                              <1> ;------------------------------------------------------------------------
  2595 00000DC7 88C4                <1> 	mov	ah, al			; SAVE SCAN CODE IN AH ALSO
  2596                              <1> 	;
  2597                              <1> 	;-----	TEST FOR OVERRUN SCAN CODE FROM KEYBOARD
  2598 00000DC9 3CFF                <1> 	cmp	al, KB_OVER_RUN		; IS THIS AN OVERRUN CHAR
  2599                              <1>         ;je	K62			; BUFFER_FULL_BEEP
  2600                              <1> 	; 24/12/2021
  2601 00000DCB 7505                <1> 	jne	short K16
  2602 00000DCD E9E9040000          <1> 	jmp	K62
  2603                              <1> K16:	
  2604 00000DD2 8A3D[765C0000]      <1> 	mov	bh, [KB_FLAG_3]		; LOAD FLAGS FOR TESTING
  2605                              <1> 	;
  2606                              <1> 	;-----	TEST TO SEE IF A READ_ID IS IN PROGRESS
  2607 00000DD8 F6C7C0              <1> 	test 	bh, RD_ID+LC_AB 	; ARE WE DOING A READ ID?
  2608 00000DDB 7442                <1> 	jz	short NOT_ID		; CONTINUE IF NOT
  2609 00000DDD 7914                <1> 	jns	short TST_ID_2		; IS THE RD_ID FLAG ON?
  2610 00000DDF 3CAB                <1> 	cmp	al, ID_1		; IS THIS THE 1ST ID CHARACTER?
  2611 00000DE1 7507                <1> 	jne	short RST_RD_ID
  2612 00000DE3 800D[765C0000]40    <1> 	or	byte [KB_FLAG_3], LC_AB ; INDICATE 1ST ID WAS OK
  2613                              <1> RST_RD_ID:
  2614 00000DEA 8025[765C0000]7F    <1> 	and	byte [KB_FLAG_3], ~RD_ID ; RESET THE READ ID FLAG
  2615 00000DF1 EB27                <1>         jmp    short ID_EX		; AND EXIT
  2616                              <1> 	; 24/12/2021
  2617                              <1> 	;jmp	K26
  2618                              <1> 	;
  2619                              <1> TST_ID_2:
  2620 00000DF3 8025[765C0000]BF    <1> 	and	byte [KB_FLAG_3], ~LC_AB ; RESET FLAG
  2621 00000DFA 3C54                <1> 	cmp	al, ID_2A		; IS THIS THE 2ND ID CHARACTER?
  2622 00000DFC 7415                <1>         je	short KX_BIT		; JUMP IF SO
  2623 00000DFE 3C41                <1> 	cmp	al, ID_2		; IS THIS THE 2ND ID CHARACTER?
  2624 00000E00 7518                <1>         jne	short ID_EX		; LEAVE IF NOT
  2625                              <1> 	; 24/12/2021
  2626                              <1> 	;jne	K26
  2627                              <1> 	;
  2628                              <1> 	;-----	A READ ID SAID THAT IT WAS ENHANCED KEYBOARD
  2629 00000E02 F6C720              <1> 	test	bh, SET_NUM_LK 		; SHOULD WE SET NUM LOCK?
  2630 00000E05 740C                <1>         jz      short KX_BIT		; EXIT IF NOT
  2631 00000E07 800D[735C0000]20    <1> 	or	byte [KB_FLAG], NUM_STATE ; FORCE NUM LOCK ON
  2632 00000E0E E817050000          <1> 	call	SND_LED			; GO SET THE NUM LOCK INDICATOR
  2633                              <1> KX_BIT:
  2634 00000E13 800D[765C0000]10    <1> 	or	byte [KB_FLAG_3], KBX	; INDICATE ENHANCED KEYBOARD WAS FOUND
  2635 00000E1A E9E5010000          <1> ID_EX:	jmp     K26			; EXIT
  2636                              <1> 	;
  2637                              <1> NOT_ID:
  2638 00000E1F 3CE0                <1> 	cmp	al, MC_E0		; IS THIS THE GENERAL MARKER CODE?
  2639 00000E21 750E                <1> 	jne	short TEST_E1
  2640 00000E23 800D[765C0000]12    <1> 	or	byte [KB_FLAG_3], LC_E0+KBX ; SET FLAG BIT, SET KBX, AND
  2641 00000E2A EB10                <1> 	jmp	short EXIT		; THROW AWAY THIS CODE
  2642                              <1> 	; 24/12/2021
  2643 00000E2C E9DA010000          <1> 	jmp	K26A	
  2644                              <1> TEST_E1:	
  2645 00000E31 3CE1                <1> 	cmp	al, MC_E1		; IS THIS THE PAUSE KEY?
  2646 00000E33 750C                <1> 	jne	short NOT_HC
  2647 00000E35 800D[765C0000]11    <1> 	or	byte [KB_FLAG_3], LC_E1+KBX ; SET FLAG BIT, SET KBX, AND
  2648 00000E3C E9CA010000          <1> EXIT:	jmp	K26A			; THROW AWAY THIS CODE
  2649                              <1> 	;
  2650                              <1> NOT_HC:
  2651 00000E41 247F                <1> 	and	al, 07Fh		; TURN OFF THE BREAK BIT
  2652 00000E43 F6C702              <1> 	test	bh, LC_E0		; LAST CODE THE E0 MARKER CODE
  2653 00000E46 740D                <1> 	jz	short NOT_LC_E0		; JUMP IF NOT
  2654                              <1> 	;
  2655 00000E48 BF[5E5B0000]        <1> 	mov	edi, _K6+6		; IS THIS A SHIFT KEY?
  2656 00000E4D AE                  <1> 	scasb
  2657                              <1> 	;je	K26 ; K16B              ; YES, THROW AWAY & RESET FLAG
  2658                              <1> 	; 24/12/2021
  2659 00000E4E 7458                <1> 	je	short K16B
  2660 00000E50 AE                  <1> 	scasb
  2661 00000E51 756A                <1> 	jne	short K16A		; NO, CONTINUE KEY PROCESSING
  2662 00000E53 EB53                <1> 	jmp	short K16B		; YES, THROW AWAY & RESET FLAG
  2663                              <1> 	; 24/12/2021
  2664                              <1> 	;jmp	K26
  2665                              <1> 	;
  2666                              <1> NOT_LC_E0:
  2667 00000E55 F6C701              <1> 	test	bh, LC_E1		; LAST CODE THE E1 MARKER CODE?
  2668 00000E58 7425                <1> 	jz	short T_SYS_KEY		; JUMP IF NOT
  2669 00000E5A B904000000          <1> 	mov	ecx, 4			; LENGHT OF SEARCH
  2670 00000E5F BF[5C5B0000]        <1> 	mov	edi, _K6+4		; IS THIS AN ALT, CTL, OR SHIFT?
  2671 00000E64 F2AE                <1> 	repne	scasb			; CHECK IT
  2672 00000E66 74D4                <1> 	je	short EXIT		; THROW AWAY IF SO
  2673                              <1> 	; 24/12/2021
  2674                              <1> 	;je	K26A			
  2675                              <1> 	;
  2676 00000E68 3C45                <1> 	cmp	al, NUM_KEY		; IS IT THE PAUSE KEY?
  2677 00000E6A 753C                <1> 	jne	short K16B		; NO, THROW AWAY & RESET FLAG
  2678                              <1> 	; 24/12/2021
  2679                              <1> 	;jne	K26
  2680 00000E6C F6C480              <1> 	test	ah, 80h			; YES, IS IT THE BREAK OF THE KEY?
  2681 00000E6F 7537                <1> 	jnz	short K16B		; YES, THROW THIS AWAY, TOO	
  2682                              <1> 	; 24/12/2021
  2683                              <1> 	;jnz	K26
  2684                              <1>         ; 20/02/2015 
  2685 00000E71 F605[745C0000]08    <1> 	test	byte [KB_FLAG_1],HOLD_STATE ; NO, ARE WE PAUSED ALREADY?
  2686 00000E78 752E                <1> 	jnz	short K16B		; YES, THROW AWAY
  2687                              <1> 	; 24/12/2021
  2688                              <1> 	;jnz	K26
  2689 00000E7A E9D2020000          <1> 	jmp     K39P                    ; NO, THIS IS THE REAL PAUSE STATE
  2690                              <1> 	;
  2691                              <1> 	;-----	TEST FOR SYSTEM KEY
  2692                              <1> T_SYS_KEY:
  2693 00000E7F 3C54                <1> 	cmp	al, SYS_KEY		; IS IT THE SYSTEM KEY?
  2694 00000E81 753A                <1> 	jnz	short K16A		; CONTINUE IF NOT
  2695                              <1> 	;
  2696 00000E83 F6C480              <1> 	test	ah, 80h			; CHECK IF THIS A BREAK CODE
  2697 00000E86 7525                <1> 	jnz	short K16C		; DO NOT TOUCH SYSTEM INDICATOR IF TRUE
  2698                              <1> 	;
  2699 00000E88 F605[745C0000]04    <1> 	test	byte [KB_FLAG_1], SYS_SHIFT ; SEE IF IN SYSTEM KEY HELD DOWN 
  2700 00000E8F 7517                <1> 	jnz	short K16B		; IF YES, DO NOT PROCESS SYSTEM INDICATOR	
  2701                              <1> 	;jnz	K26			
  2702                              <1> 	;
  2703 00000E91 800D[745C0000]04    <1> 	or	byte [KB_FLAG_1], SYS_SHIFT ; INDICATE SYSTEM KEY DEPRESSED
  2704 00000E98 B020                <1> 	mov	al, EOI			; END OF INTERRUPT COMMAND
  2705 00000E9A E620                <1> 	out	20h, al ;out INTA00, al	; SEND COMMAND TO INTERRUPT CONTROL PORT
  2706                              <1> 					; INTERRUPT-RETURN-NO-EOI
  2707 00000E9C B0AE                <1> 	mov	al, ENA_KBD		; INSURE KEYBOARD IS ENABLED
  2708 00000E9E E82C040000          <1> 	call	SHIP_IT			; EXECUTE ENABLE
  2709                              <1> 	; !!! SYSREQ !!! function/system call (INTERRUPT) must be here !!!
  2710                              <1> 	;MOV	AL, 8500H		; FUNCTION VALUE FOR MAKE OF SYSTEM KEY
  2711                              <1> 	;STI				; MAKE SURE INTERRUPTS ENABLED
  2712                              <1> 	;INT	15H			; USER INTERRUPT	
  2713 00000EA3 E96F010000          <1>         jmp     K27A                    ; END PROCESSING
  2714                              <1> 	;
  2715 00000EA8 E957010000          <1> K16B:	jmp	K26			; IGNORE SYSTEM KEY
  2716                              <1> 	;
  2717                              <1> K16C:
  2718 00000EAD 8025[745C0000]FB    <1> 	and	byte [KB_FLAG_1], ~SYS_SHIFT ; TURN OFF SHIFT KEY HELD DOWN
  2719 00000EB4 B020                <1> 	mov	al, EOI			; END OF INTERRUPT COMMAND
  2720 00000EB6 E620                <1> 	out	20h, al ;out INTA00, al ; SEND COMMAND TO INTERRUPT CONTROL PORT
  2721                              <1> 					; INTERRUPT-RETURN-NO-EOI
  2722                              <1> 	;MOV	AL, ENA_KBD		; INSURE KEYBOARD IS ENABLED
  2723                              <1> 	;CALL	SHIP_IT			; EXECUTE ENABLE
  2724                              <1> 	;
  2725                              <1> 	;MOV	AX, 8501H		; FUNCTION VALUE FOR BREAK OF SYSTEM KEY
  2726                              <1> 	;STI				; MAKE SURE INTERRUPTS ENABLED
  2727                              <1> 	;INT	15H			; USER INTERRUPT
  2728                              <1> 	;JMP	K27A			; INGONRE SYSTEM KEY				
  2729                              <1> 	;
  2730 00000EB8 E953010000          <1> 	jmp     K27			; IGNORE SYSTEM KEY
  2731                              <1> 	;
  2732                              <1> 	;-----	TEST FOR SHIFT KEYS
  2733                              <1> K16A:
  2734 00000EBD 8A1D[735C0000]      <1> 	mov	bl, [KB_FLAG]		; PUT STATE FLAGS IN BL
  2735 00000EC3 BF[585B0000]        <1> 	mov	edi, _K6		; SHIFT KEY TABLE offset
  2736 00000EC8 B908000000          <1> 	mov	ecx, _K6L		; LENGTH
  2737 00000ECD F2AE                <1> 	repne	scasb			; LOOK THROUGH THE TABLE FOR A MATCH
  2738 00000ECF 88E0                <1> 	mov	al, ah			; RECOVER SCAN CODE
  2739                              <1>         ;jne    K25                     ; IF NO MATCH, THEN SHIFT NOT FOUND
  2740                              <1> 	; 24/12/2021
  2741 00000ED1 7405                <1> 	je	short K17
  2742 00000ED3 E914010000          <1> 	jmp	K25
  2743                              <1> 	;
  2744                              <1> 	;------	SHIFT KEY FOUND
  2745                              <1> K17:
  2746 00000ED8 81EF[595B0000]      <1>         sub     edi, _K6+1              ; ADJUST PTR TO SCAN CODE MATCH
  2747 00000EDE 8AA7[605B0000]      <1>        	mov     ah, [edi+_K7]       	; GET MASK INTO AH
  2748 00000EE4 B102                <1> 	mov	cl, 2			; SETUP COUNT FOR FLAG SHIFTS
  2749 00000EE6 A880                <1> 	test	al, 80h			; TEST FOR BREAK KEY
  2750                              <1>         ;jnz	K23                     ; JUMP OF BREAK
  2751                              <1> 	; 24/12/2021
  2752 00000EE8 7405                <1> 	jz	short K17C
  2753 00000EEA E999000000          <1> 	jmp	K23
  2754                              <1> 	;
  2755                              <1> 	;-----	SHIFT MAKE FOUND, DETERMINE SET OR TOGGLE
  2756                              <1> K17C:
  2757 00000EEF 80FC10              <1> 	cmp	ah, SCROLL_SHIFT
  2758 00000EF2 732C                <1> 	jae	short K18		; IF SCROLL SHIFT OR ABOVE, TOGGLE KEY
  2759                              <1> 	;
  2760                              <1> 	;-----	PLAIN SHIFT KEY, SET SHIFT ON
  2761 00000EF4 0825[735C0000]      <1> 	or	[KB_FLAG], ah		; TURN ON SHIFT BIT
  2762 00000EFA A80C                <1>         test	al, CTL_SHIFT+ALT_SHIFT ; IS IT ALT OR CTRL?
  2763 00000EFC 7505                <1> 	jnz	short K17D		; YES, MORE FLAGS TO SET
  2764                              <1> 	;jz	K26			; NO, INTERRUPT RETURN
  2765                              <1> 	; 24/12/2021
  2766 00000EFE E901010000          <1> 	jmp	K26
  2767                              <1> K17D:
  2768 00000F03 F6C702              <1> 	test	bh, LC_E0		; IS THIS ONE OF NEW KEYS?
  2769 00000F06 740B                <1> 	jz 	short K17E		; NO, JUMP
  2770 00000F08 0825[765C0000]      <1> 	or	[KB_FLAG_3], ah		; SET BITS FOR RIGHT CTRL, ALT
  2771 00000F0E E9F1000000          <1> 	jmp	K26			; INTERRUPT RETURN
  2772                              <1> K17E:
  2773 00000F13 D2EC                <1> 	shr	ah, cl			; MOVE FLAG BITS TWO POSITIONS
  2774 00000F15 0825[745C0000]      <1> 	or	[KB_FLAG_1], ah		; SET BITS FOR LEFT CTRL, ALT
  2775 00000F1B E9E4000000          <1> 	jmp	K26
  2776                              <1> 	;
  2777                              <1> 	;-----	TOGGLED SHIFT KEY, TEST FOR 1ST MAKE OR NOT
  2778                              <1> K18:					; SHIFT-TOGGLE
  2779 00000F20 F6C304              <1> 	test	bl, CTL_SHIFT 		; CHECK CTL SHIFT STATE
  2780 00000F23 7405                <1>         jz    	short K18A              ; JUMP IF NOT CTL STATE
  2781                              <1>         ;jnz	K25                     ; JUMP IF CTL STATE
  2782                              <1> 	; 24/12/2021
  2783 00000F25 E9C2000000          <1> 	jmp	K25
  2784                              <1> K18A:
  2785 00000F2A 3C52                <1> 	cmp	al, INS_KEY		; CHECK FOR INSERT KEY
  2786 00000F2C 7525                <1> 	jne	short K22		; JUMP IF NOT INSERT KEY
  2787 00000F2E F6C308              <1> 	test	bl, ALT_SHIFT 		; CHECK FOR ALTERNATE SHIFT
  2788 00000F31 7405                <1>       	jz	short K18B		; JUMP IF NOT ALTERNATE SHIFT	
  2789                              <1> 	;jnz	K25                     ; JUMP IF ALTERNATE SHIFT
  2790                              <1> 	; 24/12/2021
  2791 00000F33 E9B4000000          <1> 	jmp	K25
  2792                              <1> K18B:
  2793 00000F38 F6C702              <1> 	test	bh, LC_E0 ;20/02/2015	; IS THIS NEW INSERT KEY?
  2794 00000F3B 7516                <1> 	jnz	short K22		; YES, THIS ONE'S NEVER A '0'
  2795                              <1> K19:	
  2796 00000F3D F6C320              <1> 	test	bl, NUM_STATE 		; CHECK FOR BASE STATE
  2797 00000F40 750C                <1> 	jnz	short K21		; JUMP IF NUM LOCK IS ON
  2798 00000F42 F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; TEST FOR SHIFT STATE
  2799 00000F45 740C                <1> 	jz	short K22		; JUMP IF BASE STATE
  2800                              <1> K20:					; NUMERIC ZERO, NOT INSERT KEY
  2801 00000F47 88C4                <1> 	mov	ah, al			; PUT SCAN CODE BACK IN AH
  2802 00000F49 E99E000000          <1>         jmp	K25               	; NUMERAL '0', STNDRD. PROCESSING
  2803                              <1> K21:					; MIGHT BE NUMERIC
  2804 00000F4E F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT
  2805 00000F51 74F4                <1> 	jz	short K20		; IS NUMERIC, STD. PROC.
  2806                              <1> 	;
  2807                              <1> K22:					; SHIFT TOGGLE KEY HIT; PROCESS IT
  2808 00000F53 8425[745C0000]      <1> 	test	ah, [KB_FLAG_1] 	; IS KEY ALREADY DEPRESSED
  2809                              <1> 	;jnz	K26
  2810                              <1> 	; 24/12/2021
  2811 00000F59 7405                <1> 	jz	short K22A
  2812 00000F5B E9A4000000          <1> 	jmp	K26			; JUMP IF KEY ALREADY DEPRESSED
  2813                              <1> K22A:
  2814 00000F60 0825[745C0000]      <1>         or      [KB_FLAG_1], ah 	; INDICATE THAT THE KEY IS DEPRESSED
  2815 00000F66 3025[735C0000]      <1> 	xor	[KB_FLAG], ah		; TOGGLE THE SHIFT STATE
  2816                              <1> 	;
  2817                              <1> 	;-----	TOGGLE LED IF CAPS, NUM  OR SCROLL KEY DEPRESSED
  2818 00000F6C F6C470              <1> 	test	ah, CAPS_SHIFT+NUM_SHIFT+SCROLL_SHIFT ; SHIFT TOGGLE?
  2819 00000F6F 7407                <1> 	jz	short K22B		; GO IF NOT
  2820                              <1> 	;
  2821                              <1> 	; 24/12/2021
  2822                              <1> 	;push	ax			; SAVE SCAN CODE AND SHIFT MASK
  2823 00000F71 50                  <1> 	push	eax
  2824 00000F72 E8B3030000          <1> 	call	SND_LED			; GO TURN MODE INDICATORS ON
  2825                              <1> 	;pop	ax			; RESTORE SCAN CODE
  2826 00000F77 58                  <1> 	pop	eax
  2827                              <1> K22B:
  2828 00000F78 3C52                <1> 	cmp	al, INS_KEY		; TEST FOR 1ST MAKE OF INSERT KEY
  2829                              <1>         ;jne	K26			; JUMP IF NOT INSERT KEY
  2830                              <1> 	; 24/12/2021
  2831 00000F7A 7405                <1> 	je	short K22C
  2832 00000F7C E983000000          <1> 	jmp	K26			; JUMP IF NOT INSERT KEY
  2833                              <1> K22C:
  2834 00000F81 88C4                <1> 	mov	ah, al		        ; SCAN CODE IN BOTH HALVES OF AX
  2835 00000F83 E999000000          <1>         jmp	K28			; FLAGS UPDATED, PROC. FOR BUFFER
  2836                              <1> 	;
  2837                              <1> 	;-----	BREAK SHIFT FOUND
  2838                              <1> K23:					; BREAK-SHIFT-FOUND
  2839 00000F88 80FC10              <1> 	cmp	ah, SCROLL_SHIFT	; IS THIS A TOGGLE KEY
  2840 00000F8B F6D4                <1> 	not	ah			; INVERT MASK
  2841 00000F8D 7355                <1> 	jae	short K24		; YES, HANDLE BREAK TOGGLE
  2842 00000F8F 2025[735C0000]      <1> 	and	[KB_FLAG], ah		; TURN OFF SHIFT BIT
  2843 00000F95 80FCFB              <1> 	cmp	ah, ~CTL_SHIFT		; IS THIS ALT OR CTL?
  2844 00000F98 7730                <1> 	ja	short K23D		; NO, ALL DONE
  2845                              <1> 	;
  2846 00000F9A F6C702              <1> 	test	bh, LC_E0		; 2ND ALT OR CTL?
  2847 00000F9D 7408                <1> 	jz	short K23A		; NO, HANSLE NORMALLY
  2848 00000F9F 2025[765C0000]      <1> 	and 	[KB_FLAG_3], ah		; RESET BIT FOR RIGHT ALT OR CTL
  2849 00000FA5 EB08                <1> 	jmp	short K23B		; CONTINUE
  2850                              <1> K23A:
  2851 00000FA7 D2FC                <1> 	sar	ah, cl			; MOVE THE MASK BIT TWO POSITIONS
  2852 00000FA9 2025[745C0000]      <1> 	and	[KB_FLAG_1], ah		; RESET BIT FOR LEFT ALT AND CTL
  2853                              <1> K23B:
  2854 00000FAF 88C4                <1> 	mov	ah, al			; SAVE SCAN CODE
  2855 00000FB1 A0[765C0000]        <1> 	mov	al, [KB_FLAG_3]		; GET RIGHT ALT & CTRL FLAGS
  2856 00000FB6 D2E8                <1> 	shr	al, cl			; MOVE TO BITS 1 & 0
  2857 00000FB8 0A05[745C0000]      <1> 	or	al, [KB_FLAG_1]		; PUT IN LEFT ALT & CTL FLAGS
  2858 00000FBE D2E0                <1> 	shl	al, cl			; MOVE BACK TO BITS 3 & 2
  2859 00000FC0 240C                <1> 	and	al, ALT_SHIFT+CTL_SHIFT ; FILTER OUT OTHER GARBAGE
  2860 00000FC2 0805[735C0000]      <1> 	or	[KB_FLAG], al		; PUT RESULT IN THE REAL FLAGS	
  2861 00000FC8 88E0                <1> 	mov	al, ah
  2862                              <1> K23D:
  2863 00000FCA 3CB8                <1> 	cmp	al, ALT_KEY+80h		; IS THIS ALTERNATE SHIFT RELEASE
  2864 00000FCC 7536                <1> 	jne	short K26		; INTERRUPT RETURN
  2865                              <1> 	;	
  2866                              <1> 	;-----	ALTERNATE SHIFT KEY RELEASED, GET THE VALUE INTO BUFFER
  2867 00000FCE A0[775C0000]        <1> 	mov	al, [ALT_INPUT]
  2868 00000FD3 B400                <1> 	mov	ah, 0			; SCAN CODE OF 0
  2869 00000FD5 8825[775C0000]      <1> 	mov	[ALT_INPUT], ah 	; ZERO OUT THE FIELD
  2870 00000FDB 3C00                <1> 	cmp	al, 0			; WAS THE INPUT = 0?
  2871 00000FDD 7425                <1> 	je	short K26		; INTERRUPT_RETURN
  2872 00000FDF E9B4020000          <1>         jmp     K61                     ; IT WASN'T, SO PUT IN BUFFER
  2873                              <1> 	;
  2874                              <1> K24:					; BREAK-TOGGLE
  2875 00000FE4 2025[745C0000]      <1> 	and	[KB_FLAG_1], ah 	; INDICATE NO LONGER DEPRESSED
  2876 00000FEA EB18                <1> 	jmp	short K26		; INTERRUPT_RETURN
  2877                              <1> 	;
  2878                              <1> 	;-----	TEST FOR HOLD STATE
  2879                              <1> 					; AL, AH = SCAN CODE
  2880                              <1> K25:					; NO-SHIFT-FOUND
  2881 00000FEC 3C80                <1> 	cmp	al, 80h			; TEST FOR BREAK KEY
  2882 00000FEE 7314                <1> 	jae	short K26		; NOTHING FOR BREAK CHARS FROM HERE ON
  2883 00000FF0 F605[745C0000]08    <1> 	test	byte [KB_FLAG_1], HOLD_STATE ; ARE WE IN HOLD STATE
  2884 00000FF7 7428                <1> 	jz	short K28		; BRANCH AROUND TEST IF NOT
  2885 00000FF9 3C45                <1> 	cmp	al, NUM_KEY
  2886 00000FFB 7407                <1> 	je	short K26		; CAN'T END HOLD ON NUM_LOCK
  2887 00000FFD 8025[745C0000]F7    <1> 	and	byte [KB_FLAG_1], ~HOLD_STATE ; TURN OFF THE HOLD STATE BIT
  2888                              <1> 	;
  2889                              <1> K26:
  2890 00001004 8025[765C0000]FC    <1> 	and	byte [KB_FLAG_3], ~(LC_E0+LC_E1) ; RESET LAST CHAR H.C. FLAG
  2891                              <1> K26A:					; INTERRUPT-RETURN
  2892 0000100B FA                  <1> 	cli				; TURN OFF INTERRUPTS
  2893 0000100C B020                <1> 	mov	al, EOI			; END OF INTERRUPT COMMAND
  2894 0000100E E620                <1> 	out	20h, al	;out INTA00, al	; SEND COMMAND TO INTERRUPT CONTROL PORT
  2895                              <1> K27:					; INTERRUPT-RETURN-NO-EOI
  2896 00001010 B0AE                <1> 	mov	al, ENA_KBD		; INSURE KEYBOARD IS ENABLED
  2897 00001012 E8B8020000          <1> 	call	SHIP_IT			; EXECUTE ENABLE
  2898                              <1> K27A:
  2899 00001017 FA                  <1> 	cli				; DISABLE INTERRUPTS
  2900 00001018 07                  <1> 	pop	es			; RESTORE REGISTERS
  2901 00001019 1F                  <1> 	pop	ds
  2902 0000101A 5F                  <1> 	pop	edi
  2903 0000101B 5E                  <1> 	pop	esi
  2904 0000101C 5A                  <1> 	pop	edx
  2905 0000101D 59                  <1> 	pop	ecx
  2906 0000101E 5B                  <1> 	pop	ebx
  2907 0000101F 58                  <1> 	pop	eax
  2908                              <1> 	;pop	ebp
  2909 00001020 CF                  <1> 	iret				; RETURN
  2910                              <1> 
  2911                              <1> 	;-----	NOT IN	HOLD STATE
  2912                              <1> K28:					; NO-HOLD-STATE
  2913 00001021 3C58                <1> 	cmp	al, 88			; TEST FOR OUT-OF-RANGE SCAN CODES
  2914 00001023 77DF                <1> 	ja	short K26		; IGNORE IF OUT-OF-RANGE	
  2915                              <1> 	;
  2916 00001025 F6C308              <1> 	test	bl, ALT_SHIFT 		; ARE WE IN ALTERNATE SHIFT
  2917 00001028 740E                <1>         jz	short K28A		; IF NOT ALTERNATE
  2918                              <1>         ; 24/12/2021
  2919                              <1> 	;jz      K38
  2920                              <1> 	;
  2921 0000102A F6C710              <1> 	test	bh, KBX			; IS THIS THE ENCHANCED KEYBOARD?
  2922 0000102D 740E                <1> 	jz	short K29		; NO, ALT STATE IS REAL
  2923                              <1> 	; 28/02/2015
  2924 0000102F F605[745C0000]04    <1> 	test	byte [KB_FLAG_1], SYS_SHIFT ; YES, IS SYSREQ KEY DOWN?
  2925 00001036 7405                <1> 	jz	short K29		; NO, ALT STATE IS REAL
  2926                              <1> 	; 24/12/2021
  2927                              <1> 	;jnz	K38			; YES, THIS IS PHONY ALT STATE 
  2928                              <1>         ;				; DUE TO PRESSING SYSREQ	
  2929 00001038 E9CD000000          <1> K28A:	jmp	K38
  2930                              <1> 	;
  2931                              <1> 	;-----	TEST FOR RESET KEY SEQUENCE (CTL ALT DEL)
  2932                              <1> K29:					; TEST-RESET
  2933 0000103D F6C304              <1> 	test	bl, CTL_SHIFT 		; ARE WE IN CONTROL SHIFT ALSO?
  2934 00001040 740B                <1> 	jz	short K31		; NO_RESET
  2935 00001042 3C53                <1> 	cmp	al, DEL_KEY		; CTL-ALT STATE, TEST FOR DELETE KEY
  2936 00001044 7507                <1> 	jne	short K31		; NO_RESET, IGNORE
  2937                              <1> 	;
  2938                              <1> 	;-----	CTL-ALT-DEL HAS BEEN FOUND
  2939                              <1>  	; 26/08/2014
  2940                              <1> cpu_reset:
  2941                              <1> 	; IBM PC/AT ROM BIOS source code - 10/06/85 (TEST4.ASM - PROC_SHUTDOWN)
  2942                              <1> 	; Send FEh (system reset command) to the keyboard controller.
  2943 00001046 B0FE                <1> 	mov	al, SHUT_CMD		; SHUTDOWN COMMAND
  2944 00001048 E664                <1> 	out	STATUS_PORT, al		; SEND TO KEYBOARD CONTROL PORT
  2945                              <1> khere:
  2946 0000104A F4                  <1> 	hlt				; WAIT FOR 80286 RESET
  2947 0000104B EBFD                <1> 	jmp 	short khere		; INSURE HALT
  2948                              <1> 
  2949                              <1> 	;
  2950                              <1> 	;-----	IN ALTERNATE SHIFT, RESET NOT FOUND
  2951                              <1> K31:					; NO-RESET
  2952 0000104D 3C39                <1> 	cmp	al, 57			; TEST FOR SPACE KEY
  2953 0000104F 7507                <1> 	jne	short K311		; NOT THERE
  2954 00001051 B020                <1> 	mov	al, ' '			; SET SPACE CHAR
  2955 00001053 E932020000          <1>         jmp     K57                     ; BUFFER_FILL
  2956                              <1> K311:
  2957 00001058 3C0F                <1> 	cmp	al, 15			; TEST FOR TAB KEY
  2958 0000105A 7509                <1> 	jne	short K312		; NOT THERE
  2959 0000105C 66B800A5            <1> 	mov	ax, 0A500h		; SET SPECIAL CODE FOR ALT-TAB
  2960 00001060 E925020000          <1>         jmp     K57                     ; BUFFER_FILL
  2961                              <1> K312:
  2962 00001065 3C4A                <1> 	cmp	al, 74			; TEST FOR KEY PAD -
  2963 00001067 7471                <1>         je	short K37B              ; GO PROCESS
  2964 00001069 3C4E                <1> 	cmp	al, 78			; TEST FOR KEY PAD +
  2965 0000106B 746D                <1>         je	short K37B              ; GO PROCESS
  2966                              <1> 	;
  2967                              <1> 	;-----	LOOK FOR KEY PAD ENTRY
  2968                              <1> K32:					; ALT-KEY-PAD
  2969 0000106D BF[345B0000]        <1> 	mov	edi, K30		; ALT-INPUT-TABLE offset
  2970 00001072 B90A000000          <1> 	mov	ecx, 10			; LOOK FOR ENTRY USING KEYPAD
  2971 00001077 F2AE                <1> 	repne	scasb			; LOOK FOR MATCH
  2972 00001079 7523                <1> 	jne	short K33		; NO_ALT_KEYPAD
  2973 0000107B F6C702              <1> 	test	bh, LC_E0		; IS THIS ONE OF THE NEW KEYS?
  2974                              <1>         ;jnz	short K37C		; YES, JUMP, NOT NUMPAD KEY
  2975                              <1> 	; 24/12/2021
  2976 0000107E 751C                <1> 	jnz	short K32B
  2977 00001080 81EF[355B0000]      <1> 	sub	edi, K30+1		; DI NOW HAS ENTRY VALUE
  2978 00001086 A0[775C0000]        <1> 	mov	al, [ALT_INPUT] 	; GET THE CURRENT BYTE
  2979 0000108B B40A                <1> 	mov	ah, 10			; MULTIPLY BY 10
  2980 0000108D F6E4                <1> 	mul	ah
  2981 0000108F 6601F8              <1> 	add	ax, di			; ADD IN THE LATEST ENTRY
  2982 00001092 A2[775C0000]        <1> 	mov	[ALT_INPUT], al 	; STORE IT AWAY
  2983                              <1> K32A:
  2984 00001097 E968FFFFFF          <1>         jmp     K26                     ; THROW AWAY THAT KEYSTROKE
  2985                              <1> K32B:
  2986                              <1> 	; 24/12/2021
  2987 0000109C EB66                <1> 	jmp	K37C
  2988                              <1> 	;
  2989                              <1> 	;-----	LOOK FOR SUPERSHIFT ENTRY
  2990                              <1> K33:					; NO-ALT-KEYPAD
  2991 0000109E C605[775C0000]00    <1>         mov     byte [ALT_INPUT], 0     ; ZERO ANY PREVIOUS ENTRY INTO INPUT
  2992 000010A5 B91A000000          <1> 	mov	ecx, 26			; (DI),(ES) ALREADY POINTING
  2993 000010AA F2AE                <1> 	repne	scasb			; LOOK FOR MATCH IN ALPHABET
  2994 000010AC 744F                <1> 	je	short K37A		; MATCH FOUND, GO FILLL THE BUFFER
  2995                              <1> 	;
  2996                              <1> 	;-----	LOOK FOR TOP ROW OF ALTERNATE SHIFT
  2997                              <1> K34:					; ALT-TOP-ROW
  2998 000010AE 3C02                <1> 	cmp	al, 2			; KEY WITH '1' ON IT
  2999 000010B0 7228                <1> 	jb	short K37B		; MUST BE ESCAPE
  3000 000010B2 3C0D                <1> 	cmp	al, 13			; IS IT IN THE REGION
  3001 000010B4 7705                <1> 	ja	short K35		; NO, ALT SOMETHING ELSE
  3002 000010B6 80C476              <1> 	add	ah, 118			; CONVERT PSEUDO SCAN CODE TO RANGE
  3003 000010B9 EB42                <1> 	jmp	short K37A		; GO FILL THE BUFFER
  3004                              <1> 	;
  3005                              <1> 	;-----	TRANSLATE ALTERNATE SHIFT PSEUDO SCAN CODES
  3006                              <1> K35:					; ALT-FUNCTION
  3007 000010BB 3C57                <1> 	cmp	al, F11_M		; IS IT F11?	
  3008 000010BD 7209                <1> 	jb	short K35A ; 20/02/2015	; NO, BRANCH
  3009 000010BF 3C58                <1> 	cmp	al, F12_M		; IS IT F12?
  3010 000010C1 7705                <1> 	ja	short K35A ; 20/02/2015	; NO, BRANCH
  3011 000010C3 80C434              <1> 	add	ah, 52			; CONVERT TO PSEUDO SCAN CODE
  3012 000010C6 EB35                <1> 	jmp	short K37A		; GO FILL THE BUFFER
  3013                              <1> K35A:
  3014 000010C8 F6C702              <1> 	test	bh, LC_E0		; DO WE HAVE ONE OF THE NEW KEYS?
  3015 000010CB 7425                <1> 	jz	short K37		; NO, JUMP
  3016 000010CD 3C1C                <1> 	cmp	al, 28			; TEST FOR KEYPAD ENTER
  3017 000010CF 7510                <1>         jne     short K35B              ; NOT THERE
  3018 000010D1 66B800A6            <1> 	mov	ax, 0A600h		; SPECIAL CODE
  3019 000010D5 E9B0010000          <1> 	jmp	K57			; BUFFER FILL
  3020                              <1> K37B:
  3021 000010DA B0F0                <1> 	mov	al, 0F0h		; USE SPECIAL ASCII CODE
  3022 000010DC E9A9010000          <1> 	jmp     K57                     ; PUT IT IN THE BUFFER
  3023                              <1> K35B:
  3024 000010E1 3C53                <1> 	cmp	al, 83			; TEST FOR DELETE KEY
  3025 000010E3 741F                <1> 	je	short K37C		; HANDLE WITH OTHER EDIT KEYS
  3026 000010E5 3C35                <1> 	cmp	al, 53			; TEST FOR KEYPAD /
  3027 000010E7 75AE                <1> 	jne	short K32A		; NOT THERE, NO OTHER E0 SPECIALS	
  3028                              <1>         ; 24/12/2021
  3029                              <1> 	;jne	K26
  3030 000010E9 66B800A4            <1> 	mov	ax, 0A400h		; SPECIAL CODE
  3031 000010ED E998010000          <1> 	jmp	K57			; BUFFER FILL
  3032                              <1> K37:
  3033 000010F2 3C3B                <1> 	cmp	al, 59			; TEST FOR FUNCTION KEYS (F1)
  3034 000010F4 72E4                <1>         jb      short K37B		; NO FN, HANDLE W/OTHER EXTENDED
  3035 000010F6 3C44                <1> 	cmp	al, 68			; IN KEYPAD REGION?
  3036 000010F8 779D                <1>         ja	short K32A		; IF SO, IGNORE
  3037                              <1> 	; 13/06/2022
  3038                              <1>         ;ja	K26
  3039 000010FA 80C42D              <1> 	add	ah, 45			; CONVERT TO PSEUDO SCAN CODE
  3040                              <1> K37A:
  3041 000010FD B000                <1> 	mov	al, 0			; ASCII CODE OF ZERO
  3042 000010FF E986010000          <1>         jmp     K57                     ; PUT IT IN THE BUFFER
  3043                              <1> K37C:
  3044 00001104 0450                <1> 	add	al, 80			; CONVERT SCAN CODE (EDIT KEYS)
  3045 00001106 88C4                <1> 	mov	ah, al			; (SCAN CODE NOT IN AH FOR INSERT)
  3046 00001108 EBF3                <1> 	jmp     short K37A              ; PUT IT IN THE BUFFER
  3047                              <1> 	;
  3048                              <1> 	;-----	NOT IN ALTERNATE SHIFT
  3049                              <1> K38:					; NOT-ALT-SHIFT
  3050                              <1> 					; BL STILL HAS SHIFT FLAGS
  3051 0000110A F6C304              <1> 	test	bl, CTL_SHIFT 		; ARE WE IN CONTROL SHIFT?
  3052 0000110D 7505                <1> 	jnz	short K38A		; YES, START PROCESSING	
  3053                              <1>         ;jz	K44                     ; NOT-CTL-SHIFT
  3054                              <1> 	; 24/12/2021
  3055 0000110F E9AB000000          <1> 	jmp	K44
  3056                              <1> 	;
  3057                              <1> 	;-----	CONTROL SHIFT, TEST SPECIAL CHARACTERS
  3058                              <1> 	;-----	TEST FOR BREAK
  3059                              <1> K38A:
  3060 00001114 3C46                <1> 	cmp	al, SCROLL_KEY		; TEST FOR BREAK
  3061 00001116 7530                <1> 	jne	short K39		; JUMP, NO-BREAK
  3062 00001118 F6C710              <1> 	test	bh, KBX			; IS THIS THE ENHANCED KEYBOARD?
  3063 0000111B 7405                <1> 	jz	short K38B		; NO, BREAK IS VALID	
  3064 0000111D F6C702              <1> 	test	bh, LC_E0		; YES, WAS LAST CODE AN E0?
  3065 00001120 7426                <1> 	jz	short K39		; NO-BREAK, TEST FOR PAUSE	
  3066                              <1> K38B:
  3067 00001122 8B1D[805C0000]      <1> 	mov	ebx, [BUFFER_HEAD] 	; RESET BUFFER TO EMPTY
  3068 00001128 891D[845C0000]      <1> 	mov	[BUFFER_TAIL], ebx
  3069 0000112E C605[725C0000]80    <1> 	mov	byte [BIOS_BREAK], 80h  ; TURN ON BIOS_BREAK BIT
  3070                              <1> 	;
  3071                              <1> 	;-----	ENABLE KEYBOARD
  3072 00001135 B0AE                <1> 	mov	al, ENA_KBD		; ENABLE KEYBOARD
  3073 00001137 E893010000          <1> 	call	SHIP_IT			; EXECUTE ENABLE
  3074                              <1> 	;
  3075                              <1> 	; CTRL+BREAK code here !!!
  3076                              <1> 	;INT	1BH			; BREAK INTERRUPT VECTOR
  3077                              <1> 	; 17/10/2015	
  3078 0000113C E88C190000          <1> 	call	ctrlbrk ; control+break subroutine
  3079                              <1> 	;
  3080                              <1> 	;sub	ax, ax			; PUT OUT DUMMY CHARACTER
  3081                              <1> 	; 24/12/2021
  3082 00001141 29C0                <1> 	sub	eax, eax
  3083 00001143 E942010000          <1> 	jmp     K57                     ; BUFFER_FILL
  3084                              <1> 	;
  3085                              <1> 	;-----	TEST FOR PAUSE
  3086                              <1> K39:					; NO_BREAK
  3087 00001148 F6C710              <1> 	test	bh, KBX			; IS THIS THE ENHANCED KEYBOARD?
  3088 0000114B 7537                <1> 	jnz	short K41		; YES, THEN THIS CAN'T BE PAUSE	
  3089 0000114D 3C45                <1> 	cmp	al, NUM_KEY		; LOOK FOR PAUSE KEY
  3090 0000114F 7533                <1> 	jne	short K41		; NO-PAUSE
  3091                              <1> K39P:
  3092 00001151 800D[745C0000]08    <1> 	or	byte [KB_FLAG_1], HOLD_STATE ; TURN ON THE HOLD FLAG
  3093                              <1> 	;
  3094                              <1> 	;-----	ENABLE KEYBOARD
  3095 00001158 B0AE                <1> 	mov	al, ENA_KBD		; ENABLE KEYBOARD
  3096 0000115A E870010000          <1> 	call	SHIP_IT			; EXECUTE ENABLE
  3097                              <1> K39A:
  3098 0000115F B020                <1> 	mov	al, EOI			; END OF INTERRUPT TO CONTROL PORT
  3099 00001161 E620                <1> 	out	20h, al ;out INTA00, al	; ALLOW FURTHER KEYSTROKE INTERRUPTS
  3100                              <1> 	;
  3101                              <1> 	;-----	DURING PAUSE INTERVAL, TURN COLOR CRT BACK ON
  3102 00001163 803D[705C0000]07    <1>         cmp     byte [CRT_MODE], 7      ; IS THIS BLACK AND WHITE CARD
  3103 0000116A 740A                <1>         je      short K40              	; YES, NOTHING TO DO
  3104 0000116C 66BAD803            <1> 	mov	dx, 03D8h		; PORT FOR COLOR CARD
  3105 00001170 A0[715C0000]        <1>         mov     al, [CRT_MODE_SET] 	; GET THE VALUE OF THE CURRENT MODE
  3106 00001175 EE                  <1> 	out	dx, al			; SET THE CRT MODE, SO THAT CRT IS ON
  3107                              <1> 	;
  3108                              <1> K40:					; PAUSE-LOOP
  3109 00001176 F605[745C0000]08    <1>         test    byte [KB_FLAG_1], HOLD_STATE ; CHECK HOLD STATE FLAG
  3110 0000117D 75F7                <1> 	jnz	short K40		; LOOP UNTIL FLAG TURNED OFF
  3111                              <1> 	;
  3112 0000117F E98CFEFFFF          <1>         jmp     K27                     ; INTERRUPT_RETURN_NO_EOI
  3113                              <1>         ;
  3114                              <1> 	;-----	TEST SPECIAL CASE KEY 55
  3115                              <1> K41:					; NO-PAUSE
  3116 00001184 3C37                <1> 	cmp	al, 55			; TEST FOR */PRTSC KEY
  3117 00001186 7513                <1> 	jne	short K42		; NOT-KEY-55
  3118 00001188 F6C710              <1> 	test	bh, KBX			; IS THIS THE ENHANCED KEYBOARD?
  3119 0000118B 7405                <1> 	jz	short K41A		; NO, CTL-PRTSC IS VALID	
  3120 0000118D F6C702              <1> 	test	bh, LC_E0		; YES, WAS LAST CODE AN E0?
  3121 00001190 7421                <1> 	jz	short K42B		; NO, TRANSLATE TO A FUNCTION
  3122                              <1> K41A:	
  3123 00001192 66B80072            <1> 	mov	ax, 114*256		; START/STOP PRINTING SWITCH
  3124 00001196 E9EF000000          <1>         jmp     K57                     ; BUFFER_FILL
  3125                              <1> 	;
  3126                              <1> 	;-----	SET UP TO TRANSLATE CONTROL SHIFT
  3127                              <1> K42:					; NOT-KEY-55
  3128 0000119B 3C0F                <1> 	cmp	al, 15			; IS IT THE TAB KEY?
  3129 0000119D 7414                <1> 	je	short K42B		; YES, XLATE TO FUNCTION CODE
  3130 0000119F 3C35                <1> 	cmp	al, 53			; IS IT THE / KEY?
  3131 000011A1 750E                <1> 	jne	short K42A		; NO, NO MORE SPECIAL CASES	
  3132 000011A3 F6C702              <1> 	test	bh, LC_E0		; YES, IS IT FROM THE KEY PAD?
  3133 000011A6 7409                <1> 	jz	short K42A		; NO, JUST TRANSLATE
  3134 000011A8 66B80095            <1> 	mov	ax, 9500h		; YES, SPECIAL CODE FOR THIS ONE
  3135 000011AC E9D9000000          <1> 	jmp	K57			; BUFFER FILL	
  3136                              <1> K42A:
  3137                              <1> 	;mov	ebx, _K8		; SET UP TO TRANSLATE CTL
  3138 000011B1 3C3B                <1> 	cmp	al, 59			; IS IT IN CHARACTER TABLE?
  3139                              <1>         ;jb	short K45F              ; YES, GO TRANSLATE CHAR
  3140                              <1> 	;;jb	K56 ; 20/02/2015
  3141                              <1> 	;;jmp	K64 ; 20/02/2015
  3142                              <1> K42B:
  3143 000011B3 BB[685B0000]        <1> 	mov	ebx, _K8		; SET UP TO TRANSLATE CTL
  3144                              <1> 	;;jmp	K64
  3145                              <1> 	;jb	K56 ;; 20/02/2015	
  3146                              <1> 	; 24/12/2021
  3147 000011B8 7267                <1> 	jb	short K45F
  3148 000011BA E9B9000000          <1> 	jmp	K64	
  3149                              <1>         ;
  3150                              <1> 	;-----	NOT IN CONTROL SHIFT
  3151                              <1> K44:					; NOT-CTL-SHIFT
  3152 000011BF 3C37                <1> 	cmp	al, 55			; PRINT SCREEN KEY?
  3153 000011C1 7528                <1> 	jne	short K45		; NOT PRINT SCREEN
  3154 000011C3 F6C710              <1> 	test	bh, KBX			; IS THIS ENHANCED KEYBOARD?
  3155 000011C6 7407                <1> 	jz	short K44A		; NO, TEST FOR SHIFT STATE	
  3156 000011C8 F6C702              <1> 	test	bh, LC_E0		; YES, LAST CODE A MARKER?
  3157 000011CB 7507                <1> 	jnz	short K44B		; YES, IS PRINT SCREEN
  3158 000011CD EB41                <1> 	jmp	short K45C		; NO, TRANSLATE TO '*' CHARACTER
  3159                              <1> K44A:
  3160 000011CF F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; NOT 101 KBD, SHIFT KEY DOWN?
  3161 000011D2 743C                <1> 	jz	short K45C		; NO, TRANSLATE TO '*' CHARACTER
  3162                              <1> 	;
  3163                              <1> 	;-----	ISSUE INTERRUPT TO INDICATE PRINT SCREEN FUNCTION
  3164                              <1> K44B:
  3165 000011D4 B0AE                <1> 	mov	al, ENA_KBD		; INSURE KEYBOARD IS ENABLED
  3166 000011D6 E8F4000000          <1> 	call	SHIP_IT			; EXECUTE ENABLE
  3167 000011DB B020                <1> 	mov	al, EOI			; END OF CURRENT INTERRUPT
  3168 000011DD E620                <1> 	out	20h, al ;out INTA00, al	; SO FURTHER THINGS CAN HAPPEN
  3169                              <1> 	; Print Screen !!!		; ISSUE PRINT SCREEN INTERRUPT (INT 05h)
  3170                              <1> 	;PUSH 	BP			; SAVE POINTER
  3171                              <1> 	;INT 	5H			; ISSUE PRINT SCREEN INTERRUPT
  3172                              <1> 	;POP	BP			; RESTORE POINTER
  3173 000011DF 8025[765C0000]FC    <1>         and     byte [KB_FLAG_3], ~(LC_E0+LC_E1) ; ZERO OUT THESE FLAGS
  3174 000011E6 E925FEFFFF          <1>         jmp     K27                     ; GO BACK WITHOUT EOI OCCURRING
  3175                              <1> 	;
  3176                              <1> 	;-----	HANDLE IN-CORE KEYS
  3177                              <1> K45:					; NOT-PRINT-SCREEN
  3178 000011EB 3C3A                <1> 	cmp	al, 58			; TEST FOR IN-CORE AREA
  3179 000011ED 7734                <1> 	ja	short K46		; JUMP IF NOT
  3180 000011EF 3C35                <1> 	cmp	al, 53			; IS THIS THE '/' KEY?
  3181 000011F1 7505                <1> 	jne	short K45A		; NO, JUMP
  3182 000011F3 F6C702              <1> 	test	bh, LC_E0		; WAS THE LAST CODE THE MARKER?
  3183 000011F6 7518                <1> 	jnz	short K45C		; YES, TRANSLATE TO CHARACTER
  3184                              <1> K45A:
  3185 000011F8 B91A000000          <1> 	mov	ecx, 26			; LENGHT OF SEARCH
  3186 000011FD BF[3E5B0000]        <1> 	mov	edi, K30+10		; POINT TO TABLE OF A-Z CHARS
  3187 00001202 F2AE                <1> 	repne	scasb			; IS THIS A LETTER KEY?
  3188                              <1> 		; 20/02/2015
  3189 00001204 7505                <1> 	jne	short K45B              ; NO, SYMBOL KEY
  3190                              <1> 	;
  3191 00001206 F6C340              <1> 	test	bl, CAPS_STATE		; ARE WE IN CAPS_LOCK?
  3192 00001209 750C                <1> 	jnz	short K45D		; TEST FOR SURE
  3193                              <1> K45B:
  3194 0000120B F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; ARE WE IN SHIFT STATE?
  3195 0000120E 750C                <1> 	jnz	short K45E		; YES, UPPERCASE
  3196                              <1> 					; NO, LOWERCASE
  3197                              <1> K45C:
  3198 00001210 BB[C05B0000]        <1> 	mov	ebx, K10		; TRANSLATE TO LOWERCASE LETTERS
  3199 00001215 EB51                <1> 	jmp	short K56	
  3200                              <1> K45D:					; ALMOST-CAPS-STATE
  3201 00001217 F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; CL ON. IS SHIFT ON, TOO?
  3202 0000121A 75F4                <1> 	jnz	short K45C		; SHIFTED TEMP OUT OF CAPS STATE
  3203                              <1> K45E:
  3204 0000121C BB[185C0000]        <1> 	mov	ebx, K11		; TRANSLATE TO UPPER CASE LETTERS
  3205 00001221 EB45                <1> K45F:	jmp	short K56
  3206                              <1> 	;
  3207                              <1> 	;-----	TEST FOR KEYS F1 - F10
  3208                              <1> K46:					; NOT IN-CORE AREA
  3209 00001223 3C44                <1> 	cmp	al, 68			; TEST FOR F1 - F10
  3210                              <1> 	;ja	short K47		; JUMP IF NOT
  3211                              <1> 	;jmp	short K53		; YES, GO DO FN KEY PROCESS			
  3212 00001225 7635                <1> 	jna	short K53		
  3213                              <1> 	;
  3214                              <1> 	;-----	HANDLE THE NUMERIC PAD KEYS
  3215                              <1> K47:					; NOT F1 - F10
  3216 00001227 3C53                <1> 	cmp	al, 83			; TEST NUMPAD KEYS
  3217 00001229 772D                <1> 	ja	short K52		; JUMP IF NOT
  3218                              <1> 	;
  3219                              <1> 	;-----	KEYPAD KEYS, MUST TEST NUM LOCK FOR DETERMINATION
  3220                              <1> K48:
  3221 0000122B 3C4A                <1> 	cmp	al , 74			; SPECIAL CASE FOR MINUS
  3222 0000122D 74ED                <1> 	je	short K45E		; GO TRANSLATE
  3223 0000122F 3C4E                <1> 	cmp	al , 78			; SPECIAL CASE FOR PLUS
  3224 00001231 74E9                <1> 	je	short K45E		; GO TRANSLATE
  3225 00001233 F6C702              <1> 	test	bh, LC_E0		; IS THIS ONE OFTHE NEW KEYS?
  3226 00001236 750A                <1> 	jnz	short K49		; YES, TRANSLATE TO BASE STATE
  3227                              <1> 	;		
  3228 00001238 F6C320              <1> 	test 	bl, NUM_STATE		; ARE WE IN NUM LOCK
  3229 0000123B 7514                <1> 	jnz	short K50		; TEST FOR SURE
  3230 0000123D F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; ARE WE IN SHIFT STATE?
  3231                              <1> 	;jnz	short K51		; IF SHIFTED, REALLY NUM STATE
  3232 00001240 75DA                <1> 	jnz	short K45E
  3233                              <1> 	;
  3234                              <1> 	;-----	BASE CASE FOR KEYPAD
  3235                              <1> K49:					
  3236 00001242 3C4C                <1> 	cmp	al, 76			; SPECIAL CASE FOR BASE STATE 5
  3237 00001244 7504                <1> 	jne	short K49A		; CONTINUE IF NOT KEYPAD 5
  3238 00001246 B0F0                <1> 	mov	al, 0F0h		; SPECIAL ASCII CODE	
  3239 00001248 EB40                <1> 	jmp	short K57		; BUFFER FILL
  3240                              <1> K49A:
  3241 0000124A BB[C05B0000]        <1> 	mov	ebx, K10		; BASE CASE TABLE	
  3242 0000124F EB27                <1> 	jmp	short K64		; CONVERT TO PSEUDO SCAN
  3243                              <1> 	;
  3244                              <1> 	;-----	MIGHT BE NUM LOCK, TEST SHIFT STATUS
  3245                              <1> K50:					; ALMOST-NUM-STATE
  3246 00001251 F6C303              <1>         test    bl, LEFT_SHIFT+RIGHT_SHIFT
  3247 00001254 75EC                <1> 	jnz 	short K49		; SHIFTED TEMP OUT OF NUM STATE
  3248 00001256 EBC4                <1> K51:	jmp	short K45E		; REALLY NUM STATE
  3249                              <1> 	;
  3250                              <1> 	;-----	TEST FOR THE NEW KEYS ON WT KEYBOARDS 
  3251                              <1> K52:					; NOT A NUMPAD KEY
  3252 00001258 3C56                <1> 	cmp	al, 86			; IS IT THE NEW WT KEY?
  3253                              <1> 	;jne	short K53		; JUMP IF NOT
  3254                              <1> 	;jmp	short K45B		; HANDLE WITH REST OF LETTER KEYS
  3255 0000125A 74AF                <1> 	je	short K45B		
  3256                              <1> 	;
  3257                              <1> 	;-----	MUST BE F11 OR F12 
  3258                              <1> K53:					; F1 - F10 COME HERE, TOO
  3259 0000125C F6C303              <1> 	test	bl, LEFT_SHIFT+RIGHT_SHIFT ; TEST SHIFT STATE
  3260 0000125F 74E1                <1> 	jz	short K49		; JUMP, LOWER CASE PSEUDO SC'S
  3261                              <1> 		; 20/02/2015 
  3262 00001261 BB[185C0000]        <1> 	mov	ebx, K11		; UPPER CASE PSEUDO SCAN CODES
  3263 00001266 EB10                <1> 	jmp	short K64		; TRANSLATE SCAN
  3264                              <1> 	;
  3265                              <1> 	;-----	TRANSLATE THE CHARACTER
  3266                              <1> K56:					; TRANSLATE-CHAR
  3267 00001268 FEC8                <1> 	dec	al			; CONVERT ORIGIN
  3268 0000126A D7                  <1> 	xlat    			; CONVERT THE SCAN CODE TO ASCII
  3269 0000126B F605[765C0000]02    <1> 	test	byte [KB_FLAG_3], LC_E0	; IS THIS A NEW KEY?
  3270 00001272 7416                <1> 	jz	short K57		; NO, GO FILL BUFFER
  3271 00001274 B4E0                <1> 	mov	ah, MC_E0		; YES, PUT SPECIAL MARKER IN AH
  3272 00001276 EB12                <1> 	jmp	short K57		; PUT IT INTO THE BUFFER	
  3273                              <1> 	;
  3274                              <1> 	;-----	TRANSLATE SCAN FOR PSEUDO SCAN CODES
  3275                              <1> K64:					; TRANSLATE-SCAN-ORGD
  3276 00001278 FEC8                <1> 	dec	al			; CONVERT ORIGIN
  3277 0000127A D7                  <1>        	xlat    	                ; CTL TABLE SCAN
  3278 0000127B 88C4                <1> 	mov	ah, al			; PUT VALUE INTO AH
  3279 0000127D B000                <1> 	mov	al, 0			; ZERO ASCII CODE
  3280 0000127F F605[765C0000]02    <1> 	test	byte [KB_FLAG_3], LC_E0	; IS THIS A NEW KEY?
  3281 00001286 7402                <1> 	jz	short K57		; NO, GO FILL BUFFER
  3282 00001288 B0E0                <1> 	mov	al, MC_E0		; YES, PUT SPECIAL MARKER IN AL
  3283                              <1> 	;
  3284                              <1> 	;-----	PUT CHARACTER INTO BUFFER
  3285                              <1> K57:					; BUFFER_FILL
  3286 0000128A 3CFF                <1> 	cmp	al, -1			; IS THIS AN IGNORE CHAR
  3287 0000128C 7405                <1>         je	short K59		; YES, DO NOTHING WITH IT
  3288                              <1> 	; 24/12/2021
  3289                              <1> 	;je	K26			; YES, DO NOTHING WITH IT
  3290 0000128E 80FCFF              <1> 	cmp	ah, -1			; LOOK FOR -1 PSEUDO SCAN
  3291                              <1> 	; 24/12/2021
  3292 00001291 7505                <1>         jne	short K61		; NEAR_INTERRUPT_RETURN
  3293                              <1> 	;je	K26			; INTERRUPT_RETURN
  3294                              <1> K59:					; NEAR_INTERRUPT_RETURN
  3295 00001293 E96CFDFFFF          <1> 	jmp	K26			; INTERRUPT_RETURN
  3296                              <1> K61:					; NOT-CAPS-STATE
  3297 00001298 8B1D[845C0000]      <1> 	mov	ebx, [BUFFER_TAIL] 	; GET THE END POINTER TO THE BUFFER
  3298 0000129E 89DE                <1> 	mov	esi, ebx		; SAVE THE VALUE
  3299 000012A0 E8AEFAFFFF          <1> 	call	_K4			; ADVANCE THE TAIL
  3300 000012A5 3B1D[805C0000]      <1> 	cmp	ebx, [BUFFER_HEAD] 	; HAS THE BUFFER WRAPPED AROUND
  3301 000012AB 740E                <1> 	je	short K62		; BUFFER_FULL_BEEP
  3302 000012AD 668906              <1> 	mov	[esi], ax		; STORE THE VALUE
  3303 000012B0 891D[845C0000]      <1> 	mov	[BUFFER_TAIL], ebx 	; MOVE THE POINTER UP
  3304 000012B6 E949FDFFFF          <1> 	jmp	K26
  3305                              <1> 	;;cli				; TURN OFF INTERRUPTS
  3306                              <1> 	;;mov	al, EOI			; END OF INTERRUPT COMMAND
  3307                              <1> 	;;out	INTA00, al		; SEND COMMAND TO INTERRUPT CONTROL PORT
  3308                              <1> 	;MOV	AL, ENA_KBD		; INSURE KEYBOARD IS ENABLED
  3309                              <1> 	;CALL	SHIP_IT			; EXECUTE ENABLE
  3310                              <1> 	;MOV	AX, 9102H		; MOVE IN POST CODE & TYPE
  3311                              <1> 	;INT	15H			; PERFORM OTHER FUNCTION
  3312                              <1> 	;;and	byte [KB_FLAG_3],~(LC_E0+LC_E1) ; RESET LAST CHAR H.C. FLAG
  3313                              <1> 	;JMP	K27A			; INTERRUPT_RETURN
  3314                              <1> 	;;jmp   K27                    
  3315                              <1> 	;
  3316                              <1> 	;-----	BUFFER IS FULL SOUND THE BEEPER
  3317                              <1> K62:
  3318 000012BB B020                <1> 	mov	al, EOI			; ENABLE INTERRUPT CONTROLLER CHIP
  3319 000012BD E620                <1> 	out	INTA00, al
  3320 000012BF 66B9A602            <1> 	mov	cx, 678			; DIVISOR FOR 1760 HZ
  3321 000012C3 B304                <1> 	mov	bl, 4			; SHORT BEEP COUNT (1/16 + 1/64 DELAY)
  3322 000012C5 E883010000          <1> 	call	beep			; GO TO COMMON BEEP HANDLER
  3323 000012CA E941FDFFFF          <1> 	jmp     K27			; EXIT   
  3324                              <1> 
  3325                              <1> SHIP_IT:
  3326                              <1> 	;---------------------------------------------------------------------------------
  3327                              <1> 	; SHIP_IT
  3328                              <1> 	;	THIS ROUTINES HANDLES TRANSMISSION OF COMMAND AND DATA BYTES
  3329                              <1> 	;	TO THE KEYBOARD CONTROLLER.
  3330                              <1> 	;---------------------------------------------------------------------------------
  3331                              <1> 	;
  3332                              <1> 	;push	ax			; SAVE DATA TO SEND
  3333                              <1> 	; 24/12/2021
  3334 000012CF 50                  <1> 	push	eax
  3335                              <1> 	;-----	WAIT FOR COMMAND TO ACCEPTED
  3336 000012D0 FA                  <1> 	cli				; DISABLE INTERRUPTS TILL DATA SENT
  3337                              <1> 	; xor	ecx, ecx		; CLEAR TIMEOUT COUNTER
  3338 000012D1 B900000100          <1> 	mov	ecx, 10000h			
  3339                              <1> S10:
  3340 000012D6 E464                <1> 	in	al, STATUS_PORT		; READ KEYBOARD CONTROLLER STATUS
  3341 000012D8 A802                <1> 	test	al, INPT_BUF_FULL	; CHECK FOR ITS INPUT BUFFER BUSY
  3342 000012DA E0FA                <1> 	loopnz	S10			; WAIT FOR COMMAND TO BE ACCEPTED
  3343                              <1> 
  3344                              <1> 	;pop	ax			; GET DATA TO SEND
  3345                              <1> 	; 24/12/2021
  3346 000012DC 58                  <1> 	pop	eax
  3347 000012DD E664                <1> 	out	STATUS_PORT, al		; SEND TO KEYBOARD CONTROLLER
  3348 000012DF FB                  <1> 	sti				; ENABLE INTERRUPTS AGAIN
  3349 000012E0 C3                  <1> 	retn				; RETURN TO CALLER
  3350                              <1> 
  3351                              <1> SND_DATA:
  3352                              <1> 	; ---------------------------------------------------------------------------------
  3353                              <1> 	; SND_DATA
  3354                              <1> 	;	THIS ROUTINES HANDLES TRANSMISSION OF COMMAND AND DATA BYTES
  3355                              <1> 	;	TO THE KEYBOARD AND RECEIPT OF ACKNOWLEDGEMENTS. IT ALSO
  3356                              <1> 	;	HANDLES ANY RETRIES IF REQUIRED
  3357                              <1> 	; ---------------------------------------------------------------------------------
  3358                              <1> 	;
  3359                              <1> 	;push	ax			; SAVE REGISTERS
  3360                              <1> 	;push	bx
  3361                              <1> 	; 24/12/2021
  3362 000012E1 50                  <1> 	push	eax
  3363 000012E2 53                  <1> 	push	ebx
  3364 000012E3 51                  <1> 	push	ecx
  3365 000012E4 88C7                <1> 	mov	bh, al			; SAVE TRANSMITTED BYTE FOR RETRIES
  3366 000012E6 B303                <1> 	mov	bl, 3			; LOAD RETRY COUNT
  3367                              <1> SD0:
  3368 000012E8 FA                  <1> 	cli				; DISABLE INTERRUPTS
  3369 000012E9 8025[755C0000]CF    <1> 	and	byte [KB_FLAG_2], ~(KB_FE+KB_FA) ; CLEAR ACK AND RESEND FLAGS
  3370                              <1> 	;
  3371                              <1> 	;-----	WAIT FOR COMMAND TO BE ACCEPTED
  3372 000012F0 B900000100          <1> 	mov	ecx, 10000h		; MAXIMUM WAIT COUNT
  3373                              <1> SD5:
  3374 000012F5 E464                <1> 	in	al, STATUS_PORT		; READ KEYBOARD PROCESSOR STATUS PORT
  3375 000012F7 A802                <1> 	test	al, INPT_BUF_FULL	; CHECK FOR ANY PENDING COMMAND
  3376 000012F9 E0FA                <1> 	loopnz	SD5			; WAIT FOR COMMAND TO BE ACCEPTED
  3377                              <1> 	;
  3378 000012FB 88F8                <1> 	mov	al, bh			; REESTABLISH BYTE TO TRANSMIT
  3379 000012FD E660                <1> 	out	PORT_A, al		; SEND BYTE
  3380 000012FF FB                  <1> 	sti				; ENABLE INTERRUPTS
  3381                              <1> 	;mov	cx, 01A00h		; LOAD COUNT FOR 10 ms+
  3382 00001300 B9FFFF0000          <1> 	mov	ecx, 0FFFFh
  3383                              <1> SD1:
  3384 00001305 F605[755C0000]30    <1> 	test	byte [KB_FLAG_2], KB_FE+KB_FA ; SEE IF EITHER BIT SET
  3385 0000130C 750F                <1> 	jnz	short SD3		; IF SET, SOMETHING RECEIVED GO PROCESS
  3386 0000130E E2F5                <1> 	loop	SD1			; OTHERWISE WAIT
  3387                              <1> SD2:
  3388 00001310 FECB                <1> 	dec	bl			; DECREMENT RETRY COUNT
  3389 00001312 75D4                <1> 	jnz	short SD0		; RETRY TRANSMISSION
  3390 00001314 800D[755C0000]80    <1> 	or	byte [KB_FLAG_2], KB_ERR ; TURN ON TRANSMIT ERROR FLAG
  3391 0000131B EB09                <1> 	jmp	short SD4		; RETRIES EXHAUSTED FORGET TRANSMISSION
  3392                              <1> SD3:
  3393 0000131D F605[755C0000]10    <1> 	test	byte [KB_FLAG_2], KB_FA ; SEE IF THIS IS AN ACKNOWLEDGE
  3394 00001324 74EA                <1> 	jz	short SD2		; IF NOT, GO RESEND
  3395                              <1> SD4:	
  3396 00001326 59                  <1> 	pop	ecx			; RESTORE REGISTERS
  3397                              <1> 	;pop	bx
  3398                              <1> 	;pop	ax
  3399                              <1> 	; 24/12/2021
  3400 00001327 5B                  <1> 	pop	ebx
  3401 00001328 58                  <1> 	pop	eax
  3402 00001329 C3                  <1> 	retn				; RETURN, GOOD TRANSMISSION
  3403                              <1> 
  3404                              <1> SND_LED:
  3405                              <1> 	; ---------------------------------------------------------------------------------
  3406                              <1> 	; SND_LED
  3407                              <1> 	;	THIS ROUTINES TURNS ON THE MODE INDICATORS.
  3408                              <1> 	;
  3409                              <1> 	;----------------------------------------------------------------------------------
  3410                              <1> 	;
  3411 0000132A FA                  <1> 	cli				; TURN OFF INTERRUPTS
  3412 0000132B F605[755C0000]40    <1> 	test	byte [KB_FLAG_2], KB_PR_LED ; CHECK FOR MODE INDICATOR UPDATE
  3413 00001332 755F                <1> 	jnz 	short SL1		; DON'T UPDATE AGAIN IF UPDATE UNDERWAY
  3414                              <1> 	;
  3415 00001334 800D[755C0000]40    <1> 	or	byte [KB_FLAG_2], KB_PR_LED ; TURN ON UPDATE IN PROCESS
  3416 0000133B B020                <1> 	mov	al, EOI			; END OF INTERRUPT COMMAND
  3417 0000133D E620                <1> 	out	20h, al ;out INTA00, al	; SEND COMMAND TO INTERRUPT CONTROL PORT
  3418 0000133F EB11                <1> 	jmp	short SL0		; GO SEND MODE INDICATOR COMMAND
  3419                              <1> SND_LED1:
  3420 00001341 FA                  <1> 	cli				; TURN OFF INTERRUPTS
  3421 00001342 F605[755C0000]40    <1> 	test	byte [KB_FLAG_2], KB_PR_LED ; CHECK FOR MODE INDICATOR UPDATE
  3422 00001349 7548                <1> 	jnz	short SL1		; DON'T UPDATE AGAIN IF UPDATE UNDERWAY
  3423                              <1> 	;
  3424 0000134B 800D[755C0000]40    <1> 	or	byte [KB_FLAG_2], KB_PR_LED ; TURN ON UPDATE IN PROCESS
  3425                              <1> SL0:
  3426 00001352 B0ED                <1> 	mov	al, LED_CMD		; LED CMD BYTE
  3427 00001354 E888FFFFFF          <1> 	call	SND_DATA		; SEND DATA TO KEYBOARD
  3428 00001359 FA                  <1> 	cli
  3429 0000135A E836000000          <1> 	call	MAKE_LED		; GO FORM INDICATOR DATA BYTE
  3430 0000135F 8025[755C0000]F8    <1> 	and	byte [KB_FLAG_2], 0F8h	; ~KB_LEDS ; CLEAR MODE INDICATOR BITS
  3431 00001366 0805[755C0000]      <1> 	or	[KB_FLAG_2], al 	; SAVE PRESENT INDICATORS FOR NEXT TIME
  3432 0000136C F605[755C0000]80    <1> 	test	byte [KB_FLAG_2], KB_ERR ; TRANSMIT ERROR DETECTED
  3433 00001373 750F                <1> 	jnz	short SL2		; IF SO, BYPASS SECOND BYTE TRANSMISSION
  3434                              <1> 	;
  3435 00001375 E867FFFFFF          <1> 	call	SND_DATA		; SEND DATA TO KEYBOARD
  3436 0000137A FA                  <1> 	cli				; TURN OFF INTERRUPTS
  3437 0000137B F605[755C0000]80    <1> 	test	byte [KB_FLAG_2], KB_ERR ; TRANSMIT ERROR DETECTED
  3438 00001382 7408                <1> 	jz	short SL3		; IF NOT, DON'T SEND AN ENABLE COMMAND
  3439                              <1> SL2:
  3440 00001384 B0F4                <1> 	mov	al, KB_ENABLE		; GET KEYBOARD CSA ENABLE COMMAND
  3441 00001386 E856FFFFFF          <1> 	call	SND_DATA		; SEND DATA TO KEYBOARD
  3442 0000138B FA                  <1> 	cli				; TURN OFF INTERRUPTS
  3443                              <1> SL3:
  3444 0000138C 8025[755C0000]3F    <1> 	and	byte [KB_FLAG_2], ~(KB_PR_LED+KB_ERR) ; TURN OFF MODE INDICATOR
  3445                              <1> SL1:					; UPDATE AND TRANSMIT ERROR FLAG
  3446 00001393 FB                  <1> 	sti				; ENABLE INTERRUPTS
  3447 00001394 C3                  <1> 	retn				; RETURN TO CALLER
  3448                              <1> 
  3449                              <1> MAKE_LED:
  3450                              <1> 	;---------------------------------------------------------------------------------
  3451                              <1> 	; MAKE_LED
  3452                              <1> 	;	THIS ROUTINES FORMS THE DATA BYTE NECESSARY TO TURN ON/OFF
  3453                              <1> 	;	THE MODE INDICATORS.
  3454                              <1> 	;---------------------------------------------------------------------------------
  3455                              <1> 	;
  3456                              <1> 	;push 	cx			; SAVE CX
  3457 00001395 A0[735C0000]        <1> 	mov	al, [KB_FLAG]		; GET CAPS & NUM LOCK INDICATORS
  3458 0000139A 2470                <1> 	and	al, CAPS_STATE+NUM_STATE+SCROLL_STATE ; ISOLATE INDICATORS
  3459                              <1> 	;mov	cl, 4			; SHIFT COUNT
  3460                              <1> 	;rol	al, cl			; SHIFT BITS OVER TO TURN ON INDICATORS
  3461 0000139C C0C004              <1> 	rol	al, 4 ; 20/02/2015
  3462 0000139F 2407                <1> 	and	al, 07h			; MAKE SURE ONLY MODE BITS ON
  3463                              <1> 	;pop	cx
  3464 000013A1 C3                  <1> 	retn				; RETURN TO CALLER
  3465                              <1> 
  3466                              <1> ; % include 'kybdata.inc'   ; KEYBOARD DATA ; 11/03/2015
  3467                              <1> 
  3468                              <1> ; /// End Of KEYBOARD FUNCTIONS ///
  1889                                  
  1890                                  %include 'video.inc' ; 07/03/2015
  1891                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.4) - VIDEO.INC
  1892                              <1> ; Last Modification: 14/06/2022
  1893                              <1> ;		  (Video Data is in 'VIDATA.INC')
  1894                              <1> ;
  1895                              <1> ; ///////// VIDEO (CGA) FUNCTIONS ///////////////
  1896                              <1> 
  1897                              <1> ; 14/06/2022
  1898                              <1> ; 26/02/2022
  1899                              <1> ; 07/02/2022
  1900                              <1> ; 02/02/2022 (simplified scroll up)
  1901                              <1> ; 16/01/2016
  1902                              <1> ; 30/06/2015
  1903                              <1> ; 27/06/2015
  1904                              <1> ; 11/03/2015
  1905                              <1> ; 02/09/2014
  1906                              <1> ; 30/08/2014
  1907                              <1> ; VIDEO FUNCTIONS
  1908                              <1> ; (write_tty - Retro UNIX 8086 v1 - U9.ASM, 01/02/2014)
  1909                              <1> 
  1910                              <1> write_tty:
  1911                              <1> 	; 02/02/2022
  1912                              <1> 	; 13/08/2015
  1913                              <1> 	; 02/09/2014
  1914                              <1> 	; 30/08/2014 (Retro UNIX 386 v1 - beginning)
  1915                              <1> 	; 01/02/2014 (Retro UNIX 8086 v1 - last update)
  1916                              <1> 	; 03/12/2013 (Retro UNIX 8086 v1 - beginning)	
  1917                              <1> 	; (Modified registers: EAX, EBX, ECX, EDX, ESI, EDI)
  1918                              <1> 	;
  1919                              <1> 	; INPUT -> AH = Color (Forecolor, Backcolor)
  1920                              <1> 	;	   AL = Character to be written
  1921                              <1> 	;	   EBX = Video Page (0 to 7)
  1922                              <1> 	;	   (BH = 0 --> Video Mode 3)
  1923                              <1> 
  1924                              <1> RVRT	equ	00001000b	; VIDEO VERTICAL RETRACE BIT
  1925                              <1> RHRZ	equ	00000001b	; VIDEO HORIZONTAL RETRACE BIT
  1926                              <1> 
  1927                              <1> ; Derived from "WRITE_TTY" procedure of IBM "pc-at" rombios source code
  1928                              <1> ; (06/10/1985), 'video.asm', INT 10H, VIDEO_IO
  1929                              <1> ;
  1930                              <1> ; 06/10/85  VIDEO DISPLAY BIOS
  1931                              <1> ;
  1932                              <1> ;--- WRITE_TTY ------------------------------------------------------------------
  1933                              <1> ;										:
  1934                              <1> ;   THIS INTERFACE PROVIDES A TELETYPE LIKE INTERFACE TO THE			:
  1935                              <1> ;   VIDEO CARDS. THE INPUT CHARACTER IS WRITTEN TO THE CURRENT			:
  1936                              <1> ;   CURSOR POSITION, AND THE CURSOR IS MOVED TO THE NEXT POSITION.		:
  1937                              <1> ;   IF THE CURSOR LEAVES THE LAST COLUMN OF THE FIELD, THE COLUMN		:
  1938                              <1> ;   IS SET TO ZERO, AND THE ROW VALUE IS INCREMENTED. IF THE ROW		:
  1939                              <1> ;   ROW VALUE LEAVES THE FIELD, THE CURSOR IS PLACED ON THE LAST ROW,		:
  1940                              <1> ;   FIRST COLUMN, AND THE ENTIRE SCREEN IS SCROLLED UP ONE LINE.		:
  1941                              <1> ;   WHEN THE SCREEN IS SCROLLED UP, THE ATTRIBUTE FOR FILLING THE		:
  1942                              <1> ;   NEWLY BLANKED LINE IS READ FROM THE CURSOR POSITION ON THE PREVIOUS		:
  1943                              <1> ;   LINE BEFORE THE SCROLL, IN CHARACTER MODE. IN GRAPHICS MODE,		:
  1944                              <1> ;   THE 0 COLOR IS USED.							:
  1945                              <1> ;   ENTRY --									:
  1946                              <1> ;     (AH) = CURRENT CRT MODE							:
  1947                              <1> ;     (AL) = CHARACTER TO BE WRITTEN						:
  1948                              <1> ;	    NOTE THAT BACK SPACE, CARRIAGE RETURN, BELL AND LINE FEED ARE	:
  1949                              <1> ;	    HANDLED AS COMMANDS RATHER THAN AS DISPLAY GRAPHICS CHARACTERS	:
  1950                              <1> ;     (BL) = FOREGROUND COLOR FOR CHAR WRITE IF CURRENTLY IN A GRAPHICS MODE	:
  1951                              <1> ;   EXIT -- 									:
  1952                              <1> ;     ALL REGISTERS SAVED							:
  1953                              <1> ;--------------------------------------------------------------------------------
  1954                              <1> 
  1955 000013A2 FA                  <1> 	cli
  1956                              <1> 	;
  1957                              <1> 	; READ CURSOR (04/12/2013)
  1958                              <1> 	; Retro UNIX 386 v1 Modifications: 30/08/2014
  1959 000013A3 08FF                <1> 	or	bh, bh
  1960                              <1> 	;jnz	beeper
  1961                              <1> 	; 02/02/2022
  1962 000013A5 7405                <1> 	jz	short u14
  1963 000013A7 E992000000          <1> 	jmp	beeper
  1964                              <1> u14:
  1965                              <1> 	; 02/02/2022
  1966                              <1> 	;; 01/09/2014
  1967                              <1> 	;cmp	byte [CRT_MODE], 3
  1968                              <1> 	;je	short m3
  1969                              <1> 	;;
  1970                              <1> 	;call	set_mode
  1971                              <1> m3:
  1972 000013AC 89DE                <1> 	mov 	esi, ebx ; 13/08/2015 (0 to 7)
  1973                              <1> 	;shl	si, 1
  1974                              <1> 	; 02/02/2022
  1975 000013AE D1E6                <1> 	shl	esi, 1
  1976 000013B0 81C6[36620000]      <1> 	add	esi, cursor_posn
  1977 000013B6 668B16              <1> 	mov	dx, [esi]
  1978                              <1> 	;
  1979                              <1> 	; dx now has the current cursor position
  1980                              <1> 	;
  1981 000013B9 3C0D                <1> 	cmp	al, 0Dh		; is it carriage return or control character
  1982 000013BB 7647                <1> 	jbe	short u8
  1983                              <1> 	;
  1984                              <1> 	; write the char to the screen
  1985                              <1> u0:	
  1986                              <1> 	; ah = attribute/color
  1987                              <1> 	; al = character
  1988                              <1> 	; bl = video page number (0 to 7)
  1989                              <1> 	; bh = 0
  1990                              <1> 	;
  1991 000013BD E8D2010000          <1> 	call	write_c_current
  1992                              <1> 	;
  1993                              <1> 	; position the cursor for next char
  1994 000013C2 FEC2                <1> 	inc	dl		; next column
  1995                              <1> 	;cmp	dl, [CRT_COLS]
  1996 000013C4 80FA50              <1> 	cmp	dl, 80		; test for column overflow 
  1997                              <1>         ;jne	set_cpos
  1998                              <1> 	; 02/02/2022
  1999 000013C7 7405                <1> 	je	short u13
  2000 000013C9 E9DE000000          <1> 	jmp	set_cpos
  2001                              <1> u13:
  2002 000013CE B200                <1> 	mov	dl, 0		; column = 0
  2003                              <1> u10:				; (line feed found)
  2004 000013D0 80FE18              <1> 	cmp	dh, 25-1 	; check for last row
  2005 000013D3 7228                <1> 	jb 	short u6
  2006                              <1> 	;
  2007                              <1> 	; scroll required
  2008                              <1> u1:	
  2009                              <1> 	; SET CURSOR POSITION (04/12/2013)
  2010 000013D5 E8D2000000          <1> 	call	set_cpos
  2011                              <1> 	;
  2012                              <1> 	; determine value to fill with during scroll
  2013                              <1> u2:
  2014                              <1> 	; READ_AC_CURRENT		:
  2015                              <1> 	;   THIS ROUTINE READS THE ATTRIBUTE AND CHARACTER
  2016                              <1> 	;    AT THE CURRENT CURSOR POSITION
  2017                              <1> 	;
  2018                              <1> 	; INPUT				
  2019                              <1> 	;	(AH) = CURRENT CRT MODE
  2020                              <1> 	;	(BH) = DISPLAY PAGE ( ALPHA MODES ONLY )
  2021                              <1> 	;	(DS) = DATA SEGMENT
  2022                              <1> 	;	(ES) = REGEN SEGMENT
  2023                              <1> 	; OUTPUT			
  2024                              <1> 	;	(AL) = CHARACTER READ
  2025                              <1> 	;	(AH) = ATTRIBUTE READ
  2026                              <1> 	;
  2027                              <1> 	; mov	ah, [CRT_MODE] ; move current mode into ah
  2028                              <1> 	;
  2029                              <1> 	; bl = video page number
  2030                              <1> 	;
  2031 000013DA E829010000          <1> 	call	find_position	; get regen location and port address
  2032                              <1> 	; dx = status port
  2033                              <1> 	; esi = cursor location/address
  2034                              <1> p11:
  2035 000013DF FB                  <1> 	sti			; enable interrupts
  2036 000013E0 90                  <1> 	nop			; allow for small interupts window
  2037 000013E1 FA                  <1> 	cli			; blocks interrupts for single loop
  2038 000013E2 EC                  <1> 	in	al, dx		; get status from adapter
  2039 000013E3 A801                <1> 	test	al, RHRZ	; is horizontal retrace low
  2040 000013E5 75F8                <1> 	jnz	short p11	; wait until it is
  2041                              <1> p12:				; now wait for either retrace high
  2042 000013E7 EC                  <1> 	in	al, dx		; get status
  2043 000013E8 A809                <1> 	test	al, RVRT+RHRZ	; is horizontal or vertical retrace high
  2044 000013EA 74FB                <1> 	jz	short p12	; wait until either is active	
  2045                              <1> p13:
  2046 000013EC 81C600800B00        <1> 	add	esi, 0B8000h	; 30/08/2014 (Retro UNIX 386 v1)
  2047 000013F2 668B06              <1> 	mov 	ax, [esi]	; get the character and attribute
  2048                              <1> 	;
  2049                              <1> 	; al = character, ah = attribute
  2050                              <1> 	;
  2051 000013F5 FB                  <1> 	sti
  2052                              <1> 	; bl = video page number 	
  2053                              <1> u3:
  2054                              <1> 	;;mov	ax, 0601h 	; scroll one line
  2055                              <1> 	;;sub	cx, cx		; upper left corner
  2056                              <1> 	;;mov	dh, 25-1 	; lower right row
  2057                              <1> 	;;;mov	dl, [CRT_COLS]
  2058                              <1> 	;mov	dl, 80		; lower right column	
  2059                              <1> 	;;dec	dl
  2060                              <1> 	;;mov	dl, 79
  2061                              <1> 
  2062                              <1> 	;;call	scroll_up	; 04/12/2013
  2063                              <1> 	;;; 11/03/2015
  2064                              <1> 	; 02/09/2014
  2065                              <1> 	;;;mov	cx, [crt_ulc] ; Upper left corner  (0000h)
  2066                              <1> 	;;;mov	dx, [crt_lrc] ; Lower right corner (184Fh)
  2067                              <1> 	; 11/03/2015
  2068                              <1> 	;sub	cx, cx
  2069                              <1> 	;mov	dx, 184Fh ; dl= 79 (column), dh = 24 (row)
  2070                              <1> 	;
  2071                              <1> 	; 02/02/2022 (simplied scroll up)
  2072                              <1> 	; ((retro unix 8086 v1 'scroll_up' in 'u9.s'))
  2073                              <1> 	;
  2074 000013F6 B001                <1> 	mov	al, 1		; scroll 1 line up
  2075                              <1> 		; ah = attribute
  2076 000013F8 E935010000          <1> 	jmp	scroll_up
  2077                              <1> ;u4:
  2078                              <1> 	;;int	10h		; video-call return
  2079                              <1> 				; scroll up the screen
  2080                              <1> 				; tty return
  2081                              <1> ;u5:
  2082                              <1> 	;retn			; return to the caller
  2083                              <1> 
  2084                              <1> u6:				; set-cursor-inc
  2085 000013FD FEC6                <1> 	inc	dh		; next row
  2086                              <1> 				; set cursor
  2087                              <1> ;u7:					
  2088                              <1> 	;;mov	ah, 02h
  2089                              <1> 	;;jmp	short u4 	; establish the new cursor
  2090                              <1> 	;call	set_cpos
  2091                              <1> 	;jmp 	short u5
  2092 000013FF E9A8000000          <1> 	jmp     set_cpos
  2093                              <1> 
  2094                              <1> 	; check for control characters
  2095                              <1> u8:
  2096 00001404 7434                <1> 	je	short u9
  2097 00001406 3C0A                <1> 	cmp	al, 0Ah		; is it a line feed (0Ah)
  2098 00001408 74C6                <1> 	je	short u10
  2099 0000140A 3C07                <1> 	cmp	al, 07h 	; is it a bell
  2100 0000140C 7430                <1> 	je	short u11
  2101 0000140E 3C08                <1> 	cmp	al, 08h		; is it a backspace
  2102                              <1> 	;jne	short u0
  2103 00001410 7420                <1> 	je	short bs	; 12/12/2013
  2104                              <1> 	; 12/12/2013 (tab stop)
  2105 00001412 3C09                <1> 	cmp	al, 09h		; is it a tab stop
  2106 00001414 75A7                <1> 	jne	short u0
  2107 00001416 88D0                <1> 	mov	al, dl
  2108 00001418 6698                <1> 	cbw
  2109 0000141A B108                <1> 	mov	cl, 8
  2110 0000141C F6F1                <1> 	div	cl
  2111 0000141E 28E1                <1> 	sub	cl, ah
  2112                              <1> ts:
  2113                              <1> 	; 02/09/2014
  2114                              <1> 	; 01/09/2014
  2115 00001420 B020                <1> 	mov	al, 20h
  2116                              <1> tsloop:
  2117                              <1> 	;push	cx
  2118                              <1> 	;push	ax
  2119                              <1> 	; 02/02/2022
  2120 00001422 51                  <1> 	push	ecx
  2121 00001423 50                  <1> 	push	eax
  2122 00001424 30FF                <1> 	xor 	bh, bh
  2123                              <1> 	;mov	bl, [active_page]
  2124 00001426 E881FFFFFF          <1> 	call	m3
  2125                              <1> 	; 02/02/2022
  2126 0000142B 58                  <1> 	pop	eax
  2127 0000142C 59                  <1>  	pop	ecx
  2128                              <1> 	;pop	ax  ; ah = attribute/color
  2129                              <1> 	;pop	cx
  2130 0000142D FEC9                <1> 	dec	cl
  2131 0000142F 75F1                <1> 	jnz	short tsloop
  2132 00001431 C3                  <1> 	retn
  2133                              <1> bs:	
  2134                              <1> 	; back space found
  2135 00001432 08D2                <1> 	or	dl, dl 		; is it already at start of line
  2136                              <1> 	;je	short u7 	; set_cursor
  2137 00001434 7476                <1> 	jz	short set_cpos
  2138                              <1> 	;dec	dx     		; no -- just move it back
  2139                              <1> 	; 02/02/2022
  2140 00001436 FECA                <1> 	dec	dl
  2141                              <1> 	;jmp	short u7
  2142 00001438 EB72                <1> 	jmp	short set_cpos
  2143                              <1> 
  2144                              <1> 	; carriage return found
  2145                              <1> u9:
  2146 0000143A B200                <1> 	mov	dl, 0 		; move to first column
  2147                              <1> 	;jmp	short u7
  2148 0000143C EB6E                <1> 	jmp	short set_cpos
  2149                              <1> 
  2150                              <1> 	; line feed found
  2151                              <1> ;u10:
  2152                              <1> ;	cmp	dh, 25-1 	; bottom of screen
  2153                              <1> ;	jne	short u6 	; no, just set the cursor
  2154                              <1> ;       jmp     u1              ; yes, scroll the screen
  2155                              <1> 
  2156                              <1> beeper: 
  2157                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2158                              <1> 	; 18/01/2014
  2159                              <1> 	; 03/12/2013
  2160                              <1> 	; bell found
  2161                              <1> u11:
  2162 0000143E FB                  <1> 	sti
  2163 0000143F 3A1D[46620000]      <1> 	cmp	bl, [active_page]
  2164 00001445 7551                <1> 	jne	short u12	; Do not sound the beep 
  2165                              <1> 				; if it is not written on the active page
  2166 00001447 66B93305            <1> 	mov	cx, 1331 	; divisor for 896 hz tone
  2167 0000144B B31F                <1> 	mov	bl, 31		; set count for 31/64 second for beep
  2168                              <1> 	;call	beep		; sound the pod bell
  2169                              <1> 	;jmp	short u5 	; tty_return
  2170                              <1> 	;retn
  2171                              <1> 	
  2172                              <1> TIMER	equ 	040h   		; 8254 TIMER - BASE ADDRESS
  2173                              <1> PORT_B	equ	061h		; PORT B READ/WRITE DIAGNOSTIC REGISTER
  2174                              <1> GATE2	equ	00000001b	; TIMER 2 INPUT CATE CLOCK BIT
  2175                              <1> SPK2	equ	00000010b	; SPEAKER OUTPUT DATA ENABLE BIT
  2176                              <1> 
  2177                              <1> beep:
  2178                              <1> 	; 07/02/2015
  2179                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2180                              <1> 	; 18/01/2014
  2181                              <1> 	; 03/12/2013
  2182                              <1> 	;
  2183                              <1> 	; TEST4.ASM - 06/10/85  POST AND BIOS UTILITY ROUTINES
  2184                              <1> 	;
  2185                              <1> 	; ROUTINE TO SOUND THE BEEPER USING TIMER 2 FOR TONE
  2186                              <1> 	;
  2187                              <1> 	; ENTRY:
  2188                              <1> 	;    (BL) = DURATION COUNTER ( 1 FOR 1/64 SECOND )
  2189                              <1> 	;    (CX) = FREQUENCY DIVISOR (1193180/FREQUENCY) (1331 FOR 886 HZ)
  2190                              <1> 	; EXIT:			:
  2191                              <1> 	;    (AX),(BL),(CX) MODIFIED.
  2192                              <1> 
  2193 0000144D 9C                  <1> 	pushf  ; 18/01/2014	; save interrupt status
  2194 0000144E FA                  <1> 	cli			; block interrupts during update
  2195 0000144F B0B6                <1> 	mov	al, 10110110b	; select timer 2, lsb, msb binary
  2196 00001451 E643                <1> 	out	TIMER+3, al 	; write timer mode register
  2197 00001453 EB00                <1> 	jmp	$+2		; I/O delay
  2198 00001455 88C8                <1> 	mov	al, cl		; divisor for hz (low)
  2199 00001457 E642                <1> 	out	TIMER+2,AL	; write timer 2 count - lsb
  2200 00001459 EB00                <1> 	jmp	$+2		; I/O delay
  2201 0000145B 88E8                <1> 	mov	al, ch		; divisor for hz (high)
  2202 0000145D E642                <1> 	out	TIMER+2, al	; write timer 2 count - msb
  2203 0000145F E461                <1> 	in	al, PORT_B	; get current setting of port
  2204 00001461 88C4                <1> 	mov	ah, al		; save that setting
  2205 00001463 0C03                <1> 	or	al, GATE2+SPK2	; gate timer 2 and turn speaker on
  2206 00001465 E661                <1> 	out	PORT_B, al	; and restore interrupt status
  2207                              <1> 	;popf	; 18/01/2014
  2208 00001467 FB                  <1> 	sti
  2209                              <1> g7:				; 1/64 second per count (bl)
  2210 00001468 B90B040000          <1> 	mov	ecx, 1035	; delay count for 1/64 of a second	
  2211 0000146D E827000000          <1> 	call	waitf		; go to beep delay 1/64 count
  2212 00001472 FECB                <1> 	dec	bl		; (bl) length count expired?
  2213 00001474 75F2                <1> 	jnz	short g7	; no - continue beeping speaker
  2214                              <1> 	;
  2215                              <1> 	;pushf			; save interrupt status
  2216 00001476 FA                  <1> 	cli  	; 18/01/2014	; block interrupts during update
  2217 00001477 E461                <1> 	in	al, PORT_B	; get current port value
  2218                              <1>         ;or	al, not (GATE2+SPK2) ; isolate current speaker bits in case
  2219 00001479 0CFC                <1>         or      al, ~(GATE2+SPK2)
  2220 0000147B 20C4                <1>         and	ah, al		; someone turned them off during beep
  2221 0000147D 88E0                <1> 	mov	al, ah		; recover value of port
  2222                              <1>         ;or	al, not (GATE2+SPK2) ; force speaker data off
  2223 0000147F 0CFC                <1> 	or 	al, ~(GATE2+SPK2) ; isolate current speaker bits in case
  2224 00001481 E661                <1> 	out	PORT_B, al	; and stop speaker timer
  2225                              <1> 	;popf			; restore interrupt flag state
  2226 00001483 FB                  <1> 	sti
  2227 00001484 B90B040000          <1> 	mov	ecx, 1035	; force 1/64 second delay (short)
  2228 00001489 E80B000000          <1> 	call	waitf		; minimum delay between all beeps
  2229                              <1> 	;pushf			; save interrupt status
  2230 0000148E FA                  <1> 	cli			; block interrupts during update
  2231 0000148F E461                <1> 	in	al, PORT_B	; get current port value in case	
  2232 00001491 2403                <1> 	and	al, GATE2+SPK2	; someone turned them on
  2233 00001493 08E0                <1> 	or	al, ah		; recover value of port_b
  2234 00001495 E661                <1> 	out	PORT_B, al	; restore speaker status
  2235 00001497 9D                  <1> 	popf			; restore interrupt flag state
  2236                              <1> u12:	
  2237 00001498 C3                  <1> 	retn
  2238                              <1> 
  2239                              <1> REFRESH_BIT equ	00010000b 	; REFRESH TEST BIT
  2240                              <1> 
  2241                              <1> WAITF:
  2242                              <1> waitf:
  2243                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2244                              <1> 	; 03/12/2013
  2245                              <1> 	;
  2246                              <1> ;	push	ax		; save work register (ah)	
  2247                              <1> ;waitf1:
  2248                              <1> 				; use timer 1 output bits
  2249                              <1> ;	in	al, PORT_B	; read current counter output status
  2250                              <1> ;	and	al, REFRESH_BIT	; mask for refresh determine bit
  2251                              <1> ;	cmp	al, ah		; did it just change
  2252                              <1> ;	je	short waitf1	; wait for a change in output line
  2253                              <1> ;	;
  2254                              <1> ;	mov	ah, al		; save new lflag state
  2255                              <1> ;	loop	waitf1		; decrement half cycles till count end		
  2256                              <1> ;	;
  2257                              <1> ;	pop	ax		; restore (ah)
  2258                              <1> ;	retn			; return (cx)=0
  2259                              <1> 
  2260                              <1> ; 02/02/2022
  2261                              <1> ; 06/02/2015 (unix386.s <-- dsectrm2.s)
  2262                              <1> ; 17/12/2014 (dsectrm2.s)
  2263                              <1> ; WAITF
  2264                              <1> ; /// IBM PC-XT Model 286 System BIOS Source Code - Test 4 - 06/10/85 ///
  2265                              <1> ;
  2266                              <1> ;---WAITF-----------------------------------------------------------------------
  2267                              <1> ;	FIXED TIME WAIT ROUTINE (HARDWARE CONTROLLED - NOT PROCESSOR)
  2268                              <1> ; ENTRY:
  2269                              <1> ;	(CX) =	COUNT OF 15.085737 MICROSECOND INTERVALS TO WAIT
  2270                              <1> ;	      	MEMORY REFRESH TIMER 1 OUTPUT USED AS REFERENCE
  2271                              <1> ; EXIT:
  2272                              <1> ;	       	AFTER (CX) TIME COUNT (PLUS OR MINUS 16 MICROSECONDS)
  2273                              <1> ;	(CX) = 0	
  2274                              <1> ;-------------------------------------------------------------------------------
  2275                              <1> 
  2276                              <1> ; Refresh period: 30 micro seconds (15-80 us)
  2277                              <1> ; (16/12/2014 - AWARDBIOS 1999 - ATORGS.ASM, WAIT_REFRESH)
  2278                              <1> 
  2279                              <1> ;WAITF:					; DELAY FOR (CX)*15.085737 US
  2280 00001499 50                  <1> 	push	eax ; 02/02/2022	; SAVE WORK REGISTER (AH)
  2281                              <1> 	;push	ax
  2282                              <1> 	; 16/12/2014
  2283                              <1> 	;shr	cx, 1			; convert to count of 30 micro seconds
  2284 0000149A D1E9                <1> 	shr	ecx, 1	; 21/02/2015
  2285                              <1> ;17/12/2014	
  2286                              <1> ;WAITF1:
  2287                              <1> ;	IN	AL, PORT_B   ;061h	; READ CURRENT COUNTER OUTPUT STATUS
  2288                              <1> ;	AND	AL, REFRESH_BIT	;00010000b ; MASK FOR REFRESH DETERMINE BIT
  2289                              <1> ;	CMP	AL, AH			; DID IT JUST CHANGE
  2290                              <1> ;	JE	short WAITF1		; WAIT FOR A CHANGE IN OUTPUT LINE
  2291                              <1> ;	MOV	AH, AL			; SAVE NEW FLAG STATE
  2292                              <1> ;	LOOP	WAITF1			; DECREMENT HALF CYCLES TILL COUNT END		
  2293                              <1> 	;
  2294                              <1> 	; 17/12/2014
  2295                              <1> 	;
  2296                              <1> 	; Modification from 'WAIT_REFRESH' procedure of AWARD BIOS - 1999
  2297                              <1> 	;
  2298                              <1> ;WAIT_REFRESH:  Uses port 61, bit 4 to have CPU speed independent waiting.
  2299                              <1> ;   	INPUT:  CX = number of refresh periods to wait
  2300                              <1> ;     	       (refresh periods = 1 per 30 microseconds on most machines)
  2301                              <1> WR_STATE_0:
  2302 0000149C E461                <1> 	IN	AL,PORT_B		; IN AL,SYS1
  2303 0000149E A810                <1> 	TEST	AL,010H
  2304 000014A0 74FA                <1> 	JZ	SHORT WR_STATE_0
  2305                              <1> WR_STATE_1:
  2306 000014A2 E461                <1> 	IN	AL,PORT_B		; IN AL,SYS1
  2307 000014A4 A810                <1> 	TEST	AL,010H
  2308 000014A6 75FA                <1> 	JNZ	SHORT WR_STATE_1
  2309 000014A8 E2F2                <1>         LOOP    WR_STATE_0
  2310                              <1> 	;
  2311                              <1> 	;pop	ax
  2312 000014AA 58                  <1> 	pop	eax ; 02/02/2022	; RESTORE (AH)
  2313 000014AB C3                  <1> 	RETn				; (CX) = 0
  2314                              <1> 
  2315                              <1> set_cpos:
  2316                              <1> 	; 14/06/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.4)
  2317                              <1> 	; 26/02/2022
  2318                              <1> 	; 02/02/2022
  2319                              <1> 	; 27/06/2015
  2320                              <1> 	; 01/09/2014
  2321                              <1> 	; 30/08/2014 (Retro UNIX 386 v1 - beginning)
  2322                              <1> 	;
  2323                              <1> 	; 12/12/2013 (Retro UNIX 8086 v1 - last update) 
  2324                              <1> 	; 04/12/2013 (Retro UNIX 8086 v1 - beginning)
  2325                              <1> 	;
  2326                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2327                              <1> 	;
  2328                              <1> 	; SET_CPOS
  2329                              <1> 	;	THIS ROUTINE SETS THE CURRENT CURSOR POSITION TO THE
  2330                              <1> 	;	NEW X-Y VALUES PASSED
  2331                              <1> 	; INPUT
  2332                              <1> 	;	DX - ROW,COLUMN OF NEW CURSOR
  2333                              <1> 	;	BH - DISPLAY PAGE OF CURSOR
  2334                              <1> 	; OUTPUT
  2335                              <1> 	;	CURSOR IS SET AT 6845 IF DISPLAY PAGE IS CURRENT DISPLAY
  2336                              <1> 	;
  2337 000014AC 0FB6C3              <1>         movzx   eax, bl	; BL = video page number ; 27/06/2015 (movzx)
  2338 000014AF D0E0                <1>         shl     al, 1   ; word offset
  2339 000014B1 BE[36620000]        <1> 	mov	esi, cursor_posn
  2340 000014B6 01C6                <1>         add     esi, eax
  2341 000014B8 668916              <1> 	mov	[esi], dx ; save the pointer
  2342 000014BB 381D[46620000]      <1> 	cmp	[active_page], bl
  2343 000014C1 7531                <1> 	jne	short m17
  2344                              <1> 
  2345                              <1> 	; 14/06/2022
  2346                              <1> 	;cli ; 26/02/2022
  2347                              <1> 
  2348                              <1> 	;call	m18	;h CURSOR SET
  2349                              <1> ;m17:			; SET_CPOS_RETURN
  2350                              <1> 	; 01/09/2014
  2351                              <1> 	;retn
  2352                              <1> 		; DX = row/column
  2353                              <1> m18:
  2354 000014C3 E832000000          <1> 	call	position ; determine location in regen buffer	
  2355                              <1> 	;mov	cx, [CRT_START]
  2356                              <1> 	; 26/02/2022
  2357 000014C8 0FB70D[34620000]    <1> 	movzx	ecx, word [CRT_START]
  2358 000014CF 01C1                <1> 	add	ecx, eax
  2359                              <1> 	;add	cx, ax  ; add char position in regen buffer
  2360                              <1> 			; to the start address (offset) for this page
  2361                              <1> 	;shr	cx, 1	; divide by 2 for char only count
  2362                              <1> 	; 26/02/2022
  2363 000014D1 D1E9                <1> 	shr	ecx, 1
  2364 000014D3 B40E                <1> 	mov	ah, 14	; register number for cursor
  2365                              <1> 	
  2366                              <1> 	; 14/06/2022
  2367                              <1> 	;call	m16	; output value to the 6845
  2368                              <1> 	;sti	; 26/02/2022
  2369                              <1> 	;retn
  2370                              <1> 
  2371                              <1> 	; 14/06/2022
  2372                              <1> 	; 26/02/2022
  2373                              <1> 	; 02/02/2022
  2374                              <1> 	;-----	THIS ROUTINE OUTPUTS THE CX REGISTER
  2375                              <1> 	;	TO THE 6845 REGISTERS NAMED IN (AH)
  2376                              <1> m16:
  2377                              <1> 	; 14/06/2022
  2378 000014D5 FA                  <1> 	cli	; 26/02/2022
  2379                              <1> 	;mov	dx, [addr_6845] ; address register
  2380 000014D6 66BAD403            <1> 	mov 	dx, 03D4h ; I/O address of color card
  2381 000014DA 88E0                <1> 	mov	al, ah	; get value
  2382 000014DC EE                  <1> 	out	dx, al	; register set
  2383                              <1> 	;inc	dx	; data register
  2384                              <1> 	; 02/02/2022
  2385 000014DD FEC2                <1> 	inc	dl
  2386 000014DF EB00                <1> 	jmp	$+2	; i/o delay
  2387 000014E1 88E8                <1> 	mov	al, ch	; data
  2388 000014E3 EE                  <1> 	out	dx, al	
  2389                              <1> 	;dec	dx
  2390                              <1> 	; 02/02/2022	
  2391 000014E4 FECA                <1> 	dec	dl
  2392 000014E6 88E0                <1> 	mov	al, ah
  2393 000014E8 FEC0                <1> 	inc	al	; point to other data register
  2394 000014EA EE                  <1> 	out	dx, al	; set for second register
  2395                              <1> 	;inc	dx
  2396                              <1> 	; 02/02/2022
  2397 000014EB FEC2                <1> 	inc	dl
  2398 000014ED EB00                <1> 	jmp	$+2	; i/o delay
  2399 000014EF 88C8                <1> 	mov	al, cl	; second data value
  2400 000014F1 EE                  <1> 	out	dx, al
  2401                              <1> 	; 14/06/2022
  2402 000014F2 FB                  <1> 	sti	; 26/02/2022
  2403                              <1> ;m17:
  2404 000014F3 C3                  <1> 	retn
  2405                              <1> m17:
  2406                              <1> 	; 14/06/2022
  2407                              <1> 	; ('write_tty' must not return to 'putc'/'wtty' with cf)
  2408 000014F4 F8                  <1> 	clc
  2409 000014F5 C3                  <1> 	retn
  2410                              <1> 
  2411                              <1> set_ctype:
  2412                              <1> 	; 07/02/2022
  2413                              <1> 	; 02/09/2014 (Retro UNIX 386 v1)
  2414                              <1> 	;
  2415                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2416                              <1> 
  2417                              <1> ;	CH) = BITS 4-0 = START LINE FOR CURSOR
  2418                              <1> ;       ** HARDWARE WILL ALWAYS CAUSE BLINK
  2419                              <1> ;       ** SETTING BIT 5 OR 6 WILL CAUSE ERRATIC BLINKING
  2420                              <1> ;          OR NO CURSOR AT ALL
  2421                              <1> ;	(CL) = BITS 4-0 = END LINE FOR CURSOR
  2422                              <1> 
  2423                              <1> ;------------------------------------------------
  2424                              <1> ; SET_CTYPE
  2425                              <1> ;	THIS ROUTINE SETS THE CURSOR VALUE
  2426                              <1> ; INPUT
  2427                              <1> ;	(CX) HAS CURSOR VALUE CH-START LINE, CL-STOP LINE
  2428                              <1> ; OUTPUT	
  2429                              <1> ;	NONE
  2430                              <1> ;------------------------------------------------
  2431                              <1> 
  2432 000014F6 B40A                <1> 	mov	ah, 10	; 6845 register for cursor set
  2433                              <1> 	;mov	[CURSOR_MODE], cx ; save in data area
  2434                              <1> 	;call	m16	; output cx register
  2435                              <1> 	;retn
  2436                              <1> 	; 07/02/2022
  2437 000014F8 EBDB                <1> 	jmp	short m16
  2438                              <1> 
  2439                              <1> position:
  2440                              <1> 	; 26/02/2022
  2441                              <1> 	; 02/02/2022
  2442                              <1> 	; 27/06/2015
  2443                              <1> 	; 02/09/2014
  2444                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2445                              <1> 	; 04/12/2013 (Retro UNIX 8086 v1)
  2446                              <1> 	;
  2447                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2448                              <1> 	;
  2449                              <1> 	; POSITION
  2450                              <1> 	;	THIS SERVICE ROUTINE CALCULATES THE REGEN BUFFER ADDRESS
  2451                              <1> 	;	OF A CHARACTER IN THE ALPHA MODE
  2452                              <1> 	; INPUT
  2453                              <1> 	;	AX = ROW, COLUMN POSITION
  2454                              <1> 	; OUTPUT
  2455                              <1> 	;	AX = OFFSET OF CHAR POSITION IN REGEN BUFFER
  2456                              <1> 
  2457                              <1> 		; DX = ROW, COLUMN POSITION
  2458                              <1> 	;movzx	eax, byte [CRT_COLS] ; 27/06/2015
  2459 000014FA 31C0                <1> 	xor	eax, eax ; 02/09/2014
  2460 000014FC B050                <1> 	mov	al, 80	; determine bytes to row	
  2461 000014FE F6E6                <1> 	mul	dh	; row value
  2462                              <1> 	;xor	dh, dh	; 0
  2463                              <1> 	;add	ax, dx	; add column value to the result
  2464                              <1> 	; 26/02/2022
  2465 00001500 00D0                <1> 	add	al, dl
  2466 00001502 80D400              <1> 	adc	ah, 0	
  2467                              <1> 	;shl	ax, 1	; * 2 for attribute bytes
  2468                              <1> 	; 02/02/2022
  2469 00001505 D1E0                <1> 	shl	eax, 1
  2470                              <1> 		; EAX = AX = OFFSET OF CHAR POSITION IN REGEN BUFFER
  2471 00001507 C3                  <1> 	retn
  2472                              <1> 
  2473                              <1> find_position:
  2474                              <1> 	; 02/02/2022
  2475                              <1> 	; 27/06/2015
  2476                              <1> 	; 07/09/2014
  2477                              <1> 	; 02/09/2014
  2478                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2479                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2480 00001508 0FB6CB              <1> 	movzx	ecx, bl ; video page number ; 27/06/2015 (movzx)
  2481 0000150B 89CE                <1> 	mov	esi, ecx
  2482                              <1> 	;shl	si, 1
  2483                              <1> 	; 02/02/2022
  2484 0000150D D1E6                <1> 	shl	esi, 1
  2485 0000150F 668B96[36620000]    <1> 	mov	dx, [esi+cursor_posn]
  2486 00001516 7409                <1> 	jz	short p21
  2487                              <1> 	;xor	si, si
  2488                              <1> 	; 02/02/2022
  2489 00001518 31F6                <1> 	xor	esi, esi
  2490                              <1> p20:
  2491                              <1> 	;add	si, [CRT_LEN]
  2492 0000151A 6681C6A00F          <1> 	add	si, 80*25*2 ; add length of buffer for one page		
  2493 0000151F E2F9                <1> 	loop	p20
  2494                              <1> p21:
  2495 00001521 6621D2              <1> 	and	dx, dx
  2496 00001524 7407                <1> 	jz	short p22
  2497 00001526 E8CFFFFFFF          <1> 	call 	position ; determine location in regen in page
  2498 0000152B 01C6                <1> 	add	esi, eax ; add location to start of regen page
  2499                              <1> p22:	
  2500                              <1> 	;mov	dx, [addr_6845] ; get base address of active display			
  2501                              <1> 	;mov	dx, 03D4h ; I/O address of color card
  2502                              <1> 	;add	dx, 6	; point at status port
  2503 0000152D 66BADA03            <1> 	mov	dx, 03DAh ; status port
  2504                              <1> 	; cx = 0
  2505 00001531 C3                  <1> 	retn
  2506                              <1> 
  2507                              <1> scroll_up:
  2508                              <1> 	; 02/02/2022 (simplified scroll up)
  2509                              <1> 	;	((retro unix 8086 v1 'scroll_up' in 'u9.s'))
  2510                              <1> 	; 16/01/2016
  2511                              <1> 	; 07/09/2014
  2512                              <1> 	; 02/09/2014
  2513                              <1> 	; 01/09/2014 (Retro UNIX 386 v1 - beginning)
  2514                              <1> 	; 04/04/2014
  2515                              <1> 	; 04/12/2013
  2516                              <1> 	;
  2517                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2518                              <1> 	;
  2519                              <1> 	; SCROLL UP
  2520                              <1> 	;	THIS ROUTINE MOVES A BLOCK OF CHARACTERS UP
  2521                              <1> 	;	ON THE SCREEN
  2522                              <1> 	; INPUT
  2523                              <1> 	;	(AH) = CURRENT CRT MODE
  2524                              <1> 	;	(AL) = NUMBER OF ROWS TO SCROLL
  2525                              <1> 	;	(CX) = ROW/COLUMN OF UPPER LEFT CORNER
  2526                              <1> 	;	(DX) = ROW/COLUMN OF LOWER RIGHT CORNER
  2527                              <1> 	;	(BH) = ATTRIBUTE TO BE USED ON BLANKED LINE
  2528                              <1> 	;	(DS) = DATA SEGMENT
  2529                              <1> 	;	(ES) = REGEN BUFFER SEGMENT
  2530                              <1> 	; OUTPUT
  2531                              <1> 	;	NONE -- THE REGEN BUFFER IS MODIFIED
  2532                              <1> 	;
  2533                              <1> 	;	bh = 0  (02/09/2014)
  2534                              <1> 	;
  2535                              <1> 	; ((ah = 3))
  2536                              <1> 	; cl = left upper column
  2537                              <1> 	; ch = left upper row
  2538                              <1> 	; dl = right lower column
  2539                              <1> 	; dh = right lower row
  2540                              <1> 	;
  2541                              <1> 	; al = line count 
  2542                              <1> 	; ah = attribute to be used on blanked line
  2543                              <1> 	; bl = video page number (0 to 7)
  2544                              <1> 	; 
  2545                              <1> 
  2546                              <1> 	; 02/02/2022 'scroll_up' code
  2547                              <1> 	; ------------------------------------------------------
  2548                              <1> 	; (ref: Retro UNIX 8086 v1 'scroll_up' code in 'u9.asm')
  2549                              <1> 
  2550                              <1> 	; INPUT:
  2551                              <1> 	;		
  2552                              <1> 	; al = line count 
  2553                              <1> 	;	(0 or 1) .. 0 -> clear video page
  2554                              <1> 	; ah = attribute to be used on blanked line
  2555                              <1> 	; bl = video page number (0 to 7)
  2556                              <1> 
  2557                              <1> 	;cli
  2558 00001532 31C9                <1> 	xor	ecx, ecx
  2559 00001534 88C1                <1> 	mov	cl, al ; line count (cl)
  2560 00001536 BE00800B00          <1> 	mov	esi, 0B8000h
  2561 0000153B 3A1D[46620000]      <1> 	cmp	bl, [active_page]
  2562 00001541 7411                <1> 	je	short n1
  2563 00001543 20DB                <1> 	and	bl, bl
  2564 00001545 7422                <1> 	jz	short n3
  2565 00001547 88DD                <1> 	mov	ch, bl ; video page number
  2566                              <1> n0:
  2567 00001549 6681C6A00F          <1> 	add	si, 25*80*2
  2568 0000154E FECD                <1> 	dec	ch
  2569 00001550 75F7                <1> 	jnz	short n0
  2570 00001552 EB15                <1> 	jmp	short n3
  2571                              <1> n1:
  2572 00001554 660335[34620000]    <1> 	add	si, [CRT_START]
  2573                              <1> 	;
  2574 0000155B 66BADA03            <1> 	mov	dx, 3DAh ; guaranteed to be color card here	
  2575                              <1> n2:			 ; wait_display_enable
  2576 0000155F EC                  <1> 	in	al, dx	 ; get port
  2577 00001560 A808                <1> 	test	al, RVRT ; wait for vertical retrace	
  2578 00001562 74FB                <1> 	jz	short n2 ; wait_display_enable
  2579 00001564 B025                <1> 	mov	al, 25h
  2580 00001566 B2D8                <1> 	mov	dl, 0D8h ; address control port
  2581 00001568 EE                  <1> 	out	dx, al	 ; turn off video during vertical retrace
  2582                              <1> n3:
  2583                              <1> 	; cl = line count
  2584                              <1> 	; ah = attribute/color
  2585 00001569 89F7                <1> 	mov	edi, esi
  2586 0000156B 20C9                <1> 	and	cl, cl
  2587 0000156D 741F                <1> 	jz	short n6
  2588 0000156F 6681C6A000          <1> 	add	si, 80*2 ; + 160 bytes
  2589 00001574 66B98007            <1> 	mov	cx, 24*80 ; 24 rows/lines
  2590 00001578 F366A5              <1> 	rep	movsw
  2591 0000157B B150                <1> 	mov	cl, 80 ; 1 row (will be cleared)
  2592                              <1> n4:
  2593                              <1> 	; ah = character attribute/cocor
  2594 0000157D B020                <1> 	mov	al, 20h ; fill with blanks
  2595 0000157F F366AB              <1> 	rep	stosw
  2596                              <1> 
  2597 00001582 3A1D[46620000]      <1> 	cmp	bl, [active_page]
  2598 00001588 7503                <1> 	jne	short n5
  2599                              <1> 
  2600                              <1> 	;mov	al, [crt_mode_set] ; get the value of mode set
  2601 0000158A B029                <1> 	mov	al, 29h ; (ORGS.ASM), M7 mode set table value for mode 3	
  2602                              <1> 	;mov	dx, 03D8h ; always set color card port
  2603 0000158C EE                  <1> 	out	dx, al
  2604                              <1> n5:
  2605 0000158D C3                  <1> 	retn
  2606                              <1> n6:
  2607                              <1> 	; clear video page
  2608 0000158E 66B9D007            <1> 	mov	cx, 25*80 ; 25 rows/lines
  2609 00001592 EBE9                <1> 	jmp	short n4
  2610                              <1> 
  2611                              <1> 	; 26/02/2022
  2612                              <1> %if 0	; 16/01/2016 'scroll_up' code
  2613                              <1> 	; ------------------------------------------------------
  2614                              <1> 
  2615                              <1> 	; Test	Line Count
  2616                              <1> 	or	al, al
  2617                              <1> 	jz	short al_set
  2618                              <1> 	mov	bh, dh	; subtract lower row from upper row
  2619                              <1> 	sub	bh, ch
  2620                              <1> 	inc	bh	; adjust difference by 1
  2621                              <1> 	cmp	bh, al 	; line count = amount of rows in window?
  2622                              <1> 	jne	short al_set ; if not the we're all set
  2623                              <1> 	xor	al, al	; otherwise set al to zero
  2624                              <1> al_set:
  2625                              <1> 	xor	bh, bh	; 0
  2626                              <1> 	;push	ax
  2627                              <1> 	push	eax ; 26/02/2022
  2628                              <1> 	;mov 	esi, [crt_base]
  2629                              <1>         mov     esi, 0B8000h  
  2630                              <1>         cmp     bl, [active_page]
  2631                              <1> 	jne	short n0
  2632                              <1> 	;
  2633                              <1>         mov     ax, [CRT_START]
  2634                              <1>         add     si, ax
  2635                              <1>         jmp     short n1
  2636                              <1> n0:
  2637                              <1>         and     bl, bl
  2638                              <1> 	jz	short n1
  2639                              <1> 	mov	al, bl
  2640                              <1> n0x:
  2641                              <1>         ;add    si, [CRT_LEN]
  2642                              <1>         ;add    esi, 80*25*2 
  2643                              <1>         add     si, 80*25*2
  2644                              <1>         dec	al
  2645                              <1> 	jnz	short n0x
  2646                              <1> n1:	
  2647                              <1>         ; Scroll position
  2648                              <1> 	;push	dx ; 26/02/2022
  2649                              <1> 	mov	dx, cx	; now, upper left position in DX
  2650                              <1> 	call	position
  2651                              <1> 	add	esi, eax
  2652                              <1> 	mov	edi, esi
  2653                              <1> 	;pop	dx	; lower right position in DX
  2654                              <1> 	sub	dx, cx
  2655                              <1> 	inc	dh	; dh = #rows 
  2656                              <1> 	inc	dl	; dl = #cols in block
  2657                              <1> 	;pop	ax	; al = line count, ah = attribute
  2658                              <1> 	pop	eax ; 26/02/2022
  2659                              <1> 	xor	ecx, ecx
  2660                              <1> 	mov	cx, ax
  2661                              <1> 	;mov	ah, [CRT_COLS]
  2662                              <1> 	mov	ah, 80
  2663                              <1> 	mul	ah	; determine offset to from address
  2664                              <1> 	add	ax, ax  ; *2 for attribute byte
  2665                              <1> 	;
  2666                              <1> 	;push	ax	; offset 
  2667                              <1> 	;push	dx
  2668                              <1> 	; 26/02/2022
  2669                              <1> 	push	eax
  2670                              <1> 	push	edx
  2671                              <1> 	;
  2672                              <1> 	; 04/04/2014
  2673                              <1> 	mov	dx, 3DAh ; guaranteed to be color card here
  2674                              <1> n8:                      ; wait_display_enable
  2675                              <1>         in      al, dx   ; get port
  2676                              <1> 	test	al, RVRT ; wait for vertical retrace
  2677                              <1> 	jz	short n8 ; wait_display_enable
  2678                              <1> 	mov	al, 25h
  2679                              <1> 	mov	dl, 0D8h ; address control port
  2680                              <1> 	out	dx, al	; turn off video during vertical retrace
  2681                              <1> 	;pop	dx	; #rows, #cols
  2682                              <1>        	;pop	ax	; offset
  2683                              <1> 	; 26/02/2022
  2684                              <1> 	pop	edx
  2685                              <1> 	pop	eax
  2686                              <1> 	xchg	ax, cx	; 
  2687                              <1> 	; ecx = offset, al = line count, ah = attribute
  2688                              <1> ;n9:
  2689                              <1> 	or	al, al
  2690                              <1>         jz      short n3 
  2691                              <1>         add     esi, ecx ; from address for scroll
  2692                              <1> 	mov	bh, dh  ; #rows in block
  2693                              <1> 	sub	bh, al	; #rows to be moved
  2694                              <1> n2:
  2695                              <1> 	; Move rows
  2696                              <1> 	mov	cl, dl	; get # of cols to move
  2697                              <1> 	push	esi
  2698                              <1> 	push	edi	; save start address
  2699                              <1> n10:
  2700                              <1> 	movsw		; move that line on screen
  2701                              <1> 	dec	cl
  2702                              <1>         jnz     short n10
  2703                              <1> 	pop	edi
  2704                              <1> 	pop	esi	; recover addresses
  2705                              <1>         ;mov    cl, [CRT_COLS] 
  2706                              <1> 	;add	cl, cl
  2707                              <1>         ;mov    ecx, 80*2
  2708                              <1>         mov     cx, 80*2
  2709                              <1>         add     esi, ecx  ; next line
  2710                              <1>         add     edi, ecx
  2711                              <1> 	dec	bh	 ; count of lines to move
  2712                              <1> 	jnz	short n2 ; row loop
  2713                              <1> 	; bh = 0
  2714                              <1> 	mov	dh, al	 ; #rows	
  2715                              <1> n3:
  2716                              <1> 	; attribute in ah
  2717                              <1> 	mov	al, ' '	 ; fill with blanks
  2718                              <1> n3x:
  2719                              <1> 	; Clear rows
  2720                              <1>                 ; dh =  #rows
  2721                              <1>         mov	cl, dl	; get # of cols to clear
  2722                              <1>         push    edi     ; save address
  2723                              <1> n11:
  2724                              <1>         stosw           ; store fill character
  2725                              <1> 	dec	cl
  2726                              <1>         jnz     short n11
  2727                              <1>         pop     edi     ; recover address
  2728                              <1> 	;mov	cl, [CRT_COLS]
  2729                              <1> 	;add	cl, cl
  2730                              <1>         ;mov    ecx, 80*2
  2731                              <1>         mov	cl, 80*2
  2732                              <1>         add     edi, ecx
  2733                              <1> 	dec	dh
  2734                              <1> 	jnz	short n3x ; 16/01/2016
  2735                              <1> 	;
  2736                              <1> 	cmp	bl, [active_page]
  2737                              <1> 	jne	short n6
  2738                              <1> 	;mov	al, [CRT_MODE_SET] ; get the value of mode set
  2739                              <1> 	mov	al, 29h ; (ORGS.ASM), M7 mode set table value for mode 3
  2740                              <1> 	mov	dx, 03D8h ; always set color card port
  2741                              <1> 	out	dx, al
  2742                              <1> n6:
  2743                              <1> 	retn
  2744                              <1> 
  2745                              <1> %endif
  2746                              <1> 
  2747                              <1> write_c_current:
  2748                              <1> 	; 02/02/2022
  2749                              <1> 	; 30/08/2014 (Retro UNIX 386 v1)
  2750                              <1> 	; 18/01/2014
  2751                              <1> 	; 04/12/2013
  2752                              <1> 	;
  2753                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2754                              <1> 	;
  2755                              <1> 	; WRITE_C_CURRENT
  2756                              <1> 	;	THIS ROUTINE WRITES THE CHARACTER AT
  2757                              <1> 	;	THE CURRENT CURSOR POSITION, ATTRIBUTE UNCHANGED
  2758                              <1> 	; INPUT	
  2759                              <1> 	;	(AH) = CURRENT CRT MODE
  2760                              <1> 	;	(BH) = DISPLAY PAGE
  2761                              <1> 	;	(CX) = COUNT OF CHARACTERS TO WRITE
  2762                              <1> 	;	(AL) = CHAR TO WRITE
  2763                              <1> 	;	(DS) = DATA SEGMENT
  2764                              <1> 	;	(ES) = REGEN SEGMENT
  2765                              <1> 	; OUTPUT
  2766                              <1> 	;	DISPLAY REGEN BUFFER UPDATED
  2767                              <1> 
  2768 00001594 FA                  <1> 	cli		
  2769                              <1> 	; bl = video page
  2770                              <1> 	; al = character
  2771                              <1> 	; ah = color/attribute
  2772                              <1> 	;push	dx
  2773                              <1> 	;push	ax	; save character & attribute/color
  2774                              <1> 	; 02/02/2022
  2775 00001595 52                  <1> 	push	edx
  2776 00001596 50                  <1> 	push	eax
  2777 00001597 E86CFFFFFF          <1> 	call 	find_position  ; get regen location and port address
  2778                              <1> 	; esi = regen location
  2779                              <1> 	; dx = status port
  2780                              <1> 	;
  2781                              <1> 	; WAIT FOR HORIZONTAL RETRACE OR VERTICAL RETRACE
  2782                              <1> 	;
  2783                              <1> p41:			; wait for horizontal retrace is low or vertical
  2784 0000159C FB                  <1> 	sti		; enable interrupts first
  2785 0000159D 3A1D[46620000]      <1>         cmp     bl, [active_page]
  2786 000015A3 7510                <1> 	jne	short p44 
  2787 000015A5 FA                  <1> 	cli 		; block interrupts for single loop
  2788 000015A6 EC                  <1> 	in	al, dx	; get status from the adapter
  2789 000015A7 A808                <1> 	test	al, RVRT ; check for vertical retrace first
  2790 000015A9 7509                <1> 	jnz	short p43 ; Do fast write now if vertical retrace
  2791 000015AB A801                <1> 	test	al, RHRZ  ; is horizontal retrace low
  2792 000015AD 75ED                <1> 	jnz	short p41 ; wait until it is
  2793                              <1> p42:			; wait for either retrace high
  2794 000015AF EC                  <1> 	in	al, dx	; get status again
  2795 000015B0 A809                <1> 	test	al, RVRT+RHRZ ; is horizontal or vertical retrace high
  2796 000015B2 74FB                <1> 	jz	short p42 ; wait until either retrace active
  2797                              <1> p43:	
  2798 000015B4 FB                  <1> 	sti
  2799                              <1> p44:
  2800                              <1> 	;pop	ax	; restore the character (al) & attribute (ah)
  2801                              <1> 	; 02/02/2022
  2802 000015B5 58                  <1> 	pop	eax
  2803 000015B6 81C600800B00        <1> 	add	esi, 0B8000h ; 30/08/2014 (crt_base) 
  2804                              <1> 			; Retro UNIX 386 v1 feature only!
  2805 000015BC 668906              <1> 	mov	[esi], ax
  2806                              <1> 	;pop	dx
  2807                              <1> 	; 02/02/2022
  2808 000015BF 5A                  <1> 	pop	edx
  2809 000015C0 C3                  <1> 	retn
  2810                              <1> 
  2811                              <1> %if 0	; 02/02/2022
  2812                              <1> 
  2813                              <1> set_mode:
  2814                              <1> 	; 02/02/2022
  2815                              <1> 	; 16/01/2016
  2816                              <1> 	; 02/09/2014 (Retro UNIX 386 v1)
  2817                              <1> 	;
  2818                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2819                              <1> 
  2820                              <1> ;------------------------------------------------------
  2821                              <1> ; SET MODE					      :
  2822                              <1> ;	THIS ROUTINE INITIALIZES THE ATTACHMENT TO    :
  2823                              <1> ;	THE SELECTED MODE, THE SCREEN IS BLANKED.     :
  2824                              <1> ; INPUT						      :
  2825                              <1> ;	(AL) - MODE SELECTED (RANGE 0-7)	      :
  2826                              <1> ; OUTPUT					      :
  2827                              <1> ;	NONE					      :
  2828                              <1> ;------------------------------------------------------
  2829                              <1> 
  2830                              <1> 	push	edi ; 16/01/2016
  2831                              <1> 	push	ebx
  2832                              <1> 	push	edx
  2833                              <1> 	push	ecx ; 16/01/2016
  2834                              <1>         push    eax
  2835                              <1> 
  2836                              <1> 	;mov	dx, 03D4h 	; address or color card
  2837                              <1> 	mov	al, 3
  2838                              <1> ;M8:
  2839                              <1> 	mov	[CRT_MODE], al  ; save mode in global variable
  2840                              <1> 	mov	al, 29h
  2841                              <1> 	;mov	[CRT_MODE_SET], al ; save the mode set value
  2842                              <1> 	and	al, 037h	; video off, save high resolution bit	
  2843                              <1> 	;push	dx  		; save port value
  2844                              <1> 	;add	dx, 4		; point to control register
  2845                              <1> 	mov	dx, 3D8h
  2846                              <1> 	out	dx, al		; reset video to off to suppress rolling
  2847                              <1> 	;pop	dx
  2848                              <1> ;M9:
  2849                              <1> 	mov	ebx, video_params ; initialization table
  2850                              <1> 	;mov	ax, [ebx+10]      ; get the cursor mode from the table	
  2851                              <1> 	;xchg 	ah, al
  2852                              <1> 	;mov	[CURSOR_MODE], ax ; save cursor mode
  2853                              <1> 	xor	ah, ah		  ; ah is register number during loop 
  2854                              <1> 	
  2855                              <1> ;-----	LOOP THROUGH TABLE, OUTPUTTING REGISTER ADDRESS, THEN VALUE FROM TABLE
  2856                              <1> 	; 02/02/2022
  2857                              <1> 	; dx = 3D8h
  2858                              <1> 	xor	ecx, ecx
  2859                              <1> 	mov	cl, 16
  2860                              <1> 	;mov	ecx, 16 ; 16/01/2016
  2861                              <1> M10:			;  initialization loop
  2862                              <1> 	mov	al, ah 	; get 6845 register number
  2863                              <1> 	out	dx, al
  2864                              <1> 	;inc	dx      ; point to data port
  2865                              <1> 	; 02/02/2022
  2866                              <1> 	inc	dl ; 3D9h
  2867                              <1> 	inc	ah	; next register value
  2868                              <1> 	mov	al, [ebx] ; get table value
  2869                              <1> 	out	dx, al	; out to chip
  2870                              <1> 	inc	ebx	; next in table
  2871                              <1> 	;dec	dx	; back to pointer register
  2872                              <1> 	; 02/02/2022
  2873                              <1> 	dec	dl ; 3D8h
  2874                              <1> 	loop	M10	; do the whole table
  2875                              <1> 	
  2876                              <1> ;-----	FILL REGEN AREA WITH BLANK
  2877                              <1> 	;xor	ax, ax  
  2878                              <1> 	;mov	[CRT_START], ax  ; start address saved in global
  2879                              <1> 	;mov	[ACTIVE_PAGE], al ; 0 ; (re)set page value
  2880                              <1> 	;mov	ecx, 8192 ; number of words in color card
  2881                              <1> 	; black background, light gray characeter color, space character
  2882                              <1> 	;mov	ax, 0720h ; fill char for alpha - attribute
  2883                              <1> ;M13:			  ; clear buffer
  2884                              <1> 	;add	edi, 0B8000h ; [crt_base]
  2885                              <1> 	;rep	stosw	; FILL THE REGEN BUFFER WITH BLANKS
  2886                              <1> 
  2887                              <1> ;-----	ENABLE VIDEO AND CORRECT PORT SETTING
  2888                              <1> 	;mov	dx, 3D4h ; mov dx, word [ADDR_6845]
  2889                              <1> 			 ; prepare to output to video enable port
  2890                              <1> 	;;add	dx, 4	 ; point to the mode control gerister
  2891                              <1> 	; 02/02/2022
  2892                              <1> 	;mov	dx, 3D8h
  2893                              <1> 	; 
  2894                              <1> 	;mov	al, [CRT_MODE_SET] ; get the mode set value
  2895                              <1> 	mov	al, 29h
  2896                              <1> 	out	dx, al	 ; set video enable port
  2897                              <1> 
  2898                              <1> ;----- 	DETERMINE NUMBER OF COLUMNS, BOTH FOR ENTIRE DISPLAY
  2899                              <1> ;----- 	AND THE NUMBER TO BE USED FOR TTY INTERFACE
  2900                              <1> 	;
  2901                              <1> 	;mov byte [CRT_COLS], 80h ; initialize number of columns count
  2902                              <1> 	;
  2903                              <1> ;-----	SET CURSOR POSITIONS
  2904                              <1> 	;push	edi
  2905                              <1> 	;mov	word [CRT_LEN], 80*25*2
  2906                              <1> 	mov	edi, cursor_posn
  2907                              <1> 	mov	ecx, 4	; clear all cursor positions (16 bytes)
  2908                              <1> 	xor	eax, eax
  2909                              <1> 	rep 	stosd	; fill with zeroes
  2910                              <1> 	;pop	edi
  2911                              <1> 
  2912                              <1> ;-----	SET UP OVERSCAN REGISTER
  2913                              <1> 	inc	dx	; set overscan port to a default
  2914                              <1> 	mov	al, 30h	; 30H valuye for all modes except 640X200 bw
  2915                              <1> ;M14:
  2916                              <1> 	out	dx, al	; output the correct value to 3D9 port
  2917                              <1> 	;mov	[CRT_PALETTE], al ; save the value for future use
  2918                              <1> 
  2919                              <1> ;-----	NORMAL RETURN FROM ALL VIDEO RETURNS
  2920                              <1> 	;
  2921                              <1> 	pop	eax
  2922                              <1> 	pop	ecx ; 16/01/2016
  2923                              <1> 	pop	edx
  2924                              <1> 	pop	ebx
  2925                              <1> 	pop	edi ; 16/01/2016
  2926                              <1> 	retn
  2927                              <1> 
  2928                              <1> %endif
  2929                              <1> 	
  2930                              <1> tty_sw:
  2931                              <1> 	; 02/02/2022
  2932                              <1> 	; 30/06/2015
  2933                              <1> 	; 27/06/2015 
  2934                              <1> 	; 07/09/2014
  2935                              <1> 	; 02/09/2014 (Retro UNIX 386 v1 - beginning)
  2936                              <1> 	;
  2937                              <1> 	; (Modified registers : EAX)
  2938                              <1> 	;
  2939                              <1>         ;mov     byte [u.quant], 0  ; 04/03/2014
  2940                              <1> 	;
  2941                              <1> ;act_disp_page:
  2942                              <1> 	; 30/06/2015
  2943                              <1> 	; 04/03/2014  (act_disp_page --> tty_sw)
  2944                              <1> 	; 10/12/2013
  2945                              <1> 	; 04/12/2013
  2946                              <1> 	;
  2947                              <1> 	; VIDEO.ASM - 06/10/85  VIDEO DISPLAY BIOS
  2948                              <1> 	;
  2949                              <1> 	; ACT_DISP_PAGE
  2950                              <1> 	;	THIS ROUTINE SETS THE ACTIVE DISPLAY PAGE, ALLOWING
  2951                              <1> 	;	THE FULL USE OF THE MEMORY SET ASIDE FOR THE VIDEO ATTACHMENT
  2952                              <1> 	; INPUT
  2953                              <1> 	;	AL HAS THE NEW ACTIVE DISPLAY PAGE
  2954                              <1> 	; OUTPUT
  2955                              <1> 	;	THE 6845 IS RESET TO DISPLAY THAT PAGE
  2956                              <1> 
  2957                              <1> 	;cli
  2958                              <1> 
  2959 000015C1 53                  <1> 	push	ebx
  2960                              <1> 	;push	cx
  2961                              <1> 	;push	dx
  2962                              <1> 	; 02/02/2022
  2963 000015C2 51                  <1> 	push	ecx
  2964 000015C3 52                  <1> 	push	edx
  2965                              <1> 	;
  2966 000015C4 A2[46620000]        <1> 	mov	[active_page], al ; save active page value ; [ptty]
  2967                              <1> 	;;mov	cx, [CRT_LEN] ; get saved length of regen buffer
  2968                              <1> 	;mov	cx, 25*80*2
  2969                              <1> 	; 02/02/2022
  2970 000015C9 B9A00F0000          <1> 	mov	ecx, 25*80*2
  2971                              <1> 	; 27/06/2015
  2972 000015CE 0FB6D8              <1> 	movzx	ebx, al
  2973                              <1> 	; 02/02/2022
  2974 000015D1 89D8                <1> 	mov	eax, ebx
  2975                              <1> 	;
  2976                              <1> 	;cbw	; 07/09/2014 (ah=0)
  2977                              <1> 	;mul 	cx	; display page times regen length
  2978                              <1> 	; 02/02/2022
  2979 000015D3 F7E1                <1> 	mul	ecx	
  2980                              <1> 	; 10/12/2013
  2981 000015D5 66A3[34620000]      <1> 	mov	[CRT_START], ax ; save start address for later
  2982                              <1> 	;mov	cx, ax	; start address to cx
  2983                              <1> 	; 02/02/2022
  2984 000015DB 89C1                <1> 	mov	ecx, eax
  2985                              <1> 	;sar	cx, 1
  2986                              <1> 	;shr	cx, 1	; divide by 2 for 6845 handling
  2987                              <1> 	; 02/02/2022
  2988 000015DD D1E9                <1> 	shr	ecx, 1
  2989 000015DF B40C                <1> 	mov	ah, 12	; 6845 register for start address
  2990 000015E1 E8EFFEFFFF          <1> 	call	m16
  2991                              <1> 	;sal	bx, 1
  2992                              <1> 	; 01/09/2014
  2993 000015E6 D0E3                <1> 	shl	bl, 1	; * 2 for word offset
  2994 000015E8 81C3[36620000]      <1> 	add	ebx, cursor_posn
  2995 000015EE 668B13              <1> 	mov	dx, [ebx] ; get cursor for this page
  2996 000015F1 E8CDFEFFFF          <1> 	call	m18
  2997                              <1> 	;
  2998                              <1> 	;pop	dx
  2999                              <1> 	;pop	cx
  3000                              <1> 	; 02/02/2022
  3001 000015F6 5A                  <1> 	pop	edx
  3002 000015F7 59                  <1> 	pop	ecx
  3003 000015F8 5B                  <1> 	pop	ebx
  3004                              <1> 	;
  3005                              <1> 	;sti
  3006                              <1> 	;
  3007 000015F9 C3                  <1> 	retn
  3008                              <1> 
  3009                              <1> ; %include 'vidata.inc' ; VIDEO DATA ; 11/03/2015
  3010                              <1> 
  3011                              <1> ; /// End Of VIDEO FUNCTIONS ///
  1891                                  
  1892                                  setup_rtc_int:
  1893                                  ; source: http://wiki.osdev.org/RTC
  1894 000015FA FA                      	cli		; disable interrupts
  1895                                  	; default int frequency is 1024 Hz (Lower 4 bits of register A is 0110b or 6)
  1896                                  	; in order to change this ...
  1897                                  	; frequency  = 32768 >> (rate-1) --> 32768 >> 5 = 1024
  1898                                  	; (rate must be above 2 and not over 15)
  1899                                  	; new rate = 15 --> 32768 >> (15-1) = 2 Hz
  1900 000015FB B08A                    	mov	al, 8Ah 
  1901 000015FD E670                    	out	70h, al ; set index to register A, disable NMI
  1902 000015FF 90                      	nop
  1903 00001600 E471                    	in	al, 71h ; get initial value of register A
  1904 00001602 88C4                    	mov 	ah, al
  1905 00001604 80E4F0                  	and	ah, 0F0h
  1906 00001607 B08A                    	mov	al, 8Ah 
  1907 00001609 E670                    	out	70h, al ; reset index to register A
  1908 0000160B 88E0                    	mov	al, ah
  1909 0000160D 0C0F                    	or	al, 0Fh	; new rate (0Fh -> 15)
  1910 0000160F E671                    	out	71h, al ; write only our rate to A. Note, rate is the bottom 4 bits. 
  1911                                  	; enable RTC interrupt
  1912 00001611 B08B                    	mov	al, 8Bh ;
  1913 00001613 E670                    	out	70h, al ; select register B and disable NMI
  1914 00001615 90                      	nop
  1915 00001616 E471                    	in	al, 71h ; read the current value of register B
  1916 00001618 88C4                    	mov	ah, al  ;
  1917 0000161A B08B                    	mov 	al, 8Bh ;
  1918 0000161C E670                    	out	70h, al ; set the index again (a read will reset the index to register B)	
  1919 0000161E 88E0                    	mov	al, ah  ;
  1920 00001620 0C40                    	or	al, 40h ;
  1921 00001622 E671                    	out	71h, al ; write the previous value ORed with 0x40. This turns on bit 6 of register B
  1922 00001624 FB                      	sti
  1923 00001625 C3                      	retn
  1924                                  
  1925                                  ; Write memory information
  1926                                  ; Temporary Code
  1927                                  ; 06/11/2014
  1928                                  ; 14/08/2015 
  1929                                  memory_info:	
  1930 00001626 A1[1C620000]            	mov	eax, [memory_size] ; in pages
  1931 0000162B 50                      	push	eax
  1932 0000162C C1E00C                  	shl	eax, 12		   ; in bytes
  1933 0000162F BB0A000000              	mov	ebx, 10
  1934 00001634 89D9                    	mov	ecx, ebx	   ; 10
  1935 00001636 BE[855E0000]            	mov	esi, mem_total_b_str	
  1936 0000163B E8AE000000              	call	bintdstr
  1937 00001640 58                      	pop	eax
  1938 00001641 B107                    	mov	cl, 7
  1939 00001643 BE[A95E0000]            	mov	esi, mem_total_p_str
  1940 00001648 E8A1000000              	call	bintdstr	
  1941                                  	; 14/08/2015
  1942 0000164D E8B9000000              	call	calc_free_mem
  1943                                  	; edx = calculated free pages
  1944                                  	; ecx = 0
  1945 00001652 A1[20620000]            	mov 	eax, [free_pages]
  1946 00001657 39D0                    	cmp	eax, edx ; calculated free mem value 
  1947                                  		; and initial free mem value are same or not?
  1948 00001659 751D                    	jne 	short pmim ; print mem info with '?' if not
  1949 0000165B 52                      	push 	edx ; free memory in pages	
  1950                                  	;mov 	eax, edx
  1951 0000165C C1E00C                  	shl	eax, 12 ; convert page count
  1952                                  			; to byte count
  1953 0000165F B10A                    	mov	cl, 10
  1954 00001661 BE[C95E0000]            	mov	esi, free_mem_b_str
  1955 00001666 E883000000              	call	bintdstr
  1956 0000166B 58                      	pop	eax
  1957 0000166C B107                    	mov	cl, 7
  1958 0000166E BE[ED5E0000]            	mov	esi, free_mem_p_str
  1959 00001673 E876000000              	call	bintdstr
  1960                                  pmim:
  1961 00001678 BE[735E0000]            	mov	esi, msg_memory_info
  1962                                  pmim_nb:	
  1963 0000167D AC                      	lodsb
  1964 0000167E 08C0                    	or	al, al
  1965 00001680 740D                    	jz	short pmim_ok
  1966 00001682 56                      	push	esi
  1967 00001683 31DB                    	xor	ebx, ebx ; 0
  1968                                  			; Video page 0 (bl=0)
  1969 00001685 B407                    	mov	ah, 07h ; Black background, 
  1970                                  			; light gray forecolor
  1971 00001687 E816FDFFFF              	call	write_tty
  1972 0000168C 5E                      	pop	esi
  1973 0000168D EBEE                    	jmp	short pmim_nb
  1974                                  pmim_ok:
  1975 0000168F C3                      	retn
  1976                                  
  1977                                  ; Convert binary number to hexadecimal string
  1978                                  ; 10/05/2015  
  1979                                  ; dsectpm.s (28/02/2015)
  1980                                  ; Retro UNIX 386 v1 - Kernel v0.2.0.6  
  1981                                  ; 01/12/2014
  1982                                  ; 25/11/2014
  1983                                  ;
  1984                                  bytetohex:
  1985                                  	; INPUT ->
  1986                                  	; 	AL = byte (binary number)
  1987                                  	; OUTPUT ->
  1988                                  	;	AX = hexadecimal string
  1989                                  	;
  1990 00001690 53                      	push	ebx
  1991 00001691 31DB                    	xor	ebx, ebx
  1992 00001693 88C3                    	mov	bl, al
  1993 00001695 C0EB04                  	shr	bl, 4
  1994 00001698 8A9B[DE160000]          	mov	bl, [ebx+hexchrs]
  1995 0000169E 86D8                    	xchg	bl, al
  1996 000016A0 80E30F                  	and	bl, 0Fh
  1997 000016A3 8AA3[DE160000]          	mov	ah, [ebx+hexchrs]
  1998 000016A9 5B                      	pop	ebx	
  1999 000016AA C3                      	retn
  2000                                  
  2001                                  wordtohex:
  2002                                  	; INPUT ->
  2003                                  	; 	AX = word (binary number)
  2004                                  	; OUTPUT ->
  2005                                  	;	EAX = hexadecimal string
  2006                                  	;
  2007 000016AB 53                      	push	ebx
  2008 000016AC 31DB                    	xor	ebx, ebx
  2009 000016AE 86E0                    	xchg	ah, al
  2010 000016B0 6650                    	push	ax
  2011 000016B2 88E3                    	mov	bl, ah
  2012 000016B4 C0EB04                  	shr	bl, 4
  2013 000016B7 8A83[DE160000]          	mov	al, [ebx+hexchrs]
  2014 000016BD 88E3                    	mov	bl, ah
  2015 000016BF 80E30F                  	and	bl, 0Fh
  2016 000016C2 8AA3[DE160000]          	mov	ah, [ebx+hexchrs]
  2017 000016C8 C1E010                  	shl	eax, 16
  2018 000016CB 6658                    	pop	ax
  2019 000016CD 5B                      	pop	ebx
  2020 000016CE EBC0                    	jmp	short bytetohex
  2021                                  	;mov	bl, al
  2022                                  	;shr	bl, 4
  2023                                  	;mov	bl, [ebx+hexchrs]
  2024                                  	;xchg	bl, al	 	
  2025                                  	;and	bl, 0Fh
  2026                                  	;mov	ah, [ebx+hexchrs]
  2027                                  	;pop	ebx	
  2028                                  	;retn
  2029                                  
  2030                                  dwordtohex:
  2031                                  	; INPUT ->
  2032                                  	; 	EAX = dword (binary number)
  2033                                  	; OUTPUT ->
  2034                                  	;	EDX:EAX = hexadecimal string
  2035                                  	;
  2036 000016D0 50                      	push	eax
  2037 000016D1 C1E810                  	shr	eax, 16
  2038 000016D4 E8D2FFFFFF              	call	wordtohex
  2039 000016D9 89C2                    	mov	edx, eax
  2040 000016DB 58                      	pop	eax
  2041                                  	;call	wordtohex
  2042                                  	;retn
  2043                                  	; 02/01/2022
  2044 000016DC EBCD                    	jmp	short wordtohex
  2045                                  
  2046                                  ; 10/05/2015
  2047                                  hex_digits:
  2048                                  hexchrs:
  2049 000016DE 303132333435363738-     	db '0123456789ABCDEF'
  2049 000016E7 39414243444546     
  2050                                  
  2051                                  ; Convert binary number to decimal/numeric string
  2052                                  ; 06/11/2014
  2053                                  ; Temporary Code
  2054                                  ;
  2055                                  
  2056                                  bintdstr:
  2057                                  	; EAX = binary number
  2058                                  	; ESI = decimal/numeric string address
  2059                                  	; EBX = divisor (10)
  2060                                  	; ECX = string length (<=10)
  2061 000016EE 01CE                    	add	esi, ecx
  2062                                  btdstr0:
  2063 000016F0 4E                      	dec	esi
  2064 000016F1 31D2                    	xor	edx, edx
  2065 000016F3 F7F3                    	div	ebx
  2066 000016F5 80C230                  	add	dl, 30h
  2067 000016F8 8816                    	mov	[esi], dl
  2068 000016FA FEC9                    	dec	cl
  2069 000016FC 740C                    	jz	short btdstr2 ; 02/01/2022 (short jump)
  2070 000016FE 09C0                    	or	eax, eax
  2071 00001700 75EE                    	jnz	short btdstr0
  2072                                  btdstr1:
  2073 00001702 4E                      	dec	esi
  2074 00001703 C60620                          mov     byte [esi], 20h ; blank space
  2075 00001706 FEC9                    	dec	cl
  2076 00001708 75F8                    	jnz	short btdstr1
  2077                                  btdstr2:
  2078 0000170A C3                      	ret
  2079                                  
  2080                                  ; Calculate free memory pages on M.A.T.
  2081                                  ; 06/11/2014
  2082                                  ; Temporary Code
  2083                                  ;
  2084                                  
  2085                                  calc_free_mem:
  2086 0000170B 31D2                    	xor	edx, edx
  2087                                  	;xor	ecx, ecx
  2088                                  	;mov	cx, [mat_size] ; in pages
  2089                                  	; 02/01/2022
  2090 0000170D 8B0D[30620000]          	mov	ecx, [mat_size] ; in pages
  2091 00001713 C1E10A                  	shl	ecx, 10	; 1024 dwords per page
  2092 00001716 BE00001000              	mov	esi, MEM_ALLOC_TBL
  2093                                  cfm0:
  2094 0000171B AD                      	lodsd
  2095 0000171C 51                      	push	ecx
  2096 0000171D B920000000              	mov	ecx, 32
  2097                                  cfm1:
  2098 00001722 D1E8                    	shr	eax, 1
  2099 00001724 7301                    	jnc	short cfm2
  2100 00001726 42                      	inc	edx
  2101                                  cfm2:
  2102 00001727 E2F9                    	loop	cfm1
  2103 00001729 59                      	pop	ecx
  2104 0000172A E2EF                    	loop	cfm0
  2105 0000172C C3                      	ret
  2106                                  
  2107                                  %include 'diskio.inc'  ; 07/03/2015
  2108                              <1> ; Retro UNIX 386 v1.1 Kernel (v0.2.1.6) - DISKIO.INC
  2109                              <1> ; Last Modification: 18/07/2022
  2110                              <1> ; 	(Initialized Disk Parameters Data is in 'DISKDATA.INC') 
  2111                              <1> ; 	(Uninitialized Disk Parameters Data is in 'DISKBSS.INC') 
  2112                              <1> 
  2113                              <1> ; DISK I/O SYSTEM - Erdogan Tan (Retro UNIX 386 v1 project)
  2114                              <1> 
  2115                              <1> ; ///////// DISK I/O SYSTEM ///////////////
  2116                              <1> 
  2117                              <1> ; 11/07/2022
  2118                              <1> ;; 06/02/2015
  2119                              <1> ;diskette_io:
  2120                              <1> ;	pushfd
  2121                              <1> ;	push 	cs
  2122                              <1> ;	call 	DISKETTE_IO_1
  2123                              <1> ;	retn
  2124                              <1> 	
  2125                              <1> ;;;;;; DISKETTE I/O ;;;;;;;;;;;;;;;;;;;; 06/02/2015 ;;;
  2126                              <1> ;//////////////////////////////////////////////////////
  2127                              <1> 
  2128                              <1> ; 11/07/2022 - (direct call instead of int 13h simulation)
  2129                              <1> ;		Function in AL
  2130                              <1> ;			0 = reset
  2131                              <1> ;			1 = read
  2132                              <1> ;			2 = write
  2133                              <1> ;		Disk drive number in DL
  2134                              <1> ;			0 & 1 = floppy disks	
  2135                              <1> ;			80h .. 83h = hard disks
  2136                              <1> ;		Sector address (LBA) in ECX
  2137                              <1> ;		Buffer address in EBX
  2138                              <1> ;		R/W sector count is (always) 1
  2139                              <1> ;
  2140                              <1> ;		Return:
  2141                              <1> ;			Status in AH (>0 = error code)
  2142                              <1> ;			if CF = 1 -> error code in AH
  2143                              <1> ;			if CF = 0 -> successful
  2144                              <1> ;			AL = undefined
  2145                              <1> ;
  2146                              <1> ;		Modified registers: (only) EAX
  2147                              <1> 
  2148                              <1> ; 10/07/2022
  2149                              <1> ; 08/07/2022 - (diskio code has been simplified/shortened 
  2150                              <1> ;		by removing unused IBM PC-AT disk functions)
  2151                              <1> ; DISKETTE I/O - Erdogan Tan (Retro UNIX 386 v1 project)
  2152                              <1> ; 20/02/2015
  2153                              <1> ; 06/02/2015 (unix386.s)
  2154                              <1> ; 16/12/2014 - 02/01/2015 (dsectrm2.s)
  2155                              <1> ;
  2156                              <1> ; Code (DELAY) modifications - AWARD BIOS 1999 (ADISK.EQU, COMMON.MAC)
  2157                              <1> ;
  2158                              <1> ; ADISK.EQU
  2159                              <1> 
  2160                              <1> ;----- Wait control constants 
  2161                              <1> 
  2162                              <1> ;amount of time to wait while RESET is active.
  2163                              <1> 
  2164                              <1> WAITCPU_RESET_ON   EQU	21		;Reset on must last at least 14us
  2165                              <1> 					;at 250 KBS xfer rate.
  2166                              <1> 					;see INTEL MCS, 1985, pg. 5-456
  2167                              <1> 
  2168                              <1> WAITCPU_FOR_STATUS EQU	100		;allow 30 microseconds for
  2169                              <1> 					;status register to become valid
  2170                              <1> 					;before re-reading.
  2171                              <1> 
  2172                              <1> ;After sending a byte to NEC, status register may remain
  2173                              <1> ;incorrectly set for 24 us.
  2174                              <1> 
  2175                              <1> WAITCPU_RQM_LOW	   EQU	24		;number of loops to check for
  2176                              <1> 					;RQM low.
  2177                              <1> 
  2178                              <1> ; COMMON.MAC
  2179                              <1> ;
  2180                              <1> ;	Timing macros
  2181                              <1> ;
  2182                              <1> 
  2183                              <1> %macro 		SIODELAY 0 		; SHORT IODELAY
  2184                              <1> 		jmp short $+2
  2185                              <1> %endmacro		
  2186                              <1> 
  2187                              <1> %macro		IODELAY  0		; NORMAL IODELAY
  2188                              <1> 		jmp short $+2
  2189                              <1> 		jmp short $+2
  2190                              <1> %endmacro
  2191                              <1> 
  2192                              <1> %macro		NEWIODELAY 0
  2193                              <1> 		out 0EBh,al
  2194                              <1> %endmacro 
  2195                              <1> 
  2196                              <1> ; (According to) AWARD BIOS 1999 - ATORGS.ASM (dw -> equ, db -> equ)
  2197                              <1> ;;; WAIT_FOR_MEM
  2198                              <1> ;WAIT_FDU_INT_LO	equ	017798		; 2.5 secs in 30 micro units.
  2199                              <1> ;WAIT_FDU_INT_HI	equ	1
  2200                              <1> WAIT_FDU_INT_LH		equ	83334		; 27/02/2015 (2.5 seconds waiting)
  2201                              <1> ;;; WAIT_FOR_PORT
  2202                              <1> ;WAIT_FDU_SEND_LO	equ	16667		; .5 secons in 30 us units.
  2203                              <1> ;WAIT_FDU_SEND_HI	equ	0
  2204                              <1> WAIT_FDU_SEND_LH	equ 	16667		; 27/02/2015	
  2205                              <1> ;Time to wait while waiting for each byte of NEC results = .5
  2206                              <1> ;seconds.  .5 seconds = 500,000 micros.  500,000/30 = 16,667.
  2207                              <1> ;WAIT_FDU_RESULTS_LO	equ	16667		; .5 seconds in 30 micro units.
  2208                              <1> ;WAIT_FDU_RESULTS_HI	equ	0
  2209                              <1> WAIT_FDU_RESULTS_LH	equ	16667  ; 27/02/2015
  2210                              <1> ;;; WAIT_REFRESH
  2211                              <1> ;amount of time to wait for head settle, per unit in parameter
  2212                              <1> ;table = 1 ms.
  2213                              <1> WAIT_FDU_HEAD_SETTLE	equ	33		; 1 ms in 30 micro units.
  2214                              <1> 
  2215                              <1> 
  2216                              <1> ; //////////////// DISKETTE I/O ////////////////
  2217                              <1> 
  2218                              <1> ; 11/12/2014 (copy from IBM PC-XT Model 286 BIOS - POSTEQU.INC)
  2219                              <1> 
  2220                              <1> ;----------------------------------------
  2221                              <1> ;	EQUATES USED BY POST AND BIOS	:
  2222                              <1> ;----------------------------------------
  2223                              <1> 
  2224                              <1> ;--------- 8042 KEYBOARD INTERFACE AND DIAGNOSTIC CONTROL REGISTERS ------------
  2225                              <1> ;PORT_A		EQU	060H		; 8042 KEYBOARD SCAN CODE/CONTROL PORT
  2226                              <1> ;PORT_B		EQU	061H		; PORT B READ/WRITE DIAGNOSTIC REGISTER
  2227                              <1> ;REFRESH_BIT	EQU	00010000B	; REFRESH TEST BIT
  2228                              <1> 
  2229                              <1> ;----------------------------------------
  2230                              <1> ;	CMOS EQUATES FOR THIS SYSTEM	:
  2231                              <1> ;-------------------------------------------------------------------------------
  2232                              <1> ;CMOS_PORT	EQU	070H		; I/O ADDRESS OF CMOS ADDRESS PORT
  2233                              <1> ;CMOS_DATA	EQU	071H		; I/O ADDRESS OF CMOS DATA PORT
  2234                              <1> ;NMI		EQU	10000000B	; DISABLE NMI INTERRUPTS MASK -
  2235                              <1> 					;  HIGH BIT OF CMOS LOCATION ADDRESS
  2236                              <1> 
  2237                              <1> ;---------- CMOS TABLE LOCATION ADDRESS'S ## -----------------------------------
  2238                              <1> CMOS_DISKETTE	EQU	010H		; DISKETTE DRIVE TYPE BYTE	      ;
  2239                              <1> ;		EQU	011H		; - RESERVED			      ;C
  2240                              <1> CMOS_DISK	EQU	012H		; FIXED DISK TYPE BYTE		      ;H
  2241                              <1> ;		EQU	013H		; - RESERVED			      ;E
  2242                              <1> CMOS_EQUIP	EQU	014H		; EQUIPMENT WORD LOW BYTE	      ;C
  2243                              <1> 
  2244                              <1> ;---------- DISKETTE EQUATES ---------------------------------------------------
  2245                              <1> INT_FLAG	EQU	10000000B	; INTERRUPT OCCURRENCE FLAG
  2246                              <1> DSK_CHG 	EQU	10000000B	; DISKETTE CHANGE FLAG MASK BIT
  2247                              <1> DETERMINED	EQU	00010000B	; SET STATE DETERMINED IN STATE BITS
  2248                              <1> HOME		EQU	00010000B	; TRACK 0 MASK
  2249                              <1> SENSE_DRV_ST	EQU	00000100B	; SENSE DRIVE STATUS COMMAND
  2250                              <1> TRK_SLAP	EQU	030H		; CRASH STOP (48 TPI DRIVES)
  2251                              <1> QUIET_SEEK	EQU	00AH		; SEEK TO TRACK 10
  2252                              <1> ;MAX_DRV 	EQU	2		; MAX NUMBER OF DRIVES
  2253                              <1> HD12_SETTLE	EQU	15		; 1.2 M HEAD SETTLE TIME
  2254                              <1> HD320_SETTLE	EQU	20		; 320 K HEAD SETTLE TIME
  2255                              <1> MOTOR_WAIT	EQU	37		; 2 SECONDS OF COUNTS FOR MOTOR TURN OFF
  2256                              <1> 
  2257                              <1> ;---------- DISKETTE ERRORS ----------------------------------------------------
  2258                              <1> ;TIME_OUT	EQU	080H		; ATTACHMENT FAILED TO RESPOND
  2259                              <1> ;BAD_SEEK	EQU	040H		; SEEK OPERATION FAILED
  2260                              <1> BAD_NEC 	EQU	020H		; DISKETTE CONTROLLER HAS FAILED
  2261                              <1> BAD_CRC 	EQU	010H		; BAD CRC ON DISKETTE READ
  2262                              <1> MED_NOT_FND	EQU	00CH		; MEDIA TYPE NOT FOUND
  2263                              <1> DMA_BOUNDARY	EQU	009H		; ATTEMPT TO DMA ACROSS 64K BOUNDARY
  2264                              <1> BAD_DMA 	EQU	008H		; DMA OVERRUN ON OPERATION
  2265                              <1> MEDIA_CHANGE	EQU	006H		; MEDIA REMOVED ON DUAL ATTACH CARD
  2266                              <1> RECORD_NOT_FND	EQU	004H		; REQUESTED SECTOR NOT FOUND
  2267                              <1> WRITE_PROTECT	EQU	003H		; WRITE ATTEMPTED ON WRITE PROTECT DISK
  2268                              <1> BAD_ADDR_MARK	EQU	002H		; ADDRESS MARK NOT FOUND
  2269                              <1> BAD_CMD 	EQU	001H		; BAD COMMAND PASSED TO DISKETTE I/O
  2270                              <1> 
  2271                              <1> ;---------- DISK CHANGE LINE EQUATES -------------------------------------------
  2272                              <1> NOCHGLN 	EQU	001H		; NO DISK CHANGE LINE AVAILABLE
  2273                              <1> CHGLN		EQU	002H		; DISK CHANGE LINE AVAILABLE
  2274                              <1> 
  2275                              <1> ;---------- MEDIA/DRIVE STATE INDICATORS ---------------------------------------
  2276                              <1> TRK_CAPA	EQU	00000001B	; 80 TRACK CAPABILITY
  2277                              <1> FMT_CAPA	EQU	00000010B	; MULTIPLE FORMAT CAPABILITY (1.2M)
  2278                              <1> DRV_DET 	EQU	00000100B	; DRIVE DETERMINED
  2279                              <1> MED_DET 	EQU	00010000B	; MEDIA DETERMINED BIT
  2280                              <1> DBL_STEP	EQU	00100000B	; DOUBLE STEP BIT
  2281                              <1> RATE_MSK	EQU	11000000B	; MASK FOR CLEARING ALL BUT RATE
  2282                              <1> RATE_500	EQU	00000000B	; 500 KBS DATA RATE
  2283                              <1> RATE_300	EQU	01000000B	; 300 KBS DATA RATE
  2284                              <1> RATE_250	EQU	10000000B	; 250 KBS DATA RATE
  2285                              <1> STRT_MSK	EQU	00001100B	; OPERATION START RATE MASK
  2286                              <1> SEND_MSK	EQU	11000000B	; MASK FOR SEND RATE BITS
  2287                              <1> 
  2288                              <1> ;---------- MEDIA/DRIVE STATE INDICATORS COMPATIBILITY -------------------------
  2289                              <1> M3D3U		EQU	00000000B	; 360 MEDIA/DRIVE NOT ESTABLISHED
  2290                              <1> M3D1U		EQU	00000001B	; 360 MEDIA,1.2DRIVE NOT ESTABLISHED
  2291                              <1> M1D1U		EQU	00000010B	; 1.2 MEDIA/DRIVE NOT ESTABLISHED
  2292                              <1> MED_UNK 	EQU	00000111B	; NONE OF THE ABOVE
  2293                              <1> 
  2294                              <1> ;---------- INTERRUPT EQUATES --------------------------------------------------
  2295                              <1> ;EOI		EQU	020H		; END OF INTERRUPT COMMAND TO 8259
  2296                              <1> ;INTA00		EQU	020H		; 8259 PORT
  2297                              <1> INTA01		EQU	021H		; 8259 PORT
  2298                              <1> INTB00		EQU	0A0H		; 2ND 8259
  2299                              <1> INTB01		EQU	0A1H		;
  2300                              <1> 
  2301                              <1> ;-------------------------------------------------------------------------------
  2302                              <1> DMA08		EQU	008H		; DMA STATUS REGISTER PORT ADDRESS
  2303                              <1> DMA		EQU	000H		; DMA CH.0 ADDRESS REGISTER PORT ADDRESS
  2304                              <1> DMA18		EQU	0D0H		; 2ND DMA STATUS PORT ADDRESS
  2305                              <1> DMA1		EQU	0C0H		; 2ND DMA CH.0 ADDRESS REGISTER ADDRESS
  2306                              <1> ;-------------------------------------------------------------------------------
  2307                              <1> ;TIMER		EQU	040H		; 8254 TIMER - BASE ADDRESS
  2308                              <1> 
  2309                              <1> ;-------------------------------------------------------------------------------
  2310                              <1> DMA_PAGE	EQU	081H		; START OF DMA PAGE REGISTERS
  2311                              <1> 
  2312                              <1> ; 10/07/2022
  2313                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2314                              <1> ; 06/02/2015 (unix386.s, protected mode modifications)
  2315                              <1> ; (unix386.s <-- dsectrm2.s)
  2316                              <1> ; 11/12/2014 (copy from IBM PC-XT Model 286 BIOS - DSEG.INC)
  2317                              <1> 
  2318                              <1> ; 10/12/2014
  2319                              <1> ;
  2320                              <1> ;int40h:
  2321                              <1> ;	pushf
  2322                              <1> ;	push 	cs
  2323                              <1> ;	;cli
  2324                              <1> ;	call 	DISKETTE_IO_1
  2325                              <1> ;	retn
  2326                              <1> 
  2327                              <1> ; DSKETTE ----- 04/21/86 DISKETTE BIOS
  2328                              <1> ; (IBM PC XT Model 286 System BIOS Source Code, 04-21-86)
  2329                              <1> ;
  2330                              <1> 
  2331                              <1> ;-- Retro UNIX 386 v1.1 (Kernel v0.2.1.5) ---08/07/2022-------------------------
  2332                              <1> ; DISKETTE I/O
  2333                              <1> ;	THIS INTERFACE PROVIDES ACCESS TO THE 5 1/4 INCH 360 KB,
  2334                              <1> ;	1.2 MB, 720 KB AND 1.44 MB DISKETTE DRIVES.
  2335                              <1> ; INPUT
  2336                              <1> ;	(AH)= 00H RESET DISKETTE SYSTEM
  2337                              <1> ;		HARD RESET TO NEC, PREPARE COMMAND, RECALIBRATE REQUIRED
  2338                              <1> ;		ON ALL DRIVES
  2339                              <1> ;------------------------------------------------------------------------------- 
  2340                              <1> ;	(AH)= 01H  READ THE DESIRED SECTORS INTO MEMORY
  2341                              <1> ;-------------------------------------------------------------------------------
  2342                              <1> ;	(AH)= 02H  WRITE THE DESIRED SECTORS FROM MEMORY
  2343                              <1> ;-------------------------------------------------------------------------------
  2344                              <1> ;
  2345                              <1> ;	REGISTERS FOR READ/WRITE
  2346                              <1> ;	(DL) - DRIVE NUMBER (0-1 ALLOWED, VALUE CHECKED)
  2347                              <1> ;	(DH) - HEAD NUMBER (0-1 ALLOWED, NOT VALUE CHECKED)
  2348                              <1> ;	(CH) - TRACK NUMBER (NOT VALUE CHECKED)
  2349                              <1> ;		MEDIA	DRIVE	TRACK NUMBER
  2350                              <1> ;		320/360	320/360	    0-39
  2351                              <1> ;		320/360	1.2M	    0-39
  2352                              <1> ;		1.2M	1.2M	    0-79
  2353                              <1> ;		720K	720K	    0-79
  2354                              <1> ;		1.44M	1.44M	    0-79	
  2355                              <1> ;	(CL) - 	SECTOR NUMBER (NOT VALUE CHECKED)
  2356                              <1> ;		MEDIA	DRIVE	SECTOR NUMBER
  2357                              <1> ;		320/360	320/360	     1-8/9
  2358                              <1> ;		320/360	1.2M	     1-8/9
  2359                              <1> ;		1.2M	1.2M	     1-15
  2360                              <1> ;		720K	720K	     1-9
  2361                              <1> ;		1.44M	1.44M	     1-18		
  2362                              <1> ;	(AL)	NUMBER OF SECTORS (NOT VALUE CHECKED)
  2363                              <1> ;		MEDIA	DRIVE	MAX NUMBER OF SECTORS
  2364                              <1> ;		320/360	320/360	        8/9
  2365                              <1> ;		320/360	1.2M	        8/9
  2366                              <1> ;		1.2M	1.2M		15
  2367                              <1> ;		720K	720K		9
  2368                              <1> ;		1.44M	1.44M		18
  2369                              <1> ;
  2370                              <1> ;	(EBX) - ADDRESS OF BUFFER
  2371                              <1> ;
  2372                              <1> ;-------------------------------------------------------------------------------
  2373                              <1> ; OUTPUT FOR ALL FUNCTIONS
  2374                              <1> ;	AH = STATUS OF OPERATION
  2375                              <1> ;		STATUS BITS ARE DEFINED IN THE EQUATES FOR @DISKETTE_STATUS
  2376                              <1> ;		VARIABLE IN THE DATA SEGMENT OF THIS MODULE
  2377                              <1> ;	CY = 0	SUCCESSFUL OPERATION (AH=0 ON RETURN)
  2378                              <1> ;	CY = 1	FAILED OPERATION (AH HAS ERROR REASON)
  2379                              <1> ;	FOR READ/WRITE/VERIFY
  2380                              <1> ;		DS,BX,DX,CX PRESERVED
  2381                              <1> ;	NOTE: IF AN ERROR IS REPORTED BY THE DISKETTE CODE, THE APPROPRIATE 
  2382                              <1> ;		ACTION IS TO RESET THE DISKETTE, THEN RETRY THE OPERATION.
  2383                              <1> ;		ON READ ACCESSES, NO MOTOR START DELAY IS TAKEN, SO THAT 
  2384                              <1> ;		THREE RETRIES ARE REQUIRED ON READS TO ENSURE THAT THE 
  2385                              <1> ;		PROBLEM IS NOT DUE TO MOTOR START-UP.
  2386                              <1> ;-------------------------------------------------------------------------------
  2387                              <1> ;
  2388                              <1> ; DISKETTE STATE MACHINE - ABSOLUTE ADDRESS 40:90 (DRIVE A) & 91 (DRIVE B)
  2389                              <1> ;
  2390                              <1> ;   -----------------------------------------------------------------
  2391                              <1> ;   |       |       |       |       |       |       |       |       |
  2392                              <1> ;   |   7   |   6   |   5   |   4   |   3   |   2   |   1   |   0   |
  2393                              <1> ;   |       |       |       |       |       |       |       |       |
  2394                              <1> ;   -----------------------------------------------------------------
  2395                              <1> ;	|	|	|	|	|	|	|	|
  2396                              <1> ;	|	|	|	|	|	-----------------
  2397                              <1> ;	|	|	|	|	|		|
  2398                              <1> ;	|	|	|	|    RESERVED		|
  2399                              <1> ;	|	|	|	|		  PRESENT STATE
  2400                              <1> ;	|	|	|	|	000: 360K IN 360K DRIVE UNESTABLISHED
  2401                              <1> ;	|	|	|	|	001: 360K IN 1.2M DRIVE UNESTABLISHED
  2402                              <1> ;	|	|	|	|	010: 1.2M IN 1.2M DRIVE UNESTABLISHED
  2403                              <1> ;	|	|	|	|	011: 360K IN 360K DRIVE ESTABLISHED
  2404                              <1> ;	|	|	|	|	100: 360K IN 1.2M DRIVE ESTABLISHED
  2405                              <1> ;	|	|	|	|	101: 1.2M IN 1.2M DRIVE ESTABLISHED
  2406                              <1> ;	|	|	|	|	110: RESERVED
  2407                              <1> ;	|	|	|	|	111: NONE OF THE ABOVE
  2408                              <1> ;	|	|	|	|
  2409                              <1> ;	|	|	|	------>	MEDIA/DRIVE ESTABLISHED
  2410                              <1> ;	|	|	|
  2411                              <1> ;	|	|	-------------->	DOUBLE STEPPING REQUIRED
  2412                              <1> ;	|	|					 (360K IN 1.2M DRIVE)
  2413                              <1> ;	|	|
  2414                              <1> ;	------------------------------>	DATA TRANSFER RATE FOR THIS DRIVE:
  2415                              <1> ;
  2416                              <1> ;						00: 500 KBS
  2417                              <1> ;						01: 300 KBS
  2418                              <1> ;						10: 250 KBS
  2419                              <1> ;						11: RESERVED
  2420                              <1> ;
  2421                              <1> ;
  2422                              <1> 
  2423                              <1> struc MD
  2424 00000000 ??                  <1> 	.SPEC1:	  resb	1	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2425 00000001 ??                  <1> 	.SPEC2:	  resb	1	; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2426 00000002 ??                  <1> 	.OFF_TIM: resb	1	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2427 00000003 ??                  <1> 	.BYT_SEC: resb	1	; 512 BYTES/SECTOR
  2428 00000004 ??                  <1> 	.SEC_TRK: resb	1	; EOT (LAST SECTOR ON TRACK)
  2429 00000005 ??                  <1> 	.GAP:	  resb	1	; GAP LENGTH
  2430 00000006 ??                  <1> 	.DTL:	  resb	1	; DTL
  2431 00000007 ??                  <1> 	.GAP3:	  resb	1	; GAP LENGTH FOR FORMAT
  2432 00000008 ??                  <1> 	.FIL_BYT: resb	1	; FILL BYTE FOR FORMAT
  2433 00000009 ??                  <1> 	.HD_TIM:  resb	1	; HEAD SETTLE TIME (MILLISECONDS)
  2434 0000000A ??                  <1> 	.STR_TIM: resb	1	; MOTOR START TIME (1/8 SECONDS)
  2435 0000000B ??                  <1> 	.MAX_TRK: resb	1	; MAX. TRACK NUMBER
  2436 0000000C ??                  <1> 	.RATE:	  resb	1	; DATA TRANSFER RATE
  2437                              <1> endstruc
  2438                              <1> 
  2439                              <1> BIT7OFF	EQU	7FH
  2440                              <1> BIT7ON	EQU	80H
  2441                              <1> 
  2442                              <1> ; 11/07/2022 - (direct call instead of int 13h simulation)
  2443                              <1> ;		Function in AL
  2444                              <1> ;			0 = reset
  2445                              <1> ;			1 = read
  2446                              <1> ;			2 = write
  2447                              <1> ;		Disk drive number in DL
  2448                              <1> ;			0 & 1 = floppy disks	
  2449                              <1> ;			80h .. 83h = hard disks
  2450                              <1> ;		Sector address (LBA) in ECX
  2451                              <1> ;		Buffer address in EBX
  2452                              <1> ;		R/W sector count is (always) 1
  2453                              <1> ;
  2454                              <1> ;		Return:
  2455                              <1> ;			Status in AH (>0 = error code)
  2456                              <1> ;			if CF = 1 -> error code in AH
  2457                              <1> ;			if CF = 0 -> successful
  2458                              <1> ;			AL = undefined
  2459                              <1> ;
  2460                              <1> ;		Modified registers: (only) EAX
  2461                              <1> 
  2462                              <1> ; 11/07/2022
  2463                              <1> ;;int13h: ; 16/02/2015
  2464                              <1> ;; 16/02/2015 - 21/02/2015
  2465                              <1> ;int40h:
  2466                              <1> ;	pushfd
  2467                              <1> ;	push 	cs
  2468                              <1> ;	call 	DISKETTE_IO_1
  2469                              <1> ;	retn	
  2470                              <1> 
  2471                              <1> DISKETTE_IO_1:
  2472                              <1> 
  2473                              <1> 	;sti				; INTERRUPTS BACK ON
  2474                              <1> 	; 11/07/2022
  2475                              <1> 	; save registers
  2476 0000172D 55                  <1> 	push	ebp			; ANY
  2477                              <1> 
  2478                              <1> 	; 11/07/2022
  2479                              <1> 	;push	edi			; ANY
  2480                              <1> 	;push	edx			; DRIVE NUMBER (DL)
  2481                              <1> 	;push	ebx			; BUFFER ADDRESS
  2482                              <1> 	;push	ecx			; SECTOR ADDRESS (LBA)
  2483                              <1> 	;push	esi			; ANY
  2484                              <1> 
  2485                              <1> 	; 11/07/2022
  2486 0000172E 89DD                <1> 	mov	ebp, ebx ; buffer address
  2487 00001730 C605[9C620000]00    <1> 	mov	byte [DSKETTE_STATUS], 0 ; RESET DISKETTE STATUS
  2488 00001737 0FB6FA              <1> 	movzx	edi, dl ; drive number (0 or 1)
  2489                              <1> 	
  2490 0000173A 08C0                <1> 	or	al, al			; RESET ?
  2491 0000173C 7507                <1> 	jnz	short DISKETTE_RW_1	; NO
  2492                              <1> 
  2493 0000173E E84D010000          <1> 	call	DSK_RESET
  2494                              <1> 
  2495 00001743 EB37                <1> 	jmp	short DISKETTE_RW_2	
  2496                              <1> 
  2497                              <1> DISKETTE_RW_1:
  2498                              <1> 	; 12/07/2022
  2499                              <1> 	; 11/07/2022
  2500                              <1> 	; ecx = sector address (LBA, < 2880)
  2501                              <1> 	; ebp = buffer address
  2502                              <1> 	; edi = drive number (0 or 1)
  2503                              <1> 	;  al = function (read = 1 or write = 2)
  2504                              <1> 
  2505 00001745 88C2                <1> 	mov	dl, al ; *
  2506                              <1> convert_to_chs:
  2507                              <1> 	;;;
  2508 00001747 B004                <1> 	mov	al, 4 ; MD.SEC_TRK ; sector per track (drv.spt)
  2509 00001749 E8D9050000          <1> 	call	GET_PARM
  2510                              <1> 	; 12/07/2022
  2511 0000174E 88E6                <1> 	mov	dh, ah ; spt
  2512 00001750 89C8                <1> 	mov	eax, ecx ; sector address (LBA) 
  2513 00001752 F6F6                <1> 	div	dh  ; AX/DH
  2514 00001754 88E1                <1> 	mov	cl, ah ; sector number - 1
  2515 00001756 FEC1                <1> 	inc	cl  ; sector number (1 based)
  2516 00001758 28ED                <1> 	sub	ch, ch ; head = 0 
  2517                              <1> 	; heads = 2
  2518 0000175A D0E8                <1> 	shr	al, 1 ; al = al/2
  2519 0000175C 80D500              <1> 	adc	ch, 0 ; head = 1 or head = 0
  2520 0000175F C1E110              <1> 	shl	ecx, 16
  2521 00001762 88C1                <1> 	mov	cl, al ; track (cylinder)
  2522 00001764 88D5                <1> 	mov	ch, dl ; function number 
  2523 00001766 89CE                <1> 	mov	esi, ecx ; byte 0 = track, byte 1 = function
  2524                              <1> 			 ; byte 2 = sector, byte 3 = head
  2525 00001768 C1C610              <1> 	rol	esi, 16
  2526                              <1> 			 ; byte 0 = sector, byte 1 = head
  2527                              <1> 			 ; byte 2 = track, byte 3 = function		
  2528                              <1> 	;;; 
  2529 0000176B 80FA02              <1> 	cmp	dl, 2 ; *
  2530 0000176E 7407                <1> 	je	short DISKETTE_W
  2531                              <1> DISKETTE_R:	
  2532                              <1> 	; dl = 1 ; *
  2533 00001770 E809000000          <1> 	call	DSK_READ
  2534 00001775 EB05                <1> 	jmp	short DISKETTE_RW_2
  2535                              <1> DISKETTE_W:
  2536 00001777 E80F000000          <1> 	call	DSK_WRITE
  2537                              <1> DISKETTE_RW_2:
  2538                              <1> 	; 11/07/2022
  2539                              <1> 	; Restore registers
  2540                              <1> 	;pop	esi
  2541                              <1> 	;pop	ecx
  2542                              <1> 	;pop	ebx
  2543                              <1> 	;pop	edx
  2544                              <1> 	;pop	edi
  2545                              <1> 
  2546                              <1> 	; 11/07/2022
  2547 0000177C 5D                  <1> 	pop	ebp
  2548 0000177D C3                  <1> 	retn
  2549                              <1> 
  2550                              <1> ;-------------------------------------------------------------------------------
  2551                              <1> ; DISK_READ	(AH = 01H)  ; Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2552                              <1> ;	DISKETTE READ.
  2553                              <1> ;
  2554                              <1> ; ON ENTRY:	EDI	: DRIVE #
  2555                              <1> ;		SI-HI	: HEAD #
  2556                              <1> ;		SI-LOW	: # OF SECTORS
  2557                              <1> ;		ES	: BUFFER SEGMENT
  2558                              <1> ;		[BP]	: SECTOR #
  2559                              <1> ;		[BP+1]	: TRACK #
  2560                              <1> ;		[BP+2]	: BUFFER OFFSET
  2561                              <1> ;
  2562                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2563                              <1> ;-------------------------------------------------------------------------------
  2564                              <1> 
  2565                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2566                              <1> ; 06/02/2015, ES:BX -> EBX (unix386.s)
  2567                              <1> 
  2568                              <1> DSK_READ:
  2569 0000177E 8025[9A620000]7F    <1> 	and	byte [MOTOR_STATUS], 01111111b ; INDICATE A READ OPERATION
  2570 00001785 66B846E6            <1> 	mov	ax, 0E646h		; AX = NEC COMMAND, DMA COMMAND
  2571                              <1> 	;call	RD_WR_VF		; COMMON READ/WRITE/VERIFY
  2572                              <1> 	;retn
  2573 00001789 EB0B                <1> 	jmp	short RD_WR_VF
  2574                              <1> 
  2575                              <1> ;-------------------------------------------------------------------------------
  2576                              <1> ; DISK_WRITE	(AH = 02H)
  2577                              <1> ;	DISKETTE WRITE.
  2578                              <1> ;
  2579                              <1> ; ON ENTRY:	EDI	: DRIVE #
  2580                              <1> ;		SI-HI	: HEAD #
  2581                              <1> ;		SI-LOW	: # OF SECTORS
  2582                              <1> ;		ES	: BUFFER SEGMENT
  2583                              <1> ;		[BP]	: SECTOR #
  2584                              <1> ;		[BP+1]	: TRACK #
  2585                              <1> ;		[BP+2]	: BUFFER OFFSET
  2586                              <1> ;
  2587                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2588                              <1> ;-------------------------------------------------------------------------------
  2589                              <1> 
  2590                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2591                              <1> ; 06/02/2015, ES:BX -> EBX (unix386.s)
  2592                              <1> 
  2593                              <1> DSK_WRITE:
  2594 0000178B 66B84AC5            <1> 	mov	ax, 0C54Ah		; AX = NEC COMMAND, DMA COMMAND
  2595 0000178F 800D[9A620000]80    <1>         or	byte [MOTOR_STATUS], 10000000b ; INDICATE WRITE OPERATION
  2596                              <1> 	;;call	RD_WR_VF		; COMMON READ/WRITE/VERIFY
  2597                              <1> 	;;retn
  2598                              <1> 	;jmp	short RD_WR_VF
  2599                              <1> 
  2600                              <1> ;-------------------------------------------------------------------------------
  2601                              <1> ; RD_WR_VF
  2602                              <1> ;	COMMON READ, WRITE
  2603                              <1> ;	MAIN LOOP FOR STATE RETRIES.
  2604                              <1> ;
  2605                              <1> ; ON ENTRY:	AH = READ/WRITE NEC PARAMETER
  2606                              <1> ;		AL = READ/WRITE DMA PARAMETER
  2607                              <1> ;
  2608                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2609                              <1> ;-------------------------------------------------------------------------------
  2610                              <1> 
  2611                              <1> RD_WR_VF:
  2612                              <1> 	; 18/07/2022
  2613                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2614 00001796 50                  <1> 	push	eax ; 24/12/2021	; SAVE DMA, NEC PARAMETERS
  2615 00001797 E8C9010000          <1> 	call	XLAT_NEW		; TRANSLATE STATE TO PRESENT ARCH.
  2616 0000179C E82B020000          <1> 	call	SETUP_STATE		; INITIALIZE START AND END RATE
  2617 000017A1 58                  <1> 	pop	eax ; 24/12/2021	; RESTORE READ/WRITE PARAMETER
  2618                              <1> DO_AGAIN:
  2619 000017A2 50                  <1> 	push	eax ; 24/12/2021	; SAVE READ/WRITE PARAMETER
  2620 000017A3 E865020000          <1> 	call	MED_CHANGE		; MEDIA CHANGE AND RESET IF CHANGED
  2621 000017A8 58                  <1> 	pop	eax ; 24/12/2021	; RESTORE READ/WRITE PARAMETER
  2622                              <1> 	; 24/12/2021
  2623 000017A9 7305                <1> 	jnc	short RWV
  2624 000017AB E9B6000000          <1> 	jmp	RWV_END			; MEDIA CHANGE ERROR OR TIME-OUT
  2625                              <1> RWV:
  2626 000017B0 50                  <1> 	push	eax ; 24/12/2021	; SAVE READ/WRITE/VERIFY PARAMETER
  2627 000017B1 8AB7[A7620000]      <1> 	mov	dh, [DSK_STATE+edi]	; GET RATE STATE OF THIS DRIVE
  2628 000017B7 80E6C0              <1> 	and	dh, RATE_MSK		; KEEP ONLY RATE
  2629 000017BA E85F050000          <1> 	call	CMOS_TYPE		; RETURN DRIVE TYPE IN AL
  2630                              <1> 	; 20/02/2015
  2631 000017BF 7445                <1> 	jz	short RWV_ASSUME	; ERROR IN CMOS
  2632 000017C1 3C01                <1> 	cmp	al, 1			; 40 TRACK DRIVE?
  2633 000017C3 750D                <1> 	jne	short RWV_1		; NO, BYPASS CMOS VALIDITY CHECK
  2634 000017C5 F687[A7620000]01    <1> 	test	byte [DSK_STATE+edi], TRK_CAPA ; CHECK FOR 40 TRACK DRIVE
  2635 000017CC 740F                <1> 	jz	short RWV_2		; YES, CMOS IS CORRECT
  2636                              <1> 	;mov	al, 2			; CHANGE TO 1.2M
  2637                              <1> 	; 12/07/2022
  2638 000017CE FEC0                <1> 	inc	al  ; al = 2
  2639 000017D0 EB0B                <1> 	jmp	short RWV_2
  2640                              <1> RWV_1:
  2641                              <1> 	; 12/07/2022
  2642                              <1> 	;jb	short RWV_2		; NO DRIVE SPECIFIED, CONTINUE
  2643 000017D2 F687[A7620000]01    <1> 	test	byte [DSK_STATE+edi], TRK_CAPA ; IS IT REALLY 40 TRACK?
  2644 000017D9 7502                <1> 	jnz	short RWV_2		; NO, 80 TRACK
  2645 000017DB B001                <1> 	mov	al, 1			; IT IS 40 TRACK, FIX CMOS VALUE
  2646                              <1> 	; 12/07/2022
  2647                              <1> 	;jmp	short RWV_3
  2648                              <1> RWV_2:
  2649                              <1> 	; 12/07/2022
  2650                              <1> 	;or	al, al			; TEST FOR NO DRIVE
  2651                              <1> 	;jz	short RWV_ASSUME	; ASSUME TYPE, USE MAX TRACK
  2652                              <1> RWV_3:
  2653                              <1> 	; 12/07/2022
  2654                              <1> 	;mov	dl, al	; 11/07/2022
  2655 000017DD E81F010000          <1> 	call	DR_TYPE_CHECK		; RTN EBX = MEDIA/DRIVE PARAM TBL.
  2656 000017E2 7222                <1> 	jc	short RWV_ASSUME	; TYPE NOT IN TABLE (BAD CMOS)
  2657                              <1> 
  2658                              <1> ;-----	SEARCH FOR MEDIA/DRIVE PARAMETER TABLE
  2659                              <1> 
  2660 000017E4 57                  <1> 	push	edi			; SAVE DRIVE #
  2661                              <1> 	;xor	ebx, ebx		; EBX = INDEX TO DR_TYPE TABLE
  2662 000017E5 BB[BC5C0000]        <1> 	mov	ebx, DR_TYPE
  2663                              <1> 	;mov	ecx, DR_CNT		; ECX = LOOP COUNT
  2664 000017EA B106                <1> 	mov	cl, DR_CNT
  2665                              <1> RWV_DR_SEARCH:
  2666                              <1> 	;mov	ah, [DR_TYPE+ebx]	; GET DRIVE TYPE
  2667 000017EC 8A23                <1> 	mov	ah, [ebx]
  2668 000017EE 80E47F              <1> 	and	ah, BIT7OFF		; MASK OUT MSB
  2669 000017F1 38E0                <1> 	cmp	al, ah			; DRIVE TYPE MATCH?
  2670                              <1> 	; 12/07/2022
  2671                              <1> 	;cmp	dl, ah ; 11/07/2022
  2672 000017F3 7509                <1> 	jne	short RWV_NXT_MD	; NO, CHECK NEXT DRIVE TYPE
  2673                              <1> RWV_DR_FND:
  2674                              <1> 	;mov	edi, [DR_TYPE+ebx+1] 	; EDI = MEDIA/DRIVE PARAMETER TABLE
  2675 000017F5 43                  <1> 	inc	ebx
  2676 000017F6 8B3B                <1> 	mov	edi, [ebx]
  2677 000017F8 4B                  <1> 	dec	ebx
  2678                              <1> RWV_MD_SEARH:
  2679 000017F9 3A770C              <1>         cmp	dh, [edi+MD.RATE]       ; MATCH?
  2680 000017FC 741D                <1> 	je	short RWV_MD_FND	; YES, GO GET 1ST SPECIFY BYTE
  2681                              <1> RWV_NXT_MD:
  2682 000017FE 83C305              <1> 	add	ebx, 5			; CHECK NEXT DRIVE TYPE
  2683                              <1> 	;loop	RWV_DR_SEARCH
  2684 00001801 FEC9                <1> 	dec	cl
  2685 00001803 75E7                <1> 	jnz	short RWV_DR_SEARCH 
  2686 00001805 5F                  <1> 	pop	edi			; RESTORE DRIVE #
  2687                              <1> 
  2688                              <1> ;-----	ASSUME PRIMARY DRIVE IS INSTALLED AS SHIPPED
  2689                              <1> 
  2690                              <1> RWV_ASSUME:
  2691 00001806 BB[DA5C0000]        <1> 	mov	ebx, MD_TBL1		; POINT TO 40 TRACK 250 KBS
  2692 0000180B F687[A7620000]01    <1> 	test	byte [DSK_STATE+edi], TRK_CAPA ; TEST FOR 80 TRACK
  2693 00001812 740A                <1> 	jz	short RWV_MD_FND1	; MUST BE 40 TRACK
  2694 00001814 BB[F45C0000]        <1> 	mov	ebx, MD_TBL3		; POINT TO 80 TRACK 500 KBS
  2695 00001819 EB03                <1> 	jmp	short RWV_MD_FND1	; GO SPECIFY PARAMTERS
  2696                              <1> 
  2697                              <1> ;-----	EBX POINTS TO MEDIA/DRIVE PARAMETER TABLE
  2698                              <1> 	 			
  2699                              <1> RWV_MD_FND:
  2700 0000181B 89FB                <1> 	mov	ebx, edi		; EBX = MEDIA/DRIVE PARAMETER TABLE
  2701 0000181D 5F                  <1> 	pop	edi			; RESTORE DRIVE #
  2702                              <1> 	
  2703                              <1> ;-----	SEND THE SPECIFY COMMAND TO THE CONTROLLER
  2704                              <1> 
  2705                              <1> RWV_MD_FND1:
  2706 0000181E E824010000          <1> 	call	SEND_SPEC_MD
  2707 00001823 E851020000          <1> 	call	CHK_LASTRATE		; ZF=1 ATTEMP RATE IS SAME AS LAST RATE
  2708 00001828 7405                <1> 	jz	short RWV_DBL		; YES,SKIP SEND RATE COMMAND
  2709 0000182A E82C020000          <1> 	call	SEND_RATE		; SEND DATA RATE TO NEC
  2710                              <1> RWV_DBL:
  2711 0000182F 53                  <1> 	push	ebx			; SAVE MEDIA/DRIVE PARAM TBL ADDRESS
  2712 00001830 E847040000          <1> 	call	SETUP_DBL		; CHECK FOR DOUBLE STEP
  2713 00001835 5B                  <1> 	pop	ebx			; RESTORE ADDRESS
  2714 00001836 7221                <1> 	jc	short CHK_RET		; ERROR FROM READ ID, POSSIBLE RETRY
  2715                              <1> 	;pop	eax ; 24/12/2021	; RESTORE NEC COMMAND
  2716                              <1> 	;push	eax ; 24/12/2021	; SAVE NEC COMMAND
  2717                              <1> 	; 08/07/2022
  2718 00001838 8B0424              <1> 	mov	eax, [esp]
  2719                              <1> 	; 18/07/2022
  2720                              <1> 	;push	ebx			; SAVE MEDIA/DRIVE PARAM TBL ADDRESS
  2721 0000183B E84C020000          <1> 	call	DMA_SETUP		; SET UP THE DMA
  2722                              <1> 	;pop	ebx
  2723 00001840 58                  <1> 	pop	eax ; 24/12/2021	; RESTORE NEC COMMAND
  2724 00001841 722D                <1> 	jc	short RWV_BAC		; CHECK FOR DMA BOUNDARY ERROR
  2725 00001843 50                  <1> 	push	eax ; 24/12/2021	; SAVE NEC COMMAND
  2726 00001844 53                  <1> 	push	ebx			; SAVE MEDIA/DRIVE PARAM TBL ADDRESS
  2727 00001845 E88C020000          <1> 	call	NEC_INIT		; INITIALIZE NEC
  2728 0000184A 5B                  <1> 	pop	ebx			; RESTORE ADDRESS
  2729 0000184B 720C                <1> 	jc	short CHK_RET		; ERROR - EXIT
  2730 0000184D E8B5020000          <1> 	call	RWV_COM			; OP CODE COMMON TO READ/WRITE
  2731 00001852 7205                <1> 	jc	short CHK_RET		; ERROR - EXIT
  2732 00001854 E8FC020000          <1> 	call	NEC_TERM		; TERMINATE, GET STATUS, ETC.
  2733                              <1> CHK_RET:
  2734 00001859 E89B030000          <1> 	call	RETRY			; CHECK FOR, SETUP RETRY
  2735 0000185E 58                  <1> 	pop	eax ; 24/12/2021	; RESTORE READ/WRITE PARAMETER
  2736 0000185F 7305                <1> 	jnc	short RWV_END		; CY = 0 NO RETRY
  2737 00001861 E93CFFFFFF          <1>         jmp	DO_AGAIN                ; CY = 1 MEANS RETRY
  2738                              <1> RWV_END:
  2739 00001866 E846030000          <1> 	call	DSTATE			; ESTABLISH STATE IF SUCCESSFUL
  2740 0000186B E8D7030000          <1> 	call	NUM_TRANS		; AL = NUMBER TRANSFERRED
  2741                              <1> RWV_BAC:
  2742                              <1> 	; 08/07/2022			; BAD DMA ERROR ENTRY
  2743                              <1> 	;push	eax ; 24/12/2021	; SAVE NUMBER TRANSFERRED
  2744                              <1> 	;CALL	XLAT_OLD		; TRANSLATE STATE TO COMPATIBLE MODE
  2745                              <1> 	;pop	eax ; 24/12/2021	; RESTORE NUMBER TRANSFERRED
  2746                              <1> 	;;call	SETUP_END		; VARIOUS CLEANUPS
  2747                              <1> 	;;retn
  2748                              <1> 	;jmp	SETUP_END
  2749                              <1> 
  2750                              <1> ;-------------------------------------------------------------------------------
  2751                              <1> ; SETUP_END
  2752                              <1> ;	RESTORES @MOTOR_COUNT TO PARAMETER PROVIDED IN TABLE 
  2753                              <1> ;	AND LOADS @DSKETTE_STATUS TO AH, AND SETS CY.
  2754                              <1> ;
  2755                              <1> ; ON EXIT:
  2756                              <1> ;	AH, @DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2757                              <1> ;-------------------------------------------------------------------------------
  2758                              <1> SETUP_END:
  2759                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5) 
  2760                              <1> 	;mov	dl, 2			; GET THE MOTOR WAIT PARAMETER
  2761                              <1> 	;push	ax			; SAVE NUMBER TRANSFERRED
  2762 00001870 50                  <1> 	push	eax ; 24/12/2021
  2763 00001871 B002                <1> 	mov	al, 2 ; 08/07/2022
  2764 00001873 E8AF040000          <1> 	call	GET_PARM
  2765 00001878 8825[9B620000]      <1> 	mov	[MOTOR_COUNT], ah	; STORE UPON RETURN
  2766                              <1> 	;pop	ax			; RESTORE NUMBER TRANSFERRED
  2767 0000187E 58                  <1> 	pop	eax ; 24/12/2021
  2768 0000187F 8A25[9C620000]      <1> 	mov	ah, [DSKETTE_STATUS]	; GET STATUS OF OPERATION
  2769 00001885 08E4                <1> 	or	ah, ah			; CHECK FOR ERROR
  2770 00001887 7406                <1> 	jz	short NUN_ERR		; NO ERROR
  2771 00001889 30C0                <1> 	xor 	al, al			; CLEAR NUMBER RETURNED
  2772                              <1> ;NUN_ERR: 
  2773 0000188B 80FC01              <1> 	cmp	ah, 1			; SET THE CARRY FLAG TO INDICATE
  2774 0000188E F5                  <1> 	cmc				; SUCCESS OR FAILURE
  2775                              <1> NUN_ERR:
  2776 0000188F C3                  <1> 	retn
  2777                              <1> 
  2778                              <1> ;-------------------------------------------------------------------------------
  2779                              <1> ; DISK_RESET	(AH = 00H)	
  2780                              <1> ;		RESET THE DISKETTE SYSTEM.
  2781                              <1> ;
  2782                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2783                              <1> ;-------------------------------------------------------------------------------
  2784                              <1> DSK_RESET:
  2785                              <1> 	; 17/07/2022
  2786                              <1> 	; 12/07/2022
  2787                              <1> 	; 11/07/2022
  2788                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2789 00001890 66BAF203            <1> 	mov	dx, 03F2h		; ADAPTER CONTROL PORT
  2790 00001894 FA                  <1> 	cli				; NO INTERRUPTS
  2791 00001895 A0[9A620000]        <1> 	mov	al, [MOTOR_STATUS]	; GET DIGITAL OUTPUT REGISTER REFLECTION
  2792 0000189A 243F                <1> 	and	al, 00111111b		; KEEP SELECTED AND MOTOR ON BITS
  2793 0000189C C0C004              <1> 	rol	al, 4			; MOTOR VALUE TO HIGH NIBBLE
  2794                              <1> 					; DRIVE SELECT TO LOW NIBBLE
  2795 0000189F 0C08                <1> 	or	al, 00001000b		; TURN ON INTERRUPT ENABLE
  2796 000018A1 EE                  <1> 	out	dx, al			; RESET THE ADAPTER
  2797 000018A2 C605[99620000]00    <1> 	mov	byte [SEEK_STATUS], 0	; SET RECALIBRATE REQUIRED ON ALL DRIVES
  2798                              <1> 	;JMP	$+2			; WAIT FOR I/O
  2799                              <1> 	;JMP	$+2			; WAIT FOR I/O (TO INSURE MINIMUM
  2800                              <1> 					;      PULSE WIDTH)
  2801                              <1> 	; 19/12/2014
  2802                              <1> 	NEWIODELAY
  2193 000018A9 E6EB                <2>  out 0EBh,al
  2803                              <1> 
  2804                              <1> 	; 17/12/2014 
  2805                              <1> 	; AWARD BIOS 1999 - RESETDRIVES (ADISK.ASM)
  2806 000018AB B915000000          <1> 	mov	ecx, WAITCPU_RESET_ON	; cx = 21 -- Min. 14 micro seconds !?
  2807                              <1> wdw1:
  2808                              <1> 	NEWIODELAY   ; 27/02/2015
  2193 000018B0 E6EB                <2>  out 0EBh,al
  2809 000018B2 E2FC                <1> 	loop	wdw1
  2810                              <1> 	;
  2811 000018B4 0C04                <1> 	or	al, 00000100b		; TURN OFF RESET BIT
  2812 000018B6 EE                  <1> 	out	dx, al			; RESET THE ADAPTER
  2813                              <1> 	; 16/12/2014
  2814                              <1> 	IODELAY
  2188 000018B7 EB00                <2>  jmp short $+2
  2189 000018B9 EB00                <2>  jmp short $+2
  2815                              <1> 	;
  2816                              <1> 	;sti				; ENABLE THE INTERRUPTS
  2817 000018BB E862060000          <1> 	call	WAIT_INT		; WAIT FOR THE INTERRUPT
  2818 000018C0 7236                <1> 	jc	short DR_ERR		; IF ERROR, RETURN IT
  2819                              <1> 	;mov	cx, 11000000b		; CL = EXPECTED @NEC_STATUS
  2820                              <1> 	; 12/07/2022
  2821                              <1> 	;xor	ecx, ecx
  2822                              <1> 	; 17/07/2022
  2823                              <1> 	;xor	ch, ch
  2824 000018C2 B1C0                <1> 	mov	cl, 11000000b
  2825                              <1> NXT_DRV:
  2826                              <1> 	; 24/12/2021
  2827 000018C4 51                  <1> 	push	ecx			; SAVE FOR CALL
  2828 000018C5 B8[F7180000]        <1> 	mov	eax, DR_POP_ERR 	; LOAD NEC_OUTPUT ERROR ADDRESS
  2829 000018CA 50                  <1> 	push	eax			;
  2830 000018CB B408                <1> 	mov	ah, 08h			; SENSE INTERRUPT STATUS COMMAND
  2831 000018CD E846050000          <1> 	call	NEC_OUTPUT
  2832 000018D2 58                  <1> 	pop	eax			; THROW AWAY ERROR RETURN
  2833 000018D3 E879060000          <1> 	call	RESULTS			; READ IN THE RESULTS
  2834                              <1> 	; 24/12/2021
  2835 000018D8 59                  <1> 	pop	ecx			; RESTORE AFTER CALL
  2836 000018D9 721D                <1> 	jc	short DR_ERR		; ERROR RETURN
  2837 000018DB 3A0D[9D620000]      <1> 	cmp	cl, [NEC_STATUS]	; TEST FOR DRIVE READY TRANSITION
  2838 000018E1 7515                <1> 	jnz	short DR_ERR		; EVERYTHING OK
  2839 000018E3 FEC1                <1> 	inc	cl			; NEXT EXPECTED @NEC_STATUS
  2840 000018E5 80F9C3              <1> 	cmp	cl, 11000011b		; ALL POSSIBLE DRIVES CLEARED
  2841 000018E8 76DA                <1> 	jbe	short NXT_DRV		; FALL THRU IF 11000100B OR >
  2842                              <1> 	;
  2843 000018EA E82F000000          <1> 	call	SEND_SPEC		; SEND SPECIFY COMMAND TO NEC
  2844                              <1> RESBAC:
  2845 000018EF E87CFFFFFF          <1> 	call	SETUP_END		; VARIOUS CLEANUPS
  2846                              <1> 	
  2847                              <1> 	; 11/07/2022
  2848                              <1> 	; CF = 1 -> error (error code in AH)
  2849                              <1> 	; CF = 0 -> OK
  2850                              <1> 	
  2851                              <1> 	;; 24/12/2021
  2852                              <1> 	;mov	ebx, esi		; GET SAVED AL TO BL
  2853                              <1> 	;; 11/07/2022
  2854                              <1> 	;; byte 0 = sector, byte 1 = head, byte 2 = track, byte 3 = function 
  2855                              <1> 	;rol	ebx, 8
  2856                              <1> 	; bl = function (reset = 0)
  2857                              <1> 	;
  2858                              <1> 	;mov	al, bl			; PUT BACK FOR RETURN
  2859                              <1> 	
  2860                              <1> 	; 11/07/2022  
  2861 000018F4 B000                <1> 	mov	al, 0	; (reset function = 0)
  2862                              <1> 
  2863 000018F6 C3                  <1> 	retn
  2864                              <1> 
  2865                              <1> DR_POP_ERR:
  2866                              <1> 	; 24/12/2021
  2867 000018F7 59                  <1> 	pop	ecx			; CLEAR STACK
  2868                              <1> DR_ERR:
  2869 000018F8 800D[9C620000]20    <1> 	or	byte [DSKETTE_STATUS], BAD_NEC ; SET ERROR CODE
  2870 000018FF EBEE                <1> 	jmp	short RESBAC		; RETURN FROM RESET
  2871                              <1> 
  2872                              <1> ;-------------------------------------------------------------------------------
  2873                              <1> ; FNC_ERR
  2874                              <1> ;	INVALID FUNCTION REQUESTED OR INVALID DRIVE: 
  2875                              <1> ;	SET BAD COMMAND IN STATUS.
  2876                              <1> ;
  2877                              <1> ; ON EXIT: 	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  2878                              <1> ;-------------------------------------------------------------------------------
  2879                              <1> 
  2880                              <1> 	; 11/07/2022 - not needed (because diskio is used by kernel only)
  2881                              <1> 	
  2882                              <1> ;FNC_ERR:				; INVALID FUNCTION REQUEST
  2883                              <1> ;	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2884                              <1> ;	; 24/12/2021
  2885                              <1> ;	mov	eax, esi		; RESTORE AL
  2886                              <1> ;	mov	ah, BAD_CMD		; SET BAD COMMAND ERROR
  2887                              <1> ;	mov	[DSKETTE_STATUS], ah	; STORE IN DATA AREA
  2888                              <1> ;	stc				; SET CARRY INDICATING ERROR
  2889                              <1> ;	retn
  2890                              <1> 
  2891                              <1> ;----------------------------------------------------------------
  2892                              <1> ; DR_TYPE_CHECK							:
  2893                              <1> ;	CHECK IF THE GIVEN DRIVE TYPE IN REGISTER (AL)		:
  2894                              <1> ;	IS SUPPORTED IN BIOS DRIVE TYPE TABLE			:
  2895                              <1> ; ON ENTRY:							:
  2896                              <1> ;	AL = DRIVE TYPE						:
  2897                              <1> ; ON EXIT:							:
  2898                              <1> ;	CY = 0 	DRIVE TYPE SUPPORTED				:
  2899                              <1> ;	     EBX = OFFSET TO MEDIA/DRIVE PARAMETER TABLE	:
  2900                              <1> ;	CY = 1	DRIVE TYPE NOT SUPPORTED 			:
  2901                              <1> ; REGISTERS ALTERED: EBX, AH ; 11/07/2022 			:
  2902                              <1> ;----------------------------------------------------------------
  2903                              <1> DR_TYPE_CHECK:
  2904                              <1> 	; 12/07/2022
  2905                              <1> 	; 11/07/2022
  2906                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2907                              <1> 	; 24/12/2021
  2908                              <1> 	;push	eax ; 11/07/2022
  2909                              <1> 	;push	ecx ; 08/07/2022
  2910                              <1> 	;xor	ebx,ebx			; EBX = INDEX TO DR_TYPE TABLE
  2911 00001901 BB[BC5C0000]        <1> 	mov	ebx, DR_TYPE
  2912                              <1> 	;;mov	ecx, DR_CNT		; ECX = LOOP COUNT
  2913                              <1> 	;mov	cl, DR_CNT
  2914 00001906 B406                <1> 	mov	ah, DR_CNT ; 11/07/2022
  2915                              <1> TYPE_CHK:	
  2916                              <1> 	;;mov	ah, [DR_TYPE+ebx]	; GET DRIVE TYPE
  2917                              <1> 	;mov	ah, [ebx]
  2918                              <1> 	;cmp	al, ah			; DRIVE TYPE MATCH?
  2919 00001908 3A03                <1> 	cmp	al, [ebx] ; 11/07/2022
  2920 0000190A 740E                <1> 	je	short DR_TYPE_VALID	; YES, RETURN WITH CARRY RESET
  2921                              <1> 	; 16/02/2015 (32 bit address modification)
  2922 0000190C 83C305              <1> 	add	ebx, 5			; CHECK NEXT DRIVE TYPE
  2923                              <1> 	;loop	TYPE_CHK
  2924                              <1> 	;dec	cl
  2925 0000190F FECC                <1> 	dec	ah ; 11/07/2022
  2926 00001911 75F5                <1> 	jnz	short TYPE_CHK
  2927                              <1> 	;
  2928 00001913 BB[1B5D0000]        <1> 	mov	ebx, MD_TBL6		; 1.44MB fd parameter table
  2929                              <1> 					; Default for GET_PARM (11/12/2014)
  2930                              <1> 	;
  2931 00001918 F9                  <1> 	stc				; DRIVE TYPE NOT FOUND IN TABLE
  2932                              <1> 	;jmp	short TYPE_RTN
  2933                              <1> 	; 12/07/2022
  2934 00001919 C3                  <1> 	retn
  2935                              <1> DR_TYPE_VALID:
  2936                              <1> 	;mov	ebx, [DR_TYPE+ebx+1] 	; EBX = MEDIA TABLE
  2937 0000191A 43                  <1> 	inc	ebx
  2938 0000191B 8B1B                <1> 	mov	ebx, [ebx]
  2939                              <1> TYPE_RTN:
  2940                              <1> 	;pop	ecx ; 08/07/2022
  2941                              <1> 	; 24/12/2021
  2942                              <1> 	;pop	eax ; 11/07/2022
  2943 0000191D C3                  <1> 	retn
  2944                              <1> 		
  2945                              <1> ;----------------------------------------------------------------
  2946                              <1> ; SEND_SPEC							:
  2947                              <1> ;	SEND THE SPECIFY COMMAND TO CONTROLLER USING DATA FROM	:
  2948                              <1> ;	THE DRIVE PARAMETER TABLE POINTED BY @DISK_POINTER	:
  2949                              <1> ; ON ENTRY:	@DISK_POINTER = DRIVE PARAMETER TABLE		:
  2950                              <1> ; ON EXIT:	NONE						:
  2951                              <1> ; REGISTERS ALTERED: ECX, EDX					:
  2952                              <1> ;----------------------------------------------------------------
  2953                              <1> SEND_SPEC:
  2954                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2955 0000191E 50                  <1> 	push	eax			; SAVE EAX
  2956 0000191F B8[45190000]        <1> 	mov	eax, SPECBAC		; LOAD ERROR ADDRESS
  2957 00001924 50                  <1> 	push	eax			; PUSH NEC_OUT ERROR RETURN
  2958 00001925 B403                <1> 	mov	ah, 03h			; SPECIFY COMMAND
  2959 00001927 E8EC040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2960                              <1> 	;sub	dl, dl			; FIRST SPECIFY BYTE
  2961 0000192C 28C0                <1> 	sub	al, al ; 08/07/2022
  2962 0000192E E8F4030000          <1> 	call	GET_PARM		; GET PARAMETER TO AH
  2963 00001933 E8E0040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2964                              <1> 	;mov	dl, 1			; SECOND SPECIFY BYTE
  2965 00001938 B001                <1> 	mov	al, 1 ; 08/07/2022
  2966 0000193A E8E8030000          <1> 	call	GET_PARM		; GET PARAMETER TO AH
  2967 0000193F E8D4040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2968 00001944 58                  <1> 	pop	eax			; POP ERROR RETURN
  2969                              <1> SPECBAC:
  2970 00001945 58                  <1> 	pop	eax			; RESTORE ORIGINAL EAX VALUE
  2971 00001946 C3                  <1> 	retn
  2972                              <1> 
  2973                              <1> ;----------------------------------------------------------------
  2974                              <1> ; SEND_SPEC_MD							:
  2975                              <1> ;	SEND THE SPECIFY COMMAND TO CONTROLLER USING DATA FROM	:
  2976                              <1> ;	THE MEDIA/DRIVE PARAMETER TABLE POINTED BY (EBX)	:
  2977                              <1> ; ON ENTRY:	EBX = MEDIA/DRIVE PARAMETER TABLE		:
  2978                              <1> ; ON EXIT:	NONE						:
  2979                              <1> ; REGISTERS ALTERED: EAX ; 11/07/2022				:
  2980                              <1> ;----------------------------------------------------------------
  2981                              <1> SEND_SPEC_MD:
  2982                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2983                              <1> 	;push	eax ; 11/07/2022	; SAVE RATE DATA
  2984 00001947 B8[64190000]        <1> 	mov	eax, SPEC_ESBAC		; LOAD ERROR ADDRESS
  2985 0000194C 50                  <1> 	push	eax			; PUSH NEC_OUT ERROR RETURN
  2986 0000194D B403                <1> 	mov	ah, 03h			; SPECIFY COMMAND
  2987 0000194F E8C4040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2988 00001954 8A23                <1>         mov	ah, [ebx+MD.SPEC1]      ; GET 1ST SPECIFY BYTE
  2989 00001956 E8BD040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2990 0000195B 8A6301              <1>         mov	ah, [ebx+MD.SPEC2]      ; GET SECOND SPECIFY BYTE
  2991 0000195E E8B5040000          <1> 	call	NEC_OUTPUT		; OUTPUT THE COMMAND
  2992 00001963 58                  <1> 	pop	eax			; POP ERROR RETURN
  2993                              <1> SPEC_ESBAC:
  2994                              <1> 	;pop	eax ; 11/07/2022	; RESTORE ORIGINAL EAX VALUE
  2995 00001964 C3                  <1> 	retn
  2996                              <1> 
  2997                              <1> ;-------------------------------------------------------------------------------
  2998                              <1> ; XLAT_NEW  
  2999                              <1> ;	TRANSLATES DISKETTE STATE LOCATIONS FROM COMPATIBLE
  3000                              <1> ;	MODE TO NEW ARCHITECTURE.
  3001                              <1> ;
  3002                              <1> ; ON ENTRY:	EDI = DRIVE #
  3003                              <1> ;-------------------------------------------------------------------------------
  3004                              <1> XLAT_NEW:
  3005                              <1> 	; 11/07/2022
  3006                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3007                              <1> 	;cmp	edi, 1				; VALID DRIVE
  3008                              <1> 	;ja	short XN_OUT			; IF INVALID BACK
  3009                              <1> 	;
  3010 00001965 80BF[A7620000]00    <1> 	cmp	byte [DSK_STATE+edi], 0		; NO DRIVE ?
  3011 0000196C 7401                <1> 	jz	short DO_DET			; IF NO DRIVE ATTEMPT DETERMINE
  3012                              <1> 	;
  3013                              <1> 	;mov	al, [HF_CNTRL]			; DRIVE INFORMATION
  3014                              <1> 	;mov	ecx, edi			; ECX = DRIVE NUMBER
  3015                              <1> 	;or	cl, cl
  3016                              <1> 	;jz	short XN_0  ; 08/07/2022
  3017                              <1> 	;shl	cl, 2				; CL = SHIFT COUNT, A=0, B=4
  3018                              <1> 	;;mov	al, [HF_CNTRL]			; DRIVE INFORMATION
  3019                              <1> 	;ror	al, cl				; TO LOW NIBBLE
  3020                              <1> ;XN_0:	
  3021                              <1> 	;and	al, DRV_DET+FMT_CAPA+TRK_CAPA	; KEEP DRIVE BITS
  3022                              <1>         ;and	byte [DSK_STATE+edi], ~(DRV_DET+FMT_CAPA+TRK_CAPA)
  3023                              <1> 	;or	[DSK_STATE+edi], al		; UPDATE DRIVE STATE
  3024                              <1> XN_OUT:
  3025 0000196E C3                  <1> 	retn
  3026                              <1> DO_DET:
  3027                              <1> 	;;call	DRIVE_DET			; TRY TO DETERMINE
  3028                              <1> 	;;retn
  3029                              <1> 	;jmp	DRIVE_DET
  3030                              <1> 
  3031                              <1> ;-------------------------------------------------------------------------------
  3032                              <1> ; DRIVE_DET
  3033                              <1> ;	DETERMINES WHETHER DRIVE IS 80 OR 40 TRACKS AND
  3034                              <1> ;	UPDATES STATE INFORMATION ACCORDINGLY.
  3035                              <1> ; ON ENTRY:	EDI = DRIVE #
  3036                              <1> ;-------------------------------------------------------------------------------
  3037                              <1> DRIVE_DET:
  3038                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3039 0000196F E8EE030000          <1> 	call	MOTOR_ON		; TURN ON MOTOR IF NOT ALREADY ON
  3040 00001974 E857050000          <1> 	call	RECAL			; RECALIBRATE DRIVE
  3041 00001979 724E                <1> 	jc	short DD_BAC		; ASSUME NO DRIVE PRESENT
  3042 0000197B B530                <1> 	mov	ch, TRK_SLAP		; SEEK TO TRACK 48
  3043 0000197D E8CF040000          <1> 	call	SEEK
  3044 00001982 7245                <1> 	jc	short DD_BAC		; ERROR NO DRIVE
  3045 00001984 B50B                <1> 	mov	ch, QUIET_SEEK+1	; SEEK TO TRACK 10
  3046                              <1> SK_GIN:
  3047 00001986 FECD                <1> 	dec	ch			; DECREMENT TO NEXT TRACK
  3048                              <1> 	;push	cx		
  3049                              <1> 	; 24/12/2021
  3050 00001988 51                  <1> 	push	ecx			; SAVE TRACK
  3051 00001989 E8C3040000          <1> 	call	SEEK
  3052 0000198E 723A                <1> 	jc	short POP_BAC		; POP AND RETURN
  3053 00001990 B8[CA190000]        <1> 	mov	eax, POP_BAC		; LOAD NEC OUTPUT ERROR ADDRESS
  3054 00001995 50                  <1> 	push	eax
  3055 00001996 B404                <1> 	mov	ah, SENSE_DRV_ST	; SENSE DRIVE STATUS COMMAND BYTE
  3056 00001998 E87B040000          <1> 	call	NEC_OUTPUT		; OUTPUT TO NEC
  3057                              <1> 	; 08/07/2022
  3058 0000199D 89F8                <1> 	mov	eax, edi		; AL = DRIVE
  3059 0000199F 88C4                <1> 	mov	ah, al			; AH = DRIVE
  3060 000019A1 E872040000          <1> 	call	NEC_OUTPUT		; OUTPUT TO NEC
  3061 000019A6 E8A6050000          <1> 	call	RESULTS			; GO GET STATUS
  3062 000019AB 58                  <1> 	pop	eax			; THROW AWAY ERROR ADDRESS
  3063                              <1> 	;pop	cx			; RESTORE TRACK
  3064                              <1> 	; 24/12/2021
  3065 000019AC 59                  <1> 	pop	ecx
  3066 000019AD F605[9D620000]10    <1> 	test	byte [NEC_STATUS], HOME	; TRACK 0 ?
  3067 000019B4 74D0                <1> 	jz	short SK_GIN		; GO TILL TRACK 0
  3068 000019B6 08ED                <1> 	or	ch, ch			; IS HOME AT TRACK 0
  3069 000019B8 7408                <1> 	jz	short IS_80		; MUST BE 80 TRACK DRIVE
  3070                              <1> 
  3071                              <1> ;	DRIVE IS A 360; SET DRIVE TO DETERMINED;
  3072                              <1> ;	SET MEDIA TO DETERMINED AT RATE 250.
  3073                              <1> 
  3074 000019BA 808F[A7620000]94    <1> 	or	byte [DSK_STATE+edi], DRV_DET+MED_DET+RATE_250
  3075 000019C1 C3                  <1> 	retn				; ALL INFORMATION SET
  3076                              <1> IS_80:
  3077 000019C2 808F[A7620000]01    <1> 	or	byte [DSK_STATE+edi], TRK_CAPA ; SETUP 80 TRACK CAPABILITY
  3078                              <1> DD_BAC:
  3079 000019C9 C3                  <1> 	retn
  3080                              <1> POP_BAC:
  3081                              <1> 	;pop	cx			; THROW AWAY
  3082                              <1> 	; 24/12/2021
  3083 000019CA 59                  <1> 	pop	ecx
  3084 000019CB C3                  <1> 	retn
  3085                              <1> 
  3086                              <1> ;-------------------------------------------------------------------------------
  3087                              <1> ; SETUP_STATE:	INITIALIZES START AND END RATES.
  3088                              <1> ;-------------------------------------------------------------------------------
  3089                              <1> SETUP_STATE:
  3090                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3091 000019CC F687[A7620000]10    <1> 	test	byte [DSK_STATE+edi], MED_DET ; MEDIA DETERMINED ?
  3092 000019D3 7537                <1> 	jnz	short J1C		; NO STATES IF DETERMINED
  3093 000019D5 66B84000            <1>        	mov	ax, (RATE_500*256)+RATE_300 ; AH = START RATE, AL = END RATE
  3094 000019D9 F687[A7620000]04    <1> 	test	byte [DSK_STATE+edi], DRV_DET ; DRIVE ?
  3095 000019E0 740D                <1> 	jz	short AX_SET		; DO NOT KNOW DRIVE
  3096 000019E2 F687[A7620000]02    <1> 	test	byte [DSK_STATE+edi], FMT_CAPA ; MULTI-RATE?
  3097 000019E9 7504                <1> 	jnz	short AX_SET		; JUMP IF YES
  3098 000019EB 66B88080            <1>         mov	ax, RATE_250*257	; START A END RATE 250 FOR 360 DRIVE
  3099                              <1> AX_SET:	
  3100 000019EF 80A7[A7620000]1F    <1> 	and	byte [DSK_STATE+edi], ~(RATE_MSK+DBL_STEP) ; TURN OFF THE RATE
  3101 000019F6 08A7[A7620000]      <1> 	or	[DSK_STATE+edi], ah	; RATE FIRST TO TRY
  3102 000019FC 8025[A4620000]F3    <1> 	and	byte [LASTRATE], ~STRT_MSK ; ERASE LAST TO TRY RATE BITS
  3103 00001A03 C0C804              <1> 	ror	al, 4			; TO OPERATION LAST RATE LOCATION
  3104 00001A06 0805[A4620000]      <1> 	or	[LASTRATE], al		; LAST RATE
  3105                              <1> J1C:	
  3106 00001A0C C3                  <1> 	retn
  3107                              <1> 
  3108                              <1> ;-------------------------------------------------------------------------------
  3109                              <1> ; MED_CHANGE	
  3110                              <1> ;	CHECKS FOR MEDIA CHANGE, RESETS MEDIA CHANGE, 
  3111                              <1> ;	CHECKS MEDIA CHANGE AGAIN.
  3112                              <1> ;
  3113                              <1> ; ON EXIT:	CY = 1 MEANS MEDIA CHANGE OR TIMEOUT
  3114                              <1> ;		@DSKETTE_STATUS = ERROR CODE
  3115                              <1> ;-------------------------------------------------------------------------------
  3116                              <1> MED_CHANGE:
  3117                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3118 00001A0D E897050000          <1> 	call	READ_DSKCHNG		; READ DISK CHANCE LINE STATE
  3119 00001A12 7446                <1> 	jz	short MC_OUT		; BYPASS HANDLING DISK CHANGE LINE
  3120 00001A14 80A7[A7620000]EF    <1> 	and	byte [DSK_STATE+edi], ~MED_DET ; CLEAR STATE FOR THIS DRIVE
  3121                              <1> 
  3122                              <1> ;	THIS SEQUENCE ENSURES WHENEVER A DISKETTE IS CHANGED THAT
  3123                              <1> ;	ON THE NEXT OPERATION THE REQUIRED MOTOR START UP TIME WILL
  3124                              <1> ;	BE WAITED. (DRIVE MOTOR MAY GO OFF UPON DOOR OPENING).
  3125                              <1> 
  3126 00001A1B 89F9                <1> 	mov	ecx, edi		; CL = DRIVE #
  3127 00001A1D B001                <1> 	mov	al, 1			; MOTOR ON BIT MASK
  3128 00001A1F D2E0                <1> 	shl	al, cl			; TO APPROPRIATE POSITION
  3129 00001A21 F6D0                <1> 	not	al			; KEEP ALL BUT MOTOR ON
  3130 00001A23 FA                  <1> 	cli				; NO INTERRUPTS
  3131 00001A24 2005[9A620000]      <1> 	and	[MOTOR_STATUS], al	; TURN MOTOR OFF INDICATOR
  3132 00001A2A FB                  <1> 	sti				; INTERRUPTS ENABLED
  3133 00001A2B E832030000          <1> 	call	MOTOR_ON		; TURN MOTOR ON
  3134                              <1> 
  3135                              <1> ;-----	THIS SEQUENCE OF SEEKS IS USED TO RESET DISKETTE CHANGE SIGNAL
  3136                              <1> 
  3137 00001A30 E85BFEFFFF          <1> 	call	DSK_RESET		; RESET NEC
  3138 00001A35 B501                <1> 	mov	ch, 1			; MOVE TO CYLINDER 1
  3139 00001A37 E815040000          <1> 	call	SEEK			; ISSUE SEEK
  3140 00001A3C 30ED                <1> 	xor	ch, ch			; MOVE TO CYLINDER 0
  3141 00001A3E E80E040000          <1> 	call	SEEK			; ISSUE SEEK
  3142 00001A43 C605[9C620000]06    <1> 	mov	byte [DSKETTE_STATUS], MEDIA_CHANGE ; STORE IN STATUS
  3143                              <1> OK1:
  3144 00001A4A E85A050000          <1> 	call	READ_DSKCHNG		; CHECK MEDIA CHANGED AGAIN
  3145 00001A4F 7407                <1> 	jz	short OK2		; IF ACTIVE, NO DISKETTE, TIMEOUT
  3146                              <1> OK4:
  3147 00001A51 C605[9C620000]80    <1> 	mov	byte [DSKETTE_STATUS], TIME_OUT ; TIMEOUT IF DRIVE EMPTY
  3148                              <1> OK2:		
  3149 00001A58 F9                  <1> 	stc				; MEDIA CHANGED, SET CY
  3150 00001A59 C3                  <1> 	retn
  3151                              <1> MC_OUT:
  3152                              <1> 	;clc	; 08/07/2022		; NO MEDIA CHANGED, CLEAR CY
  3153 00001A5A C3                  <1> 	retn
  3154                              <1> 
  3155                              <1> ;-------------------------------------------------------------------------------
  3156                              <1> ; SEND_RATE
  3157                              <1> ;	SENDS DATA RATE COMMAND TO NEC
  3158                              <1> ; ON ENTRY:	EDI = DRIVE #
  3159                              <1> ; ON EXIT:	NONE
  3160                              <1> ; REGISTERS ALTERED: EDX, EAX ; 11/07/2022
  3161                              <1> ;-------------------------------------------------------------------------------
  3162                              <1> SEND_RATE:
  3163                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3164                              <1> 	;push	ax			; SAVE REG.
  3165                              <1> 	; 24/12/2021
  3166                              <1> 	;push	eax ; 11/07/2022
  3167 00001A5B 8025[A4620000]3F    <1> 	and	byte [LASTRATE], ~SEND_MSK ; ELSE CLEAR LAST RATE ATTEMPTED
  3168 00001A62 8A87[A7620000]      <1> 	mov	al, [DSK_STATE+edi]	; GET RATE STATE OF THIS DRIVE
  3169 00001A68 24C0                <1> 	and	al, SEND_MSK		; KEEP ONLY RATE BITS
  3170 00001A6A 0805[A4620000]      <1> 	or	[LASTRATE], al		; SAVE NEW RATE FOR NEXT CHECK
  3171 00001A70 C0C002              <1> 	rol	al, 2			; MOVE TO BIT OUTPUT POSITIONS
  3172 00001A73 66BAF703            <1> 	mov	dx, 03F7h		; OUTPUT NEW DATA RATE
  3173 00001A77 EE                  <1> 	out	dx, al
  3174                              <1> 	;pop	ax			; RESTORE REG.
  3175                              <1> 	; 24/12/2021
  3176                              <1> 	;pop	eax ; 11/07/2022
  3177 00001A78 C3                  <1> 	retn
  3178                              <1> 
  3179                              <1> ;-------------------------------------------------------------------------------
  3180                              <1> ; CHK_LASTRATE
  3181                              <1> ;	CHECK PREVIOUS DATE RATE SNT TO THE CONTROLLER.
  3182                              <1> ; ON ENTRY:
  3183                              <1> ;	EDI = DRIVE #
  3184                              <1> ; ON EXIT:
  3185                              <1> ;	ZF =  1 DATA RATE IS THE SAME AS THE LAST RATE SENT TO NEC
  3186                              <1> ;	ZF =  0 DATA RATE IS DIFFERENT FROM LAST RATE
  3187                              <1> ; REGISTERS ALTERED: EAX ; 11/07/2022
  3188                              <1> ;-------------------------------------------------------------------------------
  3189                              <1> CHK_LASTRATE:
  3190                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3191                              <1> 	;push	ax			; SAVE REG.
  3192                              <1> 	; 24/12/2021
  3193                              <1> 	;push	eax ; 11/07/2022
  3194 00001A79 8A25[A4620000]      <1> 	mov	ah, [LASTRATE] ; 08/07/2022 (BugFix) 
  3195                              <1> 					; GET LAST DATA RATE SELECTED
  3196 00001A7F 8A87[A7620000]      <1> 	mov	al, [DSK_STATE+edi]	; GET RATE STATE OF THIS DRIVE
  3197 00001A85 6625C0C0            <1>        	and	ax, SEND_MSK*257        ; KEEP ONLY RATE BITS OF BOTH
  3198 00001A89 38E0                <1> 	cmp	al, ah			; COMPARE TO PREVIOUSLY TRIED
  3199                              <1> 					; ZF = 1 RATE IS THE SAME
  3200                              <1> 	;pop	ax			; RESTORE REG.
  3201                              <1> 	; 24/12/2021
  3202                              <1> 	;pop	eax ; 11/07/2022
  3203 00001A8B C3                  <1> 	retn
  3204                              <1> 
  3205                              <1> ;-------------------------------------------------------------------------------
  3206                              <1> ; DMA_SETUP
  3207                              <1> ;	THIS ROUTINE SETS UP THE DMA FOR READ/WRITE/VERIFY OPERATIONS.
  3208                              <1> ;
  3209                              <1> ; ON ENTRY:	AL = DMA COMMAND
  3210                              <1> ;
  3211                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  3212                              <1> ;-------------------------------------------------------------------------------
  3213                              <1> 
  3214                              <1> ; SI = Head #, # of Sectors or DASD Type
  3215                              <1> 
  3216                              <1> ; 22/08/2015
  3217                              <1> ; 08/02/2015 - Protected Mode Modification
  3218                              <1> ; 06/02/2015 - 07/02/2015
  3219                              <1> ; NOTE: Buffer address must be in 1st 16MB of Physical Memory (24 bit limit).
  3220                              <1> ; (DMA Addres = Physical Address)
  3221                              <1> ; (Retro UNIX 386 v1 Kernel/System Mode Virtual Address = Physical Address)
  3222                              <1> ;
  3223                              <1> ; 04/02/2016 (clc)
  3224                              <1> ; 20/02/2015 modification (source: AWARD BIOS 1999, DMA_SETUP)
  3225                              <1> ; 16/12/2014 (IODELAY)
  3226                              <1> 
  3227                              <1> DMA_SETUP:
  3228                              <1> 	; 18/07/2022
  3229                              <1> 	; 11/07/2022
  3230                              <1> 	;	ebp = buffer address
  3231                              <1> 	
  3232                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3233                              <1> 	;; 20/02/2015
  3234                              <1> 	;mov	edx, [ebp+4] ; 11/07/2022 ; Buffer address
  3235                              <1> 	; 08/07/2022 - not needed for Retro UNIX 386 v1.1
  3236                              <1> 	;test	edx, 0FF000000h		; 16 MB limit (22/08/2015, bugfix)
  3237                              <1> 	;jnz	short dma_bnd_err_stc
  3238                              <1> 
  3239                              <1> 	; al = dma command
  3240                              <1> 	
  3241                              <1> ;	; 18/07/2022
  3242                              <1> ;	;	(512 bytes/sector only!) 
  3243                              <1> ;	; 24/12/2021
  3244                              <1> ;	push	eax			; DMA command
  3245                              <1> ;	;push	edx ; 11/07/2022	; *
  3246                              <1> ;	;mov	dl, 3			; GET BYTES/SECTOR PARAMETER
  3247                              <1> ;	mov	al, 3 ; 08/07/2022
  3248                              <1> ;	call	GET_PARM		; 
  3249                              <1> ;	mov	cl, ah 			; SHIFT COUNT (0=128, 1=256, 2=512 ETC)
  3250                              <1> ;	;mov	ax, si			; Sector count
  3251                              <1> ;	;mov	ah, al			; AH = # OF SECTORS
  3252                              <1> ;	;sub	al, al			; AL = 0, AX = # SECTORS * 256
  3253                              <1> ;	;shr	ax, 1			; AX = # SECTORS * 128
  3254                              <1> ;	;shl	ax, cl			; SHIFT BY PARAMETER VALUE
  3255                              <1> ;	; 08/07/2022
  3256                              <1> ;	; 24/12/2021
  3257                              <1> ;	;mov	edx, esi
  3258                              <1> ;	sub	eax, eax
  3259                              <1> ;	;mov	ah, dl
  3260                              <1> ;	;shr	eax, 1
  3261                              <1> ;	mov	al, 128
  3262                              <1> ;	shl	eax, cl
  3263                              <1> ;	;
  3264                              <1> ;	dec	eax			; -1 FOR DMA VALUE
  3265                              <1> ;	mov	ecx, eax
  3266                              <1> ;	;pop	edx ; 11/07/2022	; *
  3267                              <1> ;	; 24/12/2021
  3268                              <1> ;	pop	eax
  3269                              <1> 
  3270                              <1> 	; 08/07/2022
  3271                              <1> 	;cmp	al, 42h
  3272                              <1>         ;jne	short NOT_VERF
  3273                              <1> 	;mov	edx, 0FF0000h
  3274                              <1> 	;jmp	short J33
  3275                              <1> ;NOT_VERF:
  3276                              <1> 	; 11/07/2022
  3277 00001A8C 89EA                <1> 	mov	edx, ebp
  3278                              <1> 	;
  3279                              <1> 	;add	dx, cx			; check for (64K) overflow
  3280                              <1> 	; 18/07/2022
  3281                              <1> 	; (512 bytes/sector)
  3282 00001A8E 6681C2FF01          <1> 	add	dx, 511 
  3283 00001A93 7239                <1> 	jc	short dma_bnd_err
  3284                              <1> 	;
  3285                              <1> 	;sub	dx, cx ; 11/07/2022	; Restore start address
  3286                              <1> J33:
  3287                              <1> 	; 08/07/2022
  3288 00001A95 FA                  <1> 	cli				; DISABLE INTERRUPTS DURING DMA SET-UP
  3289 00001A96 E60C                <1> 	out	DMA+12, al		; SET THE FIRST/LAST F/F
  3290                              <1> 	IODELAY				; WAIT FOR I/O
  2188 00001A98 EB00                <2>  jmp short $+2
  2189 00001A9A EB00                <2>  jmp short $+2
  3291 00001A9C E60B                <1> 	out	DMA+11, al		; OUTPUT THE MODE BYTE
  3292                              <1> 	;mov	eax, edx		; Buffer address
  3293                              <1> 	; 11/07/2022
  3294 00001A9E 89E8                <1> 	mov	eax, ebp ; buffer address
  3295 00001AA0 E604                <1> 	out	DMA+4, al		; OUTPUT LOW ADDRESS
  3296                              <1> 	IODELAY				; WAIT FOR I/O
  2188 00001AA2 EB00                <2>  jmp short $+2
  2189 00001AA4 EB00                <2>  jmp short $+2
  3297 00001AA6 88E0                <1> 	mov	al, ah
  3298 00001AA8 E604                <1> 	out	DMA+4, al		; OUTPUT HIGH ADDRESS
  3299 00001AAA C1E810              <1> 	shr	eax, 16
  3300                              <1> 	IODELAY				; I/O WAIT STATE
  2188 00001AAD EB00                <2>  jmp short $+2
  2189 00001AAF EB00                <2>  jmp short $+2
  3301 00001AB1 E681                <1> 	out	081h, al		; OUTPUT highest BITS TO PAGE REGISTER
  3302                              <1> 	IODELAY
  2188 00001AB3 EB00                <2>  jmp short $+2
  2189 00001AB5 EB00                <2>  jmp short $+2
  3303                              <1> 	;;mov	ax, cx			; Byte count - 1
  3304                              <1> 	;mov	al, cl
  3305                              <1> 	; 18/07/2022
  3306                              <1> 	; (Byte count - 1 = 511)
  3307 00001AB7 B0FF                <1> 	mov	al, 0FFh ; 511-256
  3308 00001AB9 E605                <1> 	out	DMA+5, al		; LOW BYTE OF COUNT
  3309                              <1> 	IODELAY				; WAIT FOR I/O
  2188 00001ABB EB00                <2>  jmp short $+2
  2189 00001ABD EB00                <2>  jmp short $+2
  3310                              <1> 	;;mov	al, ah
  3311                              <1> 	;mov	al, ch
  3312                              <1> 	; 18/07/2022
  3313 00001ABF B001                <1> 	mov	al, 1 ; 256
  3314 00001AC1 E605                <1> 	out	DMA+5, al		; HIGH BYTE OF COUNT
  3315                              <1> 	IODELAY
  2188 00001AC3 EB00                <2>  jmp short $+2
  2189 00001AC5 EB00                <2>  jmp short $+2
  3316 00001AC7 FB                  <1> 	sti				; RE-ENABLE INTERRUPTS
  3317 00001AC8 B002                <1> 	mov	al, 2			; MODE FOR 8237
  3318 00001ACA E60A                <1> 	out	DMA+10, al		; INITIALIZE THE DISKETTE CHANNEL
  3319                              <1> 	
  3320 00001ACC F8                  <1> 	clc	; 04/02/2016
  3321                              <1> 	
  3322 00001ACD C3                  <1> 	retn
  3323                              <1> 
  3324                              <1> 	; 18/07/2022
  3325                              <1> ;dma_bnd_err_stc:
  3326                              <1> ;	stc
  3327                              <1> 
  3328                              <1> dma_bnd_err:
  3329 00001ACE C605[9C620000]09    <1> 	mov	byte [DSKETTE_STATUS], DMA_BOUNDARY ; SET ERROR
  3330 00001AD5 C3                  <1> 	retn				; CY SET BY ABOVE IF ERROR
  3331                              <1> 
  3332                              <1> ;-------------------------------------------------------------------------------
  3333                              <1> ; NEC_INIT	
  3334                              <1> ;	THIS ROUTINE SEEKS TO THE REQUESTED TRACK AND INITIALIZES
  3335                              <1> ;	THE NEC FOR THE READ/WRITE/VERIFY/FORMAT OPERATION.
  3336                              <1> ;
  3337                              <1> ; ON ENTRY:	AH = NEC COMMAND TO BE PERFORMED
  3338                              <1> ;
  3339                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  3340                              <1> ;-------------------------------------------------------------------------------
  3341                              <1> NEC_INIT:
  3342                              <1> 	; 11/07/2022
  3343                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3344                              <1> 	;push	ax			; SAVE NEC COMMAND
  3345                              <1> 	; 24/12/2021
  3346 00001AD6 50                  <1> 	push	eax
  3347 00001AD7 E886020000          <1> 	call	MOTOR_ON		; TURN MOTOR ON FOR SPECIFIC DRIVE
  3348                              <1> 
  3349                              <1> ;-----	DO THE SEEK OPERATION
  3350                              <1> 
  3351                              <1> 	;mov	ch, [ebp+1]		; CH = TRACK #
  3352                              <1> 	; 11/07/2022
  3353 00001ADC 89F1                <1> 	mov	ecx, esi ; byte 2 = track, byte = 1 head, byte 0 = sector
  3354 00001ADE C1E908              <1> 	shr	ecx, 8
  3355                              <1> 	; ch = track #	
  3356                              <1> 
  3357 00001AE1 E86B030000          <1> 	call	SEEK			; MOVE TO CORRECT TRACK
  3358                              <1> 	;pop	ax			; RECOVER COMMAND
  3359                              <1> 	; 24/12/2021
  3360 00001AE6 58                  <1> 	pop	eax
  3361 00001AE7 721D                <1> 	jc	short ER_1		; ERROR ON SEEK
  3362 00001AE9 BB[061B0000]        <1> 	mov	ebx, ER_1		; LOAD ERROR ADDRESS
  3363 00001AEE 53                  <1> 	push	ebx			; PUSH NEC_OUT ERROR RETURN
  3364                              <1> 
  3365                              <1> ;-----	SEND OUT THE PARAMETERS TO THE CONTROLLER
  3366                              <1> 
  3367 00001AEF E824030000          <1> 	call	NEC_OUTPUT		; OUTPUT THE OPERATION COMMAND
  3368 00001AF4 89F0                <1> 	mov	eax, esi		; AH = HEAD #
  3369 00001AF6 89FB                <1> 	mov	ebx, edi		; BL = DRIVE #
  3370 00001AF8 C0E402              <1> 	sal	ah, 2			; MOVE IT TO BIT 2
  3371 00001AFB 80E404              <1> 	and	ah, 00000100b		; ISOLATE THAT BIT
  3372 00001AFE 08DC                <1> 	or	ah, bl			; OR IN THE DRIVE NUMBER
  3373 00001B00 E813030000          <1> 	call	NEC_OUTPUT		; FALL THRU CY SET IF ERROR
  3374 00001B05 5B                  <1> 	pop	ebx			; THROW AWAY ERROR RETURN
  3375                              <1> ER_1:
  3376 00001B06 C3                  <1> 	retn
  3377                              <1> 
  3378                              <1> ;-------------------------------------------------------------------------------
  3379                              <1> ; RWV_COM
  3380                              <1> ;	THIS ROUTINE SENDS PARAMETERS TO THE NEC SPECIFIC TO THE 
  3381                              <1> ;	READ/WRITE/VERIFY OPERATIONS.
  3382                              <1> ;
  3383                              <1> ; ON ENTRY:	EBX = ADDRESS OF MEDIA/DRIVE PARAMETER TABLE
  3384                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  3385                              <1> ;-------------------------------------------------------------------------------
  3386                              <1> RWV_COM:
  3387                              <1> 	; 11/07/2022
  3388                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3389 00001B07 B8[541B0000]        <1> 	mov	eax, ER_2		; LOAD ERROR ADDRESS
  3390 00001B0C 50                  <1> 	push	eax			; PUSH NEC_OUT ERROR RETURN
  3391                              <1> 	;mov	ah, [ebp+1]		; OUTPUT TRACK #
  3392                              <1> 	; 11/07/2022
  3393 00001B0D 89F0                <1> 	mov	eax, esi ; byte 0 = sector, byte 1 = head, byte 2 = track
  3394 00001B0F C1E808              <1> 	shr	eax, 8
  3395                              <1> 	; ah = track # 
  3396 00001B12 E801030000          <1> 	call	NEC_OUTPUT
  3397 00001B17 89F0                <1> 	mov	eax, esi		; OUTPUT HEAD #
  3398                              <1> 	; ah = head #
  3399 00001B19 E8FA020000          <1> 	call	NEC_OUTPUT
  3400                              <1>         ;mov	ah, [ebp]		; OUTPUT SECTOR #
  3401 00001B1E 89F0                <1> 	mov	eax, esi
  3402 00001B20 88C4                <1> 	mov	ah, al
  3403                              <1>  	; ah = sector #
  3404 00001B22 E8F1020000          <1> 	CALL	NEC_OUTPUT
  3405                              <1> 	;mov	dl, 3			; BYTES/SECTOR PARAMETER FROM BLOCK
  3406 00001B27 B003                <1> 	mov	al, 3 ; 08/07/2022
  3407 00001B29 E8F9010000          <1> 	call	GET_PARM 		; .. TO THE NEC
  3408 00001B2E E8E5020000          <1> 	call	NEC_OUTPUT		; OUTPUT TO CONTROLLER
  3409                              <1> 	;mov	dl, 4			; EOT PARAMETER FROM BLOCK
  3410 00001B33 B004                <1> 	mov	al, 4 ; 08/07/2022
  3411 00001B35 E8ED010000          <1> 	call	GET_PARM 		; .. TO THE NEC
  3412 00001B3A E8D9020000          <1> 	call	NEC_OUTPUT		; OUTPUT TO CONTROLLER
  3413 00001B3F 8A6305              <1>         mov	ah, [ebx+MD.GAP]	; GET GAP LENGTH
  3414                              <1> _R15:
  3415 00001B42 E8D1020000          <1> 	call	NEC_OUTPUT
  3416                              <1> 	;mov	dl, 6			; DTL PARAMETER PROM BLOCK
  3417 00001B47 B006                <1> 	mov	al, 6 ; 08/07/2022
  3418 00001B49 E8D9010000          <1> 	call	GET_PARM		; .. TO THE NEC
  3419 00001B4E E8C5020000          <1> 	call	NEC_OUTPUT		; OUTPUT TO CONTROLLER
  3420 00001B53 58                  <1> 	pop	eax			; THROW AWAY ERROR EXIT
  3421                              <1> ER_2:
  3422 00001B54 C3                  <1> 	retn
  3423                              <1> 
  3424                              <1> ;-------------------------------------------------------------------------------
  3425                              <1> ; NEC_TERM
  3426                              <1> ;	THIS ROUTINE WAITS FOR THE OPERATION THEN ACCEPTS THE STATUS 
  3427                              <1> ;	FROM THE NEC FOR THE READ/WRITE/VERIFY/FORWAT OPERATION.
  3428                              <1> ;
  3429                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  3430                              <1> ;-------------------------------------------------------------------------------
  3431                              <1> 
  3432                              <1> NEC_TERM:
  3433                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3434                              <1> 
  3435                              <1> ;-----	LET THE OPERATION HAPPEN
  3436                              <1> 
  3437 00001B55 56                  <1> 	push	esi			; SAVE HEAD #, # OF SECTORS
  3438 00001B56 E8C7030000          <1> 	call	WAIT_INT		; WAIT FOR THE INTERRUPT
  3439 00001B5B 9C                  <1> 	pushfd	; 24/12/2021
  3440 00001B5C E8F0030000          <1> 	call	RESULTS			; GET THE NEC STATUS
  3441 00001B61 724B                <1> 	jc	short SET_END_POP
  3442 00001B63 9D                  <1> 	popfd	; 24/12/2021
  3443 00001B64 723E                <1> 	jc	short SET_END		; LOOK FOR ERROR
  3444                              <1> 
  3445                              <1> ;-----	CHECK THE RESULTS RETURNED BY THE CONTROLLER
  3446                              <1> 
  3447 00001B66 FC                  <1> 	cld				; SET THE CORRECT DIRECTION
  3448 00001B67 BE[9D620000]        <1> 	mov	esi, NEC_STATUS		; POINT TO STATUS FIELD
  3449 00001B6C AC                  <1> 	lodsb				; GET ST0
  3450 00001B6D 24C0                <1> 	and	al, 11000000b		; TEST FOR NORMAL TERMINATION
  3451 00001B6F 7433                <1> 	jz	short SET_END
  3452 00001B71 3C40                <1> 	cmp	al, 01000000b		; TEST FOR ABNORMAL TERMINATION
  3453 00001B73 7527                <1> 	jnz	short J18		; NOT ABNORMAL, BAD NEC
  3454                              <1> 
  3455                              <1> ;-----	ABNORMAL TERMINATION, FIND OUT WHY
  3456                              <1> 
  3457 00001B75 AC                  <1> 	lodsb				; GET ST1
  3458 00001B76 D0E0                <1> 	sal	al, 1			; TEST FOR EDT FOUND
  3459 00001B78 B404                <1> 	mov	ah, RECORD_NOT_FND
  3460 00001B7A 7222                <1> 	jc	short J19
  3461 00001B7C C0E002              <1> 	sal	al, 2
  3462 00001B7F B410                <1> 	mov	ah, BAD_CRC
  3463 00001B81 721B                <1> 	jc	short J19
  3464 00001B83 D0E0                <1> 	sal	al, 1			; TEST FOR DMA OVERRUN
  3465 00001B85 B408                <1> 	mov	ah, BAD_DMA
  3466 00001B87 7215                <1> 	jc	short J19
  3467 00001B89 C0E002              <1> 	sal	al, 2			; TEST FOR RECORD NOT FOUND
  3468 00001B8C B404                <1> 	mov	ah, RECORD_NOT_FND
  3469 00001B8E 720E                <1> 	jc	short J19
  3470 00001B90 D0E0                <1> 	sal	al, 1
  3471 00001B92 B403                <1> 	mov	ah, WRITE_PROTECT	; TEST FOR WRITE_PROTECT
  3472 00001B94 7208                <1> 	jc	short J19
  3473 00001B96 D0E0                <1> 	sal	al, 1			; TEST MISSING ADDRESS MARK
  3474 00001B98 B402                <1> 	mov	ah, BAD_ADDR_MARK
  3475 00001B9A 7202                <1> 	jc	short J19
  3476                              <1> 
  3477                              <1> ;----- 	NEC MUST HAVE FAILED
  3478                              <1> J18:
  3479 00001B9C B420                <1> 	mov	ah, BAD_NEC
  3480                              <1> J19:
  3481 00001B9E 0825[9C620000]      <1> 	or	[DSKETTE_STATUS], ah
  3482                              <1> SET_END:
  3483 00001BA4 803D[9C620000]01    <1> 	cmp	byte [DSKETTE_STATUS], 1 ; SET ERROR CONDITION
  3484 00001BAB F5                  <1> 	cmc
  3485 00001BAC 5E                  <1> 	pop	esi
  3486 00001BAD C3                  <1> 	retn				; RESTORE HEAD #, # OF SECTORS
  3487                              <1> 
  3488                              <1> SET_END_POP:
  3489 00001BAE 9D                  <1> 	popfd	; 24/12/2021
  3490 00001BAF EBF3                <1> 	jmp	short SET_END
  3491                              <1> 
  3492                              <1> ;-------------------------------------------------------------------------------
  3493                              <1> ; DSTATE:	ESTABLISH STATE UPON SUCCESSFUL OPERATION.
  3494                              <1> ;-------------------------------------------------------------------------------
  3495                              <1> DSTATE:
  3496                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3497 00001BB1 803D[9C620000]00    <1> 	cmp	byte [DSKETTE_STATUS], 0 ; CHECK FOR ERROR
  3498 00001BB8 753E                <1> 	jne	short SETBAC		; IF ERROR JUMP
  3499 00001BBA 808F[A7620000]10    <1> 	or	byte [DSK_STATE+edi], MED_DET ; NO ERROR, MARK MEDIA AS DETERMINED
  3500 00001BC1 F687[A7620000]04    <1> 	test	byte [DSK_STATE+edi], DRV_DET ; DRIVE DETERMINED ?
  3501 00001BC8 752E                <1> 	jnz	short SETBAC		; IF DETERMINED NO TRY TO DETERMINE
  3502 00001BCA 8A87[A7620000]      <1> 	mov	al, [DSK_STATE+edi]	; LOAD STATE
  3503 00001BD0 24C0                <1> 	and	al, RATE_MSK		; KEEP ONLY RATE
  3504 00001BD2 3C80                <1> 	cmp	al, RATE_250		; RATE 250 ?
  3505 00001BD4 751B                <1> 	jne	short M_12		; NO, MUST BE 1.2M OR 1.44M DRIVE
  3506                              <1> 
  3507                              <1> ;----- 	CHECK IF IT IS 1.44M
  3508                              <1> 
  3509 00001BD6 E843010000          <1> 	call	CMOS_TYPE		; RETURN DRIVE TYPE IN (AL)
  3510                              <1> 	;;20/02/2015
  3511                              <1> 	;;jc	short M_12		; CMOS BAD
  3512 00001BDB 7414                <1> 	jz	short M_12 ;; 20/02/2015
  3513 00001BDD 3C04                <1> 	cmp	al, 4			; 1.44MB DRIVE ?
  3514 00001BDF 7410                <1> 	je	short M_12		; YES
  3515                              <1> M_720:
  3516 00001BE1 80A7[A7620000]FD    <1> 	and	byte [DSK_STATE+edi], ~FMT_CAPA ; TURN OFF FORMAT CAPABILITY
  3517 00001BE8 808F[A7620000]04    <1> 	or	byte [DSK_STATE+edi], DRV_DET  ; MARK DRIVE DETERMINED
  3518 00001BEF EB07                <1> 	jmp	short SETBAC		; BACK
  3519                              <1> M_12:	
  3520 00001BF1 808F[A7620000]06    <1> 	or	byte [DSK_STATE+edi], DRV_DET+FMT_CAPA 
  3521                              <1> 					; TURN ON DETERMINED & FMT CAPA
  3522                              <1> SETBAC:
  3523 00001BF8 C3                  <1> 	retn
  3524                              <1> 
  3525                              <1> ;-------------------------------------------------------------------------------
  3526                              <1> ; RETRY	
  3527                              <1> ;	DETERMINES WHETHER A RETRY IS NECESSARY. 
  3528                              <1> ;	IF RETRY IS REQUIRED THEN STATE INFORMATION IS UPDATED FOR RETRY.
  3529                              <1> ;
  3530                              <1> ; ON EXIT:	CY = 1 FOR RETRY, CY = 0 FOR NO RETRY
  3531                              <1> ;-------------------------------------------------------------------------------
  3532                              <1> RETRY:
  3533                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3534 00001BF9 803D[9C620000]00    <1> 	cmp	byte [DSKETTE_STATUS], 0 ; GET STATUS OF OPERATION
  3535 00001C00 7444                <1> 	je	short NO_RETRY		; SUCCESSFUL OPERATION
  3536 00001C02 803D[9C620000]80    <1> 	cmp	byte [DSKETTE_STATUS], TIME_OUT ; IF TIME OUT NO RETRY
  3537 00001C09 743B                <1> 	je	short NO_RETRY
  3538 00001C0B 8AA7[A7620000]      <1> 	mov	ah, [DSK_STATE+edi]	; GET MEDIA STATE OF DRIVE
  3539 00001C11 F6C410              <1> 	test	ah, MED_DET		; ESTABLISHED/DETERMINED ?
  3540 00001C14 7530                <1> 	jnz	short NO_RETRY		; IF ESTABLISHED STATE THEN TRUE ERROR
  3541 00001C16 80E4C0              <1> 	and	ah, RATE_MSK		; ISOLATE RATE
  3542 00001C19 8A2D[A4620000]      <1> 	mov	ch, [LASTRATE]		; GET START OPERATION STATE
  3543 00001C1F C0C504              <1> 	rol	ch, 4			; TO CORRESPONDING BITS
  3544 00001C22 80E5C0              <1> 	and	ch, RATE_MSK		; ISOLATE RATE BITS
  3545 00001C25 38E5                <1> 	cmp	ch, ah			; ALL RATES TRIED
  3546 00001C27 741D                <1> 	je	short NO_RETRY		; IF YES, THEN TRUE ERROR
  3547                              <1> 
  3548                              <1> ;	SETUP STATE INDICATOR FOR RETRY ATTEMPT TO NEXT RATE
  3549                              <1> ;	 00000000B (500) -> 10000000B	(250)
  3550                              <1> ;	 10000000B (250) -> 01000000B	(300)
  3551                              <1> ;	 01000000B (300) -> 00000000B	(500)
  3552                              <1> 
  3553 00001C29 80FC01              <1> 	cmp	ah, RATE_500+1		; SET CY FOR RATE 500
  3554 00001C2C D0DC                <1> 	rcr	ah, 1			; TO NEXT STATE
  3555 00001C2E 80E4C0              <1> 	and	ah, RATE_MSK		; KEEP ONLY RATE BITS
  3556 00001C31 80A7[A7620000]1F    <1> 	and	byte [DSK_STATE+edi], ~(RATE_MSK+DBL_STEP)
  3557                              <1> 					; RATE, DBL STEP OFF
  3558 00001C38 08A7[A7620000]      <1> 	or	[DSK_STATE+edi], ah	; TURN ON NEW RATE
  3559 00001C3E C605[9C620000]00    <1> 	mov	byte [DSKETTE_STATUS], 0 ; RESET STATUS FOR RETRY
  3560 00001C45 F9                  <1> 	stc				; SET CARRY FOR RETRY
  3561                              <1> NO_RETRY:	; 08/07/2022
  3562 00001C46 C3                  <1> 	retn				; RETRY RETURN
  3563                              <1> 
  3564                              <1> ;NO_RETRY:
  3565                              <1> 	;clc				; CLEAR CARRY NO RETRY
  3566                              <1> 	;RETn				; NO RETRY RETURN
  3567                              <1> 
  3568                              <1> ;-------------------------------------------------------------------------------
  3569                              <1> ; NUM_TRANS
  3570                              <1> ;	THIS ROUTINE CALCULATES THE NUMBER OF SECTORS THAT WERE
  3571                              <1> ;	ACTUALLY TRANSFERRED TO/FROM THE DISKETTE.
  3572                              <1> ;
  3573                              <1> ; ON ENTRY:	[BP+1] = TRACK
  3574                              <1> ;		SI-HI  = HEAD
  3575                              <1> ;		[BP]   = START SECTOR
  3576                              <1> ;
  3577                              <1> ; ON EXIT:	AL = NUMBER ACTUALLY TRANSFERRED
  3578                              <1> ;-------------------------------------------------------------------------------
  3579                              <1> NUM_TRANS:
  3580                              <1> 	; 11/07/2022
  3581                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3582 00001C47 30C0                <1> 	xor	al, al			; CLEAR FOR ERROR
  3583 00001C49 803D[9C620000]00    <1> 	cmp	byte [DSKETTE_STATUS], 0 ; CHECK FOR ERROR
  3584                              <1> 	; 24/12/2021
  3585 00001C50 7529                <1> 	jne	short NT_OUT		; IF ERROR 0 TRANSFERRED
  3586                              <1> 	;mov	dl, 4			; SECTORS/TRACK OFFSET TO DL
  3587 00001C52 B004                <1> 	mov	al, 4 ; 08/07/2022
  3588 00001C54 E8CE000000          <1> 	call	GET_PARM		; AH = SECTORS/TRACK
  3589                              <1> 	;mov	bl, [NEC_STATUS+5]	; GET ENDING SECTOR
  3590 00001C59 A0[A2620000]        <1> 	mov	al, [NEC_STATUS+5]
  3591 00001C5E 89F1                <1> 	mov	ecx, esi		; CH = HEAD # STARTED
  3592 00001C60 88CB                <1> 	mov	bl, cl ; 11/07/2022 ; sector #
  3593 00001C62 3A2D[A1620000]      <1> 	cmp	ch, [NEC_STATUS+4]	; GET HEAD ENDED UP ON
  3594 00001C68 750D                <1> 	jne	short DIF_HD		; IF ON SAME HEAD, THEN NO ADJUST
  3595                              <1> 	; 11/07/2022
  3596                              <1> 	;mov	ch, [NEC_STATUS+3]	; GET TRACK ENDED UP ON
  3597                              <1> 	;cmp	ch, [ebp+1]		; IS IT ASKED FOR TRACK
  3598                              <1> 	;jz	short SAME_TR		; IF SAME TRACK NO INCREASE
  3599 00001C6A C1E908              <1> 	shr	ecx, 8 ; byte 3 = track # --> byte 2
  3600 00001C6D 3A2D[A0620000]      <1> 	cmp	ch, [NEC_STATUS+3]
  3601 00001C73 7404                <1> 	je	short SAME_TRK		
  3602                              <1> 	; 11/07/2022
  3603                              <1> 	;add	bl, ah			; ADD SECTORS/TRACK
  3604 00001C75 00E0                <1> 	add	al, ah
  3605                              <1> DIF_HD:
  3606                              <1> 	;add	bl, ah			; ADD SECTORS/TRACK
  3607 00001C77 00E0                <1> 	add	al, ah
  3608                              <1> SAME_TRK:
  3609                              <1> 	;sub	bl, [ebp]		; SUBTRACT START FROM END
  3610                              <1> 	;mov	al, bl			; TO AL
  3611 00001C79 28D8                <1> 	sub	al, bl
  3612                              <1> NT_OUT:
  3613 00001C7B C3                  <1> 	retn
  3614                              <1> 
  3615                              <1> ;-------------------------------------------------------------------------------
  3616                              <1> ; SETUP_DBL
  3617                              <1> ;	CHECK DOUBLE STEP.
  3618                              <1> ;
  3619                              <1> ; ON ENTRY :	EDI = DRIVE #
  3620                              <1> ;
  3621                              <1> ; ON EXIT :	CY = 1 MEANS ERROR
  3622                              <1> ;-------------------------------------------------------------------------------
  3623                              <1> SETUP_DBL:
  3624                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3625 00001C7C 8AA7[A7620000]      <1> 	mov	ah, [DSK_STATE+edi]	; ACCESS STATE
  3626 00001C82 F6C410              <1> 	test	ah, MED_DET		; ESTABLISHED STATE ?
  3627 00001C85 7578                <1> 	jnz	short NO_DBL		; IF ESTABLISHED THEN DOUBLE DONE
  3628                              <1> 
  3629                              <1> ;-----	CHECK FOR TRACK 0 TO SPEED UP ACKNOWLEDGE OF UNFORMATTED DISKETTE
  3630                              <1> 
  3631 00001C87 C605[99620000]00    <1> 	mov	byte [SEEK_STATUS], 0	; SET RECALIBRATE REQUIRED ON ALL DRIVES
  3632 00001C8E E8CF000000          <1> 	call	MOTOR_ON		; ENSURE MOTOR STAY ON
  3633 00001C93 B500                <1> 	mov	ch, 0			; LOAD TRACK 0
  3634 00001C95 E8B7010000          <1> 	call	SEEK			; SEEK TO TRACK 0
  3635 00001C9A E862000000          <1> 	call	READ_ID			; READ ID FUNCTION
  3636 00001C9F 7243                <1> 	jc	short SD_ERR		; IF ERROR NO TRACK 0
  3637                              <1> 
  3638                              <1> ;-----	INITIALIZE START AND MAX TRACKS (TIMES 2 FOR BOTH HEADS)
  3639                              <1> 
  3640 00001CA1 66B95004            <1> 	mov	cx, 0450h 		; START, MAX TRACKS
  3641 00001CA5 F687[A7620000]01    <1> 	test	byte [DSK_STATE+edi], TRK_CAPA ; TEST FOR 80 TRACK CAPABILITY
  3642 00001CAC 7402                <1> 	jz	short CNT_OK		; IF NOT COUNT IS SETUP
  3643 00001CAE B1A0                <1> 	mov	cl, 0A0h		; MAXIMUM TRACK 1.2 MB
  3644                              <1> 
  3645                              <1> ;	ATTEMPT READ ID OF ALL TRACKS, ALL HEADS UNTIL SUCCESS; UPON SUCCESS,
  3646                              <1> ;	MUST SEE IF ASKED FOR TRACK IN SINGLE STEP MODE = TRACK ID READ; IF NOT
  3647                              <1> ;	THEN SET DOUBLE STEP ON.
  3648                              <1> 
  3649                              <1> CNT_OK:
  3650 00001CB0 C605[9B620000]FF    <1>        	mov	byte [MOTOR_COUNT], 0FFh ; ENSURE MOTOR STAYS ON FOR OPERATION 
  3651                              <1> 	; 24/12/2021
  3652 00001CB7 51                  <1> 	push	ecx			; SAVE TRACK, COUNT
  3653 00001CB8 C605[9C620000]00    <1> 	mov	byte [DSKETTE_STATUS], 0 ; CLEAR STATUS, EXPECT ERRORS
  3654 00001CBF 31C0                <1> 	xor	eax, eax		; CLEAR EAX
  3655 00001CC1 D0ED                <1> 	shr	ch, 1			; HALVE TRACK, CY = HEAD
  3656 00001CC3 C0D003              <1> 	rcl	al, 3			; AX = HEAD IN CORRECT BIT
  3657                              <1> 	; 24/12/2021
  3658 00001CC6 50                  <1> 	push	eax			; SAVE HEAD
  3659 00001CC7 E885010000          <1> 	call	SEEK			; SEEK TO TRACK
  3660                              <1> 	; 24/12/2021
  3661 00001CCC 58                  <1> 	pop	eax			; RESTORE HEAD
  3662 00001CCD 09C7                <1> 	or	edi, eax		; DI = HEAD OR'ED DRIVE
  3663 00001CCF E82D000000          <1> 	call	READ_ID			; READ ID HEAD 0
  3664 00001CD4 9C                  <1> 	pushf				; SAVE RETURN FROM READ_ID
  3665 00001CD5 6681E7FB00          <1> 	and	di, 11111011b		; TURN OFF HEAD 1 BIT
  3666 00001CDA 9D                  <1> 	popf				; RESTORE ERROR RETURN
  3667                              <1> 	; 24/12/2021
  3668 00001CDB 59                  <1> 	pop	ecx			; RESTORE COUNT
  3669 00001CDC 7308                <1> 	jnc	short DO_CHK		; IF OK, ASKED = RETURNED TRACK ?
  3670 00001CDE FEC5                <1> 	inc	ch			; INC FOR NEXT TRACK
  3671 00001CE0 38CD                <1> 	cmp	ch, cl			; REACHED MAXIMUM YET
  3672 00001CE2 75CC                <1> 	jnz	short CNT_OK		; CONTINUE TILL ALL TRIED
  3673                              <1> 
  3674                              <1> ;-----	FALL THRU, READ ID FAILED FOR ALL TRACKS
  3675                              <1> 
  3676                              <1> SD_ERR:	
  3677 00001CE4 F9                  <1> 	stc				; SET CARRY FOR ERROR
  3678 00001CE5 C3                  <1> 	retn				; SETUP_DBL ERROR EXIT
  3679                              <1> 
  3680                              <1> DO_CHK:
  3681 00001CE6 8A0D[A0620000]      <1> 	mov	cl, [NEC_STATUS+3]	; LOAD RETURNED TRACK
  3682 00001CEC 888F[A9620000]      <1> 	mov	[DSK_TRK+edi], cl	; STORE TRACK NUMBER
  3683 00001CF2 D0ED                <1> 	shr	ch, 1			; HALVE TRACK
  3684 00001CF4 38CD                <1> 	cmp	ch, cl			; IS IT THE SAME AS ASKED FOR TRACK
  3685 00001CF6 7407                <1> 	jz	short NO_DBL		; IF SAME THEN NO DOUBLE STEP
  3686 00001CF8 808F[A7620000]20    <1> 	or	byte [DSK_STATE+edi], DBL_STEP ; TURN ON DOUBLE STEP REQUIRED
  3687                              <1> NO_DBL:
  3688 00001CFF F8                  <1> 	clc				; CLEAR ERROR FLAG
  3689 00001D00 C3                  <1> 	retn
  3690                              <1> 
  3691                              <1> ;-------------------------------------------------------------------------------
  3692                              <1> ; READ_ID
  3693                              <1> ;	READ ID FUNCTION.
  3694                              <1> ;
  3695                              <1> ; ON ENTRY:	EDI : BIT 2 = HEAD; BITS 1,0 = DRIVE
  3696                              <1> ;
  3697                              <1> ; ON EXIT: 	EDI : BIT 2 IS RESET, BITS 1,0 = DRIVE
  3698                              <1> ;		@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION
  3699                              <1> ;-------------------------------------------------------------------------------
  3700                              <1> READ_ID:
  3701                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3702 00001D01 B8[1D1D0000]        <1> 	mov	eax, ER_3		; MOVE NEC OUTPUT ERROR ADDRESS
  3703 00001D06 50                  <1> 	push	eax
  3704 00001D07 B44A                <1> 	mov	ah, 4Ah			; READ ID COMMAND
  3705 00001D09 E80A010000          <1> 	call	NEC_OUTPUT		; TO CONTROLLER
  3706 00001D0E 89F8                <1> 	mov	eax, edi		; DRIVE # TO AH, HEAD 0
  3707 00001D10 88C4                <1> 	mov	ah, al
  3708 00001D12 E801010000          <1> 	call	NEC_OUTPUT		; TO CONTROLLER
  3709 00001D17 E839FEFFFF          <1> 	call	NEC_TERM		; WAIT FOR OPERATION, GET STATUS
  3710 00001D1C 58                  <1> 	pop	eax			; THROW AWAY ERROR ADDRESS
  3711                              <1> ER_3:
  3712 00001D1D C3                  <1> 	retn
  3713                              <1> 
  3714                              <1> ;-------------------------------------------------------------------------------
  3715                              <1> ; CMOS_TYPE
  3716                              <1> ;	RETURNS CMOS DISKETTE TYPE
  3717                              <1> ;
  3718                              <1> ; ON ENTRY:	EDI = DRIVE #
  3719                              <1> ;
  3720                              <1> ; ON EXIT:	AL = TYPE; CY REFLECTS STATUS
  3721                              <1> ;-------------------------------------------------------------------------------
  3722                              <1> 
  3723                              <1> CMOS_TYPE: ; 11/12/2014
  3724                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3725 00001D1E 8A87[3C5D0000]      <1> 	mov	al, [edi+fd0_type] ; diskette type
  3726 00001D24 20C0                <1> 	and 	al, al ; 18/12/2014
  3727 00001D26 C3                  <1> 	retn
  3728                              <1> 
  3729                              <1> ;-------------------------------------------------------------------------------
  3730                              <1> ; GET_PARM
  3731                              <1> ;	THIS ROUTINE FETCHES THE INDEXED POINTER FROM THE DISK_BASE
  3732                              <1> ;	BLOCK POINTED TO BY THE DATA VARIABLE @DISK_POINTER. A BYTE FROM
  3733                              <1> ;	THAT TABLE IS THEN MOVED INTO AH, THE INDEX OF THAT BYTE BEING
  3734                              <1> ;	THE PARAMETER IN DL.
  3735                              <1> ;
  3736                              <1> ; ON ENTRY:	AL = INDEX OF BYTE TO BE FETCHED ; 08/07/2022
  3737                              <1> ;
  3738                              <1> ; ON EXIT:	AH = THAT BYTE FROM BLOCK
  3739                              <1> ;		AL DESTROYED
  3740                              <1> ;-------------------------------------------------------------------------------
  3741                              <1> GET_PARM:
  3742                              <1> 	; 11/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3743                              <1> 	;	 ENTRY:
  3744                              <1> 	;	     AL = INDEX
  3745                              <1> 	;	    EDI = DRIVE #
  3746                              <1> 	; 	 RETURN:
  3747                              <1> 	;	     AH = REQUESTED PARAMETER
  3748                              <1> 	;	     AL DESTROYED
  3749                              <1> 	
  3750                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3751                              <1> 	; 08/02/2015 (protected mode modifications, bx -> ebx)
  3752                              <1> 	;push	esi ; 11/07/2022
  3753 00001D27 53                  <1> 	push	ebx			; SAVE EBX	
  3754 00001D28 0FB6D8              <1> 	movzx	ebx, al			; EBX = INDEX
  3755                              <1>    	; 17/12/2014
  3756                              <1> 	;mov	ax, [cfd] ; current (AL) and previous fd (AH)
  3757                              <1> 	; 11/07/2022
  3758                              <1> 	;cmp	al, ah
  3759                              <1> 	;je	short gpndc
  3760                              <1> 
  3761                              <1> 	; 11/07/2022
  3762 00001D2B 89F8                <1> 	mov	eax, edi
  3763 00001D2D 3A05[315D0000]      <1> 	cmp	al, [pfd] ; is same with previous drive # ?
  3764 00001D33 7423                <1> 	je	short gpndc	
  3765                              <1> 
  3766 00001D35 A2[315D0000]        <1> 	mov	[pfd], al ; current drive -> previous drive
  3767                              <1> 
  3768 00001D3A 53                  <1> 	push	ebx ; 08/02/2015
  3769                              <1> 	
  3770                              <1> 	;mov	bl, al 
  3771                              <1> 	; 11/12/2014
  3772                              <1> 	;mov	al, [ebx+fd0_type]	; Drive type (0,1,2,3,4)
  3773                              <1> 	; 11/07/2022
  3774 00001D3B 8A87[3C5D0000]      <1> 	mov	al, [edi+fd0_type]	; Drive type (0,1,2,3,4)	
  3775                              <1> 	; 18/12/2014
  3776 00001D41 20C0                <1> 	and	al, al
  3777 00001D43 7507                <1> 	jnz	short gpdtc
  3778 00001D45 BB[1B5D0000]        <1> 	mov	ebx, MD_TBL6		; 1.44 MB param. tbl. (default)
  3779 00001D4A EB05                <1>         jmp     short gpdpu
  3780                              <1> gpdtc:	
  3781 00001D4C E8B0FBFFFF          <1> 	call	DR_TYPE_CHECK
  3782                              <1> 	; cf = 1 -> EBX points to 1.44MB fd parameter table (default)
  3783                              <1> gpdpu:
  3784 00001D51 891D[B85C0000]      <1> 	mov	[DISK_POINTER], ebx
  3785 00001D57 5B                  <1> 	pop	ebx
  3786                              <1> gpndc:
  3787                              <1> 	;mov	esi, [DISK_POINTER] ; 08/02/2015, si -> esi
  3788                              <1> 	;mov	ah, [esi+ebx]		; GET THE WORD
  3789                              <1> 	; 11/07/2022
  3790 00001D58 031D[B85C0000]      <1> 	add	ebx, [DISK_POINTER]
  3791 00001D5E 8A23                <1> 	mov	ah, [ebx] 
  3792 00001D60 5B                  <1> 	pop	ebx			; RESTORE EBX
  3793                              <1> 	;pop	esi ; 11/07/2022
  3794 00001D61 C3                  <1> 	retn
  3795                              <1> 
  3796                              <1> ;-------------------------------------------------------------------------------
  3797                              <1> ; MOTOR_ON
  3798                              <1> ;	TURN MOTOR ON AND WAIT FOR MOTOR START UP TIME. THE @MOTOR_COUNT
  3799                              <1> ;	IS REPLACED WITH A SUFFICIENTLY HIGH NUMBER (0FFH) TO ENSURE
  3800                              <1> ;	THAT THE MOTOR DOES NOT GO OFF DURING THE OPERATION. IF THE
  3801                              <1> ;	MOTOR NEEDED TO BE TURNED ON, THE MULTI-TASKING HOOK FUNCTION
  3802                              <1> ;	(AX=90FDH, INT 15) IS CALLED TELLING THE OPERATING SYSTEM
  3803                              <1> ;	THAT THE BIOS IS ABOUT TO WAIT FOR MOTOR START UP. IF THIS
  3804                              <1> ;	FUNCTION RETURNS WITH CY = 1, IT MEANS THAT THE MINIMUM WAIT
  3805                              <1> ;	HAS BEEN COMPLETED. AT THIS POINT A CHECK IS MADE TO ENSURE
  3806                              <1> ;	THAT THE MOTOR WASN'T TURNED OFF BY THE TIMER. IF THE HOOK DID
  3807                              <1> ;	NOT WAIT, THE WAIT FUNCTION (AH=086H) IS CALLED TO WAIT THE
  3808                              <1> ;	PRESCRIBED AMOUNT OF TIME. IF THE CARRY FLAG IS SET ON RETURN,
  3809                              <1> ;	IT MEANS THAT THE FUNCTION IS IN USE AND DID NOT PERFORM THE
  3810                              <1> ;	WAIT. A TIMER 1 WAIT LOOP WILL THEN DO THE WAIT.
  3811                              <1> ;
  3812                              <1> ; ON ENTRY:	EDI = DRIVE #
  3813                              <1> ; ON EXIT:	EAX, ECX, EDX DESTROYED
  3814                              <1> ;-------------------------------------------------------------------------------
  3815                              <1> MOTOR_ON:
  3816                              <1> 	; 12/07/2022
  3817                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3818 00001D62 53                  <1> 	push	ebx			; SAVE REG.
  3819 00001D63 E820000000          <1> 	call	TURN_ON			; TURN ON MOTOR
  3820 00001D68 721C                <1> 	jc	short MOT_IS_ON		; IF CY=1 NO WAIT
  3821                              <1> 	;call	XLAT_OLD		; TRANSLATE STATE TO COMPATIBLE MODE
  3822                              <1> 	; 08/07/2022
  3823                              <1> 	;call	XLAT_NEW ; 12/07/2022	; TRANSLATE STATE TO PRESENT ARCH,
  3824                              <1> 	;call	TURN_ON 		; CHECK AGAIN IF MOTOR ON
  3825                              <1> 	;jc	short MOT_IS_ON		; IF NO WAIT MEANS IT IS ON
  3826                              <1> M_WAIT:
  3827                              <1> 	;mov	dl,10			; GET THE MOTOR WAIT PARAMETER
  3828 00001D6A B00A                <1> 	mov	al, 10 ; 08/07/2022
  3829 00001D6C E8B6FFFFFF          <1> 	call	GET_PARM
  3830                              <1> 	; 08/07/2022			; AH = MOTOR WAIT PARAMETER
  3831 00001D71 80FC08              <1> 	cmp	ah, 8			; SEE IF AT LEAST A SECOND IS SPECIFIED			
  3832                              <1> 	;jae	short GP2		; IF YES, CONTINUE
  3833 00001D74 7302                <1> 	jae	short J13
  3834 00001D76 B408                <1> 	mov	ah, 8			; ONE SECOND WAIT FOR MOTOR START UP
  3835                              <1> 
  3836                              <1> ;-----	AS CONTAINS NUMBER OF 1/8 SECONDS (125000 MICROSECONDS) TO WAIT
  3837                              <1> GP2:	
  3838                              <1> ;----- 	FOLLOWING LOOPS REQUIRED WHEN RTC WAIT FUNCTION IS ALREADY IN USE
  3839                              <1> J13:					; WAIT FOR 1/8 SECOND PER (AL)
  3840 00001D78 B95E200000          <1> 	mov	ecx, 8286		; COUNT FOR 1/8 SECOND AT 15.085737 US
  3841 00001D7D E817F7FFFF          <1> 	call	WAITF			; GO TO FIXED WAIT ROUTINE
  3842                              <1> 	;dec	al			; DECREMENT TIME VALUE
  3843 00001D82 FECC                <1> 	dec	ah
  3844 00001D84 75F2                <1> 	jnz	short J13		; ARE WE DONE YET
  3845                              <1> MOT_IS_ON:
  3846 00001D86 5B                  <1> 	pop	ebx			; RESTORE REG.
  3847 00001D87 C3                  <1> 	retn
  3848                              <1> 
  3849                              <1> ;-------------------------------------------------------------------------------
  3850                              <1> ; TURN_ON
  3851                              <1> ;	TURN MOTOR ON AND RETURN WAIT STATE.
  3852                              <1> ;
  3853                              <1> ; ON ENTRY:	EDI = DRIVE #
  3854                              <1> ;
  3855                              <1> ; ON EXIT:	CY = 0 MEANS WAIT REQUIRED
  3856                              <1> ;		CY = 1 MEANS NO WAIT REQUIRED
  3857                              <1> ;		EAX, EBX, ECX, EDX DESTROYED
  3858                              <1> ;-------------------------------------------------------------------------------
  3859                              <1> TURN_ON:
  3860                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3861 00001D88 89FB                <1> 	mov	ebx, edi		; EBX = DRIVE #
  3862 00001D8A 88D9                <1> 	mov	cl, bl			; CL = DRIVE #
  3863 00001D8C C0C304              <1> 	rol	bl, 4			; BL = DRIVE SELECT
  3864 00001D8F FA                  <1> 	cli				; NO INTERRUPTS WHILE DETERMINING STATUS
  3865 00001D90 C605[9B620000]FF    <1> 	mov	byte [MOTOR_COUNT], 0FFh ; ENSURE MOTOR STAYS ON FOR OPERATION
  3866 00001D97 A0[9A620000]        <1> 	mov	al, [MOTOR_STATUS]	; GET DIGITAL OUTPUT REGISTER REFLECTION
  3867 00001D9C 2430                <1> 	and	al, 00110000b		; KEEP ONLY DRIVE SELECT BITS
  3868 00001D9E B401                <1> 	mov	ah, 1			; MASK FOR DETERMINING MOTOR BIT
  3869 00001DA0 D2E4                <1> 	shl	ah, cl			; AH = MOTOR ON, A=00000001, B=00000010
  3870                              <1> 
  3871                              <1> ;  AL = DRIVE SELECT FROM @MOTOR_STATUS
  3872                              <1> ;  BL = DRIVE SELECT DESIRED
  3873                              <1> ;  AH = MOTOR ON MASK DESIRED
  3874                              <1> 
  3875 00001DA2 38D8                <1> 	cmp	al, bl			; REQUESTED DRIVE ALREADY SELECTED ?
  3876 00001DA4 7508                <1> 	jne	short TURN_IT_ON	; IF NOT SELECTED JUMP
  3877 00001DA6 8425[9A620000]      <1> 	test	ah, [MOTOR_STATUS]	; TEST MOTOR ON BIT
  3878 00001DAC 7535                <1> 	jnz	short NO_MOT_WAIT	; JUMP IF MOTOR ON AND SELECTED
  3879                              <1> 
  3880                              <1> TURN_IT_ON:
  3881 00001DAE 08DC                <1> 	or	ah, bl			; AH = DRIVE SELECT AND MOTOR ON
  3882 00001DB0 8A3D[9A620000]      <1> 	mov	bh, [MOTOR_STATUS]	; SAVE COPY OF @MOTOR_STATUS BEFORE
  3883 00001DB6 80E70F              <1> 	and	bh, 00001111b		; KEEP ONLY MOTOR BITS
  3884 00001DB9 8025[9A620000]CF    <1> 	and	byte [MOTOR_STATUS], 11001111b ; CLEAR OUT DRIVE SELECT
  3885 00001DC0 0825[9A620000]      <1> 	or	[MOTOR_STATUS], ah	; OR IN DRIVE SELECTED AND MOTOR ON
  3886 00001DC6 A0[9A620000]        <1> 	mov	al, [MOTOR_STATUS]	; GET DIGITAL OUTPUT REGISTER REFLECTION
  3887 00001DCB 88C3                <1> 	mov	bl, al			; BL=@MOTOR_STATUS AFTER, BH=BEFORE
  3888 00001DCD 80E30F              <1> 	and	bl, 00001111b		; KEEP ONLY MOTOR BITS
  3889 00001DD0 FB                  <1> 	sti				; ENABLE INTERRUPTS AGAIN
  3890 00001DD1 243F                <1> 	and	al, 00111111b		; STRIP AWAY UNWANTED BITS
  3891 00001DD3 C0C004              <1> 	rol	al, 4			; PUT BITS IN DESIRED POSITIONS
  3892 00001DD6 0C0C                <1> 	or	al, 00001100b		; NO RESET, ENABLE DMA/INTERRUPT
  3893 00001DD8 66BAF203            <1> 	mov	dx, 03F2h		; SELECT DRIVE AND TURN ON MOTOR
  3894 00001DDC EE                  <1> 	out	dx, al
  3895 00001DDD 38FB                <1> 	cmp	bl, bh			; NEW MOTOR TURNED ON ?
  3896                              <1> 	;je	short NO_MOT_WAIT	; NO WAIT REQUIRED IF JUST SELECT
  3897 00001DDF 7403                <1> 	je	short no_mot_w1 ; 27/02/2015 
  3898 00001DE1 F8                  <1> 	clc				; RESET CARRY MEANING WAIT
  3899 00001DE2 C3                  <1> 	retn
  3900                              <1> 
  3901                              <1> NO_MOT_WAIT:
  3902 00001DE3 FB                  <1> 	sti
  3903                              <1> no_mot_w1: ; 27/02/2015
  3904 00001DE4 F9                  <1> 	stc				; SET NO WAIT REQUIRED
  3905                              <1> 	;sti				; INTERRUPTS BACK ON
  3906 00001DE5 C3                  <1> 	retn
  3907                              <1> 
  3908                              <1> ;-------------------------------------------------------------------------------
  3909                              <1> ; HD_WAIT
  3910                              <1> ;	WAIT FOR HEAD SETTLE TIME.
  3911                              <1> ;
  3912                              <1> ; ON ENTRY:	DI = DRIVE #
  3913                              <1> ;
  3914                              <1> ; ON EXIT:	EAX, EBX, ECX, EDX DESTROYED
  3915                              <1> ;-------------------------------------------------------------------------------
  3916                              <1> HD_WAIT:
  3917                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3918                              <1> 	;mov	dl, 9			; GET HEAD SETTLE PARAMETER
  3919 00001DE6 B009                <1> 	mov	al, 9	; 08/07/2022
  3920 00001DE8 E83AFFFFFF          <1> 	CALL	GET_PARM
  3921 00001DED 08E4                <1> 	or	ah, ah	; 17/12/2014	; CHECK FOR ANY WAIT?
  3922 00001DEF 7519                <1> 	jnz	short DO_WAT		; IF THERE DO NOT ENFORCE
  3923 00001DF1 F605[9A620000]80    <1>         test	byte [MOTOR_STATUS], 10000000b ; SEE IF A WRITE OPERATION
  3924                              <1> 	;jz	short ISNT_WRITE	; IF NOT, DO NOT ENFORCE ANY VALUES
  3925                              <1> 	;or	ah, ah			; CHECK FOR ANY WAIT?
  3926                              <1> 	;jnz	short DO_WAT		; IF THERE DO NOT ENFORCE
  3927 00001DF8 741D                <1> 	jz	short HW_DONE
  3928 00001DFA B40F                <1> 	mov	ah, HD12_SETTLE		; LOAD 1.2M HEAD SETTLE MINIMUM
  3929 00001DFC 8A87[A7620000]      <1> 	mov	al, [DSK_STATE+edi]	; LOAD STATE
  3930 00001E02 24C0                <1> 	and	al, RATE_MSK		; KEEP ONLY RATE
  3931 00001E04 3C80                <1> 	cmp	al, RATE_250		; 1.2 M DRIVE ?
  3932 00001E06 7502                <1> 	jnz	short DO_WAT		; DEFAULT HEAD SETTLE LOADED
  3933                              <1> ;GP3:
  3934 00001E08 B414                <1> 	mov	ah, HD320_SETTLE	; USE 320/360 HEAD SETTLE
  3935                              <1> ;	jmp	short DO_WAT
  3936                              <1> 
  3937                              <1> ;ISNT_WRITE:
  3938                              <1> ;	or	ah, ah			; CHECK FOR NO WAIT
  3939                              <1> ;	jz	short HW_DONE		; IF NOT WRITE AND 0 ITS OK
  3940                              <1> 
  3941                              <1> ;-----	AH CONTAINS NUMBER OF MILLISECONDS TO WAIT
  3942                              <1> DO_WAT:
  3943                              <1> ;	mov	al, ah			; AL = # MILLISECONDS
  3944                              <1> ;	;xor	ah, ah			; AX = # MILLISECONDS
  3945                              <1> J29:					; 	1 MILLISECOND LOOP
  3946                              <1> 	;mov	cx, WAIT_FDU_HEAD_SETTLE ; 33 ; 1 ms in 30 micro units.
  3947                              <1> 	;mov	ecx, 66			; COUNT AT 15.085737 US PER COUNT
  3948                              <1> 	; 08/07/2022
  3949 00001E0A 29C9                <1> 	sub	ecx, ecx
  3950 00001E0C B142                <1> 	mov	cl, 66
  3951 00001E0E E886F6FFFF          <1> 	call	WAITF			; DELAY FOR 1 MILLISECOND
  3952                              <1> 	;dec	al			; DECREMENT THE COUNT
  3953 00001E13 FECC                <1> 	dec	ah
  3954 00001E15 75F3                <1> 	jnz	short J29		; DO AL MILLISECOND # OF TIMES
  3955                              <1> HW_DONE:
  3956 00001E17 C3                  <1> 	retn
  3957                              <1> 
  3958                              <1> ;-------------------------------------------------------------------------------
  3959                              <1> ; NEC_OUTPUT
  3960                              <1> ;	THIS ROUTINE SENDS A BYTE TO THE NEC CONTROLLER AFTER TESTING
  3961                              <1> ;	FOR CORRECT DIRECTION AND CONTROLLER READY THIS ROUTINE WILL
  3962                              <1> ;	TIME OUT IF THE BYTE IS NOT ACCEPTED WITHIN A REASONABLE AMOUNT
  3963                              <1> ;	OF TIME, SETTING THE DISKETTE STATUS ON COMPLETION.
  3964                              <1> ; 
  3965                              <1> ; ON ENTRY: 	AH = BYTE TO BE OUTPUT
  3966                              <1> ;
  3967                              <1> ; ON EXIT:	CY = 0  SUCCESS
  3968                              <1> ;		CY = 1  FAILURE -- DISKETTE STATUS UPDATED
  3969                              <1> ;		        IF A FAILURE HAS OCCURRED, THE RETURN IS MADE ONE LEVEL
  3970                              <1> ;		        HIGHER THAN THE CALLER OF NEC OUTPUT. THIS REMOVES THE
  3971                              <1> ;		        REQUIREMENT OF TESTING AFTER EVERY CALL OF NEC_OUTPUT.
  3972                              <1> ;
  3973                              <1> ;		EAX, ECX, EDX DESTROYED
  3974                              <1> ;-------------------------------------------------------------------------------
  3975                              <1> 
  3976                              <1> ; 09/12/2014 [Erdogan Tan] 
  3977                              <1> ;	(from 'PS2 Hardware Interface Tech. Ref. May 88', Page 09-05.)
  3978                              <1> ; Diskette Drive Controller Status Register (3F4h)
  3979                              <1> ;	This read only register facilitates the transfer of data between
  3980                              <1> ;	the system microprocessor and the controller.
  3981                              <1> ; Bit 7 - When set to 1, the Data register is ready to transfer data 
  3982                              <1> ;	  with the system micrprocessor.
  3983                              <1> ; Bit 6 - The direction of data transfer. If this bit is set to 0,
  3984                              <1> ;	  the transfer is to the controller.
  3985                              <1> ; Bit 5 - When this bit is set to 1, the controller is in the non-DMA mode.
  3986                              <1> ; Bit 4 - When this bit is set to 1, a Read or Write command is being executed.
  3987                              <1> ; Bit 3 - Reserved.
  3988                              <1> ; Bit 2 - Reserved.
  3989                              <1> ; Bit 1 - When this bit is set to 1, dskette drive 1 is in the seek mode.
  3990                              <1> ; Bit 0 - When this bit is set to 1, dskette drive 0 is in the seek mode.
  3991                              <1> 
  3992                              <1> ; Data Register (3F5h)
  3993                              <1> ; This read/write register passes data, commands and parameters, and provides
  3994                              <1> ; diskette status information.
  3995                              <1>   		
  3996                              <1> NEC_OUTPUT:
  3997                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3998                              <1> 	;push	ebx			; SAVE REG.
  3999 00001E18 BAF4030000          <1> 	mov	edx, 03F4h		; STATUS PORT
  4000                              <1> 	;xor	ecx, ecx		; COUNT FOR TIME OUT
  4001                              <1> 	; 16/12/2014
  4002                              <1> 	; waiting for (max.) 0.5 seconds
  4003                              <1>         ;;mov	byte [wait_count], 0 ;; 27/02/2015
  4004                              <1> 	;
  4005                              <1> 	; 17/12/2014
  4006                              <1> 	; Modified from AWARD BIOS 1999 - ADISK.ASM - SEND_COMMAND
  4007                              <1> 	;
  4008                              <1> 	;WAIT_FOR_PORT:	Waits for a bit at a port pointed to by DX to
  4009                              <1> 	;		go on.
  4010                              <1> 	;INPUT:
  4011                              <1> 	;	AH=Mask for isolation bits.
  4012                              <1> 	;	AL=pattern to look for.
  4013                              <1> 	;	DX=Port to test for
  4014                              <1> 	;	ECX=Number of memory refresh periods to delay.
  4015                              <1> 	;	     (normally 30 microseconds per period.)
  4016                              <1> 	;
  4017                              <1> 	;WFP_SHORT:  
  4018                              <1> 	;	Wait for port if refresh cycle is short (15-80 Us range).
  4019                              <1> 	;
  4020                              <1> 
  4021 00001E1D B91B410000          <1> 	mov	ecx, WAIT_FDU_SEND_LH   ; 16667 (27/02/2015)
  4022                              <1> ;
  4023                              <1> ;WFPS_OUTER_LP:
  4024                              <1> ;	;
  4025                              <1> ;WFPS_CHECK_PORT:
  4026                              <1> J23:
  4027 00001E22 EC                  <1> 	in	al, dx			; GET STATUS
  4028 00001E23 24C0                <1> 	and	al, 11000000b		; KEEP STATUS AND DIRECTION
  4029 00001E25 3C80                <1> 	cmp	al, 10000000b		; STATUS 1 AND DIRECTION 0 ?
  4030 00001E27 7418                <1> 	jz	short J27		; STATUS AND DIRECTION OK
  4031                              <1> WFPS_HI:
  4032 00001E29 E461                <1> 	in	al, PORT_B	; 061h	; SYS1	; wait for hi to lo
  4033 00001E2B A810                <1> 	test	al, 010h		; transition on memory
  4034 00001E2D 75FA                <1> 	jnz	short WFPS_HI		; refresh.
  4035                              <1> WFPS_LO:
  4036 00001E2F E461                <1> 	in	al, PORT_B		; SYS1
  4037 00001E31 A810                <1> 	test	al, 010h
  4038 00001E33 74FA                <1> 	jz	short WFPS_LO
  4039                              <1> 	;loop	short WFPS_CHECK_PORT
  4040 00001E35 E2EB                <1> 	loop	J23	; 27/02/2015	; REPEAT TILL DELAY FINISHED
  4041                              <1> 
  4042                              <1> 	; fail
  4043                              <1> 
  4044                              <1> ;WFPS_TIMEOUT:
  4045                              <1> 
  4046                              <1> ;-----	FALL THRU TO ERROR RETURN
  4047                              <1> 
  4048 00001E37 800D[9C620000]80    <1> 	or	byte [DSKETTE_STATUS], TIME_OUT
  4049                              <1> 	;pop	ebx			; RESTORE REG.
  4050 00001E3E 58                  <1> 	pop	eax ; 08/02/2015	; DISCARD THE RETURN ADDRESS
  4051 00001E3F F9                  <1> 	stc				; INDICATE ERROR TO CALLER
  4052 00001E40 C3                  <1> 	retn
  4053                              <1> 
  4054                              <1> ;-----	DIRECTION AND STATUS OK; OUTPUT BYTE
  4055                              <1> 
  4056                              <1> J27:	
  4057 00001E41 88E0                <1> 	mov	al, ah			; GET BYTE TO OUTPUT
  4058 00001E43 42                  <1> 	inc	edx			; DATA PORT = STATUS PORT + 1
  4059 00001E44 EE                  <1> 	out	dx, al			; OUTPUT THE BYTE
  4060                              <1> 	;;NEWIODELAY  ;; 27/02/2015
  4061                              <1> 	; 27/02/2015
  4062 00001E45 9C                  <1> 	pushfd	; 24/12/2021		; SAVE FLAGS
  4063                              <1> 	;mov	ecx, 3			; 30 TO 45 MICROSECONDS WAIT FOR
  4064 00001E46 29C9                <1> 	sub	ecx, ecx
  4065 00001E48 B103                <1> 	mov	cl, 3 ; 24/12/2021
  4066 00001E4A E84AF6FFFF          <1> 	call 	WAITF			; NEC FLAGS UPDATE CYCLE
  4067 00001E4F 9D                  <1> 	popfd	; 24/12/2021		; RESTORE FLAGS FOR EXIT
  4068                              <1> 	;pop	ebx			; RESTORE REG
  4069 00001E50 C3                  <1> 	retn				; CY = 0 FROM TEST INSTRUCTION
  4070                              <1> 
  4071                              <1> ;-------------------------------------------------------------------------------
  4072                              <1> ; SEEK
  4073                              <1> ;	THIS ROUTINE WILL MOVE THE HEAD ON THE NAMED DRIVE TO THE NAMED
  4074                              <1> ;	TRACK. IF THE DRIVE HAS NOT BEEN ACCESSED SINCE THE DRIVE
  4075                              <1> ;	RESET COMMAND WAS ISSUED, THE DRIVE WILL BE RECALIBRATED.
  4076                              <1> ;
  4077                              <1> ; ON ENTRY:	EDI = DRIVE #
  4078                              <1> ;		CH = TRACK #
  4079                              <1> ;
  4080                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION.
  4081                              <1> ;		EAX, EBX, ECX, EDX DESTROYED
  4082                              <1> ;-------------------------------------------------------------------------------
  4083                              <1> SEEK:
  4084                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4085 00001E51 89FB                <1> 	mov	ebx, edi		; EBX = DRIVE #
  4086 00001E53 B001                <1> 	mov	al, 1			; ESTABLISH MASK FOR RECALIBRATE TEST
  4087 00001E55 86CB                <1> 	xchg	cl, bl			; SET DRIVE VALUE INTO CL
  4088 00001E57 D2C0                <1> 	rol	al, cl			; SHIFT MASK BY THE DRIVE VALUE
  4089 00001E59 86CB                <1> 	xchg	cl, bl			; RECOVER DRIVE VALUE
  4090 00001E5B 8405[99620000]      <1> 	test	al, [SEEK_STATUS]	; TEST FOR RECALIBRATE REQUIRED
  4091 00001E61 7526                <1> 	jnz	short J28A		; JUMP IF RECALIBRATE NOT REQUIRED
  4092                              <1> 
  4093 00001E63 0805[99620000]      <1> 	or	[SEEK_STATUS], al	; TURN ON THE NO RECALIBRATE BIT IN FLAG
  4094 00001E69 E862000000          <1> 	call	RECAL			; RECALIBRATE DRIVE
  4095 00001E6E 730E                <1> 	jnc	short AFT_RECAL		; RECALIBRATE DONE
  4096                              <1> 
  4097                              <1> ;-----	ISSUE RECALIBRATE FOR 80 TRACK DISKETTES
  4098                              <1> 
  4099 00001E70 C605[9C620000]00    <1> 	mov	byte [DSKETTE_STATUS], 0 ; CLEAR OUT INVALID STATUS
  4100 00001E77 E854000000          <1> 	call	RECAL			; RECALIBRATE DRIVE
  4101 00001E7C 7251                <1> 	jc	short RB		; IF RECALIBRATE FAILS TWICE THEN ERROR
  4102                              <1> 
  4103                              <1> AFT_RECAL:
  4104 00001E7E C687[A9620000]00    <1> 	mov	byte [DSK_TRK+edi], 0	; SAVE NEW CYLINDER AS PRESENT POSITION
  4105 00001E85 08ED                <1> 	or	ch, ch			; CHECK FOR SEEK TO TRACK 0
  4106 00001E87 743F                <1> 	jz	short DO_WAIT		; HEAD SETTLE, CY = 0 IF JUMP
  4107                              <1> 
  4108                              <1> ;-----	DRIVE IS IN SYNCHRONIZATION WITH CONTROLLER, SEEK TO TRACK
  4109                              <1> 
  4110 00001E89 F687[A7620000]20    <1> J28A:	test	byte [DSK_STATE+edi], DBL_STEP ; CHECK FOR DOUBLE STEP REQUIRED
  4111 00001E90 7402                <1> 	jz	short _R7		; SINGLE STEP REQUIRED BYPASS DOUBLE
  4112 00001E92 D0E5                <1> 	shl	ch, 1			; DOUBLE NUMBER OF STEP TO TAKE
  4113                              <1> 
  4114 00001E94 3AAF[A9620000]      <1> _R7:	cmp	ch, [DSK_TRK+edi]	; SEE IF ALREADY AT THE DESIRED TRACK
  4115 00001E9A 7433                <1> 	je	short RB		; IF YES, DO NOT NEED TO SEEK
  4116                              <1> 
  4117 00001E9C BA[CF1E0000]        <1> 	mov	edx, NEC_ERR		; LOAD RETURN ADDRESS
  4118 00001EA1 52                  <1> 	push	edx ; (*)		; ON STACK FOR NEC OUTPUT ERROR
  4119 00001EA2 88AF[A9620000]      <1> 	mov	[DSK_TRK+edi], ch	; SAVE NEW CYLINDER AS PRESENT POSITION
  4120 00001EA8 B40F                <1> 	mov	ah, 0Fh			; SEEK COMMAND TO NEC
  4121 00001EAA E869FFFFFF          <1> 	call	NEC_OUTPUT
  4122 00001EAF 89FB                <1> 	mov	ebx, edi		; EBX = DRIVE #
  4123 00001EB1 88DC                <1> 	mov	ah, bl			; OUTPUT DRIVE NUMBER
  4124 00001EB3 E860FFFFFF          <1> 	call	NEC_OUTPUT
  4125 00001EB8 8AA7[A9620000]      <1> 	mov	ah, [DSK_TRK+edi]	; GET CYLINDER NUMBER
  4126 00001EBE E855FFFFFF          <1> 	call	NEC_OUTPUT
  4127 00001EC3 E827000000          <1> 	call	CHK_STAT_2		; ENDING INTERRUPT AND SENSE STATUS
  4128                              <1> 
  4129                              <1> ;-----	WAIT FOR HEAD SETTLE
  4130                              <1> 
  4131                              <1> DO_WAIT:
  4132 00001EC8 9C                  <1> 	pushfd	; 24/12/2021		; SAVE STATUS
  4133 00001EC9 E818FFFFFF          <1> 	call	HD_WAIT			; WAIT FOR HEAD SETTLE TIME
  4134 00001ECE 9D                  <1> 	popfd	; 24/12/2021		; RESTORE STATUS
  4135                              <1> RB:
  4136                              <1> NEC_ERR:
  4137                              <1> 	; 08/02/2015 (code trick here from original IBM PC/AT DISKETTE.ASM)
  4138                              <1> 	; (*) nec_err -> retn (push edx -> pop edx) -> nec_err -> retn
  4139 00001ECF C3                  <1> 	retn				; RETURN TO CALLER
  4140                              <1> 
  4141                              <1> ;-------------------------------------------------------------------------------
  4142                              <1> ; RECAL
  4143                              <1> ;	RECALIBRATE DRIVE
  4144                              <1> ;
  4145                              <1> ; ON ENTRY:	EDI = DRIVE #
  4146                              <1> ;
  4147                              <1> ; ON EXIT:	CY REFLECTS STATUS OF OPERATION.
  4148                              <1> ;-------------------------------------------------------------------------------
  4149                              <1> RECAL:
  4150                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4151                              <1> 	;push	cx
  4152                              <1> 	; 24/12/2021
  4153 00001ED0 51                  <1> 	push	ecx
  4154 00001ED1 B8[ED1E0000]        <1> 	mov	eax, RC_BACK		; LOAD NEC_OUTPUT ERROR
  4155 00001ED6 50                  <1> 	push	eax
  4156 00001ED7 B407                <1> 	mov	ah, 07h			; RECALIBRATE COMMAND
  4157 00001ED9 E83AFFFFFF          <1> 	call	NEC_OUTPUT
  4158 00001EDE 89FB                <1> 	mov	ebx, edi		; EBX = DRIVE #
  4159 00001EE0 88DC                <1> 	mov	ah, bl
  4160 00001EE2 E831FFFFFF          <1> 	call	NEC_OUTPUT		; OUTPUT THE DRIVE NUMBER
  4161 00001EE7 E803000000          <1> 	call	CHK_STAT_2		; GET THE INTERRUPT AND SENSE INT STATUS
  4162 00001EEC 58                  <1> 	pop	eax			; THROW AWAY ERROR
  4163                              <1> RC_BACK:
  4164                              <1> 	;pop	cx
  4165                              <1> 	; 24/12/2021
  4166 00001EED 59                  <1> 	pop	ecx
  4167 00001EEE C3                  <1> 	RETn
  4168                              <1> 
  4169                              <1> ;-------------------------------------------------------------------------------
  4170                              <1> ; CHK_STAT_2
  4171                              <1> ;	THIS ROUTINE HANDLES THE INTERRUPT RECEIVED AFTER RECALIBRATE,
  4172                              <1> ;	OR SEEK TO THE ADAPTER. THE INTERRUPT IS WAITED FOR, THE
  4173                              <1> ;	INTERRUPT STATUS SENSED, AND THE RESULT RETURNED TO THE CALLER.
  4174                              <1> ;
  4175                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION.
  4176                              <1> ;-------------------------------------------------------------------------------
  4177                              <1> CHK_STAT_2:
  4178                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4179 00001EEF B8[171F0000]        <1>         mov	eax, CS_BACK		; LOAD NEC_OUTPUT ERROR ADDRESS
  4180 00001EF4 50                  <1> 	push	eax
  4181 00001EF5 E828000000          <1> 	call	WAIT_INT		; WAIT FOR THE INTERRUPT
  4182 00001EFA 721A                <1> 	jc	short J34		; IF ERROR, RETURN IT
  4183 00001EFC B408                <1> 	mov	ah, 08h			; SENSE INTERRUPT STATUS COMMAND
  4184 00001EFE E815FFFFFF          <1> 	call	NEC_OUTPUT
  4185 00001F03 E849000000          <1> 	call	RESULTS			; READ IN THE RESULTS
  4186 00001F08 720C                <1> 	jc	short J34
  4187 00001F0A A0[9D620000]        <1> 	mov	al, [NEC_STATUS]	; GET THE FIRST STATUS BYTE
  4188 00001F0F 2460                <1> 	and	al, 01100000b		; ISOLATE THE BITS
  4189 00001F11 3C60                <1> 	cmp	al, 01100000b		; TEST FOR CORRECT VALUE
  4190 00001F13 7403                <1> 	jz	short J35		; IF ERROR, GO MARK IT
  4191 00001F15 F8                  <1> 	clc				; GOOD RETURN
  4192                              <1> J34:
  4193 00001F16 58                  <1> 	pop	eax			; THROW AWAY ERROR RETURN
  4194                              <1> CS_BACK:
  4195 00001F17 C3                  <1> 	retn
  4196                              <1> J35:
  4197 00001F18 800D[9C620000]40    <1> 	or	byte [DSKETTE_STATUS], BAD_SEEK
  4198 00001F1F F9                  <1> 	stc				; ERROR RETURN CODE
  4199 00001F20 EBF4                <1> 	jmp	short J34
  4200                              <1> 
  4201                              <1> ;-------------------------------------------------------------------------------
  4202                              <1> ; WAIT_INT
  4203                              <1> ;	THIS ROUTINE WAITS FOR AN INTERRUPT TO OCCUR A TIME OUT ROUTINE
  4204                              <1> ;	TAKES PLACE DURING THE WAIT, SO THAT AN ERROR MAY BE RETURNED
  4205                              <1> ;	IF THE DRIVE IS NOT READY.
  4206                              <1> ;
  4207                              <1> ; ON EXIT: 	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION.
  4208                              <1> ;-------------------------------------------------------------------------------
  4209                              <1> 
  4210                              <1> ; 17/12/2014
  4211                              <1> ; 2.5 seconds waiting !
  4212                              <1> ;(AWARD BIOS - 1999, WAIT_FDU_INT_LOW, WAIT_FDU_INT_HI)
  4213                              <1> ; amount of time to wait for completion interrupt from NEC.
  4214                              <1> 
  4215                              <1> WAIT_INT:
  4216                              <1> 	; 12/07/2022
  4217                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4218 00001F22 FB                  <1> 	sti				; TURN ON INTERRUPTS, JUST IN CASE
  4219                              <1> 	; 12/07/2022
  4220                              <1> 	;clc				; CLEAR TIMEOUT INDICATOR
  4221                              <1>        ;mov	bl, 10			; CLEAR THE COUNTERS
  4222                              <1>        ;xor	cx, cx			; FOR 2 SECOND WAIT
  4223                              <1> 
  4224                              <1> 	; Modification from AWARD BIOS - 1999 (ATORGS.ASM, WAIT
  4225                              <1> 	;
  4226                              <1> 	;WAIT_FOR_MEM:	
  4227                              <1> 	;	Waits for a bit at a specified memory location pointed
  4228                              <1> 	;	to by ES:[DI] to become set.
  4229                              <1> 	;INPUT:
  4230                              <1> 	;	AH=Mask to test with.
  4231                              <1> 	;	ES:[DI] = memory location to watch.
  4232                              <1> 	;	BH:CX=Number of memory refresh periods to delay.
  4233                              <1> 	;	     (normally 30 microseconds per period.)
  4234                              <1> 
  4235                              <1> 	; waiting for (max.) 2.5 secs in 30 micro units.
  4236                              <1> ;	mov 	cx, WAIT_FDU_INT_LO		; 017798
  4237                              <1> ;;	mov 	bl, WAIT_FDU_INT_HI
  4238                              <1> ;	mov 	bl, WAIT_FDU_INT_HI + 1
  4239                              <1> 	; 27/02/2015
  4240 00001F23 B986450100          <1> 	mov 	ecx, WAIT_FDU_INT_LH	; 83334 (2.5 seconds)		
  4241                              <1> WFMS_CHECK_MEM:
  4242 00001F28 F605[99620000]80    <1> 	test	byte [SEEK_STATUS], INT_FLAG ; TEST FOR INTERRUPT OCCURRING
  4243 00001F2F 7516                <1>         jnz     short J37
  4244                              <1> WFMS_HI:
  4245 00001F31 E461                <1> 	in	al, PORT_B  ; 061h	; SYS1, wait for lo to hi
  4246 00001F33 A810                <1> 	test	al, 010h		; transition on memory
  4247 00001F35 75FA                <1> 	jnz	short WFMS_HI		; refresh.
  4248                              <1> WFMS_LO:
  4249 00001F37 E461                <1> 	in	al, PORT_B		; SYS1
  4250 00001F39 A810                <1> 	test	al, 010h
  4251 00001F3B 74FA                <1> 	jz	short WFMS_LO
  4252 00001F3D E2E9                <1>         loop	WFMS_CHECK_MEM
  4253                              <1> ;WFMS_OUTER_LP:
  4254                              <1> ;;	or	bl, bl			; check outer counter
  4255                              <1> ;;	jz	short J36A		; WFMS_TIMEOUT
  4256                              <1> ;	dec	bl
  4257                              <1> ;	jz	short J36A	
  4258                              <1> ;	jmp	short WFMS_CHECK_MEM
  4259                              <1> 
  4260                              <1> 	;17/12/2014
  4261                              <1> 	;16/12/2014
  4262                              <1> ;	mov     byte [wait_count], 0    ; Reset (INT 08H) counter
  4263                              <1> ;J36:
  4264                              <1> ;	test	byte [SEEK_STATUS], INT_FLAG ; TEST FOR INTERRUPT OCCURRING
  4265                              <1> ;	jnz	short J37
  4266                              <1> 	;16/12/2014
  4267                              <1> 	;loop	J36			; COUNT DOWN WHILE WAITING
  4268                              <1> 	;dec	bl			; SECOND LEVEL COUNTER
  4269                              <1> 	;jnz	short J36
  4270                              <1> ;       cmp     byte [wait_count], 46   ; (46/18.2 seconds)
  4271                              <1> ;	jb	short J36
  4272                              <1> 
  4273                              <1> ;WFMS_TIMEOUT:
  4274                              <1> ;J36A:
  4275 00001F3F 800D[9C620000]80    <1> 	or	byte [DSKETTE_STATUS], TIME_OUT ; NOTHING HAPPENED
  4276 00001F46 F9                  <1> 	stc				; ERROR RETURN
  4277                              <1> J37:
  4278 00001F47 9C                  <1> 	pushf				; SAVE CURRENT CARRY
  4279 00001F48 8025[99620000]7F    <1> 	and	byte [SEEK_STATUS], ~INT_FLAG ; TURN OFF INTERRUPT FLAG
  4280 00001F4F 9D                  <1> 	popf				; RECOVER CARRY
  4281 00001F50 C3                  <1> 	retn				; GOOD RETURN CODE
  4282                              <1> 
  4283                              <1> ;-------------------------------------------------------------------------------
  4284                              <1> ; RESULTS
  4285                              <1> ;	THIS ROUTINE WILL READ ANYTHING THAT THE NEC CONTROLLER RETURNS 
  4286                              <1> ;	FOLLOWING AN INTERRUPT.
  4287                              <1> ;
  4288                              <1> ; ON EXIT:	@DSKETTE_STATUS, CY REFLECT STATUS OF OPERATION.
  4289                              <1> ;		EAX, EBX, ECX, EDX DESTROYED
  4290                              <1> ;-------------------------------------------------------------------------------
  4291                              <1> RESULTS:
  4292                              <1> 	; 12/07/2022
  4293                              <1> 	; 11/07/2022
  4294                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4295 00001F51 57                  <1> 	push	edi
  4296 00001F52 BF[9D620000]        <1> 	mov	edi, NEC_STATUS		; POINTER TO DATA AREA
  4297 00001F57 B307                <1> 	mov	bl, 7			; MAX STATUS BYTES
  4298 00001F59 66BAF403            <1> 	mov	dx, 03F4h		; STATUS PORT
  4299                              <1> 
  4300                              <1> ;-----	WAIT FOR REQUEST FOR MASTER
  4301                              <1> 
  4302                              <1> _R10: 
  4303                              <1> 	; 16/12/2014
  4304                              <1> 	; wait for (max) 0.5 seconds
  4305                              <1> 	;mov	bh, 2			; HIGH ORDER COUNTER
  4306                              <1> 	;xor	cx, cx			; COUNTER
  4307                              <1> 
  4308                              <1> 	;Time to wait while waiting for each byte of NEC results = .5
  4309                              <1> 	;seconds.  .5 seconds = 500,000 micros.  500,000/30 = 16,667.
  4310                              <1> 	; 27/02/2015
  4311                              <1> 
  4312 00001F5D B91B410000          <1> 	mov 	ecx, WAIT_FDU_RESULTS_LH ; 16667  
  4313                              <1> 	;mov	cx, WAIT_FDU_RESULTS_LO  ; 16667
  4314                              <1> 	;mov	bh, WAIT_FDU_RESULTS_HI+1 ; 0+1
  4315                              <1> 
  4316                              <1> WFPSR_OUTER_LP:
  4317                              <1> 	;
  4318                              <1> WFPSR_CHECK_PORT:
  4319                              <1> J39:					; WAIT FOR MASTER
  4320 00001F62 EC                  <1> 	in	al, dx			; GET STATUS
  4321 00001F63 24C0                <1> 	and	al, 11000000b		; KEEP ONLY STATUS AND DIRECTION
  4322 00001F65 3CC0                <1> 	cmp	al, 11000000b		; STATUS 1 AND DIRECTION 1 ?
  4323 00001F67 7418                <1> 	jz	short J42		; STATUS AND DIRECTION OK
  4324                              <1> WFPSR_HI:
  4325 00001F69 E461                <1> 	in	al, PORT_B	;061h	; SYS1	; wait for hi to lo
  4326 00001F6B A810                <1> 	test	al, 010h		; transition on memory
  4327 00001F6D 75FA                <1> 	jnz	short WFPSR_HI		; refresh.
  4328                              <1> WFPSR_LO:
  4329 00001F6F E461                <1> 	in	al, PORT_B		; SYS1
  4330 00001F71 A810                <1> 	test	al, 010h
  4331 00001F73 74FA                <1> 	jz	short WFPSR_LO
  4332 00001F75 E2EB                <1>         loop	WFPSR_CHECK_PORT
  4333                              <1> 	
  4334                              <1> 	;; 27/02/2015
  4335                              <1> 	;;dec	bh
  4336                              <1> 	;;jnz	short WFPSR_OUTER_LP
  4337                              <1> 	;jmp	short WFPSR_TIMEOUT	; fail
  4338                              <1> 
  4339                              <1> 	;;mov	byte [wait_count], 0
  4340                              <1> ;J39:					; WAIT FOR MASTER
  4341                              <1> ;	in	al, dx			; GET STATUS
  4342                              <1> ;	and	al, 11000000b		; KEEP ONLY STATUS AND DIRECTION
  4343                              <1> ;	cmp	al, 11000000b		; STATUS 1 AND DIRECTION 1 ?
  4344                              <1> ;	jz	short J42		; STATUS AND DIRECTION OK
  4345                              <1> 	;loop	J39			; LOOP TILL TIMEOUT
  4346                              <1> 	;dec	bh			; DECREMENT HIGH ORDER COUNTER
  4347                              <1> 	;jnz	short J39		; REPEAT TILL DELAY DONE
  4348                              <1> 	;
  4349                              <1> 	;;cmp	byte [wait_count], 10	; (10/18.2 seconds)
  4350                              <1> 	;;jb	short J39	
  4351                              <1> 
  4352                              <1> ;WFPSR_TIMEOUT:
  4353 00001F77 800D[9C620000]80    <1> 	or	byte [DSKETTE_STATUS], TIME_OUT
  4354 00001F7E F9                  <1> 	stc				; SET ERROR RETURN
  4355 00001F7F EB26                <1> 	jmp	short POPRES		; POP REGISTERS AND RETURN
  4356                              <1> 
  4357                              <1> ;-----	READ IN THE STATUS
  4358                              <1> 
  4359                              <1> J42:
  4360 00001F81 EB00                <1> 	JMP	$+2			; I/O DELAY
  4361                              <1> 	;inc	dx			; POINT AT DATA PORT
  4362 00001F83 FEC2                <1> 	inc	dl
  4363 00001F85 EC                  <1> 	in	al, dx			; GET THE DATA
  4364                              <1> 	; 16/12/2014
  4365                              <1> 	NEWIODELAY
  2193 00001F86 E6EB                <2>  out 0EBh,al
  4366                              <1> 	
  4367                              <1> 	;mov	[edi], al		; STORE THE BYTE
  4368                              <1> 	;inc	edi			; INCREMENT THE POINTER
  4369                              <1> 	; 11/07/2022
  4370 00001F88 AA                  <1> 	stosb
  4371                              <1> 
  4372                              <1> 	; 16/12/2014
  4373                              <1> ;	push	cx
  4374                              <1> ;	mov	cx, 30
  4375                              <1> ;wdw2:
  4376                              <1> ;	NEWIODELAY
  4377                              <1> ;	loop	wdw2
  4378                              <1> ;	pop	cx
  4379                              <1> 
  4380                              <1> 	;mov	ecx,3			; MINIMUM 24 MICROSECONDS FOR NEC
  4381                              <1> 	; 12/07/2022
  4382 00001F89 29C9                <1> 	sub	ecx, ecx
  4383 00001F8B B103                <1> 	mov	cl, 3
  4384 00001F8D E807F5FFFF          <1> 	call	WAITF			; WAIT 30 TO 45 MICROSECONDS
  4385                              <1> 	;dec	dx			; POINT AT STATUS PORT
  4386 00001F92 FECA                <1> 	dec	dl
  4387 00001F94 EC                  <1> 	in	al, dx			; GET STATUS
  4388                              <1> 	; 16/12/2014
  4389                              <1> 	NEWIODELAY
  2193 00001F95 E6EB                <2>  out 0EBh,al
  4390                              <1> 	;
  4391 00001F97 A810                <1> 	test	al, 00010000b		; TEST FOR NEC STILL BUSY
  4392 00001F99 740C                <1> 	jz	short POPRES		; RESULTS DONE ?
  4393                              <1> 
  4394 00001F9B FECB                <1> 	dec	bl			; DECREMENT THE STATUS COUNTER
  4395 00001F9D 75BE                <1>         jnz	short _R10              ; GO BACK FOR MORE
  4396 00001F9F 800D[9C620000]20    <1> 	or	byte [DSKETTE_STATUS], BAD_NEC ; TOO MANY STATUS BYTES
  4397 00001FA6 F9                  <1> 	stc				; SET ERROR FLAG
  4398                              <1> 
  4399                              <1> ;-----	RESULT OPERATION IS DONE
  4400                              <1> POPRES:
  4401 00001FA7 5F                  <1> 	pop	edi
  4402 00001FA8 C3                  <1> 	retn				; RETURN WITH CARRY SET
  4403                              <1> 
  4404                              <1> ;-------------------------------------------------------------------------------
  4405                              <1> ; READ_DSKCHNG
  4406                              <1> ;	READS THE STATE OF THE DISK CHANGE LINE.
  4407                              <1> ;
  4408                              <1> ; ON ENTRY:	EDI = DRIVE #
  4409                              <1> ;
  4410                              <1> ; ON EXIT:	EDI = DRIVE #
  4411                              <1> ;		ZF = 0 : DISK CHANGE LINE INACTIVE
  4412                              <1> ;		ZF = 1 : DISK CHANGE LINE ACTIVE
  4413                              <1> ;		EAX, ECX, EDX DESTROYED
  4414                              <1> ;-------------------------------------------------------------------------------
  4415                              <1> READ_DSKCHNG:
  4416                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4417 00001FA9 E8B4FDFFFF          <1> 	call	MOTOR_ON		; TURN ON THE MOTOR IF OFF
  4418 00001FAE 66BAF703            <1> 	mov	dx, 03F7h		; ADDRESS DIGITAL INPUT REGISTER
  4419 00001FB2 EC                  <1> 	in	al, dx			; INPUT DIGITAL INPUT REGISTER
  4420 00001FB3 A880                <1> 	test	al, DSK_CHG		; CHECK FOR DISK CHANGE LINE ACTIVE
  4421 00001FB5 C3                  <1> 	retn				; RETURN TO CALLER WITH ZERO FLAG SET
  4422                              <1> 
  4423                              <1> fdc_int:  
  4424                              <1> 	  ; 30/07/2015	
  4425                              <1> 	  ; 16/02/2015
  4426                              <1> ;int_0Eh: ; 11/12/2014
  4427                              <1> 
  4428                              <1> ;--- HARDWARE INT 0EH -- ( IRQ LEVEL  6 ) --------------------------------------
  4429                              <1> ; DISK_INT
  4430                              <1> ;	THIS ROUTINE HANDLES THE DISKETTE INTERRUPT.
  4431                              <1> ;
  4432                              <1> ; ON EXIT:	THE INTERRUPT FLAG IS SET IN @SEEK_STATUS.
  4433                              <1> ;-------------------------------------------------------------------------------
  4434                              <1> DISK_INT_1:
  4435                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4436                              <1> 	;push	eax			; SAVE WORK REGISTER
  4437                              <1> 	; 24/12/2021
  4438 00001FB6 50                  <1> 	push	eax
  4439 00001FB7 1E                  <1> 	push	ds
  4440 00001FB8 66B81000            <1> 	mov	ax, KDATA
  4441 00001FBC 8ED8                <1> 	mov 	ds, ax
  4442 00001FBE 800D[99620000]80    <1>         or	byte [SEEK_STATUS], INT_FLAG ; TURN ON INTERRUPT OCCURRED
  4443 00001FC5 B020                <1> 	mov	al, EOI			; END OF INTERRUPT MARKER
  4444 00001FC7 E620                <1> 	out	INTA00, al		; INTERRUPT CONTROL PORT
  4445 00001FC9 1F                  <1> 	pop	ds
  4446                              <1> 	;pop	ax			; RECOVER REGISTER
  4447                              <1> 	; 24/12/2021
  4448 00001FCA 58                  <1> 	pop	eax
  4449 00001FCB CF                  <1> 	iretd				; RETURN FROM INTERRUPT
  4450                              <1> 
  4451                              <1> ;-------------------------------------------------------------------------------
  4452                              <1> ; DSKETTE_SETUP
  4453                              <1> ;	THIS ROUTINE DOES A PRELIMINARY CHECK TO SEE WHAT TYPE OF
  4454                              <1> ;	DISKETTE DRIVES ARE ATTACH TO THE SYSTEM.
  4455                              <1> ;-------------------------------------------------------------------------------
  4456                              <1> DSKETTE_SETUP:
  4457                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4458                              <1> 	;push	eax			; SAVE REGISTERS
  4459                              <1> 	;push	ebx
  4460                              <1> 	;push	ecx
  4461 00001FCC 52                  <1> 	push	edx
  4462                              <1> 	;push	edi
  4463                              <1> 	; 14/12/2014
  4464                              <1> 	;mov	dword [DISK_POINTER], MD_TBL6
  4465                              <1> 	;
  4466                              <1> 	;or	byte [RTC_WAIT_FLAG], 1	; NO RTC WAIT, FORCE USE OF LOOP
  4467                              <1> 
  4468 00001FCD 31FF                <1> 	xor	edi, edi 		; INITIALIZE DRIVE POINTER
  4469 00001FCF 29C9                <1> 	sub	ecx, ecx
  4470 00001FD1 66890D[A7620000]    <1> 	mov	[DSK_STATE], cx ; 0	; INITIALIZE STATES
  4471                              <1> 	; 08/07/2022
  4472                              <1> 	;and	byte [LASTRATE], ~(STRT_MSK+SEND_MSK) ; CLEAR START & SEND
  4473 00001FD8 800D[A4620000]C0    <1> 	or	byte [LASTRATE], SEND_MSK ; INITIALIZE SENT TO IMPOSSIBLE
  4474 00001FDF 880D[99620000]      <1> 	mov	[SEEK_STATUS], cl ; 0	; INDICATE RECALIBRATE NEEDED
  4475 00001FE5 880D[9B620000]      <1> 	mov	[MOTOR_COUNT], cl ; 0	; INITIALIZE MOTOR COUNT
  4476 00001FEB 880D[9A620000]      <1> 	mov	[MOTOR_STATUS], cl ; 0	; INITIALIZE DRIVES TO OFF STATE
  4477 00001FF1 880D[9C620000]      <1> 	mov	[DSKETTE_STATUS], cl ; 0 ; NO ERRORS
  4478                              <1> 	;
  4479                              <1> 	; 28/02/2015
  4480                              <1> 	;mov	word [cfd], 100h 
  4481 00001FF7 E894F8FFFF          <1> 	call	DSK_RESET
  4482 00001FFC 5A                  <1> 	pop	edx
  4483 00001FFD C3                  <1> 	retn
  4484                              <1> 
  4485                              <1> ;//////////////////////////////////////////////////////
  4486                              <1> ;; END OF DISKETTE I/O ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  4487                              <1> ;
  4488                              <1> 
  4489                              <1> ; 12/07/2022
  4490                              <1> ;int13h: ; 21/02/2015
  4491                              <1> ;	pushfd
  4492                              <1> ;	push 	cs
  4493                              <1> ;	call 	DISK_IO
  4494                              <1> ;	retn
  4495                              <1> 
  4496                              <1> ;;;;;; DISK I/O ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 21/02/2015 ;;;
  4497                              <1> ;/////////////////////////////////////////////////////////////////////
  4498                              <1> 
  4499                              <1> ; 11/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4500                              <1> ; ((Direct call instead of int 13h simulation))
  4501                              <1> ;
  4502                              <1> ;		Function in AL
  4503                              <1> ;			0 = reset
  4504                              <1> ;			1 = read
  4505                              <1> ;			2 = write
  4506                              <1> ;		Disk drive number in DL
  4507                              <1> ;			0 & 1 = floppy disks	
  4508                              <1> ;			80h .. 83h = hard disks
  4509                              <1> ;		Sector address (LBA) in ECX
  4510                              <1> ;		Buffer address in EBX
  4511                              <1> ;		R/W sector count is (always) 1
  4512                              <1> ;
  4513                              <1> ;		Return:
  4514                              <1> ;			Status in AH (>0 = error code)
  4515                              <1> ;			if CF = 1 -> error code in AH
  4516                              <1> ;			if CF = 0 -> successful
  4517                              <1> ;			AL = undefined
  4518                              <1> ;
  4519                              <1> ;		Modified registers: (only) EAX
  4520                              <1> 
  4521                              <1> ; 10/07/2022
  4522                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4523                              <1> 
  4524                              <1> ; DISK I/O - Erdogan Tan (Retro UNIX 386 v1 project)
  4525                              <1> ; 23/02/2015
  4526                              <1> ; 21/02/2015 (unix386.s)
  4527                              <1> ; 22/12/2014 - 14/02/2015 (dsectrm2.s)
  4528                              <1> ;
  4529                              <1> ; Original Source Code:
  4530                              <1> ; DISK ----- 09/25/85 FIXED DISK BIOS
  4531                              <1> ; (IBM PC XT Model 286 System BIOS Source Code, 04-21-86)
  4532                              <1> ;
  4533                              <1> ; Modifications: by reference of AWARD BIOS 1999 (D1A0622) 
  4534                              <1> ;		 Source Code - ATORGS.ASM, AHDSK.ASM
  4535                              <1> ;
  4536                              <1> 
  4537                              <1> ;The wait for controller to be not busy is 10 seconds.
  4538                              <1> ;10,000,000 / 30 = 333,333.  333,333 decimal = 051615h
  4539                              <1> ;;WAIT_HDU_CTLR_BUSY_LO	equ	1615h		
  4540                              <1> ;;WAIT_HDU_CTLR_BUSY_HI	equ	  05h
  4541                              <1> WAIT_HDU_CTRL_BUSY_LH	equ	51615h	 ;21/02/2015		
  4542                              <1> 
  4543                              <1> ;The wait for controller to issue completion interrupt is 10 seconds.
  4544                              <1> ;10,000,000 / 30 = 333,333.  333,333 decimal = 051615h
  4545                              <1> ;;WAIT_HDU_INT_LO	equ	1615h
  4546                              <1> ;;WAIT_HDU_INT_HI	equ	  05h
  4547                              <1> WAIT_HDU_INT_LH		equ	51615h	; 21/02/2015
  4548                              <1> 
  4549                              <1> ;The wait for Data request on read and write longs is
  4550                              <1> ;2000 us. (?)
  4551                              <1> ;;WAIT_HDU_DRQ_LO	equ	1000	; 03E8h
  4552                              <1> ;;WAIT_HDU_DRQ_HI	equ	0
  4553                              <1> WAIT_HDU_DRQ_LH		equ	1000	; 21/02/2015
  4554                              <1> 
  4555                              <1> ; Port 61h (PORT_B)
  4556                              <1> SYS1		equ	61h	; PORT_B  (diskette.inc)
  4557                              <1> 
  4558                              <1> ; 23/12/2014
  4559                              <1> %define CMD_BLOCK       ebp-8  ; 21/02/2015
  4560                              <1> 
  4561                              <1> 	; 11/07/2022
  4562                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4563                              <1> 
  4564                              <1> ;--- INT 13H -------------------------------------------------------------------
  4565                              <1> ;									       :
  4566                              <1> ; FIXED DISK I/O INTERFACE						       :
  4567                              <1> ;									       :
  4568                              <1> ;	THIS INTERFACE PROVIDES ACCESS TO 5 1/4" FIXED DISKS THROUGH           :
  4569                              <1> ;	THE IBM FIXED DISK CONTROLLER.					       :
  4570                              <1> ;									       :
  4571                              <1> ;	THE  BIOS  ROUTINES  ARE  MEANT  TO  BE  ACCESSED  THROUGH	       :
  4572                              <1> ;	SOFTWARE  INTERRUPTS  ONLY.    ANY  ADDRESSES  PRESENT	IN	       :
  4573                              <1> ;	THESE  LISTINGS  ARE  INCLUDED	 ONLY	FOR  COMPLETENESS,	       :
  4574                              <1> ;	NOT  FOR  REFERENCE.  APPLICATIONS   WHICH  REFERENCE  ANY	       :
  4575                              <1> ;	ABSOLUTE  ADDRESSES  WITHIN  THE  CODE	SEGMENTS  OF  BIOS	       :
  4576                              <1> ;	VIOLATE  THE  STRUCTURE  AND  DESIGN  OF  BIOS. 		       :
  4577                              <1> ;									       :
  4578                              <1> ;------------------------------------------------------------------------------:
  4579                              <1> ;									       :
  4580                              <1> ; INPUT  (AH)= HEX COMMAND VALUE					       :
  4581                              <1> ;									       :
  4582                              <1> ;	(AH)= 00H  RESET DISK (DL = 80H,81H) / DISKETTE 		       :
  4583                              <1> ;	(AH)= 01H  READ THE DESIRED SECTORS INTO MEMORY                        :
  4584                              <1> ;	(AH)= 02H  WRITE THE DESIRED SECTORS FROM MEMORY                       :
  4585                              <1> ;									       :
  4586                              <1> ;------------------------------------------------------------------------------:
  4587                              <1> ;									       :
  4588                              <1> ;	REGISTERS USED FOR FIXED DISK OPERATIONS			       :
  4589                              <1> ;									       :
  4590                              <1> ;		(DL)	-  DRIVE NUMBER     (80H-81H FOR DISK. VALUE CHECKED)  :
  4591                              <1> ;		(DH)	-  HEAD NUMBER	    (0-15 ALLOWED, NOT VALUE CHECKED)  :
  4592                              <1> ;		(CH)	-  CYLINDER NUMBER  (0-1023, NOT VALUE CHECKED)(SEE CL):
  4593                              <1> ;		(CL)	-  SECTOR NUMBER    (1-17, NOT VALUE CHECKED)	       :
  4594                              <1> ;									       :
  4595                              <1> ;			   NOTE: HIGH 2 BITS OF CYLINDER NUMBER ARE PLACED     :
  4596                              <1> ;				 IN THE HIGH 2 BITS OF THE CL REGISTER	       :
  4597                              <1> ;				 (10 BITS TOTAL)			       :
  4598                              <1> ;									       :
  4599                              <1> ;		(AL)	-  NUMBER OF SECTORS (MAXIMUM POSSIBLE RANGE 1-80H,    :
  4600                              <1> ;					      FOR READ/WRITE LONG 1-79H)       :
  4601                              <1> ;									       :
  4602                              <1> ;		(EBX)   -  ADDRESS OF BUFFER FOR READS AND WRITES,	       :
  4603                              <1> ;			   (NOT REQUIRED FOR VERIFY)			       :
  4604                              <1> ;									       :
  4605                              <1> ;------------------------------------------------------------------------------:
  4606                              <1> ; OUTPUT								       :
  4607                              <1> ;	AH = STATUS OF CURRENT OPERATION				       :
  4608                              <1> ;	     STATUS BITS ARE DEFINED IN THE EQUATES BELOW		       :
  4609                              <1> ;	CY = 0	SUCCESSFUL OPERATION (AH=0 ON RETURN)			       :
  4610                              <1> ;	CY = 1	FAILED OPERATION (AH HAS ERROR REASON)			       :
  4611                              <1> ;									       :
  4612                              <1> ;	NOTE:	ERROR 11H  INDICATES THAT THE DATA READ HAD A RECOVERABLE      :
  4613                              <1> ;		ERROR WHICH WAS CORRECTED BY THE ECC ALGORITHM.  THE DATA      :
  4614                              <1> ;		IS PROBABLY GOOD,   HOWEVER THE BIOS ROUTINE INDICATES AN      :
  4615                              <1> ;		ERROR TO ALLOW THE CONTROLLING PROGRAM A CHANCE TO DECIDE      :
  4616                              <1> ;		FOR ITSELF.  THE  ERROR  MAY  NOT  RECUR  IF  THE DATA IS      :
  4617                              <1> ;		REWRITTEN.						       :
  4618                              <1> ;									       :
  4619                              <1> ;	IF DRIVE PARAMETERS WERE REQUESTED (DL >= 80H), 		       :
  4620                              <1> ;	   INPUT:							       :
  4621                              <1> ;	     (DL) = DRIVE NUMBER					       :
  4622                              <1> ;	   OUTPUT:							       :
  4623                              <1> ;	     (DL) = NUMBER OF CONSECUTIVE ACKNOWLEDGING DRIVES ATTACHED (1-2)  :
  4624                              <1> ;		    (CONTROLLER CARD ZERO TALLY ONLY)			       :
  4625                              <1> ;	     (DH) = MAXIMUM USEABLE VALUE FOR HEAD NUMBER		       :
  4626                              <1> ;	     (CH) = MAXIMUM USEABLE VALUE FOR CYLINDER NUMBER		       :
  4627                              <1> ;	     (CL) = MAXIMUM USEABLE VALUE FOR SECTOR NUMBER		       :
  4628                              <1> ;		    AND CYLINDER NUMBER HIGH BITS			       :
  4629                              <1> ;									       :
  4630                              <1> ;	REGISTERS WILL BE PRESERVED EXCEPT WHEN THEY ARE USED TO RETURN        :
  4631                              <1> ;	INFORMATION.							       :
  4632                              <1> ;									       :
  4633                              <1> ;	NOTE: IF AN ERROR IS REPORTED BY THE DISK CODE, THE APPROPRIATE        :
  4634                              <1> ;		ACTION IS TO RESET THE DISK, THEN RETRY THE OPERATION.	       :
  4635                              <1> ;									       :
  4636                              <1> ;-------------------------------------------------------------------------------
  4637                              <1> 
  4638                              <1> SENSE_FAIL	EQU	0FFH		; NOT IMPLEMENTED
  4639                              <1> NO_ERR		EQU	0E0H		; STATUS ERROR/ERROR REGISTER=0
  4640                              <1> WRITE_FAULT	EQU	0CCH		; WRITE FAULT ON SELECTED DRIVE
  4641                              <1> UNDEF_ERR	EQU	0BBH		; UNDEFINED ERROR OCCURRED
  4642                              <1> NOT_RDY 	EQU	0AAH		; DRIVE NOT READY
  4643                              <1> TIME_OUT	EQU	80H		; ATTACHMENT FAILED TO RESPOND
  4644                              <1> BAD_SEEK	EQU	40H		; SEEK OPERATION FAILED
  4645                              <1> BAD_CNTLR	EQU	20H		; CONTROLLER HAS FAILED
  4646                              <1> DATA_CORRECTED	EQU	11H		; ECC CORRECTED DATA ERROR
  4647                              <1> BAD_ECC 	EQU	10H		; BAD ECC ON DISK READ
  4648                              <1> BAD_TRACK	EQU	0BH		; NOT IMPLEMENTED
  4649                              <1> BAD_SECTOR	EQU	0AH		; BAD SECTOR FLAG DETECTED
  4650                              <1> ;DMA_BOUNDARY	EQU	09H		; DATA EXTENDS TOO FAR
  4651                              <1> INIT_FAIL	EQU	07H		; DRIVE PARAMETER ACTIVITY FAILED
  4652                              <1> BAD_RESET	EQU	05H		; RESET FAILED
  4653                              <1> ;RECORD_NOT_FND	EQU	04H		; REQUESTED SECTOR NOT FOUND
  4654                              <1> ;BAD_ADDR_MARK	EQU	02H		; ADDRESS MARK NOT FOUND
  4655                              <1> ;BAD_CMD 	EQU	01H		; BAD COMMAND PASSED TO DISK I/O
  4656                              <1> 
  4657                              <1> ;--------------------------------------------------------
  4658                              <1> ;							:
  4659                              <1> ; FIXED DISK PARAMETER TABLE				:
  4660                              <1> ;  -  THE TABLE IS COMPOSED OF A BLOCK DEFINED AS:	:
  4661                              <1> ;							:
  4662                              <1> ;  +0	(1 WORD) - MAXIMUM NUMBER OF CYLINDERS		:
  4663                              <1> ;  +2	(1 BYTE) - MAXIMUM NUMBER OF HEADS		:
  4664                              <1> ;  +3	(1 WORD) - NOT USED/SEE PC-XT			:
  4665                              <1> ;  +5	(1 WORD) - STARTING WRITE PRECOMPENSATION CYL	:
  4666                              <1> ;  +7	(1 BYTE) - MAXIMUM ECC DATA BURST LENGTH	:
  4667                              <1> ;  +8	(1 BYTE) - CONTROL BYTE 			:
  4668                              <1> ;		   BIT	  7 DISABLE RETRIES -OR-	:
  4669                              <1> ;		   BIT	  6 DISABLE RETRIES		:
  4670                              <1> ;		   BIT	  3 MORE THAN 8 HEADS		:
  4671                              <1> ;  +9	(3 BYTES)- NOT USED/SEE PC-XT			:
  4672                              <1> ; +12	(1 WORD) - LANDING ZONE 			:
  4673                              <1> ; +14	(1 BYTE) - NUMBER OF SECTORS/TRACK		:
  4674                              <1> ; +15	(1 BYTE) - RESERVED FOR FUTURE USE		:
  4675                              <1> ;							:
  4676                              <1> ;	 - TO DYNAMICALLY DEFINE A SET OF PARAMETERS	:
  4677                              <1> ;	   BUILD A TABLE FOR UP TO 15 TYPES AND PLACE	:
  4678                              <1> ;	   THE CORRESPONDING VECTOR INTO INTERRUPT 41	:
  4679                              <1> ;	   FOR DRIVE 0 AND INTERRUPT 46 FOR DRIVE 1.	:
  4680                              <1> ;							:
  4681                              <1> ;--------------------------------------------------------
  4682                              <1> 
  4683                              <1> ;--------------------------------------------------------
  4684                              <1> ;							:
  4685                              <1> ; HARDWARE SPECIFIC VALUES				:
  4686                              <1> ;							:
  4687                              <1> ;  -  CONTROLLER I/O PORT				:
  4688                              <1> ;							:
  4689                              <1> ;     > WHEN READ FROM: 				:
  4690                              <1> ;	HF_PORT+0 - READ DATA (FROM CONTROLLER TO CPU)	:
  4691                              <1> ;	HF_PORT+1 - GET ERROR REGISTER			:
  4692                              <1> ;	HF_PORT+2 - GET SECTOR COUNT			:
  4693                              <1> ;	HF_PORT+3 - GET SECTOR NUMBER			:
  4694                              <1> ;	HF_PORT+4 - GET CYLINDER LOW			:
  4695                              <1> ;	HF_PORT+5 - GET CYLINDER HIGH (2 BITS)		:
  4696                              <1> ;	HF_PORT+6 - GET SIZE/DRIVE/HEAD 		:
  4697                              <1> ;	HF_PORT+7 - GET STATUS REGISTER 		:
  4698                              <1> ;							:
  4699                              <1> ;     > WHEN WRITTEN TO:				:
  4700                              <1> ;	HF_PORT+0 - WRITE DATA (FROM CPU TO CONTROLLER) :
  4701                              <1> ;	HF_PORT+1 - SET PRECOMPENSATION CYLINDER	:
  4702                              <1> ;	HF_PORT+2 - SET SECTOR COUNT			:
  4703                              <1> ;	HF_PORT+3 - SET SECTOR NUMBER			:
  4704                              <1> ;	HF_PORT+4 - SET CYLINDER LOW			:
  4705                              <1> ;	HF_PORT+5 - SET CYLINDER HIGH (2 BITS)		:
  4706                              <1> ;	HF_PORT+6 - SET SIZE/DRIVE/HEAD 		:
  4707                              <1> ;	HF_PORT+7 - SET COMMAND REGISTER		:
  4708                              <1> ;							:
  4709                              <1> ;--------------------------------------------------------
  4710                              <1> 
  4711                              <1> ;HF_PORT 	EQU	01F0H	; DISK PORT
  4712                              <1> ;HF1_PORT	equ	0170h	
  4713                              <1> ;HF_REG_PORT	EQU	03F6H
  4714                              <1> ;HF1_REG_PORT	equ	0376h
  4715                              <1> 
  4716                              <1> HDC1_BASEPORT	equ	1F0h
  4717                              <1> HDC2_BASEPORT	equ	170h		
  4718                              <1> 
  4719                              <1> align 2
  4720                              <1> 
  4721                              <1> ;-----		STATUS REGISTER
  4722                              <1> 
  4723                              <1> ST_ERROR	EQU	00000001B	;
  4724                              <1> ST_INDEX	EQU	00000010B	;
  4725                              <1> ST_CORRCTD	EQU	00000100B	; ECC CORRECTION SUCCESSFUL
  4726                              <1> ST_DRQ		EQU	00001000B	;
  4727                              <1> ST_SEEK_COMPL	EQU	00010000B	; SEEK COMPLETE
  4728                              <1> ST_WRT_FLT	EQU	00100000B	; WRITE FAULT
  4729                              <1> ST_READY	EQU	01000000B	;
  4730                              <1> ST_BUSY 	EQU	10000000B	;
  4731                              <1> 
  4732                              <1> ;-----		ERROR REGISTER
  4733                              <1> 
  4734                              <1> ERR_DAM 	EQU	00000001B	; DATA ADDRESS MARK NOT FOUND
  4735                              <1> ERR_TRK_0	EQU	00000010B	; TRACK 0 NOT FOUND ON RECAL
  4736                              <1> ERR_ABORT	EQU	00000100B	; ABORTED COMMAND
  4737                              <1> ;		EQU	00001000B	; NOT USED
  4738                              <1> ERR_ID		EQU	00010000B	; ID NOT FOUND
  4739                              <1> ;		EQU	00100000B	; NOT USED
  4740                              <1> ERR_DATA_ECC	EQU	01000000B
  4741                              <1> ERR_BAD_BLOCK	EQU	10000000B
  4742                              <1> 
  4743                              <1> 
  4744                              <1> RECAL_CMD	EQU	00010000B	; DRIVE RECAL	(10H)
  4745                              <1> READ_CMD	EQU	00100000B	;	READ	(20H)
  4746                              <1> WRITE_CMD	EQU	00110000B	;	WRITE	(30H)
  4747                              <1> VERIFY_CMD	EQU	01000000B	;	VERIFY	(40H)
  4748                              <1> FMTTRK_CMD	EQU	01010000B	; FORMAT TRACK	(50H)
  4749                              <1> INIT_CMD	EQU	01100000B	;   INITIALIZE	(60H)
  4750                              <1> SEEK_CMD	EQU	01110000B	;	SEEK	(70H)
  4751                              <1> DIAG_CMD	EQU	10010000B	; DIAGNOSTIC	(90H)
  4752                              <1> SET_PARM_CMD	EQU	10010001B	; DRIVE PARMS	(91H)
  4753                              <1> NO_RETRIES	EQU	00000001B	; CHD MODIFIER	(01H)
  4754                              <1> ECC_MODE	EQU	00000010B	; CMD MODIFIER	(02H)
  4755                              <1> BUFFER_MODE	EQU	00001000B	; CMD MODIFIER	(08H)
  4756                              <1> 
  4757                              <1> ;MAX_FILE	EQU	2
  4758                              <1> ;S_MAX_FILE	EQU	2
  4759                              <1> MAX_FILE	equ	4		; 22/12/2014
  4760                              <1> S_MAX_FILE	equ	4		; 22/12/2014
  4761                              <1> 
  4762                              <1> DELAY_1 	EQU	25H		; DELAY FOR OPERATION COMPLETE
  4763                              <1> DELAY_2 	EQU	0600H		; DELAY FOR READY
  4764                              <1> DELAY_3 	EQU	0100H		; DELAY FOR DATA REQUEST
  4765                              <1> 
  4766                              <1> HF_FAIL 	EQU	08H		; CMOS FLAG IN BYTE 0EH
  4767                              <1> 
  4768                              <1> ;-----		COMMAND BLOCK REFERENCE
  4769                              <1> 
  4770                              <1> ;CMD_BLOCK      EQU     BP-8            ; @CMD_BLOCK REFERENCES BLOCK HEAD IN SS
  4771                              <1> 					;  (BP) POINTS TO COMMAND BLOCK TAIL
  4772                              <1> 					;	AS DEFINED BY THE "ENTER" PARMS
  4773                              <1> ; 19/12/2014
  4774                              <1> ORG_VECTOR	equ	4*13h		; INT 13h vector
  4775                              <1> DISK_VECTOR	equ	4*40h		; INT 40h vector (for floppy disks)
  4776                              <1> ;HDISK_INT	equ	4*76h		; Primary HDC - Hardware interrupt (IRQ14)
  4777                              <1> ;HDISK_INT1	equ	4*76h		; Primary HDC - Hardware interrupt (IRQ14)
  4778                              <1> ;HDISK_INT2	equ	4*77h		; Secondary HDC - Hardware interrupt (IRQ15)
  4779                              <1> ;HF_TBL_VEC	equ	4*41h		; Pointer to 1st fixed disk parameter table
  4780                              <1> ;HF1_TBL_VEC	equ	4*46h		; Pointer to 2nd fixed disk parameter table
  4781                              <1> 
  4782                              <1> align 2
  4783                              <1> 
  4784                              <1> ;----------------------------------------------------------------
  4785                              <1> ; FIXED DISK I/O SETUP						:
  4786                              <1> ;								:
  4787                              <1> ;  -  ESTABLISH TRANSFER VECTORS FOR THE FIXED DISK		:
  4788                              <1> ;  -  PERFORM POWER ON DIAGNOSTICS				:
  4789                              <1> ;     SHOULD AN ERROR OCCUR A "1701" MESSAGE IS DISPLAYED       :
  4790                              <1> ;								:
  4791                              <1> ;----------------------------------------------------------------
  4792                              <1> 
  4793                              <1> 	; 12/07/2022
  4794                              <1> 	; 11/07/2022
  4795                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4796                              <1> 
  4797                              <1> DISK_SETUP:
  4798                              <1> 	;cli
  4799                              <1> 	;;mov	ax, ABS0 			; GET ABSOLUTE SEGMENT
  4800                              <1> 	;xor	ax, ax
  4801                              <1> 	;mov	ds, ax				; SET SEGMENT REGISTER
  4802                              <1> 	;mov	ax, [ORG_VECTOR] 		; GET DISKETTE VECTOR
  4803                              <1> 	;mov	[DISK_VECTOR], ax		; INTO INT 40H
  4804                              <1> 	;mov	ax, [ORG_VECTOR+2]
  4805                              <1> 	;mov	[DISK_VECTOR+2], ax
  4806                              <1> 	;mov	word [ORG_VECTOR], DISK_IO	; FIXED DISK HANDLER
  4807                              <1> 	;mov	[ORG_VECTOR+2], cs
  4808                              <1> 	; 1st controller (primary master, slave) - IRQ 14
  4809                              <1> 	;;mov	word [HDISK_INT], HD_INT	; FIXED DISK INTERRUPT
  4810                              <1> 	;mov	word [HDISK_INT1], HD_INT	;
  4811                              <1> 	;;mov	[HDISK_INT+2], cs
  4812                              <1> 	;mov	[HDISK_INT1+2], cs
  4813                              <1> 	; 2nd controller (secondary master, slave) - IRQ 15
  4814                              <1> 	;mov	word [HDISK_INT2], HD1_INT	;
  4815                              <1> 	;mov	[HDISK_INT2+2], cs
  4816                              <1> 	;
  4817                              <1> 	;;mov	word [HF_TBL_VEC], HD0_DPT	; PARM TABLE DRIVE 80
  4818                              <1> 	;;mov	word [HF_TBL_VEC+2], DPT_SEGM
  4819                              <1> 	;;mov	word [HF1_TBL_VEC], HD1_DPT	; PARM TABLE DRIVE 81
  4820                              <1> 	;;mov	word [HF1_TBL_VEC+2], DPT_SEGM
  4821                              <1> 	;push	cs
  4822                              <1> 	;pop	ds
  4823                              <1> 	;mov	word [HDPM_TBL_VEC],HD0_DPT	; PARM TABLE DRIVE 80h
  4824                              <1> 	;mov	word [HDPM_TBL_VEC+2],DPT_SEGM
  4825 00001FFE C705[B0620000]0000- <1> 	mov 	dword [HDPM_TBL_VEC], (DPT_SEGM*16)+HD0_DPT
  4825 00002006 0900                <1>
  4826                              <1> 	;mov	word [HDPS_TBL_VEC],HD1_DPT	; PARM TABLE DRIVE 81h
  4827                              <1> 	;mov	word [HDPS_TBL_VEC+2],DPT_SEGM
  4828 00002008 C705[B4620000]2000- <1> 	mov 	dword [HDPS_TBL_VEC], (DPT_SEGM*16)+HD1_DPT
  4828 00002010 0900                <1>
  4829                              <1> 	;mov	word [HDSM_TBL_VEC],HD2_DPT	; PARM TABLE DRIVE 82h
  4830                              <1> 	;mov	word [HDSM_TBL_VEC+2],DPT_SEGM
  4831 00002012 C705[B8620000]4000- <1> 	mov 	dword [HDSM_TBL_VEC], (DPT_SEGM*16)+HD2_DPT
  4831 0000201A 0900                <1>
  4832                              <1> 	;mov	word [HDSS_TBL_VEC],HD3_DPT	; PARM TABLE DRIVE 83h
  4833                              <1> 	;mov	word [HDSS_TBL_VEC+2],DPT_SEGM
  4834 0000201C C705[BC620000]6000- <1> 	mov 	dword [HDSS_TBL_VEC], (DPT_SEGM*16)+HD3_DPT
  4834 00002024 0900                <1>
  4835                              <1> 	;
  4836                              <1> 	;;in	al, INTB01		; TURN ON SECOND INTERRUPT CHIP
  4837                              <1> 	;;;and	al, 0BFh
  4838                              <1> 	;;and	al, 3Fh			; enable IRQ 14 and IRQ 15
  4839                              <1> 	;;;JMP	$+2
  4840                              <1> 	;;IODELAY
  4841                              <1> 	;;out	INTB01, al
  4842                              <1> 	;;IODELAY
  4843                              <1> 	;;in	al, INTA01		; LET INTERRUPTS PASS THRU TO
  4844                              <1> 	;;and	al, 0FBh 		; SECOND CHIP
  4845                              <1> 	;;;JMP	$+2
  4846                              <1> 	;;IODELAY
  4847                              <1> 	;;out	INTA01, al
  4848                              <1> 	;
  4849                              <1> 	;sti
  4850                              <1> 	;;push	ds			; MOVE ABS0 POINTER TO
  4851                              <1> 	;;pop	es			; EXTRA SEGMENT POINTER
  4852                              <1> 	;;;call	DDS			; ESTABLISH DATA SEGMENT
  4853                              <1> 	;;mov	byte [DISK_STATUS1],0 	; RESET THE STATUS INDICATOR
  4854                              <1> 	;;mov	byte [HF_NUM],0		; ZERO NUMBER OF FIXED DISKS
  4855                              <1> 	;;mov	byte [CONTROL_BYTE],0
  4856                              <1> 	;;mov	byte [PORT_OFF],0	; ZERO CARD OFFSET
  4857                              <1> 	; 20/12/2014 - private code by Erdogan Tan
  4858                              <1> 		      ; (out of original PC-AT, PC-XT BIOS code)
  4859                              <1> 	;mov	si, hd0_type
  4860 00002026 BE[3E5D0000]        <1> 	mov	esi, hd0_type
  4861                              <1> 	;;mov	cx, 4
  4862                              <1> 	;mov	ecx, 4
  4863                              <1> 	; 11/07/2022
  4864 0000202B 29C9                <1> 	sub	ecx, ecx
  4865 0000202D B104                <1> 	mov	cl, 4
  4866                              <1> hde_l:
  4867 0000202F AC                  <1> 	lodsb
  4868 00002030 3C80                <1> 	cmp	al, 80h			; 8?h = existing
  4869 00002032 7206                <1> 	jb	short _L4
  4870 00002034 FE05[AC620000]      <1> 	inc	byte [HF_NUM]		; + 1 hard (fixed) disk drives
  4871                              <1> _L4: ; 26/02/2015
  4872 0000203A E2F3                <1> 	loop	hde_l	
  4873                              <1> ;_L4:					; 0 <= [HF_NUM] =< 4
  4874                              <1> ;L4:
  4875                              <1> 	; 
  4876                              <1> 	;; 31/12/2014 - cancel controller diagnostics here
  4877                              <1> 	;;;mov 	cx, 3  ; 26/12/2014 (Award BIOS 1999)
  4878                              <1> 	;;mov 	cl, 3
  4879                              <1> 	;;
  4880                              <1> 	;;mov	dl, 80h			; CHECK THE CONTROLLER
  4881                              <1> ;;hdc_dl:
  4882                              <1> 	;;mov	ah, 14h			; USE CONTROLLER DIAGNOSTIC COMMAND
  4883                              <1> 	;;int	13h			; CALL BIOS WITH DIAGNOSTIC COMMAND
  4884                              <1> 	;;;jc	short CTL_ERRX		; DISPLAY ERROR MESSAGE IF BAD RETURN
  4885                              <1> 	;;;jc	short POD_DONE ;22/12/2014
  4886                              <1> 	;;jnc	short hdc_reset0
  4887                              <1> 	;;loop	hdc_dl
  4888                              <1> 	;;; 27/12/2014
  4889                              <1> 	;;stc
  4890                              <1> 	;;retn
  4891                              <1> 	;
  4892                              <1> ;;hdc_reset0:
  4893                              <1> 	; 18/01/2015
  4894 0000203C 8A0D[AC620000]      <1> 	mov	cl, [HF_NUM]
  4895 00002042 20C9                <1> 	and	cl, cl
  4896 00002044 740D                <1> 	jz	short POD_DONE
  4897                              <1> 	;
  4898 00002046 B27F                <1> 	mov	dl, 7Fh
  4899                              <1> hdc_reset1:
  4900 00002048 FEC2                <1> 	inc	dl
  4901                              <1> 	;; 31/12/2015
  4902                              <1> 	;;push	dx
  4903                              <1> 	;;push	cx
  4904                              <1> 	;;push	ds
  4905                              <1> 	;;sub	ax, ax
  4906                              <1> 	;;mov	ds, ax
  4907                              <1> 	;;mov	ax, [TIMER_LOW]		; GET START TIMER COUNTS
  4908                              <1> 	;;pop	ds
  4909                              <1> 	;;mov	bx, ax
  4910                              <1> 	;;add	ax, 6*182		; 60 SECONDS* 18.2
  4911                              <1> 	;;mov	cx, ax
  4912                              <1> 	;;mov	word [wait_count], 0	; 22/12/2014 (reset wait counter)
  4913                              <1> 	;;
  4914                              <1> 	;; 31/12/2014 - cancel HD_RESET_1
  4915                              <1> 	;;call	HD_RESET_1		; SET UP DRIVE 0, (1,2,3)
  4916                              <1> 	;;pop	cx
  4917                              <1> 	;;pop	dx
  4918                              <1> 	;;
  4919                              <1> 	; 18/01/2015
  4920                              <1> 	;mov	ah, 0Dh ; ALTERNATE RESET
  4921                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4922                              <1> 	;mov	ah, 5 ; ALTERNATE RESET
  4923                              <1> 	;;int	13h
  4924                              <1> 	;call	int13h
  4925                              <1> 	; 12/07/2022
  4926 0000204A 30C0                <1> 	xor	al, al  ; reset
  4927 0000204C E803000000          <1> 	call	DISK_IO	
  4928                              <1> 	;
  4929 00002051 E2F5                <1> 	loop	hdc_reset1
  4930                              <1> POD_DONE:
  4931 00002053 C3                  <1> 	retn
  4932                              <1> 
  4933                              <1> ;----------------------------------------
  4934                              <1> ;	FIXED DISK BIOS ENTRY POINT	:
  4935                              <1> ;----------------------------------------
  4936                              <1> 
  4937                              <1> ; 11/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4938                              <1> ; ((Direct call instead of int 13h simulation))
  4939                              <1> ;
  4940                              <1> ;		Function in AL
  4941                              <1> ;			0 = reset
  4942                              <1> ;			1 = read
  4943                              <1> ;			2 = write
  4944                              <1> ;		Disk drive number in DL
  4945                              <1> ;			0 & 1 = floppy disks	
  4946                              <1> ;			80h .. 83h = hard disks
  4947                              <1> ;		Sector address (LBA) in ECX
  4948                              <1> ;		Buffer address in EBX
  4949                              <1> ;		R/W sector count is (always) 1
  4950                              <1> ;
  4951                              <1> ;		Return:
  4952                              <1> ;			Status in AH (>0 = error code)
  4953                              <1> ;			if CF = 1 -> error code in AH
  4954                              <1> ;			if CF = 0 -> successful
  4955                              <1> ;			AL = undefined
  4956                              <1> ;
  4957                              <1> ;		Modified registers: (only) EAX
  4958                              <1> 	
  4959                              <1> 
  4960                              <1> ; 11/07/2022
  4961                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  4962                              <1> 
  4963                              <1> DISK_IO:
  4964                              <1> 	; 11/07/2022
  4965                              <1> 	; save registers
  4966 00002054 57                  <1> 	push	edi			; ANY
  4967 00002055 56                  <1> 	push	esi			; ANY
  4968 00002056 53                  <1> 	push	ebx			; BUFFER ADDRESS
  4969 00002057 51                  <1> 	push	ecx			; SECTOR ADDRESS (LBA)
  4970 00002058 52                  <1> 	push	edx			; DRIVE NUMBER (DL)
  4971                              <1> 
  4972                              <1> 	;cmp	dl, 80h			; TEST FOR FIXED DISK DRIVE
  4973                              <1> 	;;jae	short A1		; YES, HANDLE HERE
  4974                              <1> 	;;;;int	40H			; DISKETTE HANDLER
  4975                              <1> 	;;;call	int40h
  4976                              <1> 	;;jb	DISKETTE_IO_1
  4977                              <1> 	;; 24/12/2021
  4978                              <1> 	;jnb	short A1
  4979                              <1> 	;jmp	DISKETTE_IO_1
  4980                              <1> 
  4981                              <1> 	; 11/07/2022
  4982 00002059 80FA80              <1> 	cmp	dl, 80h
  4983 0000205C 730B                <1> 	jae	short A1
  4984                              <1> 
  4985 0000205E E8CAF6FFFF          <1> 	call	DISKETTE_IO_1
  4986                              <1> 
  4987                              <1> DISK_IO_RTN:
  4988                              <1> 	; restore registers
  4989 00002063 5A                  <1> 	pop	edx
  4990 00002064 59                  <1> 	pop	ecx
  4991 00002065 5B                  <1> 	pop	ebx
  4992 00002066 5E                  <1> 	pop	esi
  4993 00002067 5F                  <1> 	pop	edi
  4994 00002068 C3                  <1> 	retn	
  4995                              <1> 
  4996                              <1> ;RET_2:
  4997                              <1> ;	retf	4			; BACK TO CALLER
  4998                              <1> 
  4999                              <1> A1:
  5000                              <1> 	; 11/07/2022
  5001                              <1> 	;sti				; ENABLE INTERRUPTS
  5002                              <1> 	;cmp	dl, (80h + S_MAX_FILE - 1)
  5003                              <1> 	;ja	short RET_2
  5004                              <1> 	
  5005                              <1> 	; 18/01/2015
  5006                              <1> 	;;or	ah, ah
  5007                              <1> 	;or	al, al ; 11/07/2022 (reset function)
  5008                              <1> 	;jz	short A3 ; 08/07/2022
  5009                              <1> 	
  5010                              <1> 	;;cmp	ah, 5  ; Alternate reset
  5011                              <1> 	;cmp	al, 5  ; 11/07/2022
  5012                              <1> 	;je	short A2
  5013                              <1> 	
  5014                              <1> 	; 11/07/2022 - no need to check
  5015                              <1> 	;		 (only kernel calls diskio functions)
  5016                              <1> 	;;cmp	ah, M1L/4 ; cmp ah, 6
  5017                              <1> 	;jb	short A3
  5018                              <1> 	;; BAD COMMAND
  5019                              <1>         ;mov     byte [DISK_STATUS1], BAD_CMD
  5020                              <1> ;RET_2:
  5021                              <1> 	;retf	4
  5022                              <1> 
  5023                              <1> 	; 11/07/2022
  5024                              <1> 	;stc
  5025                              <1> 	;retn
  5026                              <1> A2:
  5027                              <1> 	;sub	ah, ah	; Reset
  5028                              <1> 	; 11/07/2022
  5029                              <1> 	;sub	al, al
  5030                              <1> A3:
  5031                              <1> 					; SAVE REGISTERS DURING OPERATION
  5032 00002069 C8080000            <1> 	enter	8,0			; SAVE (EBP) AND MAKE ROOM FOR @CMD_BLOCK
  5033                              <1> 	
  5034                              <1> 	; 11/07/2022
  5035                              <1> 	; 08/07/2022
  5036                              <1> 	;push	ebx			;  IN THE STACK, THE COMMAND BLOCK IS:
  5037                              <1> 	;push	ecx			;   @CMD_BLOCK == BYTE PTR [EBP]-8
  5038                              <1> 	;push	edx
  5039                              <1> 	;push	esi
  5040                              <1> 	;push	edi
  5041                              <1> 	
  5042 0000206D E80D000000          <1> 	call	DISK_IO_CONT		; PERFORM THE OPERATION
  5043                              <1> 
  5044 00002072 C9                  <1> 	leave	; 11/07/2022
  5045                              <1> 	
  5046 00002073 8A25[AB620000]      <1> 	mov	ah, [DISK_STATUS1]	; GET STATUS FROM OPERATION
  5047 00002079 80FC01              <1> 	cmp	ah, 1			; SET THE CARRY FLAG TO INDICATE
  5048 0000207C F5                  <1> 	cmc				; SUCCESS OR FAILURE
  5049                              <1> 	
  5050                              <1> 	;pop	edi			; RESTORE REGISTERS
  5051                              <1> 	;pop	esi
  5052                              <1>       	;pop	edx
  5053                              <1> 	;pop	ecx
  5054                              <1> 	;pop	ebx
  5055                              <1> 	
  5056                              <1> 	;leave				; ADJUST (ESP) AND RESTORE (EBP)
  5057                              <1> 	
  5058                              <1> 	; 11/07/2022
  5059                              <1> 	;retf	4			; THROW AWAY SAVED FLAGS
  5060                              <1> 
  5061 0000207D EBE4                <1> 	jmp	short DISK_IO_RTN
  5062                              <1> 
  5063                              <1> DISK_IO_CONT:
  5064                              <1> 	; 17/07/2022
  5065                              <1> 	; 11/07/2022
  5066                              <1> 	;	INPUT:
  5067                              <1> 	;	    AL = 0 : reset
  5068                              <1> 	;	    AL = 1 : read
  5069                              <1> 	;	    Al = 2 : write
  5070                              <1> 	; 	
  5071                              <1> 	; 10/07/2022
  5072                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5073                              <1> SU0:
  5074 0000207F C605[AB620000]00    <1> 	mov	byte [DISK_STATUS1], 0 	; RESET THE STATUS INDICATOR
  5075                              <1> 	; 10/07/2022
  5076 00002086 89DE                <1> 	mov	esi, ebx ; 21/02/2015	; DATA (BUFFER) ADDRESS
  5077                              <1> 
  5078 00002088 8A1D[AC620000]      <1> 	mov	bl, [HF_NUM]		; GET NUMBER OF DRIVES
  5079 0000208E 80E27F              <1> 	and	dl, 7Fh			; GET DRIVE AS 0 OR 1
  5080                              <1> 					; (get drive number as 0 to 3)
  5081 00002091 38D3                <1> 	cmp	bl, dl
  5082                              <1>         ;;jbe	BAD_COMMAND_POP         ; INVALID DRIVE
  5083                              <1>         ;jbe    BAD_COMMAND ;; 14/02/2015
  5084                              <1> 	; 24/12/2021
  5085 00002093 7705                <1> 	ja	short su0_su1
  5086 00002095 E98D000000          <1> 	jmp	BAD_COMMAND
  5087                              <1> su0_su1:
  5088                              <1>         ;;03/01/2015
  5089 0000209A 29DB                <1> 	sub	ebx, ebx
  5090 0000209C 88D3                <1> 	mov	bl, dl
  5091 0000209E 883D[C0620000]      <1> 	mov	[LBAMode], bh  ; 0
  5092                              <1> 	;test	byte [ebx+hd0_type], 1	; LBA ready ?
  5093                              <1> 	;jz	short su1		; no
  5094                              <1> 	;inc	byte [LBAMode]
  5095                              <1> ;su1:
  5096                              <1> 	; 21/02/2015 (32 bit modification)
  5097                              <1> 	; 04/01/2015
  5098                              <1> 	;push	ax ; ***
  5099                              <1> 	; 24/12/2021
  5100 000020A4 50                  <1> 	push	eax ; *** ; function (in AL) ; 11/07/2022
  5101                              <1> 	; 24/12/2021
  5102 000020A5 52                  <1> 	push	edx ; *
  5103 000020A6 50                  <1> 	push	eax ; function (in AL)	; 11/07/2022
  5104 000020A7 E8C4030000          <1> 	CALL	GET_VEC 		; GET DISK PARAMETERS
  5105                              <1> 	; 02/02/2015
  5106 000020AC 668B4310            <1> 	mov	ax, [ebx+16]   ; I/O port base address (1F0h, 170h)
  5107 000020B0 66A3[325D0000]      <1> 	mov	[HF_PORT], ax
  5108 000020B6 668B5312            <1> 	mov	dx, [ebx+18]   ; control port address (3F6h, 376h)
  5109 000020BA 668915[345D0000]    <1> 	mov	[HF_REG_PORT], dx
  5110 000020C1 8A4314              <1> 	mov	al, [ebx+20]   ; head register upper nibble (A0h,B0h,E0h,F0h)
  5111                              <1> 	; 23/02/2015
  5112 000020C4 A840                <1> 	test	al, 40h	 ; LBA bit (bit 6)
  5113 000020C6 7406                <1> 	jz 	short su1
  5114 000020C8 FE05[C0620000]      <1> 	inc	byte [LBAMode] ; 1 
  5115                              <1> su1: 	 
  5116 000020CE C0E804              <1> 	shr 	al, 4
  5117 000020D1 2401                <1> 	and	al, 1			
  5118 000020D3 A2[365D0000]        <1> 	mov	[hf_m_s], al 
  5119                              <1> 	;
  5120                              <1> 	; 03/01/2015
  5121 000020D8 8A4308              <1> 	mov	al, [ebx+8]		; GET CONTROL BYTE MODIFIER
  5122                              <1> 	;mov	dx, [HF_REG_PORT]	; Device Control register	
  5123 000020DB EE                  <1> 	out	dx, al			; SET EXTRA HEAD OPTION
  5124                              <1> 					; Control Byte: (= 08h, here)
  5125                              <1> 					; bit 0 - 0
  5126                              <1> 					; bit 1 - nIEN (1 = disable irq)
  5127                              <1> 					; bit 2 - SRST (software RESET)
  5128                              <1> 					; bit 3 - use extra heads (8 to 15)
  5129                              <1> 					;         -always set to 1-	
  5130                              <1> 					; (bits 3 to 7 are reserved
  5131                              <1> 					;          for ATA devices)
  5132 000020DC 8A25[AD620000]      <1> 	mov	ah, [CONTROL_BYTE]	; SET EXTRA HEAD OPTION IN
  5133 000020E2 80E4C0              <1> 	and	ah, 0C0h 		; CONTROL BYTE
  5134 000020E5 08C4                <1> 	or	ah, al
  5135 000020E7 8825[AD620000]      <1> 	mov	[CONTROL_BYTE], ah	
  5136                              <1> 	; 04/01/2015
  5137                              <1> 	;pop	ax
  5138                              <1> 	; 24/12/2021
  5139 000020ED 58                  <1> 	pop	eax ; function (in AL) ; 11/07/2022
  5140                              <1> 	;pop	dx ; * ;; 14/02/2015
  5141                              <1> 	; 24/12/2021
  5142 000020EE 5A                  <1> 	pop	edx ; *
  5143                              <1> 	;and	ah, ah	; Reset function ?
  5144 000020EF 20C0                <1> 	and	al, al	; 11/07/2022
  5145 000020F1 7506                <1> 	jnz	short su2
  5146                              <1> 	;pop	ax ; ***
  5147                              <1> 	; 24/12/2021
  5148 000020F3 58                  <1> 	pop	eax ; *** 	
  5149                              <1> 	;;pop	bx
  5150 000020F4 E9E4000000          <1>         jmp     DISK_RESET
  5151                              <1> su2:
  5152                              <1> 	; 11/07/2022
  5153                              <1> 	; ecx = sector address (lba)
  5154                              <1> 	;  dl = hard disk drive number (80h, 81h .. 83h)	 
  5155                              <1> 	;  al = function (0 = read, 1 = write)	
  5156                              <1> 
  5157 000020F9 803D[C0620000]00    <1> 	cmp	byte [LBAMode], 0
  5158 00002100 7620                <1> 	jna	short su3 ; convert LBA address to CHS parameters
  5159                              <1> 	
  5160                              <1> ;	; 02/02/2015 (LBA read/write function calls)
  5161                              <1> ;	;cmp	ah, 1Bh
  5162                              <1> ;	cmp	ah, 3 ; 08/07/2022
  5163                              <1> ;	jb	short lbarw1
  5164                              <1> ;	;;cmp	ah, 1Ch
  5165                              <1> ;	;cmp	ah, 4 ; 08/07/2022 
  5166                              <1> ;	;ja 	short invldfnc
  5167                              <1> ;	;;pop	dx ; * ; 14/02/2015
  5168                              <1> ;	;mov	ax, cx ; Lower word of LBA address (bits 0-15)
  5169                              <1> 
  5170 00002102 89C8                <1> 	mov	eax, ecx ; LBA address (21/02/2015)
  5171                              <1> 
  5172                              <1> 	; 11/07/2022
  5173                              <1> 	;; 14/02/2015
  5174                              <1> 	;mov	cl, dl ; 14/02/2015
  5175                              <1> 
  5176                              <1> 	;;mov	dx, bx
  5177                              <1> 	;mov	dx, si ; higher word of LBA address (bits 16-23)
  5178                              <1> 	;;mov	bx, di
  5179                              <1> 	;mov	si, di ; Buffer offset
  5180                              <1> 
  5181                              <1> 	; 11/07/2022
  5182                              <1> 	;jmp	short lbarw2
  5183                              <1> 
  5184                              <1> ;lbarw1:
  5185                              <1> ;	; convert CHS to LBA
  5186                              <1> ;	;
  5187                              <1> ;	; LBA calculation - AWARD BIOS - 1999 - AHDSK.ASM
  5188                              <1> ;	; LBA = "# of Heads" * Sectors/Track * Cylinder + Head * Sectors/Track
  5189                              <1> ;	;	+ Sector - 1
  5190                              <1> ;	;push	dx ; * ;; 14/02/2015
  5191                              <1> ;	; 24/12/2021
  5192                              <1> ;	push	edx ; *
  5193                              <1> ;	;xor	dh, dh
  5194                              <1> ;	xor	edx, edx
  5195                              <1> ;	mov	dl, [ebx+14]	; sectors per track (logical)
  5196                              <1> ;	;xor	ah, ah
  5197                              <1> ;	xor	eax, eax
  5198                              <1> ;	mov	al, [ebx+2]	; heads (logical) 
  5199                              <1> ;	dec	al
  5200                              <1> ;	;inc	ax		; 0 =  256
  5201                              <1> ;	inc	eax ; 24/12/2021
  5202                              <1> ;	mul 	dx
  5203                              <1> ;		; AX = # of Heads * Sectors/Track
  5204                              <1> ;	mov	dx, cx
  5205                              <1> ;	;and	cx, 3Fh	 ; sector (1 to 63)
  5206                              <1> ;	and	ecx, 3fh
  5207                              <1> ;	xchg	dl, dh
  5208                              <1> ;	shr	dh, 6
  5209                              <1> ;		; DX = cylinder (0 to 1023)
  5210                              <1> ;	;mul 	dx
  5211                              <1> ;		; DX:AX = # of Heads * Sectors/Track * Cylinder
  5212                              <1> ;	mul	edx
  5213                              <1> ;	dec	cl  ; sector - 1
  5214                              <1> ;	;add	ax, cx
  5215                              <1> ;	;adc	dx, 0
  5216                              <1> ;		; DX:AX = # of Heads * Sectors/Track * Cylinder + Sector -1
  5217                              <1> ;	add	eax, ecx
  5218                              <1> ;	;pop	cx ; * ; ch = head, cl = drive number (zero based)
  5219                              <1> ;	; 24/12/2021
  5220                              <1> ;	pop	ecx ; * ; ch = head, cl = drive number (zero based)
  5221                              <1> ;	;push	dx
  5222                              <1> ;	;push	ax
  5223                              <1> ;	push	eax
  5224                              <1> ;	mov	al, [ebx+14]  ; sectors per track (logical)	
  5225                              <1> ;	mul	ch
  5226                              <1> ;		; AX = Head * Sectors/Track
  5227                              <1> ;	cwd
  5228                              <1> ;	;pop	dx
  5229                              <1> ;	pop	edx
  5230                              <1> ;	;add	ax, dx
  5231                              <1> ;	;pop	dx
  5232                              <1> ;	;adc	dx, 0 ; add carry bit
  5233                              <1> ;	add	eax, edx
  5234                              <1> ;
  5235                              <1> ;lbarw2:
  5236                              <1> 	; 11/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5237                              <1> 	
  5238 00002104 29D2                <1> 	sub	edx, edx ; 21/02/2015
  5239                              <1> 	
  5240                              <1> 	; 11/07/2022
  5241                              <1> 	;mov	dl, cl ; 21/02/2015
  5242                              <1>         
  5243 00002106 C645F800            <1> 	mov     byte [CMD_BLOCK], 0 ; Features Register
  5244                              <1> 				; NOTE: Features register (1F1h, 171h)
  5245                              <1> 				; is not used for ATA device R/W functions. 
  5246                              <1> 				; It is old/obsolete 'write precompensation'
  5247                              <1> 				; register and error register
  5248                              <1> 				; for old ATA/IDE devices.
  5249                              <1> 	; 18/01/2014
  5250                              <1> 	;mov	ch, [hf_m_s]	; Drive 0 (master) or 1 (slave)
  5251 0000210A 8A0D[365D0000]      <1> 	mov	cl, [hf_m_s]
  5252                              <1> 	;shl	ch, 4		; bit 4 (drive bit)
  5253                              <1> 	;or	ch, 0E0h	; bit 5 = 1
  5254                              <1> 				; bit 6 = 1 = LBA mode
  5255                              <1> 				; bit 7 = 1
  5256 00002110 80C90E              <1> 	or	cl, 0Eh ; 1110b
  5257                              <1> 	;and	dh, 0Fh		; LBA byte 4 (bits 24 to 27)
  5258 00002113 25FFFFFF0F          <1> 	and	eax, 0FFFFFFFh
  5259 00002118 C1E11C              <1> 	shl	ecx, 28 ; 21/02/2015
  5260                              <1> 	;or	dh, ch
  5261 0000211B 09C8                <1> 	or	eax, ecx	
  5262                              <1> 	;;mov	[CMD_BLOCK+2], al ; LBA byte 1 (bits 0 to 7)
  5263                              <1> 				  ; (Sector Number Register)
  5264                              <1> 	;;mov	[CMD_BLOCK+3], ah ; LBA byte 2 (bits 8 to 15)
  5265                              <1> 				  ; (Cylinder Low Register)
  5266                              <1> 	;mov	[CMD_BLOCK+2], ax ; LBA byte 1, 2
  5267                              <1> 	;mov	[CMD_BLOCK+4], dl ; LBA byte 3 (bits 16 to 23)
  5268                              <1> 				  ; (Cylinder High Register)
  5269                              <1> 	;;mov	[CMD_BLOCK+5], dh ; LBA byte 4 (bits 24 to 27)
  5270                              <1> 				  ; (Drive/Head Register)
  5271                              <1> 	
  5272                              <1> 	;mov	[CMD_BLOCK+4], dx ; LBA byte 4, LBA & DEV select bits
  5273 0000211D 8945FA              <1> 	mov	[CMD_BLOCK+2], eax ; 21/02/2015
  5274                              <1> 	;14/02/2015
  5275                              <1> 	;mov	dl, cl ; Drive number (INIT_DRV)		
  5276 00002120 EB3D                <1> 	jmp	short su4
  5277                              <1> su3:
  5278                              <1> 	; 02/02/2015 
  5279                              <1> 	; (Temporary functions 1Bh & 1Ch are not valid for CHS mode) 
  5280                              <1> 	;cmp 	ah, 14h
  5281                              <1> 	;jna 	short chsfnc
  5282                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5283                              <1> 	;cmp	ah, 2
  5284                              <1> 	;jna	short chsfnc
  5285                              <1> 	; 11/07/2022 
  5286                              <1> 	; (al = function, read = 1 or write = 2)
  5287 00002122 3C02                <1> 	cmp	al, 2 
  5288 00002124 760B                <1> 	jna	short chsfnc
  5289                              <1> invldfnc:
  5290                              <1>         ; 14/02/2015  
  5291                              <1> 	;pop	es ; **
  5292                              <1>         ;pop	ax ; ***
  5293                              <1>         ; 24/12/2021
  5294 00002126 58                  <1> 	pop	eax ; ***
  5295                              <1> 	;;jmp	short BAD_COMMAND_POP
  5296                              <1> 	; 11/07/2022
  5297                              <1>         ;jmp     short BAD_COMMAND
  5298                              <1> 
  5299                              <1> 	; 11/07/2022
  5300                              <1> BAD_COMMAND:
  5301 00002127 C605[AB620000]01    <1> 	mov	byte [DISK_STATUS1], BAD_CMD  ; COMMAND ERROR
  5302                              <1> 	;mov	al, 0
  5303 0000212E 28C0                <1> 	sub	al, al ; 0
  5304 00002130 C3                  <1> 	retn
  5305                              <1> 
  5306                              <1> chsfnc:	
  5307 00002131 668B4305            <1> 	mov	ax, [ebx+5]		; GET WRITE PRE-COMPENSATION CYLINDER
  5308                              <1> 	;shr	ax, 2
  5309                              <1> 	; 17/07/2022
  5310 00002135 C1E802              <1> 	shr	eax, 2
  5311 00002138 8845F8              <1> 	mov	[CMD_BLOCK], al
  5312                              <1> 	;
  5313                              <1> 	;;mov	al, [ebx+8]		; GET CONTROL BYTE MODIFIER
  5314                              <1> 	;;push	edx ; *
  5315                              <1> 	;;mov	dx, [HF_REG_PORT]
  5316                              <1> 	;;out	dx, al			; SET EXTRA HEAD OPTION
  5317                              <1> 	;;pop	edx ; * 
  5318                              <1> 	;;mov	ah, [CONTROL_BYTE]	; SET EXTRA HEAD OPTION IN
  5319                              <1> 	;;and	ah, 0C0h 		; CONTROL BYTE	
  5320                              <1> 	;;or	ah, al
  5321                              <1> 	;;mov	[CONTROL_BYTE], ah
  5322                              <1> 	;
  5323 0000213B 88C8                <1> 	mov	al, cl			; GET SECTOR NUMBER
  5324 0000213D 243F                <1> 	and	al, 3Fh
  5325 0000213F 8845FA              <1> 	mov	[CMD_BLOCK+2], al
  5326 00002142 886DFB              <1> 	mov	[CMD_BLOCK+3], ch 	; GET CYLINDER NUMBER
  5327 00002145 88C8                <1> 	mov	al, cl
  5328 00002147 C0E806              <1> 	shr	al, 6
  5329 0000214A 8845FC              <1> 	mov	[CMD_BLOCK+4], al	; CYLINDER HIGH ORDER 2 BITS
  5330                              <1> 	;;05/01/2015
  5331                              <1> 	;;mov	al, dl			; DRIVE NUMBER
  5332 0000214D A0[365D0000]        <1> 	mov	al, [hf_m_s]
  5333 00002152 C0E004              <1> 	shl	al, 4
  5334 00002155 80E60F              <1> 	and	dh, 0Fh			; HEAD NUMBER
  5335 00002158 08F0                <1> 	or	al, dh
  5336 0000215A 0CA0                <1> 	or	al, 80h+20h		; ECC AND 512 BYTE SECTORS
  5337 0000215C 8845FD              <1> 	mov	[CMD_BLOCK+5], al	; ECC/SIZE/DRIVE/HEAD
  5338                              <1> su4:
  5339                              <1> 	;; 14/02/2015
  5340                              <1>         ;;pop	ax
  5341                              <1>         ;;mov	[CMD_BLOCK+1], AL	; SECTOR COUNT
  5342                              <1>         ;;push	ax
  5343                              <1>         ;;mov	al, ah			; GET INTO LOW BYTE
  5344                              <1>         ;;xor	ah, ah			; ZERO HIGH BYTE
  5345                              <1>         ;;sal	ax, 1			; *2 FOR TABLE LOOKUP
  5346                              <1> 	;pop	ax ; ***
  5347                              <1> 	; 24/12/2021
  5348 0000215F 58                  <1> 	pop	eax ; *** ; function (in AL) ; 11/07/2022
  5349                              <1> 	
  5350                              <1> 	;mov	[CMD_BLOCK+1], al
  5351 00002160 C645F901            <1>         mov	byte [CMD_BLOCK+1], 1 ; (always 1 sector r/w)
  5352                              <1> 
  5353                              <1> 	; 11/07/2022
  5354                              <1> 	;mov	ebx, esi
  5355                              <1> 	; (esi = buffer address)	
  5356                              <1> 
  5357 00002164 3C02                <1> 	cmp	al, 2
  5358 00002166 742D                <1> 	je	short DISK_WRITE
  5359                              <1> 
  5360                              <1> 	;jmp	short DISK_READ
  5361                              <1> 
  5362                              <1> ;	;xor	ebx, ebx
  5363                              <1> ;	;mov	bl, ah
  5364                              <1> ;
  5365                              <1> ;       ;xor	bh, bh
  5366                              <1> ;       ;sal	bx, 1
  5367                              <1> ;       sal	bx, 2	; 32 bit offset (21/02/2015)
  5368                              <1> ;	;;mov	si, ax			; PUT INTO SI FOR BRANCH
  5369                              <1> ;       ;;cmp	ax, M1L			; TEST WITHIN RANGE
  5370                              <1> ;       ;;jnb	short BAD_COMMAND_POP
  5371                              <1> ;   	; 08/07/2022
  5372                              <1> ;	;cmp	ebx, M1L
  5373                              <1> ;	;jnb	short BAD_COMMAND
  5374                              <1> ;
  5375                              <1> ;	xchg	ebx, esi
  5376                              <1> ;
  5377                              <1> ;	;;;pop	ax			; RESTORE AX
  5378                              <1> ;	;;;pop	bx			; AND DATA ADDRESS
  5379                              <1> ;	
  5380                              <1> ;	;;push	cx
  5381                              <1> ;	;;push	ax			; ADJUST ES:BX
  5382                              <1> ;	;mov	cx, bx			; GET 3 HIGH ORDER NIBBLES OF BX
  5383                              <1> ;	;shr	cx, 4
  5384                              <1> ;	;mov	ax, es
  5385                              <1> ;	;add	ax, cx
  5386                              <1> ;	;mov	es, ax
  5387                              <1> ;	;and	bx, 000Fh		; ES:BX CHANGED TO ES:000X
  5388                              <1> ;	;;pop	ax
  5389                              <1> ;	;;pop	cx
  5390                              <1> ;
  5391                              <1> ;	jmp	dword [esi+M1]
  5392                              <1> 
  5393                              <1> ;;BAD_COMMAND_POP:
  5394                              <1> ;;	pop	ax
  5395                              <1> ;;	pop	bx
  5396                              <1> ;
  5397                              <1> ;	; 11/07/2022
  5398                              <1> ;BAD_COMMAND:
  5399                              <1> ;	mov	byte [DISK_STATUS1], BAD_CMD  ; COMMAND ERROR
  5400                              <1> ;	;mov	al, 0
  5401                              <1> ;	sub	al, al ; 0
  5402                              <1> ;	retn
  5403                              <1> 
  5404                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5405                              <1> 
  5406                              <1> ;----------------------------------------
  5407                              <1> ;	DISK READ ROUTINE    (AH = 01H) :
  5408                              <1> ;----------------------------------------
  5409                              <1> ; 
  5410                              <1> DISK_READ:
  5411 00002168 C645FE20            <1> 	mov	byte [CMD_BLOCK+6], READ_CMD
  5412                              <1>         ;jmp	COMMANDI
  5413                              <1> 
  5414                              <1> ; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5415                              <1> 
  5416                              <1> ;----------------------------------------
  5417                              <1> ; COMMANDI				:
  5418                              <1> ;	REPEATEDLY INPUTS DATA TILL	:
  5419                              <1> ;	NSECTOR RETURNS ZERO		:
  5420                              <1> ;----------------------------------------
  5421                              <1> COMMANDI:
  5422                              <1> 	; 11/07/2022 
  5423                              <1> 	;	(check 64K boundary is not needed)
  5424                              <1> 	;call	CHECK_DMA		; CHECK 64K BOUNDARY ERROR
  5425                              <1> 	;jc	short CMD_ABORT
  5426                              <1> 	
  5427                              <1> 	;mov	di, bx
  5428                              <1> 	; 11/07/2022
  5429                              <1> 	; (esi = buffer address)
  5430                              <1> 	;mov	edi, ebx ; 21/02/2015
  5431 0000216C 89F7                <1> 	mov	edi, esi ; 11/07/2022	
  5432                              <1> 
  5433 0000216E E8A8010000          <1> 	call	COMMAND 		; OUTPUT COMMAND
  5434 00002173 751F                <1> 	jnz	short CMD_ABORT
  5435                              <1> CMD_I1:
  5436 00002175 E813020000          <1> 	call	_WAIT			; WAIT FOR DATA REQUEST INTERRUPT
  5437 0000217A 7518                <1> 	jnz	short TM_OUT		; TIME OUT
  5438                              <1> 	;;mov	cx,256			; SECTOR SIZE IN WORDS
  5439                              <1> 	;mov	ecx, 256 ; 21/02/2015	
  5440 0000217C 29C9                <1> 	sub	ecx, ecx
  5441 0000217E FEC5                <1> 	inc	ch
  5442                              <1> 	; ecx = 256
  5443                              <1> 	;mov	dx, HF_PORT
  5444 00002180 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5445 00002187 FA                  <1> 	cli
  5446 00002188 FC                  <1> 	cld
  5447 00002189 F3666D              <1> 	rep	insw			; GET THE SECTOR
  5448 0000218C FB                  <1> 	sti
  5449                              <1> 	
  5450                              <1> 	;test	byte [CMD_BLOCK+6], ECC_MODE ; CHECK FOR NORMAL INPUT
  5451                              <1> 	;jz	short CMD_I3
  5452                              <1> 	;call	WAIT_DRQ		; WAIT FOR DATA REQUEST
  5453                              <1> 	;jc	short TM_OUT
  5454                              <1> 	;;mov	dx, HF_PORT
  5455                              <1> 	;mov	dx,[HF_PORT]
  5456                              <1> 	;xor	ecx, ecx	
  5457                              <1> 	;;mov	ecx, 4  ; mov cx, 4	; OUTPUT THE ECC BYTES
  5458                              <1> 	;mov	cl, 4
  5459                              <1> ;CMD_I2: 
  5460                              <1> 	;inc	al, dx
  5461                              <1> 	;mov 	[edi], al ; 21/02/2015
  5462                              <1> 	;inc	edi
  5463                              <1> 	;loop	CMD_I2
  5464                              <1> CMD_I3: 
  5465 0000218D E817010000          <1> 	call	CHECK_STATUS
  5466 00002192 7500                <1> 	jnz	short CMD_ABORT		; ERROR RETURNED
  5467                              <1> 	; 11/07/2022
  5468                              <1> 	; (sector count = 1)
  5469                              <1> 	;dec	byte [CMD_BLOCK+1]	; CHECK FOR MORE
  5470                              <1> 	;jnz	SHORT CMD_I1
  5471                              <1> CMD_ABORT:
  5472                              <1> TM_OUT: 
  5473 00002194 C3                  <1> 	retn
  5474                              <1> 
  5475                              <1> ;---------------------------------------------------
  5476                              <1> 
  5477                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5478                              <1> 
  5479                              <1> ;----------------------------------------
  5480                              <1> ;	DISK WRITE ROUTINE   (AH = 02H) :
  5481                              <1> ;----------------------------------------
  5482                              <1> 
  5483                              <1> DISK_WRITE:
  5484 00002195 C645FE30            <1> 	mov	byte [CMD_BLOCK+6], WRITE_CMD
  5485                              <1>         ;JMP	COMMANDO
  5486                              <1> 
  5487                              <1> ; 16/07/2022
  5488                              <1> ; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5489                              <1> 
  5490                              <1> ;----------------------------------------
  5491                              <1> ; COMMANDO				:
  5492                              <1> ;	REPEATEDLY OUTPUTS DATA TILL	:
  5493                              <1> ;	NSECTOR RETURNS ZERO		:
  5494                              <1> ;----------------------------------------
  5495                              <1> COMMANDO:
  5496                              <1> 	; 11/07/2022 
  5497                              <1> 	;	(check 64K boundary is not needed)
  5498                              <1> 	;call	CHECK_DMA		; CHECK 64K BOUNDARY ERROR
  5499                              <1> 	;jc	short CMD_ABORT
  5500                              <1> CMD_OF:
  5501                              <1> 	; 11/07/2022
  5502                              <1> 	; (esi = ebx = buffer address)
  5503                              <1> 	;mov	esi, ebx ; 21/02/2015
  5504 00002199 E87D010000          <1> 	call	COMMAND 		; OUTPUT COMMAND
  5505 0000219E 75F4                <1> 	jnz	short CMD_ABORT
  5506 000021A0 E83F020000          <1> 	call	WAIT_DRQ		; WAIT FOR DATA REQUEST
  5507 000021A5 72ED                <1> 	jc	short TM_OUT		; TOO LONG
  5508                              <1> CMD_O1:
  5509                              <1> 	; 16/07/2022
  5510 000021A7 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5511                              <1> 
  5512                              <1> 	; 10/07/2022
  5513                              <1> 	;mov	ecx, 256 ; 21/02/2015
  5514 000021AE 31C9                <1> 	xor	ecx, ecx
  5515 000021B0 FEC5                <1> 	inc	ch
  5516                              <1> 	; ecx = 256
  5517 000021B2 FA                  <1> 	cli
  5518 000021B3 FC                  <1> 	cld
  5519 000021B4 F3666F              <1> 	rep	outsw
  5520 000021B7 FB                  <1> 	sti
  5521                              <1> 
  5522                              <1> 	; 10/07/2022
  5523                              <1> 	;test	byte [CMD_BLOCK+6], ECC_MODE ; CHECK FOR NORMAL OUTPUT
  5524                              <1> 	;jz	short CMD_O3
  5525                              <1> 	;
  5526                              <1> 	;call	WAIT_DRQ		; WAIT FOR DATA REQUEST
  5527                              <1> 	;jc	short TM_OUT
  5528                              <1> 	;;mov	dx, HF_PORT
  5529                              <1> 	;mov	dx, [HF_PORT]
  5530                              <1> 	;sub	ecx, ecx	
  5531                              <1> 	;;mov	ecx, 4  ; mov cx, 4	; OUTPUT THE ECC BYTES
  5532                              <1> 	;mov	cl, 4
  5533                              <1> ;CMD_O2:
  5534                              <1> 	;;lodsb
  5535                              <1> 	;mov	al, [esi]
  5536                              <1> 	;out	dx, al
  5537                              <1> 	;inc	esi
  5538                              <1> 	;loop	CMD_O2
  5539                              <1> 
  5540                              <1> CMD_O3:
  5541 000021B8 E8D0010000          <1> 	call	_WAIT			; WAIT FOR SECTOR COMPLETE INTERRUPT
  5542 000021BD 75D5                <1> 	jnz	short TM_OUT		; ERROR RETURNED
  5543 000021BF E8E5000000          <1> 	call	CHECK_STATUS
  5544 000021C4 75CE                <1> 	jnz	short CMD_ABORT
  5545                              <1> 
  5546                              <1> 	; 11/07/2022
  5547                              <1> 	; (sector count = 1)
  5548                              <1> 	;test	byte [HF_STATUS], ST_DRQ ; CHECK FOR MORE
  5549                              <1> 	;jnz	short CMD_O1
  5550                              <1> 	
  5551                              <1> 	;mov	dx, HF_PORT+2		; CHECK RESIDUAL SECTOR COUNT
  5552 000021C6 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5553 000021CD 80C202              <1> 	add	dl, 2
  5554                              <1> 	;inc	dl
  5555                              <1> 	;inc	dl
  5556 000021D0 EC                  <1> 	in	al, dx			;
  5557 000021D1 A8FF                <1> 	test	al, 0FFh 		;
  5558 000021D3 7407                <1> 	jz	short CMD_O4		; COUNT = 0  OK
  5559 000021D5 C605[AB620000]BB    <1> 	mov	byte [DISK_STATUS1], UNDEF_ERR 
  5560                              <1> 					; OPERATION ABORTED - PARTIAL TRANSFER
  5561                              <1> CMD_O4:
  5562 000021DC C3                  <1> 	retn
  5563                              <1> 
  5564                              <1> ; 10/07/2022
  5565                              <1> ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5566                              <1> 
  5567                              <1> ;----------------------------------------
  5568                              <1> ;	RESET THE DISK SYSTEM  (AH=00H) :
  5569                              <1> ;----------------------------------------
  5570                              <1> 
  5571                              <1> ; 18-1-2015 : one controller reset (not other one)
  5572                              <1> 
  5573                              <1> DISK_RESET:
  5574 000021DD FA                  <1> 	cli
  5575 000021DE E4A1                <1> 	in	al, INTB01		; GET THE MASK REGISTER
  5576                              <1> 	;JMP	$+2
  5577                              <1> 	IODELAY
  2188 000021E0 EB00                <2>  jmp short $+2
  2189 000021E2 EB00                <2>  jmp short $+2
  5578                              <1> 	;and	al, 0BFh 		; ENABLE FIXED DISK INTERRUPT
  5579 000021E4 243F                <1> 	and	al, 3Fh			; 22/12/2014 (IRQ 14 & IRQ 15)
  5580 000021E6 E6A1                <1> 	out	INTB01, al
  5581 000021E8 FB                  <1> 	sti				; START INTERRUPTS
  5582                              <1> 	; 14/02/2015
  5583                              <1> 	;mov	di, dx
  5584                              <1> 	; 24/12/2021
  5585 000021E9 89D7                <1> 	mov	edi, edx	
  5586                              <1> 	; 04/01/2015
  5587                              <1> 	;xor	di,di
  5588                              <1> drst0:
  5589 000021EB B004                <1> 	mov	al, 04h  ; bit 2 - SRST 
  5590                              <1> 	;mov	dx, HF_REG_PORT
  5591 000021ED 668B15[345D0000]    <1> 	mov	dx, [HF_REG_PORT]
  5592 000021F4 EE                  <1> 	out	dx, al			; RESET
  5593                              <1> ;	mov	cx, 10			; DELAY COUNT
  5594                              <1> ;DRD:	dec	cx
  5595                              <1> ;	jnz	short DRD		; WAIT 4.8 MICRO-SEC
  5596                              <1> 	;mov	cx, 2			; wait for 30 micro seconds	
  5597                              <1>         ;mov	ecx, 2 ; 21/02/2015
  5598                              <1> 	; 10/07/2022
  5599 000021F5 29C9                <1> 	sub	ecx, ecx
  5600 000021F7 B102                <1> 	mov	cl, 2
  5601 000021F9 E89BF2FFFF          <1> 	call    WAITF                   ; (Award Bios 1999 - WAIT_REFRESH,
  5602                              <1>                                         ; 40 micro seconds)
  5603 000021FE A0[AD620000]        <1> 	mov	al, [CONTROL_BYTE]
  5604 00002203 240F                <1> 	and	al, 0Fh			; SET HEAD OPTION
  5605 00002205 EE                  <1> 	out	dx, al			; TURN RESET OFF
  5606 00002206 E8B2010000          <1> 	call	NOT_BUSY
  5607 0000220B 7514                <1> 	jnz	short DRERR		; TIME OUT ON RESET
  5608 0000220D 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5609 00002214 FEC2                <1> 	inc	dl  ; HF_PORT+1
  5610                              <1> 	; 02/01/2015 - Award BIOS 1999 - AHDSK.ASM
  5611                              <1>         ;mov	cl, 10
  5612                              <1>         ;mov     ecx, 10 ; 21/02/2015
  5613                              <1> 	; 10/07/2022
  5614                              <1> 	;xor	ecx, ecx
  5615 00002216 B10A                <1> 	mov	cl, 10 
  5616                              <1> drst1:
  5617 00002218 EC                  <1> 	in	al, dx			; GET RESET STATUS
  5618 00002219 3C01                <1> 	cmp	al, 1
  5619                              <1> 	; 04/01/2015
  5620 0000221B 740C                <1> 	jz	short drst2
  5621                              <1> 	;jnz	short DRERR		; BAD RESET STATUS
  5622                              <1>         	; Drive/Head Register - bit 4
  5623                              <1> 	;loop	drst1
  5624                              <1> 	; 10/07/2022
  5625 0000221D FEC9                <1> 	dec	cl
  5626 0000221F 75F7                <1> 	jnz	short drst1
  5627                              <1> DRERR:	
  5628 00002221 C605[AB620000]05    <1> 	mov	byte [DISK_STATUS1], BAD_RESET ; CARD FAILED
  5629 00002228 C3                  <1> 	retn
  5630                              <1> drst2:
  5631                              <1> 	; 14/02/2015
  5632                              <1> 	;mov	dx, di
  5633                              <1> 	; 24/12/2021
  5634 00002229 89FA                <1> 	mov	edx, edi
  5635                              <1> ;drst3:
  5636                              <1> ;	; 05/01/2015
  5637                              <1> ;	shl 	di, 1
  5638                              <1> ;	; 04/01/2015
  5639                              <1> ;	mov	ax, [di+hd_cports]
  5640                              <1> ;	cmp	ax, [HF_REG_PORT]
  5641                              <1> ;	je	short drst4
  5642                              <1> ;	mov	[HF_REG_PORT], ax
  5643                              <1> ;	; 03/01/2015
  5644                              <1> ;	mov	ax, [di+hd_ports]
  5645                              <1> ;       mov     [HF_PORT], ax
  5646                              <1> ;	; 05/01/2014
  5647                              <1> ;	shr	di, 1
  5648                              <1> ;	; 04/01/2015
  5649                              <1> ;	jmp	short drst0	; reset other controller
  5650                              <1> ;drst4:
  5651                              <1> ;	; 05/01/2015
  5652                              <1> ;	shr	di, 1
  5653                              <1> ;	mov	al, [di+hd_dregs]
  5654                              <1> ;	and	al, 10h ; bit 4 only
  5655                              <1> ;	shr	al, 4 ; bit 4  -> bit 0
  5656                              <1> ;	mov	[hf_m_s], al ; (0 = master, 1 = slave)
  5657                              <1> 	;
  5658 0000222B A0[365D0000]        <1> 	mov	al, [hf_m_s] ; 18/01/2015
  5659 00002230 A801                <1> 	test	al, 1
  5660                              <1> 	;jnz	short drst6
  5661 00002232 7516                <1>         jnz     short drst4
  5662 00002234 8065FDEF            <1> 	and	byte [CMD_BLOCK+5], 0EFh ; SET TO DRIVE 0
  5663                              <1> ;drst5:
  5664                              <1> drst3:
  5665 00002238 E813000000          <1> 	call	INIT_DRV		; SET MAX HEADS
  5666                              <1> 	;mov	dx, di
  5667 0000223D E8A3000000          <1> 	call	HDISK_RECAL		; RECAL TO RESET SEEK SPEED
  5668                              <1> 	; 04/01/2014
  5669                              <1> ;	inc	di
  5670                              <1> ;	mov	dx, di
  5671                              <1> ;	cmp	dl, [HF_NUM]
  5672                              <1> ;	jb	short drst3
  5673                              <1> ;DRE:
  5674 00002242 C605[AB620000]00    <1> 	mov	byte [DISK_STATUS1], 0 	; IGNORE ANY SET UP ERRORS
  5675 00002249 C3                  <1> 	retn
  5676                              <1> ;drst6:
  5677                              <1> drst4:		; Drive/Head Register - bit 4
  5678 0000224A 804DFD10            <1> 	or	byte [CMD_BLOCK+5], 010h ; SET TO DRIVE 1     
  5679                              <1>         ;jmp    short drst5
  5680 0000224E EBE8                <1>         jmp     short drst3
  5681                              <1> 
  5682                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5683                              <1> 
  5684                              <1> ;----------------------------------------
  5685                              <1> ;	INITIALIZE DRIVE     (AH = 09H) :
  5686                              <1> ;----------------------------------------
  5687                              <1> 	; 03/01/2015
  5688                              <1> 	; According to ATA-ATAPI specification v2.0 to v5.0
  5689                              <1> 	; logical sector per logical track
  5690                              <1> 	; and logical heads - 1 would be set but
  5691                              <1> 	; it is seen as it will be good
  5692                              <1> 	; if physical parameters will be set here
  5693                              <1> 	; because, number of heads <= 16.
  5694                              <1> 	; (logical heads usually more than 16)
  5695                              <1> 	; NOTE: ATA logical parameters (software C, H, S)
  5696                              <1> 	;	== INT 13h physical parameters
  5697                              <1> 
  5698                              <1> ;INIT_DRV:
  5699                              <1> ;	mov	byte [CMD_BLOCK+6], SET_PARM_CMD
  5700                              <1> ;	call	GET_VEC 		; ES:BX -> PARAMETER BLOCK
  5701                              <1> ;	mov	al, [es:bx+2]		; GET NUMBER OF HEADS
  5702                              <1> ;	dec	al			; CONVERT TO 0-INDEX
  5703                              <1> ;	mov	ah, [CMD_BLOCK+5] 	; GET SDH REGISTER
  5704                              <1> ;	and	ah, 0F0h 		; CHANGE HEAD NUMBER
  5705                              <1> ;	or	ah, al			; TO MAX HEAD
  5706                              <1> ;	mov	[CMD_BLOCK+5], ah
  5707                              <1> ;	mov	al, [es:bx+14]		; MAX SECTOR NUMBER
  5708                              <1> ;	mov	[CMD_BLOCK+1], al
  5709                              <1> ;	sub	ax, ax
  5710                              <1> ;	mov	[CMD_BLOCK+3], al 	; ZERO FLAGS
  5711                              <1> ;	call	COMMAND 		; TELL CONTROLLER
  5712                              <1> ;	jnz	short INIT_EXIT		; CONTROLLER BUSY ERROR
  5713                              <1> ;	call	NOT_BUSY		; WAIT FOR IT TO BE DONE
  5714                              <1> ;	jnz	short INIT_EXIT		; TIME OUT
  5715                              <1> ;	call	CHECK_STATUS
  5716                              <1> ;INIT_EXIT:
  5717                              <1> ;	retn
  5718                              <1> 
  5719                              <1> ; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5720                              <1> 
  5721                              <1> ; 04/01/2015
  5722                              <1> ; 02/01/2015 - Derived from from AWARD BIOS 1999
  5723                              <1> ;				 AHDSK.ASM - INIT_DRIVE
  5724                              <1> INIT_DRV:
  5725                              <1> 	;xor	ah, ah
  5726 00002250 31C0                <1> 	xor	eax, eax ; 21/02/2015
  5727 00002252 B00B                <1> 	mov	al, 11 ; Physical heads from translated HDPT
  5728 00002254 3825[C0620000]      <1>         cmp     [LBAMode], ah   ; 0
  5729 0000225A 7702                <1> 	ja	short idrv0
  5730 0000225C B002                <1> 	mov	al, 2  ; Physical heads from standard HDPT
  5731                              <1> idrv0:
  5732                              <1> 	; DL = drive number (0 based)
  5733 0000225E E80D020000          <1> 	call	GET_VEC
  5734                              <1> 	;push	bx
  5735 00002263 53                  <1> 	push	ebx ; 21/02/2015
  5736                              <1> 	;add	bx, ax
  5737 00002264 01C3                <1> 	add	ebx, eax
  5738                              <1> 	;; 05/01/2015
  5739 00002266 8A25[365D0000]      <1> 	mov	ah, [hf_m_s] ; drive number (0= master, 1= slave)
  5740                              <1> 	;;and 	ah, 1 
  5741 0000226C C0E404              <1> 	shl	ah, 4
  5742 0000226F 80CCA0              <1> 	or	ah, 0A0h  ; Drive/Head register - 10100000b (A0h)	
  5743                              <1> 	;mov	al, [es:bx]
  5744 00002272 8A03                <1> 	mov	al, [ebx] ; 21/02/2015
  5745 00002274 FEC8                <1> 	dec	al	 ; last head number 
  5746                              <1> 	;and	al, 0Fh
  5747 00002276 08E0                <1> 	or	al, ah	 ; lower 4 bits for head number
  5748                              <1> 	;
  5749 00002278 C645FE91            <1> 	mov	byte [CMD_BLOCK+6], SET_PARM_CMD
  5750 0000227C 8845FD              <1> 	mov	[CMD_BLOCK+5], al
  5751                              <1> 	;pop	bx
  5752 0000227F 5B                  <1> 	pop	ebx
  5753 00002280 29C0                <1> 	sub	eax, eax ; 21/02/2015
  5754 00002282 B004                <1> 	mov	al, 4 ; Physical sec per track from translated HDPT
  5755 00002284 803D[C0620000]00    <1> 	cmp	byte [LBAMode], 0
  5756 0000228B 7702                <1> 	ja	short idrv1
  5757 0000228D B00E                <1> 	mov	al, 14 ; Physical sec per track from standard HDPT
  5758                              <1> idrv1:
  5759                              <1> 	;xor	ah, ah
  5760                              <1> 	;add	bx, ax
  5761 0000228F 01C3                <1> 	add	ebx, eax ; 21/02/2015
  5762                              <1> 	;mov	al, [es:bx]
  5763                              <1> 			; sector number
  5764 00002291 8A03                <1> 	mov	al, [ebx]
  5765 00002293 8845F9              <1> 	mov	[CMD_BLOCK+1], al
  5766 00002296 28C0                <1> 	sub	al, al
  5767 00002298 8845FB              <1> 	mov	[CMD_BLOCK+3], al ; ZERO FLAGS
  5768 0000229B E87B000000          <1> 	call	COMMAND 	  ; TELL CONTROLLER
  5769 000022A0 751E                <1> 	jnz	short INIT_EXIT	  ; CONTROLLER BUSY ERROR
  5770 000022A2 E816010000          <1> 	call	NOT_BUSY	  ; WAIT FOR IT TO BE DONE
  5771 000022A7 7517                <1> 	jnz	short INIT_EXIT	  ; TIME OUT
  5772                              <1> 	;call	CHECK_STATUS
  5773                              <1> 	;jmp	short CHECK_STATUS
  5774                              <1> ;INIT_EXIT:
  5775                              <1> 	;retn
  5776                              <1> 
  5777                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5778                              <1> 
  5779                              <1> ;----------------------------------------
  5780                              <1> ;	CHECK FIXED DISK STATUS 	:
  5781                              <1> ;----------------------------------------
  5782                              <1> CHECK_STATUS:
  5783 000022A9 E861010000          <1> 	call	CHECK_ST		; CHECK THE STATUS BYTE
  5784                              <1> 	;jnz	short CHECK_S1		; AN ERROR WAS FOUND
  5785                              <1> 	; 10/07/2022
  5786 000022AE 7510                <1> 	jnz	short CHECK_S2
  5787 000022B0 A801                <1> 	test	al, ST_ERROR		; WERE THERE ANY OTHER ERRORS
  5788 000022B2 7405                <1> 	jz	short CHECK_S1		; NO ERROR REPORTED
  5789 000022B4 E894010000          <1> 	call	CHECK_ER		; ERROR REPORTED
  5790                              <1> CHECK_S1:
  5791 000022B9 803D[AB620000]00    <1> 	cmp	byte [DISK_STATUS1], 0 	; SET STATUS FOR CALLER
  5792                              <1> CHECK_S2:
  5793                              <1> INIT_EXIT:	; 10/07/2022
  5794 000022C0 C3                  <1> 	retn
  5795                              <1> 
  5796                              <1> ;----------------------------------------
  5797                              <1> ;	TEST DISK READY      (AH = 10H) :
  5798                              <1> ;----------------------------------------
  5799                              <1> 
  5800                              <1> TST_RDY:				; WAIT FOR CONTROLLER
  5801 000022C1 E8F7000000          <1> 	call	NOT_BUSY
  5802 000022C6 751C                <1> 	jnz	short TR_EX
  5803 000022C8 8A45FD              <1> 	mov	al, [CMD_BLOCK+5] 	; SELECT DRIVE
  5804 000022CB 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5805 000022D2 80C206              <1> 	add	dl,6
  5806 000022D5 EE                  <1> 	out	dx, al
  5807 000022D6 E834010000          <1> 	call	CHECK_ST		; CHECK STATUS ONLY
  5808 000022DB 7507                <1> 	jnz	short TR_EX
  5809 000022DD C605[AB620000]00    <1> 	mov	byte [DISK_STATUS1], 0 	; WIPE OUT DATA CORRECTED ERROR
  5810                              <1> TR_EX:	
  5811 000022E4 C3                  <1> 	retn
  5812                              <1> 
  5813                              <1> ;----------------------------------------
  5814                              <1> ;	RECALIBRATE	     (AH = 11H) :
  5815                              <1> ;----------------------------------------
  5816                              <1> 
  5817                              <1> HDISK_RECAL:
  5818 000022E5 C645FE10            <1>         mov	byte [CMD_BLOCK+6], RECAL_CMD ; 10h, 16
  5819 000022E9 E82D000000          <1> 	call	COMMAND 		; START THE OPERATION
  5820 000022EE 7523                <1> 	jnz	short RECAL_EXIT	; ERROR
  5821 000022F0 E898000000          <1> 	call	_WAIT			; WAIT FOR COMPLETION
  5822 000022F5 7407                <1> 	jz	short RECAL_X 		; TIME OUT ONE OK ?
  5823 000022F7 E891000000          <1> 	call	_WAIT			; WAIT FOR COMPLETION LONGER
  5824 000022FC 7515                <1> 	jnz	short RECAL_EXIT	; TIME OUT TWO TIMES IS ERROR
  5825                              <1> RECAL_X:
  5826 000022FE E8A6FFFFFF          <1> 	call	CHECK_STATUS
  5827 00002303 803D[AB620000]40    <1> 	cmp	byte [DISK_STATUS1], BAD_SEEK ; SEEK NOT COMPLETE
  5828 0000230A 7507                <1> 	jne	short RECAL_EXIT	; IS OK
  5829 0000230C C605[AB620000]00    <1> 	mov	byte [DISK_STATUS1], 0
  5830                              <1> RECAL_EXIT:
  5831 00002313 803D[AB620000]00    <1>         cmp	byte [DISK_STATUS1], 0
  5832 0000231A C3                  <1> 	retn
  5833                              <1> 
  5834                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5835                              <1> 
  5836                              <1> ;--------------------------------------------------------
  5837                              <1> ; COMMAND						:
  5838                              <1> ;	THIS ROUTINE OUTPUTS THE COMMAND BLOCK		:
  5839                              <1> ; OUTPUT						:
  5840                              <1> ;	BL = STATUS					:
  5841                              <1> ;	BH = ERROR REGISTER				:
  5842                              <1> ;--------------------------------------------------------
  5843                              <1> 
  5844                              <1> COMMAND:
  5845                              <1> 	;push	ebx ; 10/07/2022	; WAIT FOR SEEK COMPLETE AND READY
  5846                              <1> 	;;mov	ecx, DELAY_2		; SET INITIAL DELAY BEFORE TEST
  5847                              <1> COMMAND1:
  5848                              <1> 	;;push	ecx			; SAVE LOOP COUNT
  5849 0000231B E8A1FFFFFF          <1> 	call	TST_RDY 		; CHECK DRIVE READY
  5850                              <1> 	;;pop	ecx
  5851                              <1> 	;pop	ebx ; 10/07/2022
  5852 00002320 7418                <1> 	jz	short COMMAND2		; DRIVE IS READY
  5853 00002322 803D[AB620000]80    <1>         cmp	byte [DISK_STATUS1], TIME_OUT ; TST_RDY TIMED OUT--GIVE UP
  5854                              <1> 	;jz	short CMD_TIMEOUT
  5855                              <1> 	;;loop	COMMAND1		; KEEP TRYING FOR A WHILE
  5856                              <1> 	;jmp	short COMMAND4		; ITS NOT GOING TO GET READY
  5857 00002329 7507                <1> 	jne	short COMMAND4
  5858                              <1> CMD_TIMEOUT:
  5859 0000232B C605[AB620000]20    <1> 	mov	byte [DISK_STATUS1], BAD_CNTLR
  5860                              <1> COMMAND4:
  5861                              <1> 	;;pop	ebx ; 10/07/2022
  5862 00002332 803D[AB620000]00    <1>         cmp	byte [DISK_STATUS1], 0	; SET CONDITION CODE FOR CALLER
  5863 00002339 C3                  <1> 	retn
  5864                              <1> COMMAND2:
  5865                              <1> 	;;pop	ebx ; 10/07/2022
  5866                              <1> 	;push	edi ; 10/07/2022
  5867 0000233A C605[A6620000]00    <1> 	mov	byte [HF_INT_FLAG], 0	; RESET INTERRUPT FLAG
  5868 00002341 FA                  <1> 	cli				; INHIBIT INTERRUPTS WHILE CHANGING MASK
  5869 00002342 E4A1                <1> 	in	al, INTB01		; TURN ON SECOND INTERRUPT CHIP
  5870                              <1> 	;and	al, 0BFh
  5871 00002344 243F                <1> 	and	al, 3Fh			; Enable IRQ 14 & 15
  5872                              <1> 	;JMP	$+2
  5873                              <1> 	IODELAY
  2188 00002346 EB00                <2>  jmp short $+2
  2189 00002348 EB00                <2>  jmp short $+2
  5874 0000234A E6A1                <1> 	out	INTB01, al
  5875 0000234C E421                <1> 	in	al, INTA01		; LET INTERRUPTS PASS THRU TO
  5876 0000234E 24FB                <1> 	and	al, 0FBh 		; SECOND CHIP
  5877                              <1> 	;JMP	$+2
  5878                              <1> 	IODELAY
  2188 00002350 EB00                <2>  jmp short $+2
  2189 00002352 EB00                <2>  jmp short $+2
  5879 00002354 E621                <1> 	out	INTA01, al
  5880 00002356 FB                  <1> 	sti
  5881                              <1> 	;xor	edi, edi		; INDEX THE COMMAND TABLE
  5882                              <1> 	; 10/07/2022
  5883 00002357 31C9                <1> 	xor	ecx, ecx
  5884                              <1> 	;mov	dx, HF_PORT+1		; DISK ADDRESS
  5885 00002359 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5886 00002360 FEC2                <1> 	inc	dl
  5887 00002362 F605[AD620000]C0    <1> 	test	byte [CONTROL_BYTE], 0C0h ; CHECK FOR RETRY SUPPRESSION
  5888 00002369 7411                <1> 	jz	short COMMAND3
  5889 0000236B 8A45FE              <1> 	mov	al, [CMD_BLOCK+6] 	; YES-GET OPERATION CODE
  5890 0000236E 24F0                <1> 	and	al, 0F0h 		; GET RID OF MODIFIERS
  5891 00002370 3C20                <1> 	cmp	al, 20h			; 20H-40H IS READ, WRITE, VERIFY
  5892 00002372 7208                <1> 	jb	short COMMAND3
  5893 00002374 3C40                <1> 	cmp	al, 40h
  5894 00002376 7704                <1> 	ja	short COMMAND3
  5895 00002378 804DFE01            <1> 	or	byte [CMD_BLOCK+6], NO_RETRIES 
  5896                              <1> 					; VALID OPERATION FOR RETRY SUPPRESS
  5897                              <1> COMMAND3:
  5898                              <1> 	;mov	al, [CMD_BLOCK+edi]	; GET THE COMMAND STRING BYTE
  5899                              <1> 	; 10/07/2022
  5900 0000237C 8A440DF8            <1> 	mov	al, [CMD_BLOCK+ecx]
  5901 00002380 EE                  <1> 	out	dx, al			; GIVE IT TO CONTROLLER
  5902                              <1> 	IODELAY
  2188 00002381 EB00                <2>  jmp short $+2
  2189 00002383 EB00                <2>  jmp short $+2
  5903                              <1> 	;inc	edi			; NEXT BYTE IN COMMAND BLOCK
  5904                              <1> 	; 10/07/2022
  5905 00002385 41                  <1> 	inc	ecx
  5906                              <1> 	;inc	dx			; NEXT DISK ADAPTER REGISTER
  5907 00002386 42                  <1> 	inc	edx   ; 10/07/2022	
  5908                              <1> 	;cmp	di, 7 ; 01/01/2015	; ALL DONE?
  5909                              <1> 	;jne	short COMMAND3		; NO--GO DO NEXT ONE
  5910 00002387 80F907              <1> 	cmp	cl, 7 ; 10/07/2022
  5911 0000238A 72F0                <1> 	jb	short COMMAND3
  5912                              <1> 	;pop	edi ; 10/07/2022
  5913 0000238C C3                  <1> 	retn				; ZERO FLAG IS SET
  5914                              <1> 
  5915                              <1> ;CMD_TIMEOUT:
  5916                              <1> ;	mov	byte [DISK_STATUS1], BAD_CNTLR
  5917                              <1> ;COMMAND4:
  5918                              <1> ;	pop	ebx
  5919                              <1> ;	cmp	byte [DISK_STATUS1], 0 	; SET CONDITION CODE FOR CALLER
  5920                              <1> ;	retn
  5921                              <1> 
  5922                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5923                              <1> 
  5924                              <1> ;----------------------------------------
  5925                              <1> ;	WAIT FOR INTERRUPT		:
  5926                              <1> ;----------------------------------------
  5927                              <1> ;WAIT:
  5928                              <1> _WAIT:
  5929 0000238D FB                  <1> 	sti				; MAKE SURE INTERRUPTS ARE ON
  5930                              <1> 	;sub	cx, cx			; SET INITIAL DELAY BEFORE TEST
  5931                              <1> 	;clc
  5932                              <1> 	;mov	ax, 9000h		; DEVICE WAIT INTERRUPT
  5933                              <1> 	;int	15h
  5934                              <1> 	;jc	short WT2		; DEVICE TIMED OUT
  5935                              <1> 	;mov	bl, DELAY_1		; SET DELAY COUNT
  5936                              <1> 
  5937                              <1> 	;mov	bl, WAIT_HDU_INT_HI
  5938                              <1> 	;; 21/02/2015
  5939                              <1> 	;;mov	bl, WAIT_HDU_INT_HI + 1
  5940                              <1> 	;;mov	cx, WAIT_HDU_INT_LO
  5941 0000238E B915160500          <1> 	mov	ecx, WAIT_HDU_INT_LH
  5942                              <1> 					; (AWARD BIOS -> WAIT_FOR_MEM)
  5943                              <1> ;-----	WAIT LOOP
  5944                              <1> 
  5945                              <1> WT1:	
  5946                              <1> 	;test	byte [HF_INT_FLAG], 80h	; TEST FOR INTERRUPT
  5947 00002393 F605[A6620000]C0    <1> 	test 	byte [HF_INT_FLAG], 0C0h
  5948                              <1> 	;loopz	WT1
  5949 0000239A 7512                <1> 	jnz	short WT3		; INTERRUPT--LETS GO
  5950                              <1> 	;dec	bl
  5951                              <1> 	;jnz	short WT1		; KEEP TRYING FOR A WHILE
  5952                              <1> 
  5953                              <1> WT1_hi:
  5954 0000239C E461                <1> 	in	al, SYS1 ; 61h (PORT_B)	; wait for lo to hi
  5955 0000239E A810                <1> 	test	al, 10h			; transition on memory
  5956 000023A0 75FA                <1> 	jnz	short WT1_hi		; refresh.
  5957                              <1> WT1_lo:
  5958 000023A2 E461                <1> 	in	al, SYS1 		; 061h (PORT_B)	
  5959 000023A4 A810                <1> 	test	al, 10h			
  5960 000023A6 74FA                <1> 	jz	short WT1_lo
  5961 000023A8 E2E9                <1> 	loop	WT1
  5962                              <1> 	;;or	bl, bl
  5963                              <1> 	;;jz	short WT2	
  5964                              <1> 	;;dec	bl
  5965                              <1> 	;;jmp	short WT1
  5966                              <1> 	;dec	bl
  5967                              <1> 	;jnz	short WT1	
  5968                              <1> WT2:	
  5969                              <1> 	; 10/07/2022
  5970                              <1> 	;mov	byte [DISK_STATUS1], TIME_OUT ; REPORT TIME OUT ERROR
  5971 000023AA B080                <1> 	mov	al, TIME_OUT
  5972 000023AC EB07                <1> 	jmp	short WT4
  5973                              <1> WT3:
  5974                              <1> 	;mov	byte [DISK_STATUS1], 0
  5975                              <1> 	;mov	byte [HF_INT_FLAG], 0
  5976 000023AE 28C0                <1> 	sub	al, al ; 0
  5977 000023B0 A2[A6620000]        <1> 	mov	byte [HF_INT_FLAG], al
  5978                              <1> WT4:
  5979                              <1> NB2:	
  5980 000023B5 A2[AB620000]        <1> 	mov	byte [DISK_STATUS1], al
  5981                              <1> 
  5982                              <1> 	;cmp	byte [DISK_STATUS1], 0 	; SET CONDITION CODE FOR CALLER
  5983 000023BA 20C0                <1> 	and	al, al
  5984                              <1> 	; zf = 0 -> time out, zf = 1 -> ok
  5985 000023BC C3                  <1> 	retn
  5986                              <1> 
  5987                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  5988                              <1> 
  5989                              <1> ;----------------------------------------
  5990                              <1> ;	WAIT FOR CONTROLLER NOT BUSY	:
  5991                              <1> ;----------------------------------------
  5992                              <1> NOT_BUSY:
  5993 000023BD FB                  <1> 	sti				; MAKE SURE INTERRUPTS ARE ON
  5994                              <1> 	;push	ebx
  5995                              <1> 	;sub	cx, cx			; SET INITIAL DELAY BEFORE TEST
  5996 000023BE 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  5997 000023C5 80C207              <1> 	add	dl, 7			; Status port (HF_PORT+7)
  5998                              <1> 	;mov	bl, DELAY_1
  5999                              <1> 					; wait for 10 seconds
  6000                              <1> 	;mov 	cx, WAIT_HDU_INT_LO	; 1615h
  6001                              <1> 	;;mov 	bl, WAIT_HDU_INT_HI	;   05h
  6002                              <1> 	;mov	bl, WAIT_HDU_INT_HI + 1
  6003 000023C8 B915160500          <1> 	mov	ecx, WAIT_HDU_INT_LH  ; 21/02/2015
  6004                              <1> 	;
  6005                              <1> 	;;mov	byte [wait_count], 0    ; Reset wait counter
  6006                              <1> NB1:	
  6007 000023CD EC                  <1> 	in	al, dx			; CHECK STATUS
  6008                              <1> 	;test	al, ST_BUSY
  6009 000023CE 2480                <1> 	and	al, ST_BUSY
  6010                              <1> 	;loopnz NB1
  6011 000023D0 74E3                <1> 	jz	short NB2 ; al = 0	; NOT BUSY--LETS GO
  6012                              <1> 	;dec	bl			
  6013                              <1> 	;jnz	short NB1		; KEEP TRYING FOR A WHILE
  6014                              <1> 
  6015                              <1> NB1_hi: 
  6016 000023D2 E461                <1> 	in	al, SYS1		; wait for hi to lo
  6017 000023D4 A810                <1> 	test	al, 010h		; transition on memory
  6018 000023D6 75FA                <1> 	jnz	short NB1_hi		; refresh.
  6019                              <1> NB1_lo: 
  6020 000023D8 E461                <1> 	in	al, SYS1
  6021 000023DA A810                <1> 	test	al, 010h
  6022 000023DC 74FA                <1> 	jz	short NB1_lo
  6023 000023DE E2ED                <1> 	loop	NB1
  6024                              <1> 	;dec	bl
  6025                              <1> 	;jnz	short NB1
  6026                              <1> 	;
  6027                              <1> 	;;cmp	byte [wait_count], 182  ; 10 seconds (182 timer ticks)
  6028                              <1> 	;;jb	short NB1
  6029                              <1> 	;
  6030                              <1> 	;mov	byte [DISK_STATUS1], TIME_OUT ; REPORT TIME OUT ERROR
  6031                              <1> 	;jmp	short NB3
  6032 000023E0 B080                <1> 	mov	al, TIME_OUT
  6033                              <1> ;NB2:	
  6034 000023E2 EBD1                <1> 	jmp	short NB2 ; 10/07/2022
  6035                              <1> 
  6036                              <1> ;	;mov	byte [DISK_STATUS1], 0
  6037                              <1> ;;NB3:	
  6038                              <1> ;	;pop	ebx
  6039                              <1> ;	mov	[DISK_STATUS1], al	;;; will be set after return
  6040                              <1> ;	;cmp	byte [DISK_STATUS1], 0 	; SET CONDITION CODE FOR CALLER
  6041                              <1> ;	or	al, al			; (zf = 0 --> timeout)
  6042                              <1> ;	retn
  6043                              <1> 
  6044                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  6045                              <1> 
  6046                              <1> ;----------------------------------------
  6047                              <1> ;	WAIT FOR DATA REQUEST		:
  6048                              <1> ;----------------------------------------
  6049                              <1> WAIT_DRQ:
  6050                              <1> 	;mov	cx, DELAY_3
  6051                              <1> 	;mov	dx, HF_PORT+7
  6052 000023E4 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  6053 000023EB 80C207              <1> 	add	dl, 7
  6054                              <1> 	;;mov	bl, WAIT_HDU_DRQ_HI	; 0
  6055                              <1> 	;mov	cx, WAIT_HDU_DRQ_LO	; 1000 (30 milli seconds)
  6056                              <1> 					; (but it is written as 2000
  6057                              <1> 					; micro seconds in ATORGS.ASM file
  6058                              <1> 					; of Award Bios - 1999, D1A0622)
  6059 000023EE B9E8030000          <1> 	mov 	ecx, WAIT_HDU_DRQ_LH ; 21/02/2015 
  6060                              <1> WQ_1:
  6061 000023F3 EC                  <1> 	in	al, dx			; GET STATUS
  6062 000023F4 A808                <1> 	test	al, ST_DRQ		; WAIT FOR DRQ
  6063 000023F6 7516                <1> 	jnz	short WQ_OK
  6064                              <1> 	;loop	WQ_1			; KEEP TRYING FOR A SHORT WHILE
  6065                              <1> WQ_hi:	
  6066 000023F8 E461                <1> 	in	al, SYS1		; wait for hi to lo
  6067 000023FA A810                <1> 	test	al, 010h		; transition on memory
  6068 000023FC 75FA                <1> 	jnz	short WQ_hi		; refresh.
  6069                              <1> WQ_lo:  
  6070 000023FE E461                <1> 	in	al, SYS1
  6071 00002400 A810                <1> 	test	al, 010h
  6072 00002402 74FA                <1> 	jz	short WQ_lo
  6073 00002404 E2ED                <1> 	loop	WQ_1
  6074                              <1> 
  6075 00002406 C605[AB620000]80    <1> 	mov	byte [DISK_STATUS1], TIME_OUT ; ERROR
  6076 0000240D F9                  <1> 	stc
  6077                              <1> WQ_OK:
  6078 0000240E C3                  <1> 	retn
  6079                              <1> ;WQ_OK:
  6080                              <1> 	;clc
  6081                              <1> 	;retn
  6082                              <1> 
  6083                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  6084                              <1> 
  6085                              <1> ;----------------------------------------
  6086                              <1> ;	CHECK FIXED DISK STATUS BYTE	:
  6087                              <1> ;----------------------------------------
  6088                              <1> CHECK_ST:
  6089                              <1> 	;mov	dx, HF_PORT+7		; GET THE STATUS
  6090 0000240F 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]
  6091 00002416 80C207              <1> 	add	dl, 7
  6092 00002419 EC                  <1> 	in	al, dx
  6093 0000241A A2[A5620000]        <1> 	mov	[HF_STATUS], al
  6094                              <1> 	;mov	ah, 0
  6095 0000241F 28E4                <1> 	sub	ah, ah ; 0
  6096 00002421 A880                <1> 	test	al, ST_BUSY		; IF STILL BUSY
  6097 00002423 751A                <1> 	jnz	short CKST_EXIT		; REPORT OK
  6098 00002425 B4CC                <1> 	mov	ah, WRITE_FAULT
  6099 00002427 A820                <1> 	test 	al, ST_WRT_FLT		; CHECK FOR WRITE FAULT
  6100 00002429 7514                <1> 	jnz	short CKST_EXIT
  6101 0000242B B4AA                <1> 	mov	ah, NOT_RDY
  6102 0000242D A840                <1> 	test	al, ST_READY		; CHECK FOR NOT READY
  6103 0000242F 740E                <1> 	jz	short CKST_EXIT
  6104 00002431 B440                <1> 	mov	ah, BAD_SEEK
  6105 00002433 A810                <1> 	test	al, ST_SEEK_COMPL	; CHECK FOR SEEK NOT COMPLETE
  6106 00002435 7408                <1> 	jz	short CKST_EXIT
  6107 00002437 B411                <1> 	mov	ah, DATA_CORRECTED
  6108 00002439 A804                <1> 	test	al, ST_CORRCTD		; CHECK FOR CORRECTED ECC
  6109 0000243B 7502                <1> 	jnz	short CKST_EXIT
  6110                              <1> 	;mov	ah, 0
  6111 0000243D 30E4                <1> 	xor	ah, ah ; 0
  6112                              <1> CKST_EXIT:
  6113 0000243F 8825[AB620000]      <1> 	mov	[DISK_STATUS1], ah	; SET ERROR FLAG
  6114 00002445 80FC11              <1> 	cmp	ah, DATA_CORRECTED	; KEEP GOING WITH DATA CORRECTED
  6115 00002448 7402                <1> 	je	short CKST_EX1
  6116                              <1> 	;cmp	ah, 0
  6117 0000244A 20E4                <1> 	and	ah, ah
  6118                              <1> CKST_EX1:
  6119 0000244C C3                  <1> 	retn
  6120                              <1> 
  6121                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  6122                              <1> 
  6123                              <1> ;----------------------------------------
  6124                              <1> ;	CHECK FIXED DISK ERROR REGISTER :
  6125                              <1> ;----------------------------------------
  6126                              <1> CHECK_ER:
  6127                              <1> 	;mov	dx, HF_PORT+1		; GET THE ERROR REGISTER
  6128 0000244D 668B15[325D0000]    <1> 	mov	dx, [HF_PORT]		;
  6129 00002454 FEC2                <1> 	inc	dl
  6130 00002456 EC                  <1> 	in	al, dx
  6131                              <1> 	; 10/07/2022
  6132                              <1> 	;mov	[HF_ERROR], al
  6133                              <1> 	;push	ebx	; 21/02/2015
  6134 00002457 29C9                <1> 	sub	ecx, ecx
  6135                              <1> 	;mov	ecx, 8			; TEST ALL 8 BITS
  6136 00002459 B108                <1> 	mov	cl, 8
  6137                              <1> CK1:	
  6138 0000245B D0E0                <1> 	shl	al, 1			; MOVE NEXT ERROR BIT TO CARRY
  6139 0000245D 7202                <1> 	jc	short CK2		; FOUND THE ERROR
  6140 0000245F E2FA                <1> 	loop	CK1			; KEEP TRYING
  6141                              <1> CK2:
  6142                              <1> 	;mov	ebx, ERR_TBL		; COMPUTE ADDRESS OF
  6143                              <1> 	;add	ebx, ecx		; ERROR CODE
  6144 00002461 81C1[285D0000]      <1> 	add	ecx, ERR_TBL ; 10/07/2022	
  6145                              <1> 
  6146                              <1> 	;;;mov	ah, byte [cs:bx]	; GET ERROR CODE
  6147                              <1> 	;;mov	ah, [bx]
  6148                              <1> 	;mov	ah, [ebx] ; 21/02/2015
  6149 00002467 8A21                <1> 	mov	ah, [ecx]	
  6150                              <1> CKEX:
  6151 00002469 8825[AB620000]      <1> 	mov	[DISK_STATUS1], ah	; SAVE ERROR CODE
  6152                              <1> 	; 10/07/2022
  6153                              <1> 	;pop	ebx
  6154                              <1> 	;;cmp	ah, 0
  6155                              <1> 	;and	ah, ah
  6156 0000246F C3                  <1> 	retn
  6157                              <1> 
  6158                              <1> ;--------------------------------------------------------
  6159                              <1> ; CHECK_DMA						:
  6160                              <1> ;  -CHECK ES:BX AND # SECTORS TO MAKE SURE THAT IT WILL :
  6161                              <1> ;   FIT WITHOUT SEGMENT OVERFLOW.			:
  6162                              <1> ;  -ES:BX HAS BEEN REVISED TO THE FORMAT SSSS:000X	:
  6163                              <1> ;  -OK IF # SECTORS < 80H (7FH IF LONG READ OR WRITE)	:
  6164                              <1> ;  -OK IF # SECTORS = 80H (7FH) AND BX <= 00H (04H)	:
  6165                              <1> ;  -ERROR OTHERWISE					:
  6166                              <1> ;--------------------------------------------------------
  6167                              <1> 
  6168                              <1> 	; 11/07/2022
  6169                              <1> 	; (not needed for hard disks and 32 bit OS)
  6170                              <1> 	;
  6171                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  6172                              <1> ;CHECK_DMA:
  6173                              <1> ;	;;push	ax			; SAVE REGISTERS
  6174                              <1> ;	;; 24/12/2021
  6175                              <1> ;	;;push	eax
  6176                              <1> ;	;mov	ax, 8000h		; AH = MAX # SECTORS
  6177                              <1> ;					; AL = MAX OFFSET
  6178                              <1> ;	; 10/07/2022
  6179                              <1> ;	;test	byte [CMD_BLOCK+6], ECC_MODE
  6180                              <1> ;	;jz	short CKD1
  6181                              <1> ;	;mov	ax, 7F04h		; ECC IS 4 MORE BYTES
  6182                              <1> ;CKD1:	
  6183                              <1> ;	;cmp	ah, [CMD_BLOCK+1]	; NUMBER OF SECTORS
  6184                              <1> ;	;ja	short CKDOK		; IT WILL FIT
  6185                              <1> ;	;jb	short CKDERR		; TOO MANY
  6186                              <1> ;	
  6187                              <1> ;	cmp	byte [CMD_BLOCK+1], 80h
  6188                              <1> ;	jb	short CKDOK
  6189                              <1> ;	ja	short CKDERR
  6190                              <1> ;	;cmp	al, bl			; CHECK OFFSET ON MAX SECTORS
  6191                              <1> ;	;jb	short CKDERR		; ERROR
  6192                              <1> ;CKD2:
  6193                              <1> ;	or	bl, bl
  6194                              <1> ;	jz	short CKDR
  6195                              <1> ;	
  6196                              <1> ;;CKDOK:	
  6197                              <1> ;	;clc				; CLEAR CARRY
  6198                              <1> ;	;;pop	ax
  6199                              <1> ;	;; 24/12/2021
  6200                              <1> ;	;pop	eax
  6201                              <1> ;	;retn				; NORMAL RETURN
  6202                              <1> ;CKDERR: 
  6203                              <1> ;	stc				; INDICATE ERROR
  6204                              <1> ;	mov	byte [DISK_STATUS1], DMA_BOUNDARY
  6205                              <1> ;	;;pop	ax
  6206                              <1> ;	;; 24/12/2021
  6207                              <1> ;	;pop	eax	
  6208                              <1> ;	retn
  6209                              <1> ;
  6210                              <1> ;	; 10/07/2022
  6211                              <1> ;CKDOK:
  6212                              <1> ;	clc
  6213                              <1> ;CKDR:
  6214                              <1> ;	retn
  6215                              <1> 
  6216                              <1> ;----------------------------------------
  6217                              <1> ;	SET UP EBX-> DISK PARMS	        :
  6218                              <1> ;----------------------------------------
  6219                              <1> 					
  6220                              <1> ; INPUT -> DL = 0 based drive number
  6221                              <1> ; OUTPUT -> EBX = disk parameter table address
  6222                              <1> 
  6223                              <1> 	; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  6224                              <1> 
  6225                              <1> GET_VEC:
  6226                              <1> 	;sub	ax, ax			; GET DISK PARAMETER ADDRESS
  6227                              <1> 	;mov	es, ax
  6228                              <1> 	;test	dl, 1
  6229                              <1> 	;jz	short GV_0
  6230                              <1> ;	les	bx, [HF1_TBL_VEC] 	; ES:BX -> DRIVE PARAMETERS
  6231                              <1> ;	jmp	short GV_EXIT
  6232                              <1> ;GV_0:
  6233                              <1> ;	les 	bx,[HF_TBL_VEC]		; ES:BX -> DRIVE PARAMETERS
  6234                              <1> ;
  6235 00002470 31DB                <1> 	xor	ebx, ebx
  6236 00002472 88D3                <1> 	mov	bl, dl
  6237                              <1> 	;02/01/2015
  6238                              <1> 	;xor	bh, bh
  6239                              <1> 	;shl	bl, 1			; port address offset
  6240                              <1> 	;mov	ax, [bx+hd_ports]	; Base port address (1F0h, 170h)
  6241                              <1> 	;shl	bl, 1			; dpt pointer offset
  6242 00002474 C0E302              <1> 	shl	bl, 2
  6243                              <1> 	;add	bx, HF_TBL_VEC		; Disk parameter table pointer
  6244 00002477 81C3[B0620000]      <1> 	add	ebx, HF_TBL_VEC ; 21/02/2015
  6245                              <1> 	;push	word [bx+2]		; dpt segment
  6246                              <1> 	;pop	es
  6247                              <1> 	;mov	bx, [bx]		; dpt offset
  6248 0000247D 8B1B                <1> 	mov	ebx, [ebx]		
  6249                              <1> ;GV_EXIT:
  6250 0000247F C3                  <1> 	retn
  6251                              <1> 
  6252                              <1> 	; 24/12/2021 - Retro UNIX 386 v1.1
  6253                              <1> hdc1_int: ; 21/02/2015
  6254                              <1> ;--- HARDWARE INT 76H -- ( IRQ LEVEL  14 ) ----------------------
  6255                              <1> ;								:
  6256                              <1> ;	FIXED DISK INTERRUPT ROUTINE				:
  6257                              <1> ;								:
  6258                              <1> ;----------------------------------------------------------------
  6259                              <1> 
  6260                              <1> ; 22/12/2014
  6261                              <1> ; IBM PC-XT Model 286 System BIOS Source Code - DISK.ASM (HD_INT)
  6262                              <1> ;	 '11/15/85'
  6263                              <1> ; AWARD BIOS 1999 (D1A0622) 
  6264                              <1> ;	Source Code - ATORGS.ASM (INT_HDISK, INT_HDISK1)
  6265                              <1> 
  6266                              <1> ;int_76h:
  6267                              <1> HD_INT:
  6268                              <1> 	;push	ax
  6269                              <1> 	; 24/12/2021
  6270 00002480 50                  <1> 	push	eax
  6271 00002481 1E                  <1> 	push	ds
  6272                              <1> 	;CALL	DDS
  6273                              <1> 	; 21/02/2015 (32 bit, 386 pm modification)
  6274 00002482 66B81000            <1> 	mov	ax, KDATA
  6275 00002486 8ED8                <1> 	mov 	ds, ax
  6276                              <1> 	;
  6277                              <1> 	;;MOV	@HF_INT_FLAG, 0FFH	; ALL DONE
  6278                              <1>         ;mov     byte [CS:HF_INT_FLAG], 0FFh
  6279 00002488 C605[A6620000]FF    <1> 	mov	byte [HF_INT_FLAG], 0FFh
  6280                              <1> 	;
  6281                              <1> 	;push	dx
  6282                              <1> 	; 24/12/2021
  6283 0000248F 52                  <1> 	push	edx
  6284 00002490 66BAF701            <1> 	mov	dx, HDC1_BASEPORT+7	; Status Register (1F7h)
  6285                              <1> 					; Clear Controller
  6286                              <1> Clear_IRQ1415:				; (Award BIOS - 1999)
  6287 00002494 EC                  <1> 	in	al, dx			;
  6288                              <1> 	;pop	dx
  6289                              <1> 	; 24/12/2021
  6290 00002495 5A                  <1> 	pop	edx
  6291                              <1> 	NEWIODELAY
  2193 00002496 E6EB                <2>  out 0EBh,al
  6292                              <1> 	;
  6293 00002498 B020                <1> 	mov	al, EOI			; NON-SPECIFIC END OF INTERRUPT
  6294 0000249A E6A0                <1> 	out	INTB00, al		; FOR CONTROLLER #2
  6295                              <1> 	;JMP	$+2			; WAIT
  6296                              <1> 	NEWIODELAY
  2193 0000249C E6EB                <2>  out 0EBh,al
  6297 0000249E E620                <1> 	out	INTA00, al		; FOR CONTROLLER #1
  6298 000024A0 1F                  <1> 	pop	ds
  6299                              <1> 	;sti				; RE-ENABLE INTERRUPTS
  6300                              <1> 	;mov	ax, 9100h		; DEVICE POST
  6301                              <1> 	;int	15h			; INTERRUPT
  6302                              <1> irq15_iret: ; 25/02/2015
  6303                              <1> 	;pop	ax
  6304                              <1> 	; 24/12/2021
  6305 000024A1 58                  <1> 	pop	eax
  6306 000024A2 CF                  <1> 	iretd				; RETURN FROM INTERRUPT
  6307                              <1> 
  6308                              <1> 	; 24/12/2021 - Retro UNIX 386 v1.1
  6309                              <1> hdc2_int: ; 21/02/2015
  6310                              <1> ;--- HARDWARE INT 77H ++ ( IRQ LEVEL  15 ) ----------------------
  6311                              <1> ;								:
  6312                              <1> ;	FIXED DISK INTERRUPT ROUTINE				:
  6313                              <1> ;								:
  6314                              <1> ;----------------------------------------------------------------
  6315                              <1> 
  6316                              <1> ;int_77h:
  6317                              <1> HD1_INT:
  6318                              <1> 	;push	ax
  6319                              <1> 	; 24/12/2021
  6320 000024A3 50                  <1> 	push	eax
  6321                              <1> 	; Check if that is a spurious IRQ (from slave PIC)
  6322                              <1> 	; 25/02/2015 (source: http://wiki.osdev.org/8259_PIC)
  6323 000024A4 B00B                <1> 	mov	al, 0Bh  ; In-Service Register
  6324 000024A6 E6A0                <1> 	out	0A0h, al
  6325 000024A8 EB00                <1>         jmp short $+2
  6326 000024AA EB00                <1> 	jmp short $+2
  6327 000024AC E4A0                <1> 	in	al, 0A0h
  6328 000024AE 2480                <1> 	and 	al, 80h ; bit 7 (is it real IRQ 15 or fake?)
  6329 000024B0 74EF                <1> 	jz	short irq15_iret ; Fake (spurious)IRQ, do not send EOI)
  6330                              <1> 	;
  6331 000024B2 1E                  <1> 	push	ds
  6332                              <1> 	;CALL	DDS
  6333                              <1> 	; 21/02/2015 (32 bit, 386 pm modification)
  6334 000024B3 66B81000            <1> 	mov	ax, KDATA
  6335 000024B7 8ED8                <1> 	mov 	ds, ax
  6336                              <1> 	;
  6337                              <1> 	;;MOV	@HF_INT_FLAG,0FFH	; ALL DONE
  6338                              <1>         ;or	byte [CS:HF_INT_FLAG], 0C0h 
  6339 000024B9 800D[A6620000]C0    <1> 	or	byte [HF_INT_FLAG], 0C0h
  6340                              <1> 	;
  6341                              <1> 	;push	dx
  6342                              <1> 	; 24/12/2021
  6343 000024C0 52                  <1> 	push	edx
  6344 000024C1 66BA7701            <1> 	mov	dx, HDC2_BASEPORT+7	; Status Register (177h)
  6345                              <1> 					; Clear Controller (Award BIOS 1999)
  6346 000024C5 EBCD                <1> 	jmp	short Clear_IRQ1415
  6347                              <1> 
  6348                              <1> ;%include 'diskdata.inc' ; 11/03/2015
  6349                              <1> ;%include 'diskbss.inc' ; 11/03/2015
  6350                              <1> 
  6351                              <1> ;////////////////////////////////////////////////////////////////////
  6352                              <1> ;; END OF DISK I/O SYTEM ///
  2108                                  %include 'memory.inc'  ; 09/03/2015
  2109                              <1> ; MEMORY.ASM - Retro UNIX 386 v1.1 MEMORY MANAGEMENT FUNCTIONS (PROCEDURES)
  2110                              <1> ; Retro UNIX 386 v1.1 Kernel (unix386.s, v0.2.1.6) - MEMORY.INC
  2111                              <1> ; Last Modification: 17/07/2022
  2112                              <1> ;
  2113                              <1> ; Source code for NASM - Netwide Assembler (2.15)
  2114                              <1> 
  2115                              <1> ; ///////// MEMORY MANAGEMENT FUNCTIONS (PROCEDURES) ///////////////
  2116                              <1> 
  2117                              <1> ;;04/11/2014 (unix386.s)	
  2118                              <1> ;PDE_A_PRESENT	equ 1		; Present flag for PDE
  2119                              <1> ;PDE_A_WRITE	equ 2		; Writable (write permission) flag
  2120                              <1> ;PDE_A_USER	equ 4		; User (non-system/kernel) page flag
  2121                              <1> ;;
  2122                              <1> ;PTE_A_PRESENT	equ 1		; Present flag for PTE (bit 0)
  2123                              <1> ;PTE_A_WRITE	equ 2		; Writable (write permission) flag (bit 1)
  2124                              <1> ;PTE_A_USER	equ 4		; User (non-system/kernel) page flag (bit 2)
  2125                              <1> ;PTE_A_ACCESS   equ 32		; Accessed flag (bit 5) ; 09/03/2015
  2126                              <1> 
  2127                              <1> ; 27/04/2015
  2128                              <1> ; 09/03/2015
  2129                              <1> PAGE_SIZE 	equ 4096	; page size in bytes
  2130                              <1> PAGE_SHIFT 	equ 12		; page table shift count
  2131                              <1> PAGE_D_SHIFT 	equ 22 ; 12+10	; page directory shift count
  2132                              <1> PAGE_OFF	equ 0FFFh	; 12 bit byte offset in page frame
  2133                              <1> PTE_MASK 	equ 03FFh	; page table entry mask
  2134                              <1> PTE_DUPLICATED  equ 200h	; duplicated page sign (AVL bit 0)
  2135                              <1> PDE_A_CLEAR	equ 0F000h	; to clear PDE attribute bits
  2136                              <1> PTE_A_CLEAR	equ 0F000h	; to clear PTE attribute bits
  2137                              <1> LOGIC_SECT_SIZE equ 512		; logical sector size
  2138                              <1> ERR_MAJOR_PF	equ 0E0h	; major error: page fault
  2139                              <1> ; 15/10/2016 (TRDOS 386 v2)
  2140                              <1> ERR_MINOR_IM	equ 4 ;15/10/2016 (1->4); insufficient (out of) memory
  2141                              <1> ERR_MINOR_PV	equ 6 ;15/10/2016 (3->6); protection violation
  2142                              <1> SWP_DISK_READ_ERR 	   equ 40
  2143                              <1> SWP_DISK_NOT_PRESENT_ERR   equ 41
  2144                              <1> SWP_SECTOR_NOT_PRESENT_ERR equ 42
  2145                              <1> SWP_NO_FREE_SPACE_ERR      equ 43
  2146                              <1> SWP_DISK_WRITE_ERR         equ 44
  2147                              <1> SWP_NO_PAGE_TO_SWAP_ERR    equ 45
  2148                              <1> PTE_A_ACCESS_BIT equ 5	; Bit 5 (accessed flag)        
  2149                              <1> SECTOR_SHIFT     equ 3	; sector shift (to convert page block number)
  2150                              <1> ; 10/06/2021 (Retro UNIX 386 v2)
  2151                              <1> ; 12/07/2016 (TRDOS 386 v2) 
  2152                              <1> PTE_SHARED	 equ 400h		; AVL bit 1, direct memory access bit	
  2153                              <1> 					; (Indicates that the page is not allocated
  2154                              <1> 					; for the process, it is a shared or system
  2155                              <1>                                         ; page, it must not be deallocated!)
  2156                              <1> ; 14/12/2020
  2157                              <1> ; (Linear Frame Buffer - video memory mark : AVL bit 1, outside M.A.T.)
  2158                              <1> PDE_EXTERNAL	equ 400h	; Page directory entry for external memory blocks
  2159                              <1> PTE_EXTERNAL	equ 400h	; Allocated kernel pages for Linear Frame Buffer
  2160                              <1> 				; (Out of memory allocation table)	
  2161                              <1> ;
  2162                              <1> ;; Retro Unix 386 v1 - paging method/principles
  2163                              <1> ;;
  2164                              <1> ;; 10/10/2014
  2165                              <1> ;; RETRO UNIX 386 v1 - PAGING METHOD/PRINCIPLES
  2166                              <1> ;;
  2167                              <1> ;; KERNEL PAGE MAP: 1 to 1 physical memory page map
  2168                              <1> ;;	(virtual address = physical address)
  2169                              <1> ;; KERNEL PAGE TABLES:
  2170                              <1> ;;	Kernel page directory and all page tables are
  2171                              <1> ;;	on memory as initialized, as equal to physical memory
  2172                              <1> ;;	layout. Kernel pages can/must not be swapped out/in.
  2173                              <1> ;;
  2174                              <1> ;;	what for: User pages may be swapped out, when accessing
  2175                              <1> ;;	a page in kernel/system mode, if it would be swapped out,
  2176                              <1> ;;	kernel would have to swap it in! But it is also may be
  2177                              <1> ;;	in use by a user process. (In system/kernel mode
  2178                              <1> ;;	kernel can access all memory pages even if they are
  2179                              <1> ;;	reserved/allocated for user processes. Swap out/in would
  2180                              <1> ;;	cause conflicts.) 
  2181                              <1> ;;	
  2182                              <1> ;;	As result of these conditions,
  2183                              <1> ;;	all kernel pages must be initialized as equal to 
  2184                              <1> ;;	physical layout for preventing page faults. 
  2185                              <1> ;;	Also, calling "allocate page" procedure after
  2186                              <1> ;;	a page fault can cause another page fault (double fault)
  2187                              <1> ;;	if all kernel page tables would not be initialized.
  2188                              <1> ;;
  2189                              <1> ;;	[first_page] = Beginning of users space, as offset to 
  2190                              <1> ;;	memory allocation table. (double word aligned)
  2191                              <1> ;;
  2192                              <1> ;;	[next_page] = first/next free space to be searched
  2193                              <1> ;;	as offset to memory allocation table. (dw aligned)
  2194                              <1> ;;
  2195                              <1> ;;	[last_page] = End of memory (users space), as offset
  2196                              <1> ;;	to memory allocation table. (double word aligned)
  2197                              <1> ;;
  2198                              <1> ;; USER PAGE TABLES:
  2199                              <1> ;;	Demand paging (& 'copy on write' allocation method) ...
  2200                              <1> ;;		'ready only' marked copies of the 
  2201                              <1> ;;		parent process's page table entries (for
  2202                              <1> ;;		same physical memory).
  2203                              <1> ;;		(A page will be copied to a new page after
  2204                              <1> ;;		 if it causes R/W page fault.)
  2205                              <1> ;;
  2206                              <1> ;;	Every user process has own (different)
  2207                              <1> ;;	page directory and page tables.	
  2208                              <1> ;;
  2209                              <1> ;;	Code starts at virtual address 0, always.
  2210                              <1> ;;	(Initial value of EIP is 0 in user mode.)
  2211                              <1> ;;	(Programs can be written/developed as simple
  2212                              <1> ;;	 flat memory programs.)
  2213                              <1> ;;
  2214                              <1> ;; MEMORY ALLOCATION STRATEGY:
  2215                              <1> ;;	Memory page will be allocated by kernel only 
  2216                              <1> ;;		(in kernel/system mode only).
  2217                              <1> ;;	* After a
  2218                              <1> ;;	  - 'not present' page fault
  2219                              <1> ;;	  - 'writing attempt on read only page' page fault 	 	
  2220                              <1> ;;	* For loading (opening, reading) a file or disk/drive
  2221                              <1> ;;	* As responce to 'allocate additional memory blocks' 
  2222                              <1> ;;	  request by running process.
  2223                              <1> ;;	* While creating a process, allocating a new buffer,
  2224                              <1> ;;	  new page tables etc.
  2225                              <1> ;;
  2226                              <1> ;;	At first,
  2227                              <1> ;;	- 'allocate page' procedure will be called;
  2228                              <1> ;,	   if it will return with a valid (>0) physical address
  2229                              <1> ;;	   (that means the relevant M.A.T. bit has been RESET)	
  2230                              <1> ;;	   relevant memory page/block will be cleared (zeroed).
  2231                              <1> ;;	- 'allocate page' will be called for allocating page
  2232                              <1> ;;	   directory, page table and running space (data/code).
  2233                              <1> ;;	- every successful 'allocate page' call will decrease
  2234                              <1> ;;	  'free_pages' count (pointer).
  2235                              <1> ;;	- 'out of (insufficient) memory error' will be returned
  2236                              <1> ;;	  if 'free_pages' points to a ZERO.
  2237                              <1> ;;	- swapping out and swapping in (if it is not a new page)
  2238                              <1> ;;	  procedures will be called as responce to 'out of memory'
  2239                              <1> ;;	  error except errors caused by attribute conflicts.
  2240                              <1> ;;	 (swapper functions)	 
  2241                              <1> ;;					
  2242                              <1> ;;	At second,
  2243                              <1> ;;	- page directory entry will be updated then page table
  2244                              <1> ;;	  entry will be updated.		
  2245                              <1> ;;
  2246                              <1> ;; MEMORY ALLOCATION TABLE FORMAT:
  2247                              <1> ;;	- M.A.T. has a size according to available memory as
  2248                              <1> ;;	  follows:
  2249                              <1> ;;		  - 1 (allocation) bit per 1 page (4096 bytes)
  2250                              <1> ;;		  - a bit with value of 0 means allocated page
  2251                              <1> ;;		  - a bit with value of 1 means a free page
  2252                              <1> ;,	- 'free_pages' pointer holds count of free pages
  2253                              <1> ;;	  depending on M.A.T.
  2254                              <1> ;;		(NOTE: Free page count will not be checked
  2255                              <1> ;;		again -on M.A.T.- after initialization. 
  2256                              <1> ;;		Kernel will trust on initial count.)
  2257                              <1> ;,	- 'free_pages' count will be decreased by allocation
  2258                              <1> ;;	  and it will be increased by deallocation procedures.
  2259                              <1> ;;	
  2260                              <1> ;;	- Available memory will be calculated during
  2261                              <1> ;;	  the kernel's initialization stage (in real mode).
  2262                              <1> ;;	  Memory allocation table and kernel page tables 
  2263                              <1> ;;	  will be formatted/sized as result of available
  2264                              <1> ;;	  memory calculation before paging is enabled.
  2265                              <1> ;;
  2266                              <1> ;; For 4GB Available/Present Memory: (max. possible memory size)
  2267                              <1> ;;	- Memory Allocation Table size will be 128 KB.
  2268                              <1> ;;	- Memory allocation for kernel page directory size 
  2269                              <1> ;;	  is always 4 KB. (in addition to total allocation size
  2270                              <1> ;;	  for page tables)
  2271                              <1> ;;	- Memory allocation for kernel page tables (1024 tables)
  2272                              <1> ;;	  is 4 MB (1024*4*1024 bytes).
  2273                              <1> ;;	- User (available) space will be started 
  2274                              <1> ;;	  at 6th MB of the memory (after 1MB+4MB).
  2275                              <1> ;;	- The first 640 KB is for kernel's itself plus
  2276                              <1> ;;	  memory allocation table and kernel's page directory
  2277                              <1> ;;	  (D0000h-EFFFFh may be used as kernel space...)	
  2278                              <1> ;;	- B0000h to B7FFFh address space (32 KB) will be used
  2279                              <1> ;; 	  for buffers.
  2280                              <1> ;;	- ROMBIOS, VIDEO BUFFER and VIDEO ROM space are reserved.
  2281                              <1> ;,	  (A0000h-AFFFFh, C0000h-CFFFFh, F0000h-FFFFFh)
  2282                              <1> ;;	- Kernel page tables start at 100000h (2nd MB)
  2283                              <1> ;;
  2284                              <1> ;; For 1GB Available Memory:
  2285                              <1> ;;	- Memory Allocation Table size will be 32 KB.
  2286                              <1> ;;	- Memory allocation for kernel page directory size 
  2287                              <1> ;;	  is always 4 KB. (in addition to total allocation size
  2288                              <1> ;;	  for page tables)
  2289                              <1> ;;	- Memory allocation for kernel page tables (256 tables)
  2290                              <1> ;;	  is 1 MB (256*4*1024 bytes).
  2291                              <1> ;;	- User (available) space will be started 
  2292                              <1> ;;	  at 3th MB of the memory (after 1MB+1MB).
  2293                              <1> ;;	- The first 640 KB is for kernel's itself plus
  2294                              <1> ;;	  memory allocation table and kernel's page directory
  2295                              <1> ;;	  (D0000h-EFFFFh may be used as kernel space...)	
  2296                              <1> ;;	- B0000h to B7FFFh address space (32 KB) will be used
  2297                              <1> ;; 	  for buffers.
  2298                              <1> ;;	- ROMBIOS, VIDEO BUFFER and VIDEO ROM space are reserved.
  2299                              <1> ;,	  (A0000h-AFFFFh, C0000h-CFFFFh, F0000h-FFFFFh)
  2300                              <1> ;;	- Kernel page tables start at 100000h (2nd MB).	
  2301                              <1> ;;
  2302                              <1> ;;
  2303                              <1> 
  2304                              <1> ;;************************************************************************************
  2305                              <1> ;; 
  2306                              <1> ;; RETRO UNIX 386 v1 - Paging (Method for Copy On Write paging principle)
  2307                              <1> ;; DEMAND PAGING - PARENT&CHILD PAGE TABLE DUPLICATION PRINCIPLES (23/04/2015)
  2308                              <1> 
  2309                              <1> ;; Main factor: "sys fork" system call 
  2310                              <1> ;;	
  2311                              <1> ;; 		FORK
  2312                              <1> ;;                      |----> parent - duplicated PTEs, read only pages
  2313                              <1> ;;  writable pages ---->|
  2314                              <1> ;;                      |----> child - duplicated PTEs, read only pages
  2315                              <1> ;; 
  2316                              <1> ;; AVL bit (0) of Page Table Entry is used as duplication sign 
  2317                              <1> ;; 
  2318                              <1> ;; AVL Bit 0 [PTE Bit 9] = 'Duplicated PTE belongs to child' sign/flag (if it is set)
  2319                              <1> ;; Note: Dirty bit (PTE bit 6) may be used instead of AVL bit 0 (PTE bit 9)
  2320                              <1> ;;       -while R/W bit is 0-. 
  2321                              <1> ;; 
  2322                              <1> ;; Duplicate page tables with writable pages (the 1st sys fork in the process):
  2323                              <1> ;; # Parent's Page Table Entries are updated to point same pages as read only, 
  2324                              <1> ;;   as duplicated PTE bit  -AVL bit 0, PTE bit 9- are reset/clear.
  2325                              <1> ;; # Then Parent's Page Table is copied to Child's Page Table.
  2326                              <1> ;; # Child's Page Table Entries are updated as duplicated child bit
  2327                              <1> ;;   -AVL bit 0, PTE bit 9- is set.	  
  2328                              <1> ;; 
  2329                              <1> ;; Duplicate page tables with read only pages (several sys fork system calls):
  2330                              <1> ;; # Parent's read only pages are copied to new child pages. 
  2331                              <1> ;;   Parent's PTE attributes are not changed.
  2332                              <1> ;;   (Because, there is another parent-child fork before this fork! We must not
  2333                              <1> ;;    destroy/mix previous fork result).
  2334                              <1> ;; # Child's Page Table Entries (which are corresponding to Parent's 
  2335                              <1> ;;   read only pages) are set as writable (while duplicated PTE bit is clear). 
  2336                              <1> ;; # Parent's PTEs with writable page attribute are updated to point same pages 
  2337                              <1> ;;   as read only, (while) duplicated PTE bit is reset (clear).
  2338                              <1> ;; # Parent's Page Table Entries (with writable page attribute) are duplicated 
  2339                              <1> ;;   as Child's Page Table Entries without copying actual page.
  2340                              <1> ;; # Child 's Page Table Entries (which are corresponding to Parent's writable 
  2341                              <1> ;;   pages) are updated as duplicated PTE bit (AVL bit 0, PTE bit 9- is set.
  2342                              <1> ;; 
  2343                              <1> ;; !? WHAT FOR (duplication after duplication):
  2344                              <1> ;; In UNIX method for sys fork (a typical 'fork' application in /etc/init)
  2345                              <1> ;; program/executable code continues from specified location as child process, 
  2346                              <1> ;; returns back previous code location as parent process, every child after 
  2347                              <1> ;; every sys fork uses last image of code and data just prior the fork.
  2348                              <1> ;; Even if the parent code changes data, the child will not see the changed data 
  2349                              <1> ;; after the fork. In Retro UNIX 8086 v1, parent's process segment (32KB)
  2350                              <1> ;; was copied to child's process segment (all of code and data) according to
  2351                              <1> ;; original UNIX v1 which copies all of parent process code and data -core- 
  2352                              <1> ;; to child space -core- but swaps that core image -of child- on to disk.
  2353                              <1> ;; If I (Erdogan Tan) would use a method of to copy parent's core
  2354                              <1> ;; (complete running image of parent process) to the child process; 
  2355                              <1> ;; for big sizes, i would force Retro UNIX 386 v1 to spend many memory pages 
  2356                              <1> ;; and times only for a sys fork. (It would excessive reservation for sys fork,
  2357                              <1> ;; because sys fork usually is prior to sys exec; sys exec always establishes
  2358                              <1> ;; a new/fresh core -running space-, by clearing all code/data content). 
  2359                              <1> ;; 'Read Only' page flag ensures page fault handler is needed only for a few write
  2360                              <1> ;; attempts between sys fork and sys exec, not more... (I say so by thinking 
  2361                              <1> ;; of "/etc/init" content, specially.) sys exec will clear page tables and
  2362                              <1> ;; new/fresh pages will be used to load and run new executable/program.
  2363                              <1> ;; That is what for i have preferred "copy on write", "duplication" method
  2364                              <1> ;; for sharing same read only pages between parent and child processes.
  2365                              <1> ;; That is a pitty i have to use new private flag (AVL bit 0, "duplicated PTE 
  2366                              <1> ;; belongs to child" sign) for cooperation on duplicated pages between a parent 
  2367                              <1> ;; and it's child processes; otherwise parent process would destroy data belongs
  2368                              <1> ;; to its child or vice versa; or some pages would remain unclaimed 
  2369                              <1> ;; -deallocation problem-.
  2370                              <1> ;; Note: to prevent conflicts, read only pages must not be swapped out... 
  2371                              <1> ;; 
  2372                              <1> ;; WHEN PARENT TRIES TO WRITE IT'S READ ONLY (DUPLICATED) PAGE:
  2373                              <1> ;; # Page fault handler will do those:
  2374                              <1> ;;   - 'Duplicated PTE' flag (PTE bit 9) is checked (on the failed PTE).
  2375                              <1> ;;   - If it is reset/clear, there is a child uses same page.
  2376                              <1> ;;   - Parent's read only page -previous page- is copied to a new writable page. 
  2377                              <1> ;;   - Parent's PTE is updated as writable page, as unique page (AVL=0)
  2378                              <1> ;;   - (Page fault handler whill check this PTE later, if child process causes to
  2379                              <1> ;;     page fault due to write attempt on read only page. Of course, the previous 
  2380                              <1> ;;     read only page will be converted to writable and unique page which belongs
  2381                              <1> ;;     to child process.)	
  2382                              <1> ;; WHEN CHILD TRIES TO WRITE IT'S READ ONLY (DUPLICATED) PAGE:
  2383                              <1> ;; # Page fault handler will do those:
  2384                              <1> ;;   - 'Duplicated PTE' flag (PTE bit 9) is checked (on the failed PTE).
  2385                              <1> ;;   - If it is set, there is a parent uses -or was using- same page.
  2386                              <1> ;;   - Same PTE address within parent's page table is checked if it has same page
  2387                              <1> ;;     address or not. 
  2388                              <1> ;;   - If parent's PTE has same address, child will continue with a new writable page.
  2389                              <1> ;;     Parent's PTE will point to same (previous) page as writable, unique (AVL=0).	
  2390                              <1> ;;   - If parent's PTE has different address, child will continue with it's 
  2391                              <1> ;;     own/same page but read only flag (0) will be changed to writable flag (1) and
  2392                              <1> ;;     'duplicated PTE (belongs to child)' flag/sign will be cleared/reset. 	  	
  2393                              <1> ;; 
  2394                              <1> ;; NOTE: When a child process is terminated, read only flags of parent's page tables
  2395                              <1> ;;       will be set as writable (and unique) in case of child process was using 
  2396                              <1> ;;       same pages with duplicated child PTE sign... Depending on sys fork and 
  2397                              <1> ;;       duplication method details, it is not possible multiple child processes
  2398                              <1> ;;       were using same page with duplicated PTEs.
  2399                              <1> ;; 
  2400                              <1> ;;************************************************************************************   
  2401                              <1> 
  2402                              <1> ;; 08/10/2014
  2403                              <1> ;; 11/09/2014 - Retro UNIX 386 v1 PAGING (further) draft
  2404                              <1> ;;		by Erdogan Tan (Based on KolibriOS 'memory.inc')
  2405                              <1> 
  2406                              <1> ;; 'allocate_page' code is derived and modified from KolibriOS
  2407                              <1> ;; 'alloc_page' procedure in 'memory.inc' 
  2408                              <1> ;; (25/08/2014, Revision: 5057) file 
  2409                              <1> ;; by KolibriOS Team (2004-2012)
  2410                              <1> 
  2411                              <1> allocate_page:
  2412                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2413                              <1> 	; 01/07/2015
  2414                              <1> 	; 05/05/2015
  2415                              <1> 	; 30/04/2015
  2416                              <1> 	; 16/10/2014
  2417                              <1> 	; 08/10/2014
  2418                              <1> 	; 09/09/2014 (Retro UNIX 386 v1 - beginning)
  2419                              <1> 	;
  2420                              <1> 	; INPUT -> none
  2421                              <1> 	;
  2422                              <1> 	; OUTPUT ->
  2423                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF THE ALLOCATED PAGE
  2424                              <1> 	;	(corresponding MEMORY ALLOCATION TABLE bit is RESET)
  2425                              <1> 	;
  2426                              <1> 	;	CF = 1 and EAX = 0 
  2427                              <1> 	; 		   if there is not a free page to be allocated	
  2428                              <1> 	;
  2429                              <1> 	; Modified Registers -> none (except EAX)
  2430                              <1> 	;
  2431 000024C7 A1[20620000]        <1> 	mov	eax, [free_pages]
  2432 000024CC 21C0                <1> 	and	eax, eax
  2433 000024CE 7438                <1> 	jz	short out_of_memory
  2434                              <1> 	;
  2435 000024D0 53                  <1> 	push	ebx
  2436 000024D1 51                  <1> 	push	ecx
  2437                              <1> 	;
  2438 000024D2 BB00001000          <1> 	mov	ebx, MEM_ALLOC_TBL   ; Memory Allocation Table offset
  2439 000024D7 89D9                <1> 	mov	ecx, ebx
  2440                              <1>  				     ; NOTE: 32 (first_page) is initial
  2441                              <1> 				     ; value of [next_page].
  2442                              <1> 				     ; It points to the first available
  2443                              <1> 				     ; page block for users (ring 3) ...	
  2444                              <1> 				     ; (MAT offset 32 = 1024/32)	
  2445                              <1> 				     ; (at the of the first 4 MB)		
  2446 000024D9 031D[24620000]      <1> 	add	ebx, [next_page] ; Free page searching starts from here
  2447                              <1> 				 ; next_free_page >> 5
  2448 000024DF 030D[28620000]      <1> 	add	ecx, [last_page] ; Free page searching ends here
  2449                              <1> 				 ; (total_pages - 1) >> 5
  2450                              <1> al_p_scan:
  2451 000024E5 39CB                <1> 	cmp	ebx, ecx
  2452 000024E7 770A                <1> 	ja	short al_p_notfound
  2453                              <1> 	;
  2454                              <1> 	; 01/07/2015
  2455                              <1> 	; AMD64 Architecture Programmers Manual
  2456                              <1> 	; Volume 3:
  2457                              <1> 	; General-Purpose and System Instructions
  2458                              <1> 	;
  2459                              <1> 	; BSF - Bit Scan Forward
  2460                              <1> 	;
  2461                              <1> 	;   Searches the value in a register or a memory location
  2462                              <1> 	;   (second operand) for the least-significant set bit. 
  2463                              <1> 	;   If a set bit is found, the instruction clears the zero flag (ZF)
  2464                              <1> 	;   and stores the index of the least-significant set bit in a destination
  2465                              <1> 	;   register (first operand). If the second operand contains 0, 
  2466                              <1> 	;   the instruction sets ZF to 1 and does not change the contents of the 
  2467                              <1> 	;   destination register. The bit index is an unsigned offset from bit 0 
  2468                              <1> 	;   of the searched value
  2469                              <1> 	;
  2470 000024E9 0FBC03              <1> 	bsf	eax, [ebx] ; Scans source operand for first bit set (1).
  2471                              <1> 			   ; Clear ZF if a bit is found set (1) and 
  2472                              <1> 			   ; loads the destination with an index to
  2473                              <1> 			   ; first set bit. (0 -> 31) 
  2474                              <1> 			   ; Sets ZF to 1 if no bits are found set.
  2475 000024EC 751C                <1> 	jnz	short al_p_found ; ZF = 0 -> a free page has been found
  2476                              <1> 			 ;
  2477                              <1> 			 ; NOTE:  a Memory Allocation Table bit 
  2478                              <1> 			 ;	  with value of 1 means 
  2479                              <1> 			 ;	  the corresponding page is free 
  2480                              <1> 			 ;	  (Retro UNIX 386 v1 feature only!)
  2481 000024EE 83C304              <1> 	add	ebx, 4
  2482                              <1> 			 ; We return back for searching next page block
  2483                              <1> 			 ; NOTE: [free_pages] is not ZERO; so, 
  2484                              <1> 			 ;	 we always will find at least 1 free page here.
  2485 000024F1 EBF2                <1>         jmp     short al_p_scan
  2486                              <1> 	;
  2487                              <1> al_p_notfound:
  2488 000024F3 81E900001000        <1> 	sub	ecx, MEM_ALLOC_TBL
  2489 000024F9 890D[24620000]      <1> 	mov	[next_page], ecx ; next/first free page = last page 
  2490                              <1> 				 ; (deallocate_page procedure will change it)
  2491 000024FF 31C0                <1> 	xor	eax, eax
  2492 00002501 A3[20620000]        <1> 	mov	[free_pages], eax ; 0
  2493 00002506 59                  <1> 	pop	ecx
  2494 00002507 5B                  <1> 	pop	ebx
  2495                              <1> 	;
  2496                              <1> ; 24/12/2021
  2497                              <1> ; ('swap_out' procedure call is disabled)
  2498                              <1> 
  2499                              <1> out_of_memory:
  2500                              <1> ;	call	swap_out
  2501                              <1> ;	jnc	short al_p_ok  ; [free_pages] = 0, re-allocation by swap_out
  2502                              <1> ;	;
  2503                              <1> ;	sub 	eax, eax ; 0
  2504 00002508 F9                  <1> 	stc
  2505 00002509 C3                  <1> 	retn
  2506                              <1> 
  2507                              <1> al_p_found:
  2508 0000250A 89D9                <1> 	mov	ecx, ebx
  2509 0000250C 81E900001000        <1> 	sub	ecx, MEM_ALLOC_TBL
  2510 00002512 890D[24620000]      <1> 	mov	[next_page], ecx ; Set first free page searching start
  2511                              <1> 				 ; address/offset (to the next)
  2512 00002518 FF0D[20620000]      <1>         dec     dword [free_pages] ; 1 page has been allocated (X = X-1) 
  2513                              <1> 	;
  2514 0000251E 0FB303              <1> 	btr	[ebx], eax	 ; The destination bit indexed by the source value
  2515                              <1> 				 ; is copied into the Carry Flag and then cleared
  2516                              <1> 				 ; in the destination.
  2517                              <1> 				 ;
  2518                              <1> 				 ; Reset the bit which is corresponding to the 
  2519                              <1> 				 ; (just) allocated page.
  2520                              <1> 	; 01/07/2015 (4*8 = 32, 1 allocation byte = 8 pages)	
  2521 00002521 C1E103              <1> 	shl	ecx, 3		 ; (page block offset * 32) + page index
  2522 00002524 01C8                <1> 	add	eax, ecx	 ; = page number
  2523 00002526 C1E00C              <1> 	shl	eax, 12		 ; physical address of the page (flat/real value)
  2524                              <1> 	; EAX = physical address of memory page
  2525                              <1> 	;
  2526                              <1> 	; NOTE: The relevant page directory and page table entry will be updated
  2527                              <1> 	;       according to this EAX value...
  2528 00002529 59                  <1> 	pop	ecx
  2529 0000252A 5B                  <1> 	pop	ebx
  2530                              <1> al_p_ok:
  2531 0000252B C3                  <1> 	retn
  2532                              <1> 
  2533                              <1> make_page_dir:
  2534                              <1> 	; 18/04/2015
  2535                              <1> 	; 12/04/2015
  2536                              <1> 	; 23/10/2014
  2537                              <1> 	; 16/10/2014
  2538                              <1> 	; 09/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2539                              <1> 	;
  2540                              <1> 	; INPUT ->
  2541                              <1> 	;	none
  2542                              <1> 	; OUTPUT ->
  2543                              <1> 	;	(EAX = 0)
  2544                              <1> 	;	cf = 1 -> insufficient (out of) memory error
  2545                              <1> 	;	cf = 0 ->
  2546                              <1> 	;	u.pgdir = page directory (physical) address of the current
  2547                              <1> 	;		  process/user.
  2548                              <1> 	;
  2549                              <1> 	; Modified Registers -> EAX
  2550                              <1> 	;
  2551 0000252C E896FFFFFF          <1> 	call	allocate_page
  2552 00002531 7216                <1> 	jc	short mkpd_error
  2553                              <1> 	;
  2554 00002533 A3[35660000]        <1> 	mov	[u.pgdir], eax    ; Page dir address for current user/process
  2555                              <1> 				  ; (Physical address)
  2556                              <1> clear_page:
  2557                              <1> 	; 18/04/2015
  2558                              <1> 	; 09/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2559                              <1> 	;
  2560                              <1> 	; INPUT ->
  2561                              <1> 	;	EAX = physical address of the page
  2562                              <1> 	; OUTPUT ->
  2563                              <1> 	;	all bytes of the page will be cleared
  2564                              <1> 	;
  2565                              <1> 	; Modified Registers -> none
  2566                              <1> 	;
  2567 00002538 57                  <1> 	push	edi
  2568 00002539 51                  <1> 	push	ecx
  2569 0000253A 50                  <1> 	push	eax
  2570 0000253B B900040000          <1> 	mov	ecx, PAGE_SIZE / 4
  2571 00002540 89C7                <1> 	mov	edi, eax
  2572 00002542 31C0                <1> 	xor	eax, eax
  2573 00002544 F3AB                <1> 	rep	stosd
  2574 00002546 58                  <1> 	pop	eax
  2575 00002547 59                  <1> 	pop	ecx
  2576 00002548 5F                  <1> 	pop	edi
  2577                              <1> mkpd_error:
  2578                              <1> mkpt_error:
  2579 00002549 C3                  <1> 	retn
  2580                              <1> 
  2581                              <1> make_page_table:
  2582                              <1> 	; 23/06/2015
  2583                              <1> 	; 18/04/2015
  2584                              <1> 	; 12/04/2015
  2585                              <1> 	; 16/10/2014
  2586                              <1> 	; 09/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2587                              <1> 	;
  2588                              <1> 	; INPUT ->
  2589                              <1> 	;	EBX = virtual (linear) address
  2590                              <1> 	;	ECX = page table attributes (lower 12 bits)
  2591                              <1> 	;	      (higher 20 bits must be ZERO)
  2592                              <1> 	;	      (bit 0 must be 1)	 
  2593                              <1> 	;	u.pgdir = page directory (physical) address
  2594                              <1> 	; OUTPUT ->
  2595                              <1> 	;	EDX = Page directory entry address
  2596                              <1> 	;	EAX = Page table address
  2597                              <1> 	;	cf = 1 -> insufficient (out of) memory error
  2598                              <1> 	;	cf = 0 -> page table address in the PDE (EDX)
  2599                              <1> 	;
  2600                              <1> 	; Modified Registers -> EAX, EDX
  2601                              <1> 	;
  2602 0000254A E878FFFFFF          <1> 	call	allocate_page
  2603 0000254F 72F8                <1> 	jc	short mkpt_error
  2604 00002551 E811000000          <1> 	call	set_pde	
  2605 00002556 EBE0                <1> 	jmp	short clear_page
  2606                              <1> 
  2607                              <1> make_page:
  2608                              <1> 	; 24/07/2015
  2609                              <1> 	; 23/06/2015 ; (Retro UNIX 386 v1 - beginning)
  2610                              <1> 	;
  2611                              <1> 	; INPUT ->
  2612                              <1> 	;	EBX = virtual (linear) address
  2613                              <1> 	;	ECX = page attributes (lower 12 bits)
  2614                              <1> 	;	      (higher 20 bits must be ZERO)
  2615                              <1> 	;	      (bit 0 must be 1)	 
  2616                              <1> 	;	u.pgdir = page directory (physical) address
  2617                              <1> 	; OUTPUT ->
  2618                              <1> 	;	EBX = Virtual address
  2619                              <1> 	;	(EDX = PTE value)
  2620                              <1> 	;	EAX = Physical address
  2621                              <1> 	;	cf = 1 -> insufficient (out of) memory error
  2622                              <1> 	;
  2623                              <1> 	; Modified Registers -> EAX, EDX
  2624                              <1> 	;
  2625 00002558 E86AFFFFFF          <1> 	call	allocate_page
  2626 0000255D 7207                <1> 	jc	short mkp_err
  2627 0000255F E821000000          <1> 	call	set_pte	
  2628 00002564 73D2                <1> 	jnc	short clear_page ; 18/04/2015
  2629                              <1> mkp_err:
  2630 00002566 C3                  <1> 	retn
  2631                              <1> 
  2632                              <1> set_pde:	; Set page directory entry (PDE)
  2633                              <1> 	; 20/07/2015
  2634                              <1> 	; 18/04/2015
  2635                              <1> 	; 12/04/2015
  2636                              <1> 	; 23/10/2014
  2637                              <1> 	; 10/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2638                              <1> 	;
  2639                              <1> 	; INPUT ->
  2640                              <1> 	;	EAX = physical address
  2641                              <1> 	;	      (use present value if EAX = 0)
  2642                              <1> 	;	EBX = virtual (linear) address
  2643                              <1> 	;	ECX = page table attributes (lower 12 bits)
  2644                              <1> 	;	      (higher 20 bits must be ZERO)
  2645                              <1> 	;	      (bit 0 must be 1)	 
  2646                              <1> 	;	u.pgdir = page directory (physical) address
  2647                              <1> 	; OUTPUT ->
  2648                              <1> 	;	EDX = PDE address
  2649                              <1> 	;	EAX = page table address (physical)
  2650                              <1> 	;	;(CF=1 -> Invalid page address)
  2651                              <1> 	;
  2652                              <1> 	; Modified Registers -> EDX
  2653                              <1> 	;
  2654 00002567 89DA                <1> 	mov	edx, ebx
  2655 00002569 C1EA16              <1> 	shr	edx, PAGE_D_SHIFT ; 22
  2656 0000256C C1E202              <1> 	shl	edx, 2 ; offset to page directory (1024*4)
  2657 0000256F 0315[35660000]      <1> 	add	edx, [u.pgdir]
  2658                              <1> 	;
  2659 00002575 21C0                <1> 	and	eax, eax
  2660 00002577 7506                <1> 	jnz	short spde_1
  2661                              <1> 	;
  2662 00002579 8B02                <1> 	mov	eax, [edx]  ; old PDE value
  2663                              <1> 	;test	al, 1
  2664                              <1> 	;jz	short spde_2
  2665 0000257B 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h  ; clear lower 12 bits
  2666                              <1> spde_1:
  2667                              <1> 	;and	cx, 0FFFh
  2668 0000257F 8902                <1> 	mov	[edx], eax
  2669 00002581 66090A              <1> 	or	[edx], cx
  2670 00002584 C3                  <1> 	retn
  2671                              <1> ;spde_2: ; error
  2672                              <1> ;	stc
  2673                              <1> ;	retn
  2674                              <1> 
  2675                              <1> set_pte:	; Set page table entry (PTE)
  2676                              <1> 	; 24/07/2015
  2677                              <1> 	; 20/07/2015
  2678                              <1> 	; 23/06/2015
  2679                              <1> 	; 18/04/2015
  2680                              <1> 	; 12/04/2015
  2681                              <1> 	; 10/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2682                              <1> 	;
  2683                              <1> 	; INPUT ->
  2684                              <1> 	;	EAX = physical page address
  2685                              <1> 	;	      (use present value if EAX = 0)
  2686                              <1> 	;	EBX = virtual (linear) address
  2687                              <1> 	;	ECX = page attributes (lower 12 bits)
  2688                              <1> 	;	      (higher 20 bits must be ZERO)
  2689                              <1> 	;	      (bit 0 must be 1)	 
  2690                              <1> 	;	u.pgdir = page directory (physical) address
  2691                              <1> 	; OUTPUT ->
  2692                              <1> 	;	EAX = physical page address
  2693                              <1> 	;	(EDX = PTE value)
  2694                              <1> 	;	EBX = virtual address
  2695                              <1> 	;
  2696                              <1> 	;	CF = 1 -> error
  2697                              <1> 	;
  2698                              <1> 	; Modified Registers -> EAX, EDX
  2699                              <1> 	;
  2700 00002585 50                  <1> 	push	eax
  2701 00002586 A1[35660000]        <1> 	mov	eax, [u.pgdir] ; 20/07/2015
  2702 0000258B E837000000          <1> 	call 	get_pde
  2703                              <1> 		; EDX = PDE address
  2704                              <1> 		; EAX = PDE value
  2705 00002590 5A                  <1> 	pop	edx ; physical page address
  2706 00002591 722A                <1> 	jc	short spte_err ; PDE not present
  2707                              <1> 	;
  2708 00002593 53                  <1> 	push	ebx ; 24/07/2015
  2709 00002594 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h ; clear lower 12 bits
  2710                              <1> 			    ; EDX = PT address (physical)	
  2711 00002598 C1EB0C              <1> 	shr	ebx, PAGE_SHIFT ; 12
  2712 0000259B 81E3FF030000        <1> 	and	ebx, PTE_MASK	; 03FFh
  2713                              <1> 			 ; clear higher 10 bits (PD bits)
  2714 000025A1 C1E302              <1> 	shl	ebx, 2   ; offset to page table (1024*4)
  2715 000025A4 01C3                <1> 	add	ebx, eax
  2716                              <1> 	;
  2717 000025A6 8B03                <1> 	mov	eax, [ebx] ; Old PTE value
  2718 000025A8 A801                <1> 	test	al, 1
  2719 000025AA 740C                <1> 	jz	short spte_0
  2720 000025AC 09D2                <1> 	or	edx, edx
  2721 000025AE 750F                <1> 	jnz	short spte_1
  2722 000025B0 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear lower 12 bits
  2723 000025B4 89C2                <1> 	mov	edx, eax
  2724 000025B6 EB09                <1> 	jmp	short spte_2	
  2725                              <1> spte_0:
  2726                              <1> 	; If this PTE contains a swap (disk) address,
  2727                              <1> 	; it can be updated by using 'swap_in' procedure
  2728                              <1> 	; only!
  2729 000025B8 21C0                <1> 	and	eax, eax
  2730 000025BA 7403                <1> 	jz	short spte_1
  2731                              <1> 	; 24/07/2015
  2732                              <1> 	; swapped page ! (on disk)
  2733 000025BC 5B                  <1> 	pop	ebx
  2734                              <1> spte_err:
  2735 000025BD F9                  <1> 	stc
  2736 000025BE C3                  <1> 	retn
  2737                              <1> spte_1: 
  2738 000025BF 89D0                <1> 	mov	eax, edx
  2739                              <1> spte_2:
  2740 000025C1 09CA                <1> 	or	edx, ecx
  2741                              <1> 	; 23/06/2015
  2742 000025C3 8913                <1> 	mov	[ebx], edx ; PTE value in EDX
  2743                              <1> 	; 24/07/2015
  2744 000025C5 5B                  <1> 	pop	ebx
  2745 000025C6 C3                  <1> 	retn
  2746                              <1> 
  2747                              <1> get_pde:	; Get present value of the relevant PDE
  2748                              <1> 	; 20/07/2015
  2749                              <1> 	; 18/04/2015
  2750                              <1> 	; 12/04/2015
  2751                              <1> 	; 10/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2752                              <1> 	;
  2753                              <1> 	; INPUT ->
  2754                              <1> 	;	EBX = virtual (linear) address
  2755                              <1> 	;	EAX = page directory (physical) address
  2756                              <1> 	; OUTPUT ->
  2757                              <1> 	;	EDX = Page directory entry address
  2758                              <1> 	;	EAX = Page directory entry value
  2759                              <1> 	;	CF = 1 -> PDE not present or invalid ? 
  2760                              <1> 	; Modified Registers -> EDX, EAX
  2761                              <1> 	;
  2762 000025C7 89DA                <1> 	mov	edx, ebx
  2763 000025C9 C1EA16              <1> 	shr	edx, PAGE_D_SHIFT ; 22  (12+10)
  2764 000025CC C1E202              <1> 	shl 	edx, 2 ; offset to page directory (1024*4)
  2765 000025CF 01C2                <1> 	add	edx, eax ; page directory address (physical)
  2766 000025D1 8B02                <1> 	mov	eax, [edx]
  2767 000025D3 A801                <1> 	test	al, PDE_A_PRESENT ; page table is present or not !
  2768 000025D5 751F                <1> 	jnz	short gpte_retn
  2769 000025D7 F9                  <1> 	stc
  2770                              <1> gpde_retn:	
  2771 000025D8 C3                  <1> 	retn
  2772                              <1> 
  2773                              <1> get_pte:
  2774                              <1> 		; Get present value of the relevant PTE
  2775                              <1> 	; 29/07/2015
  2776                              <1> 	; 20/07/2015
  2777                              <1> 	; 18/04/2015
  2778                              <1> 	; 12/04/2015
  2779                              <1> 	; 10/10/2014 ; (Retro UNIX 386 v1 - beginning)
  2780                              <1> 	;
  2781                              <1> 	; INPUT ->
  2782                              <1> 	;	EBX = virtual (linear) address
  2783                              <1> 	;	EAX = page directory (physical) address
  2784                              <1> 	; OUTPUT ->
  2785                              <1> 	;	EDX = Page table entry address (if CF=0)
  2786                              <1> 	;	      Page directory entry address (if CF=1)
  2787                              <1> 	;            (Bit 0 value is 0 if PT is not present)
  2788                              <1> 	;	EAX = Page table entry value (page address)
  2789                              <1> 	;	CF = 1 -> PDE not present or invalid ? 
  2790                              <1> 	; Modified Registers -> EAX, EDX
  2791                              <1> 	;
  2792 000025D9 E8E9FFFFFF          <1> 	call 	get_pde
  2793 000025DE 72F8                <1> 	jc	short gpde_retn	; page table is not present
  2794                              <1> 	;jnc	short gpte_1
  2795                              <1> 	;retn
  2796                              <1> ;gpte_1:
  2797 000025E0 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h ; clear lower 12 bits
  2798 000025E4 89DA                <1> 	mov	edx, ebx
  2799 000025E6 C1EA0C              <1> 	shr	edx, PAGE_SHIFT ; 12
  2800 000025E9 81E2FF030000        <1> 	and	edx, PTE_MASK	; 03FFh
  2801                              <1> 			 ; clear higher 10 bits (PD bits)
  2802 000025EF C1E202              <1> 	shl	edx, 2 ; offset from start of page table (1024*4)
  2803 000025F2 01C2                <1> 	add	edx, eax
  2804 000025F4 8B02                <1> 	mov	eax, [edx]
  2805                              <1> gpte_retn:
  2806 000025F6 C3                  <1> 	retn
  2807                              <1> 
  2808                              <1> deallocate_page_dir:
  2809                              <1> 	; 15/09/2015
  2810                              <1> 	; 05/08/2015
  2811                              <1> 	; 30/04/2015
  2812                              <1> 	; 28/04/2015
  2813                              <1> 	; 17/10/2014
  2814                              <1> 	; 12/10/2014 (Retro UNIX 386 v1 - beginning)
  2815                              <1> 	;
  2816                              <1> 	; INPUT ->
  2817                              <1> 	;	EAX = PHYSICAL ADDRESS OF THE PAGE DIRECTORY (CHILD)
  2818                              <1> 	;	EBX = PHYSICAL ADDRESS OF THE PARENT'S PAGE DIRECTORY
  2819                              <1> 	; OUTPUT ->
  2820                              <1> 	;	All of page tables in the page directory
  2821                              <1> 	;	and page dir's itself will be deallocated
  2822                              <1> 	;	except 'read only' duplicated pages (will be converted
  2823                              <1> 	;	to writable pages).
  2824                              <1> 	;
  2825                              <1> 	; Modified Registers -> EAX
  2826                              <1> 	;
  2827                              <1> 	;
  2828 000025F7 56                  <1> 	push	esi
  2829 000025F8 51                  <1> 	push	ecx
  2830 000025F9 50                  <1> 	push	eax
  2831 000025FA 89C6                <1> 	mov	esi, eax 
  2832 000025FC 31C9                <1> 	xor	ecx, ecx
  2833                              <1> 	; The 1st PDE points to Kernel Page Table 0 (the 1st 4MB),
  2834                              <1> 	; it must not be deallocated
  2835 000025FE 890E                <1> 	mov	[esi], ecx ; 0 ; clear PDE 0
  2836                              <1> dapd_0:
  2837 00002600 AD                  <1> 	lodsd
  2838 00002601 A801                <1> 	test	al, PDE_A_PRESENT ; bit 0, present flag (must be 1)
  2839 00002603 7409                <1> 	jz	short dapd_1	
  2840 00002605 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h ; clear lower 12 (attribute) bits
  2841 00002609 E812000000          <1> 	call	deallocate_page_table			
  2842                              <1> dapd_1:
  2843 0000260E 41                  <1> 	inc	ecx ; page directory entry index
  2844 0000260F 81F900040000        <1> 	cmp	ecx, PAGE_SIZE / 4 ; 1024
  2845 00002615 72E9                <1> 	jb	short dapd_0
  2846                              <1> dapd_2:
  2847 00002617 58                  <1> 	pop	eax
  2848 00002618 E870000000          <1> 	call	deallocate_page	; deallocate the page dir's itself
  2849 0000261D 59                  <1> 	pop	ecx
  2850 0000261E 5E                  <1> 	pop	esi
  2851 0000261F C3                  <1> 	retn
  2852                              <1> 
  2853                              <1> deallocate_page_table:
  2854                              <1> 	; 17/07/2022
  2855                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2856                              <1> 	; 12/07/2016 (TRDOS 386 v2)
  2857                              <1> 	; 19/09/2015
  2858                              <1> 	; 15/09/2015
  2859                              <1> 	; 05/08/2015
  2860                              <1> 	; 30/04/2015
  2861                              <1> 	; 28/04/2015
  2862                              <1> 	; 24/10/2014
  2863                              <1> 	; 23/10/2014
  2864                              <1> 	; 12/10/2014 (Retro UNIX 386 v1 - beginning)
  2865                              <1> 	;
  2866                              <1> 	; INPUT ->
  2867                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF THE PAGE TABLE
  2868                              <1> 	;	EBX = PHYSICAL ADDRESS OF THE PARENT'S PAGE DIRECTORY
  2869                              <1> 	;	(ECX = page directory entry index)
  2870                              <1> 	; OUTPUT ->
  2871                              <1> 	;	All of pages in the page table and page table's itself
  2872                              <1> 	;	will be deallocated except 'read only' duplicated pages
  2873                              <1> 	;	(will be converted to writable pages).
  2874                              <1> 	;
  2875                              <1> 	; Modified Registers -> EAX
  2876                              <1> 	;
  2877 00002620 56                  <1> 	push	esi
  2878 00002621 57                  <1> 	push	edi
  2879 00002622 52                  <1> 	push	edx
  2880 00002623 50                  <1> 	push	eax ; *
  2881 00002624 89C6                <1> 	mov	esi, eax 
  2882 00002626 31FF                <1> 	xor	edi, edi ; 0
  2883                              <1> dapt_0:
  2884 00002628 AD                  <1> 	lodsd
  2885 00002629 A801                <1> 	test	al, PTE_A_PRESENT ; bit 0, present flag (must be 1)
  2886 0000262B 7453                <1> 	jz	short dapt_1
  2887                              <1> 	;
  2888 0000262D A802                <1> 	test	al, PTE_A_WRITE   ; bit 1, writable (r/w) flag
  2889                              <1> 				  ; (must be 1)
  2890 0000262F 753D                <1> 	jnz	short dapt_3
  2891                              <1> 	; Read only -duplicated- page (belongs to a parent or a child)
  2892 00002631 66A90002            <1>         test    ax, PTE_DUPLICATED ; Was this page duplicated 
  2893                              <1> 				   ; as child's page ?
  2894 00002635 7442                <1> 	jz	short dapt_4 ; Clear PTE but don't deallocate the page!
  2895                              <1> 	; check the parent's PTE value is read only & same page or not.. 
  2896                              <1> 	; ECX = page directory entry index (0-1023)
  2897 00002637 53                  <1> 	push	ebx
  2898 00002638 51                  <1> 	push	ecx
  2899                              <1> 	;shl	cx, 2 ; *4 
  2900                              <1> 	; 17/07/2022
  2901 00002639 C1E102              <1> 	shl	ecx, 2
  2902 0000263C 01CB                <1> 	add	ebx, ecx ; PDE offset (for the parent)
  2903 0000263E 8B0B                <1> 	mov	ecx, [ebx]
  2904 00002640 F6C101              <1> 	test	cl, PDE_A_PRESENT ; present (valid) or not ?
  2905 00002643 7427                <1> 	jz	short dapt_2	; parent process does not use this page
  2906 00002645 6681E100F0          <1> 	and	cx, PDE_A_CLEAR ; 0F000h ; Clear attribute bits
  2907                              <1> 	; EDI = page table entry index (0-1023)
  2908 0000264A 89FA                <1> 	mov	edx, edi 
  2909                              <1> 	;shl	dx, 2 ; *4
  2910                              <1> 	; 17/07/2022
  2911 0000264C C1E202              <1> 	shl	edx, 2
  2912 0000264F 01CA                <1> 	add	edx, ecx ; PTE offset (for the parent)
  2913 00002651 8B1A                <1> 	mov	ebx, [edx]
  2914 00002653 F6C301              <1> 	test	bl, PTE_A_PRESENT ; present or not ?
  2915 00002656 7414                <1> 	jz	short dapt_2	; parent process does not use this page
  2916 00002658 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; Clear attribute bits 
  2917 0000265C 6681E300F0          <1> 	and	bx, PTE_A_CLEAR ; 0F000h ; Clear attribute bits
  2918 00002661 39D8                <1> 	cmp	eax, ebx	; parent's and child's pages are same ?
  2919 00002663 7507                <1> 	jne	short dapt_2	; not same page
  2920                              <1> 				; deallocate the child's page
  2921 00002665 800A02              <1>         or      byte [edx], PTE_A_WRITE ; convert to writable page (parent)
  2922 00002668 59                  <1> 	pop	ecx
  2923 00002669 5B                  <1> 	pop	ebx
  2924 0000266A EB0D                <1> 	jmp	short dapt_4
  2925                              <1> 
  2926                              <1> ; 24/12/2021
  2927                              <1> ; ('dapt_1' is disabled)
  2928                              <1> ;
  2929                              <1> ;dapt_1:
  2930                              <1> ;	or	eax, eax	; swapped page ?
  2931                              <1> ;	jz	short dapt_5	; no
  2932                              <1> ;				; yes
  2933                              <1> ;	shr	eax, 1
  2934                              <1> ;	call	unlink_swap_block ; Deallocate swapped page block
  2935                              <1> ;				  ; on the swap disk (or in file)
  2936                              <1> ;	jmp	short dapt_5
  2937                              <1> dapt_2:
  2938 0000266C 59                  <1> 	pop	ecx
  2939 0000266D 5B                  <1> 	pop	ebx
  2940                              <1> dapt_3:	
  2941                              <1> 	; 12/07/2016
  2942 0000266E 66A90004            <1> 	test	ax, PTE_SHARED ; shared or direct memory access indicator
  2943 00002672 7505                <1> 	jnz	short dapt_4   ; AVL bit 1 = 1, do not deallocate this page!
  2944                              <1> 	;
  2945                              <1> 	;and	ax, PTE_A_CLEAR ; 0F000h ; clear lower 12 (attribute) bits
  2946 00002674 E814000000          <1> 	call	deallocate_page ; set the mem allocation bit of this page
  2947                              <1> dapt_4:
  2948 00002679 C746FC00000000      <1> 	mov	dword [esi-4], 0 ; clear/reset PTE (child, dupl. as parent)
  2949                              <1> dapt_1:	; 24/12/2021
  2950                              <1> dapt_5:
  2951 00002680 47                  <1> 	inc	edi ; page table entry index
  2952 00002681 81FF00040000        <1> 	cmp	edi, PAGE_SIZE / 4 ; 1024
  2953 00002687 729F                <1> 	jb	short dapt_0
  2954                              <1> 	;
  2955 00002689 58                  <1> 	pop	eax ; *
  2956 0000268A 5A                  <1> 	pop	edx
  2957 0000268B 5F                  <1> 	pop	edi	
  2958 0000268C 5E                  <1> 	pop	esi
  2959                              <1> 	;
  2960                              <1> 	;call	deallocate_page	; deallocate the page table's itself
  2961                              <1> 	;retn
  2962                              <1> 
  2963                              <1> deallocate_page:
  2964                              <1> 	; 15/09/2015
  2965                              <1> 	; 28/04/2015
  2966                              <1> 	; 10/03/2015
  2967                              <1> 	; 17/10/2014
  2968                              <1> 	; 12/10/2014 (Retro UNIX 386 v1 - beginning)
  2969                              <1> 	;
  2970                              <1> 	; INPUT -> 
  2971                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF THE ALLOCATED PAGE
  2972                              <1> 	; OUTPUT ->
  2973                              <1> 	;	[free_pages] is increased
  2974                              <1> 	;	(corresponding MEMORY ALLOCATION TABLE bit is SET)
  2975                              <1> 	;	CF = 1 if the page is already deallocated
  2976                              <1> 	; 	       (or not allocated) before.  
  2977                              <1> 	;
  2978                              <1> 	; Modified Registers -> EAX
  2979                              <1> 	;
  2980 0000268D 53                  <1> 	push	ebx
  2981 0000268E 52                  <1> 	push	edx
  2982                              <1> 	;
  2983 0000268F C1E80C              <1> 	shr	eax, PAGE_SHIFT      ; shift physical address to 
  2984                              <1> 				     ; 12 bits right
  2985                              <1> 				     ; to get page number
  2986 00002692 89C2                <1> 	mov	edx, eax
  2987                              <1> 	; 15/09/2015
  2988 00002694 C1EA03              <1> 	shr	edx, 3		     ; to get offset to M.A.T.
  2989                              <1> 				     ; (1 allocation bit = 1 page)
  2990                              <1> 				     ; (1 allocation bytes = 8 pages)
  2991 00002697 80E2FC              <1> 	and	dl, 0FCh 	     ; clear lower 2 bits
  2992                              <1> 				     ; (to get 32 bit position)			
  2993                              <1> 	;
  2994 0000269A BB00001000          <1> 	mov	ebx, MEM_ALLOC_TBL   ; Memory Allocation Table address
  2995 0000269F 01D3                <1> 	add	ebx, edx
  2996 000026A1 83E01F              <1> 	and	eax, 1Fh	     ; lower 5 bits only
  2997                              <1> 				     ; (allocation bit position)	 
  2998 000026A4 3B15[24620000]      <1> 	cmp 	edx, [next_page]     ; is the new free page address lower
  2999                              <1> 				     ; than the address in 'next_page' ?
  3000                              <1> 				     ; (next/first free page value)		
  3001 000026AA 7306                <1> 	jnb	short dap_1	     ; no	
  3002 000026AC 8915[24620000]      <1> 	mov	[next_page], edx     ; yes
  3003                              <1> dap_1:
  3004 000026B2 0FAB03              <1> 	bts	[ebx], eax	     ; unlink/release/deallocate page
  3005                              <1> 				     ; set relevant bit to 1.
  3006                              <1> 				     ; set CF to the previous bit value	
  3007                              <1> 	;cmc			     ; complement carry flag	
  3008                              <1> 	;jc	short dap_2	     ; do not increase free_pages count
  3009                              <1> 				     ; if the page is already deallocated
  3010                              <1> 				     ; before.	
  3011 000026B5 FF05[20620000]      <1>         inc     dword [free_pages]
  3012                              <1> dap_2:
  3013 000026BB 5A                  <1> 	pop	edx
  3014 000026BC 5B                  <1> 	pop	ebx
  3015 000026BD C3                  <1> 	retn
  3016                              <1> 
  3017                              <1> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  3018                              <1> ;;                                                              ;;
  3019                              <1> ;; Copyright (C) KolibriOS team 2004-2012. All rights reserved. ;;
  3020                              <1> ;; Distributed under terms of the GNU General Public License    ;;
  3021                              <1> ;;                                                              ;;
  3022                              <1> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  3023                              <1> 
  3024                              <1> ;;$Revision: 5057 $
  3025                              <1> 
  3026                              <1> 
  3027                              <1> ;;align 4
  3028                              <1> ;;proc alloc_page
  3029                              <1> 
  3030                              <1> ;;        pushfd
  3031                              <1> ;;        cli
  3032                              <1> ;;        push    ebx
  3033                              <1> ;;;//-
  3034                              <1> ;;        cmp     [pg_data.pages_free], 1
  3035                              <1> ;;        jle     .out_of_memory
  3036                              <1> ;;;//-
  3037                              <1> ;;
  3038                              <1> ;;        mov     ebx, [page_start]
  3039                              <1> ;;        mov     ecx, [page_end]
  3040                              <1> ;;.l1:
  3041                              <1> ;;        bsf     eax, [ebx];
  3042                              <1> ;;        jnz     .found
  3043                              <1> ;;        add     ebx, 4
  3044                              <1> ;;        cmp     ebx, ecx
  3045                              <1> ;;        jb      .l1
  3046                              <1> ;;        pop     ebx
  3047                              <1> ;;        popfd
  3048                              <1> ;;        xor     eax, eax
  3049                              <1> ;;        ret
  3050                              <1> ;;.found:
  3051                              <1> ;;;//-
  3052                              <1> ;;        dec     [pg_data.pages_free]
  3053                              <1> ;;        jz      .out_of_memory
  3054                              <1> ;;;//-
  3055                              <1> ;;        btr     [ebx], eax
  3056                              <1> ;;        mov     [page_start], ebx
  3057                              <1> ;;        sub     ebx, sys_pgmap
  3058                              <1> ;;        lea     eax, [eax+ebx*8]
  3059                              <1> ;;        shl     eax, 12
  3060                              <1> ;;;//-       dec [pg_data.pages_free]
  3061                              <1> ;;        pop     ebx
  3062                              <1> ;;        popfd
  3063                              <1> ;;        ret
  3064                              <1> ;;;//-
  3065                              <1> ;;.out_of_memory:
  3066                              <1> ;;        mov     [pg_data.pages_free], 1
  3067                              <1> ;;        xor     eax, eax
  3068                              <1> ;;        pop     ebx
  3069                              <1> ;;        popfd
  3070                              <1> ;;        ret
  3071                              <1> ;;;//-
  3072                              <1> ;;endp
  3073                              <1> 
  3074                              <1> duplicate_page_dir:
  3075                              <1> 	; 21/09/2015
  3076                              <1> 	; 31/08/2015
  3077                              <1> 	; 20/07/2015
  3078                              <1> 	; 28/04/2015
  3079                              <1> 	; 27/04/2015
  3080                              <1> 	; 18/04/2015
  3081                              <1> 	; 12/04/2015
  3082                              <1> 	; 18/10/2014
  3083                              <1> 	; 16/10/2014 (Retro UNIX 386 v1 - beginning)
  3084                              <1> 	;
  3085                              <1> 	; INPUT -> 
  3086                              <1> 	;	[u.pgdir] = PHYSICAL (real/flat) ADDRESS of the parent's
  3087                              <1> 	;		    page directory.
  3088                              <1> 	; OUTPUT ->
  3089                              <1> 	;	EAX =  PHYSICAL (real/flat) ADDRESS of the child's
  3090                              <1> 	;	       page directory.
  3091                              <1> 	;	(New page directory with new page table entries.)
  3092                              <1> 	;	(New page tables with read only copies of the parent's
  3093                              <1> 	;	pages.)
  3094                              <1> 	;	EAX = 0 -> Error (CF = 1)
  3095                              <1> 	;
  3096                              <1> 	; Modified Registers -> none (except EAX)
  3097                              <1> 	;
  3098 000026BE E804FEFFFF          <1> 	call	allocate_page
  3099 000026C3 723E                <1> 	jc	short dpd_err
  3100                              <1> 	;
  3101 000026C5 55                  <1> 	push	ebp ; 20/07/2015
  3102 000026C6 56                  <1> 	push	esi
  3103 000026C7 57                  <1> 	push	edi
  3104 000026C8 53                  <1> 	push	ebx
  3105 000026C9 51                  <1> 	push	ecx
  3106 000026CA 8B35[35660000]      <1> 	mov	esi, [u.pgdir]
  3107 000026D0 89C7                <1> 	mov	edi, eax
  3108 000026D2 50                  <1> 	push	eax ; save child's page directory address
  3109                              <1> 	; 31/08/2015
  3110                              <1> 	; copy PDE 0 from the parent's page dir to the child's page dir
  3111                              <1> 	; (use same system space for all user page tables) 
  3112 000026D3 A5                  <1> 	movsd
  3113 000026D4 BD00004000          <1> 	mov	ebp, 1024*4096 ; pass the 1st 4MB (system space)
  3114 000026D9 B9FF030000          <1> 	mov	ecx, (PAGE_SIZE / 4) - 1 ; 1023
  3115                              <1> dpd_0:	
  3116 000026DE AD                  <1> 	lodsd
  3117                              <1> 	;or	eax, eax
  3118                              <1>         ;jnz     short dpd_1
  3119 000026DF A801                <1> 	test	al, PDE_A_PRESENT ;  bit 0 =  1
  3120 000026E1 7508                <1> 	jnz	short dpd_1
  3121                              <1>  	; 20/07/2015 (virtual address at the end of the page table)	
  3122 000026E3 81C500004000        <1> 	add	ebp, 1024*4096 ; page size * PTE count
  3123 000026E9 EB0F                <1> 	jmp	short dpd_2
  3124                              <1> dpd_1:	
  3125 000026EB 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h ; clear attribute bits
  3126 000026EF 89C3                <1> 	mov	ebx, eax
  3127                              <1> 	; EBX = Parent's page table address
  3128 000026F1 E81F000000          <1> 	call	duplicate_page_table
  3129 000026F6 720C                <1> 	jc	short dpd_p_err
  3130                              <1> 	; EAX = Child's page table address
  3131 000026F8 0C07                <1> 	or	al, PDE_A_PRESENT + PDE_A_WRITE + PDE_A_USER
  3132                              <1> 			 ; set bit 0, bit 1 and bit 2 to 1
  3133                              <1> 			 ; (present, writable, user)
  3134                              <1> dpd_2:
  3135 000026FA AB                  <1> 	stosd
  3136 000026FB E2E1                <1> 	loop	dpd_0
  3137                              <1> 	;
  3138 000026FD 58                  <1> 	pop	eax  ; restore child's page directory address
  3139                              <1> dpd_3:
  3140 000026FE 59                  <1> 	pop	ecx
  3141 000026FF 5B                  <1> 	pop	ebx
  3142 00002700 5F                  <1> 	pop	edi
  3143 00002701 5E                  <1> 	pop	esi
  3144 00002702 5D                  <1> 	pop	ebp ; 20/07/2015
  3145                              <1> dpd_err:
  3146 00002703 C3                  <1> 	retn
  3147                              <1> dpd_p_err:
  3148                              <1> 	; release the allocated pages missing (recover free space)
  3149 00002704 58                  <1> 	pop	eax  ; the new page directory address (physical)
  3150 00002705 8B1D[35660000]      <1> 	mov	ebx, [u.pgdir] ; parent's page directory address 
  3151 0000270B E8E7FEFFFF          <1> 	call 	deallocate_page_dir
  3152 00002710 29C0                <1> 	sub	eax, eax ; 0
  3153 00002712 F9                  <1> 	stc
  3154 00002713 EBE9                <1> 	jmp	short dpd_3	
  3155                              <1> 
  3156                              <1> duplicate_page_table:
  3157                              <1> 	; 31/12/2021
  3158                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3159                              <1> 	; 20/02/2017 (TRDOS 386 v2)
  3160                              <1> 	; 21/09/2015
  3161                              <1> 	; 20/07/2015
  3162                              <1> 	; 05/05/2015
  3163                              <1> 	; 28/04/2015
  3164                              <1> 	; 27/04/2015
  3165                              <1> 	; 18/04/2015
  3166                              <1> 	; 18/10/2014
  3167                              <1> 	; 16/10/2014 (Retro UNIX 386 v1 - beginning)
  3168                              <1> 	;
  3169                              <1> 	; INPUT -> 
  3170                              <1> 	;	EBX = PHYSICAL (real/flat) ADDRESS of the parent's page table.
  3171                              <1> 	;       20/02/2017		 
  3172                              <1> 	;	EBP = Linear address of the page (from 'duplicate_page_dir')
  3173                              <1> 	;	      (Linear address = CORE + user's virtual address) 	
  3174                              <1> 	; OUTPUT ->
  3175                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS of the child's page table.
  3176                              <1> 	;	      (with 'read only' attribute of page table entries)
  3177                              <1> 	;	20/02/2017
  3178                              <1> 	;	EBP = Next linear page address (for 'duplicate_page_dir')
  3179                              <1> 	;	
  3180                              <1> 	;	CF = 1 -> error 
  3181                              <1> 	;
  3182                              <1> 	; Modified Registers -> EBP (except EAX)
  3183                              <1> 	;
  3184 00002715 E8ADFDFFFF          <1> 	call	allocate_page
  3185 0000271A 725B                <1> 	jc	short dpt_err
  3186                              <1> 	;
  3187 0000271C 50                  <1> 	push	eax ; *
  3188 0000271D 56                  <1> 	push	esi
  3189 0000271E 57                  <1> 	push	edi
  3190 0000271F 52                  <1> 	push	edx
  3191 00002720 51                  <1> 	push	ecx
  3192                              <1> 	;
  3193 00002721 89DE                <1> 	mov	esi, ebx
  3194 00002723 89C7                <1> 	mov	edi, eax
  3195 00002725 89C2                <1> 	mov	edx, eax
  3196 00002727 81C200100000        <1> 	add	edx, PAGE_SIZE 	
  3197                              <1> dpt_0:
  3198 0000272D AD                  <1> 	lodsd
  3199 0000272E 21C0                <1> 	and	eax, eax
  3200 00002730 7435                <1> 	jz	short dpt_3
  3201 00002732 A801                <1> 	test	al, PTE_A_PRESENT ;  bit 0 =  1
  3202                              <1> 	; 24/12/2021
  3203 00002734 7503                <1> 	jnz	short dpt_1
  3204                              <1> 	;jz	short dpt_p_err
  3205                              <1> 	; 31/12/2021
  3206 00002736 F9                  <1> 	stc
  3207 00002737 EB39                <1> 	jmp	short dpt_p_err
  3208                              <1> 
  3209                              <1> ; 24/12/2021
  3210                              <1> ; ('reload_page' procedure call is disabled)
  3211                              <1> ;
  3212                              <1> ;	; 20/07/2015
  3213                              <1> ;	; ebp = virtual (linear) address of the memory page
  3214                              <1> ;	call	reload_page ; 28/04/2015
  3215                              <1> ;	jc	short dpt_p_err
  3216                              <1> dpt_1:
  3217                              <1> 	; 21/09/2015
  3218 00002739 89C1                <1> 	mov	ecx, eax
  3219 0000273B 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear attribute bits
  3220 0000273F F6C102              <1> 	test	cl, PTE_A_WRITE ; writable page ?
  3221 00002742 751A                <1> 	jnz	short dpt_2
  3222                              <1> 	; Read only (parent) page
  3223                              <1> 	; 	- there is a third process which uses this page -
  3224                              <1> 	; Allocate a new page for the child process
  3225 00002744 E87EFDFFFF          <1> 	call	allocate_page
  3226 00002749 7227                <1> 	jc	short dpt_p_err
  3227 0000274B 57                  <1> 	push	edi
  3228 0000274C 56                  <1> 	push	esi
  3229 0000274D 89CE                <1> 	mov	esi, ecx
  3230 0000274F 89C7                <1> 	mov	edi, eax
  3231 00002751 B900040000          <1> 	mov	ecx, PAGE_SIZE/4
  3232 00002756 F3A5                <1> 	rep	movsd	; copy page (4096 bytes)
  3233 00002758 5E                  <1> 	pop	esi
  3234 00002759 5F                  <1> 	pop	edi
  3235                              <1> 	;
  3236                              <1> 
  3237                              <1> ; 24/12/2021
  3238                              <1> ; ('add_to_swap_queue' procedure call is disabled)
  3239                              <1> ; 
  3240                              <1> ;	push	ebx
  3241                              <1> ;	push	eax
  3242                              <1> ;	; 20/07/2015
  3243                              <1> ;	mov	ebx, ebp
  3244                              <1> ;	; ebx = virtual (linear) address of the memory page
  3245                              <1> ;	call	add_to_swap_queue
  3246                              <1> ;	pop	eax
  3247                              <1> ;	pop	ebx
  3248                              <1> 
  3249                              <1> 	; 21/09/2015
  3250 0000275A 0C07                <1> 	or	al, PTE_A_USER+PTE_A_WRITE+PTE_A_PRESENT 
  3251                              <1> 		; user + writable + present page
  3252 0000275C EB09                <1> 	jmp	short dpt_3
  3253                              <1> dpt_2:
  3254                              <1> 	;or	ax, PTE_A_USER+PTE_A_PRESENT 
  3255 0000275E 0C05                <1> 	or	al, PTE_A_USER+PTE_A_PRESENT 
  3256                              <1> 		    ; (read only page!)
  3257 00002760 8946FC              <1> 	mov	[esi-4], eax ; update parent's PTE
  3258 00002763 660D0002            <1> 	or      ax, PTE_DUPLICATED  ; (read only page & duplicated PTE!)
  3259                              <1> dpt_3:
  3260 00002767 AB                  <1> 	stosd  ; EDI points to child's PTE  	 
  3261                              <1> 	;
  3262 00002768 81C500100000        <1> 	add	ebp, 4096 ; 20/07/2015 (next page)
  3263                              <1> 	;
  3264 0000276E 39D7                <1> 	cmp	edi, edx
  3265 00002770 72BB                <1> 	jb	short dpt_0
  3266                              <1> dpt_p_err:
  3267 00002772 59                  <1> 	pop	ecx
  3268 00002773 5A                  <1> 	pop	edx
  3269 00002774 5F                  <1> 	pop	edi
  3270 00002775 5E                  <1> 	pop	esi
  3271 00002776 58                  <1> 	pop	eax ; *
  3272                              <1> dpt_err:
  3273 00002777 C3                  <1> 	retn
  3274                              <1> 
  3275                              <1> page_fault_handler: ; CPU EXCEPTION 0Eh (14) : Page Fault !
  3276                              <1> 	; 31/12/2021
  3277                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3278                              <1> 	; 21/09/2015
  3279                              <1> 	; 19/09/2015
  3280                              <1> 	; 17/09/2015
  3281                              <1> 	; 28/08/2015
  3282                              <1> 	; 20/07/2015
  3283                              <1> 	; 28/06/2015
  3284                              <1> 	; 03/05/2015
  3285                              <1> 	; 30/04/2015
  3286                              <1> 	; 18/04/2015
  3287                              <1> 	; 12/04/2015
  3288                              <1> 	; 30/10/2014
  3289                              <1> 	; 11/09/2014
  3290                              <1> 	; 10/09/2014 (Retro UNIX 386 v1 - beginning)
  3291                              <1> 	;
  3292                              <1> 	; Note: This is not an interrupt/exception handler.
  3293                              <1> 	;	This is a 'page fault remedy' subroutine 
  3294                              <1> 	;	which will be called by standard/uniform
  3295                              <1> 	;	exception handler.
  3296                              <1> 	;
  3297                              <1> 	; INPUT -> 
  3298                              <1> 	;	[error_code] = 32 bit ERROR CODE (lower 5 bits are valid)
  3299                              <1> 	;
  3300                              <1> 	;	cr2 = the virtual (linear) address 
  3301                              <1> 	;	      which has caused to page fault (19/09/2015)
  3302                              <1> 	;
  3303                              <1> 	; OUTPUT ->
  3304                              <1> 	;	(corresponding PAGE TABLE ENTRY is mapped/set)
  3305                              <1> 	;	EAX = 0 -> no error
  3306                              <1> 	;	EAX > 0 -> error code in EAX (also CF = 1)
  3307                              <1> 	;
  3308                              <1> 	; Modified Registers -> none (except EAX)
  3309                              <1> 	;	
  3310                              <1>         ;
  3311                              <1>         ; ERROR CODE:
  3312                              <1> 	;	 31  .....	4   3	2   1	0
  3313                              <1> 	;	+---+-- --+---+---+---+---+---+---+
  3314                              <1> 	;	|   Reserved  | I | R | U | W | P |
  3315                              <1> 	;	+---+-- --+---+---+---+---+---+---+
  3316                              <1> 	;
  3317                              <1> 	; P : PRESENT -	When set, the page fault was caused by 
  3318                              <1>     	;		a page-protection violation. When not set,
  3319                              <1> 	;		it was caused by a non-present page.
  3320                              <1> 	; W : WRITE   -	When set, the page fault was caused by
  3321                              <1> 	;		a page write. When not set, it was caused
  3322                              <1> 	;		by a page read.
  3323                              <1> 	; U : USER    -	When set, the page fault was caused 
  3324                              <1> 	;		while CPL = 3. 
  3325                              <1> 	;		This does not necessarily mean that
  3326                              <1> 	;		the page fault was a privilege violation.
  3327                              <1> 	; R : RESERVD -	When set, the page fault was caused by
  3328                              <1> 	;     WRITE	reading a 1 in a reserved field.
  3329                              <1> 	; I : INSTRUC -	When set, the page fault was caused by
  3330                              <1> 	;     FETCH	an instruction fetch
  3331                              <1> 	;
  3332                              <1> 	;; x86 (32 bit) VIRTUAL ADDRESS TRANSLATION
  3333                              <1> 	;  31               22                  12 11                    0
  3334                              <1> 	; +-------------------+-------------------+-----------------------+
  3335                              <1>        	; | PAGE DIR. ENTRY # | PAGE TAB. ENTRY # |        OFFSET         |
  3336                              <1>        	; +-------------------+-------------------+-----------------------+
  3337                              <1> 	;
  3338                              <1> 
  3339                              <1> 	;; CR3 REGISTER (Control Register 3)
  3340                              <1> 	;  31                                   12             5 4 3 2   0
  3341                              <1> 	; +---------------------------------------+-------------+---+-----+
  3342                              <1>       	; |                                       |  		|P|P|     |
  3343                              <1>       	; |   PAGE DIRECTORY TABLE BASE ADDRESS   |  reserved	|C|W|rsvrd|
  3344                              <1>       	; |                                       | 		|D|T|     |
  3345                              <1>    	; +---------------------------------------+-------------+---+-----+
  3346                              <1> 	;
  3347                              <1> 	;	PWT    - WRITE THROUGH
  3348                              <1> 	;	PCD    - CACHE DISABLE		
  3349                              <1> 	;
  3350                              <1> 	;
  3351                              <1> 	;; x86 PAGE DIRECTORY ENTRY (4 KByte Page)
  3352                              <1> 	;  31                                   12 11  9 8 7 6 5 4 3 2 1 0
  3353                              <1> 	; +---------------------------------------+-----+---+-+-+---+-+-+-+
  3354                              <1>       	; |                                       |     | | | | |P|P|U|R| |
  3355                              <1>       	; |     PAGE TABLE BASE ADDRESS 31..12    | AVL |G|0|D|A|C|W|/|/|P|
  3356                              <1>       	; |                                       |     | | | | |D|T|S|W| |
  3357                              <1>    	; +---------------------------------------+-----+---+-+-+---+-+-+-+
  3358                              <1> 	;
  3359                              <1>         ;       P      - PRESENT
  3360                              <1>         ;       R/W    - READ/WRITE
  3361                              <1>         ;       U/S    - USER/SUPERVISOR
  3362                              <1> 	;	PWT    - WRITE THROUGH
  3363                              <1> 	;	PCD    - CACHE DISABLE	
  3364                              <1> 	;	A      - ACCESSED	
  3365                              <1>         ;       D      - DIRTY (IGNORED)
  3366                              <1> 	;	PAT    - PAGE ATTRIBUTE TABLE INDEX (CACHE BEHAVIOR)
  3367                              <1> 	;	G      - GLOBAL	(IGNORED) 
  3368                              <1>         ;       AVL    - AVAILABLE FOR SYSTEMS PROGRAMMER USE
  3369                              <1> 	;
  3370                              <1> 	;
  3371                              <1> 	;; x86 PAGE TABLE ENTRY (4 KByte Page)
  3372                              <1> 	;  31                                   12 11  9 8 7 6 5 4 3 2 1 0
  3373                              <1> 	; +---------------------------------------+-----+---+-+-+---+-+-+-+
  3374                              <1>       	; |                                       |     | |P| | |P|P|U|R| |
  3375                              <1>       	; |     PAGE FRAME BASE ADDRESS 31..12    | AVL |G|A|D|A|C|W|/|/|P|
  3376                              <1>       	; |                                       |     | |T| | |D|T|S|W| |
  3377                              <1>    	; +---------------------------------------+-----+---+-+-+---+-+-+-+
  3378                              <1> 	;
  3379                              <1>         ;       P      - PRESENT
  3380                              <1>         ;       R/W    - READ/WRITE
  3381                              <1>         ;       U/S    - USER/SUPERVISOR
  3382                              <1> 	;	PWT    - WRITE THROUGH
  3383                              <1> 	;	PCD    - CACHE DISABLE	
  3384                              <1> 	;	A      - ACCESSED	
  3385                              <1>         ;       D      - DIRTY
  3386                              <1> 	;	PAT    - PAGE ATTRIBUTE TABLE INDEX (CACHE BEHAVIOR)
  3387                              <1> 	;	G      - GLOBAL	 
  3388                              <1>         ;       AVL    - AVAILABLE FOR SYSTEMS PROGRAMMER USE
  3389                              <1> 	;
  3390                              <1> 	;
  3391                              <1> 	;; 80386 PAGE TABLE ENTRY (4 KByte Page)
  3392                              <1> 	;  31                                   12 11  9 8 7 6 5 4 3 2 1 0
  3393                              <1> 	; +---------------------------------------+-----+-+-+-+-+---+-+-+-+
  3394                              <1>       	; |                                       |     | | | | | | |U|R| |
  3395                              <1>       	; |     PAGE FRAME BASE ADDRESS 31..12    | AVL |0|0|D|A|0|0|/|/|P|
  3396                              <1>       	; |                                       |     | | | | | | |S|W| |
  3397                              <1>       	; +---------------------------------------+-----+-+-+-+-+---+-+-+-+
  3398                              <1> 	;
  3399                              <1>         ;       P      - PRESENT
  3400                              <1>         ;       R/W    - READ/WRITE
  3401                              <1>         ;       U/S    - USER/SUPERVISOR
  3402                              <1>         ;       D      - DIRTY
  3403                              <1>         ;       AVL    - AVAILABLE FOR SYSTEMS PROGRAMMER USE
  3404                              <1> 	;
  3405                              <1>         ;       NOTE: 0 INDICATES INTEL RESERVED. DO NOT DEFINE.
  3406                              <1> 	;
  3407                              <1> 	;
  3408                              <1> 	;; Invalid Page Table Entry
  3409                              <1> 	; 31                                                           1 0
  3410                              <1>       	; +-------------------------------------------------------------+-+
  3411                              <1>       	; |                                                             | |
  3412                              <1>       	; |                          AVAILABLE                          |0|
  3413                              <1>       	; |                                                             | |
  3414                              <1>       	; +-------------------------------------------------------------+-+
  3415                              <1> 	;
  3416                              <1> 
  3417 00002778 53                  <1> 	push	ebx
  3418 00002779 52                  <1> 	push	edx
  3419 0000277A 51                  <1> 	push	ecx
  3420                              <1> 	;
  3421                              <1> 	; 21/09/2015 (debugging)
  3422 0000277B FF05[45660000]      <1> 	inc	dword [u.pfcount] ; page fault count for running process
  3423 00002781 FF05[CC620000]      <1> 	inc	dword [PF_Count]  ; total page fault count	
  3424                              <1> 	; 28/06/2015
  3425                              <1> 	;mov	edx, [error_code] ; Lower 5 bits are valid
  3426 00002787 8A15[C4620000]      <1> 	mov	dl, [error_code]
  3427                              <1> 	;
  3428 0000278D F6C201              <1> 	test	dl, 1	; page fault was caused by a non-present page
  3429                              <1> 			; sign
  3430 00002790 7425                <1> 	jz	short pfh_alloc_np
  3431                              <1> 	; 
  3432                              <1> 	; If it is not a 'write on read only page' type page fault
  3433                              <1> 	; major page fault error with minor reason must be returned without 
  3434                              <1> 	; fixing the problem. 'sys_exit with error' will be needed
  3435                              <1> 	; after return here!
  3436                              <1> 	; Page fault will be remedied, by copying page contents
  3437                              <1> 	; to newly allocated page with write permission;
  3438                              <1> 	; sys_fork -> sys_exec -> copy on write, demand paging method is 
  3439                              <1> 	; used for working with minimum possible memory usage. 
  3440                              <1> 	; sys_fork will duplicate page directory and tables of parent  
  3441                              <1> 	; process with 'read only' flag. If the child process attempts to
  3442                              <1> 	; write on these read only pages, page fault will be directed here
  3443                              <1> 	; for allocating a new page with same data/content. 
  3444                              <1> 	;
  3445                              <1> 	; IMPORTANT : Retro UNIX 386 v1 (and SINGLIX and TR-DOS)
  3446                              <1> 	; will not force to separate CODE and DATA space 
  3447                              <1> 	; in a process/program... 
  3448                              <1> 	; CODE segment/section may contain DATA!
  3449                              <1> 	; It is flat, smoth and simplest programming method already as in 
  3450                              <1> 	; Retro UNIX 8086 v1 and MS-DOS programs.
  3451                              <1> 	;	
  3452 00002792 F6C202              <1> 	test	dl, 2	; page fault was caused by a page write
  3453                              <1> 			; sign
  3454 00002795 7418                <1>         jz      pfh_p_err
  3455                              <1> 	; 31/08/2015
  3456 00002797 F6C204              <1> 	test	dl, 4	; page fault was caused while CPL = 3 (user mode)
  3457                              <1> 			; sign.  (U+W+P = 4+2+1 = 7)
  3458 0000279A 7413                <1>         jz	short pfh_pv_err
  3459                              <1> 	;
  3460                              <1> 	; make a new page and copy the parent's page content
  3461                              <1> 	; as the child's new page content
  3462                              <1> 	;
  3463 0000279C 0F20D3              <1> 	mov	ebx, cr2 ; CR2 contains the linear address 
  3464                              <1> 			 ; which has caused to page fault
  3465 0000279F E87C000000          <1> 	call 	copy_page
  3466 000027A4 7202                <1>         jc	short pfh_im_err ; insufficient memory
  3467                              <1> 	;
  3468 000027A6 EB72                <1>         jmp     pfh_cpp_ok
  3469                              <1> 
  3470                              <1> 	; 31/12/2021 (short jump)
  3471                              <1> pfh_im_err:
  3472 000027A8 B8E4000000          <1> 	mov	eax, ERR_MAJOR_PF + ERR_MINOR_IM ; Error code in AX
  3473                              <1> 			; Major (Primary) Error: Page Fault
  3474                              <1> 			; Minor (Secondary) Error: Insufficient Memory !
  3475 000027AD EB6D                <1> 	jmp	short pfh_err_retn
  3476                              <1> 
  3477                              <1> 	; 31/12/2021
  3478                              <1> pfh_p_err: ; 09/03/2015
  3479                              <1> pfh_pv_err:
  3480                              <1> 	; Page fault was caused by a protection-violation
  3481 000027AF B8E6000000          <1> 	mov	eax, ERR_MAJOR_PF + ERR_MINOR_PV ; Error code in AX
  3482                              <1> 			; Major (Primary) Error: Page Fault
  3483                              <1> 			; Minor (Secondary) Error: Protection violation !
  3484 000027B4 F9                  <1> 	stc
  3485 000027B5 EB65                <1> 	jmp	short pfh_err_retn
  3486                              <1> 	
  3487                              <1> pfh_alloc_np:
  3488 000027B7 E80BFDFFFF          <1> 	call	allocate_page	; (allocate a new page)
  3489 000027BC 72EA                <1>         jc	short pfh_im_err ; 'insufficient memory' error
  3490                              <1> pfh_chk_cpl:
  3491                              <1> 	; EAX = Physical (base) address of the allocated (new) page
  3492                              <1> 		; (Lower 12 bits are ZERO, because 
  3493                              <1> 		;	the address is on a page boundary)
  3494 000027BE 80E204              <1> 	and	dl, 4	; CPL = 3 ?
  3495 000027C1 7505                <1> 	jnz	short pfh_um
  3496                              <1> 			; Page fault handler for kernel/system mode (CPL=0)		
  3497 000027C3 0F20DB              <1> 	mov	ebx, cr3 ; CR3 (Control Register 3) contains physical address
  3498                              <1> 			 ; of the current/active page directory
  3499                              <1> 			 ; (Always kernel/system mode page directory, here!)
  3500                              <1> 			 ; Note: Lower 12 bits are 0. (page boundary)
  3501 000027C6 EB06                <1> 	jmp	short pfh_get_pde
  3502                              <1> 	;
  3503                              <1> pfh_um:			; Page fault handler for user/appl. mode (CPL=3)
  3504 000027C8 8B1D[35660000]      <1>  	mov	ebx, [u.pgdir] ; Page directory of current/active process
  3505                              <1> 			; Physical address of the USER's page directory
  3506                              <1> 			; Note: Lower 12 bits are 0. (page boundary)
  3507                              <1> pfh_get_pde:
  3508 000027CE 80CA03              <1> 	or	dl, 3	; USER + WRITE + PRESENT or SYSTEM + WRITE + PRESENT
  3509 000027D1 0F20D1              <1> 	mov	ecx, cr2 ; CR2 contains the virtual address 
  3510                              <1> 			 ; which has been caused to page fault
  3511                              <1> 			 ;
  3512 000027D4 C1E914              <1> 	shr	ecx, 20	 ; shift 20 bits right
  3513 000027D7 80E1FC              <1> 	and	cl, 0FCh ; mask lower 2 bits to get PDE offset		
  3514                              <1> 	;
  3515 000027DA 01CB                <1> 	add	ebx, ecx ; now, EBX points to the relevant page dir entry 
  3516 000027DC 8B0B                <1> 	mov	ecx, [ebx] ; physical (base) address of the page table 	
  3517 000027DE F6C101              <1> 	test	cl, 1	 ; check bit 0 is set (1) or not (0).
  3518 000027E1 740B                <1> 	jz	short pfh_set_pde ; Page directory entry is not valid,
  3519                              <1> 			  	  ; set/validate page directory entry
  3520 000027E3 6681E100F0          <1> 	and	cx, PDE_A_CLEAR ; 0F000h ; Clear attribute bits
  3521 000027E8 89CB                <1> 	mov	ebx, ecx ; Physical address of the page table
  3522 000027EA 89C1                <1> 	mov	ecx, eax ; new page address (physical) 	
  3523 000027EC EB16                <1> 	jmp	short pfh_get_pte
  3524                              <1> pfh_set_pde:
  3525                              <1> 	;; NOTE: Page directories and page tables never be swapped out!
  3526                              <1> 	;;	 (So, we know this PDE is empty or invalid)
  3527                              <1> 	;
  3528 000027EE 08D0                <1> 	or	al, dl	 ; lower 3 bits are used as U/S, R/W, P flags
  3529 000027F0 8903                <1> 	mov	[ebx], eax ; Let's put the new page directory entry here !
  3530 000027F2 30C0                <1> 	xor	al, al	 ; clear lower (3..8) bits
  3531 000027F4 89C3                <1> 	mov	ebx, eax
  3532 000027F6 E8CCFCFFFF          <1> 	call	allocate_page	 ; (allocate a new page)
  3533 000027FB 72AB                <1> 	jc	short pfh_im_err   ; 'insufficient memory' error
  3534                              <1> pfh_spde_1:
  3535                              <1> 	; EAX = Physical (base) address of the allocated (new) page
  3536 000027FD 89C1                <1> 	mov	ecx, eax
  3537 000027FF E834FDFFFF          <1> 	call	clear_page ; Clear page content
  3538                              <1> pfh_get_pte:
  3539 00002804 0F20D0              <1> 	mov	eax, cr2 ; virtual address
  3540                              <1> 			 ; which has been caused to page fault
  3541 00002807 89C7                <1> 	mov	edi, eax ; 20/07/2015
  3542 00002809 C1E80C              <1> 	shr	eax, 12	 ; shift 12 bit right to get 
  3543                              <1> 			 ; higher 20 bits of the page fault address 
  3544 0000280C 25FF030000          <1> 	and	eax, 3FFh ; mask PDE# bits, the result is PTE# (0 to 1023)
  3545 00002811 C1E002              <1> 	shl	eax, 2	; shift 2 bits left to get PTE offset
  3546 00002814 01C3                <1> 	add	ebx, eax ; now, EBX points to the relevant page table entry 
  3547                              <1> ; 24/12/2021
  3548                              <1> ;	mov	eax, [ebx] ; get previous value of pte
  3549                              <1> ;		; bit 0 of EAX is always 0 (otherwise we would not be here)
  3550                              <1> ; 24/12/2021
  3551                              <1> ; ('swap_in' procedure call has been disabled)
  3552                              <1> ;
  3553                              <1> ;	and	eax, eax
  3554                              <1> ;	jz	short pfh_gpte_1
  3555                              <1> ;	; 20/07/2015
  3556                              <1> ;	xchg	ebx, ecx ; new page address (physical)
  3557                              <1> ;	push	ebp ; 20/07/2015
  3558                              <1> ;	mov	ebp, cr2
  3559                              <1> ;		; ECX = physical address of the page table entry
  3560                              <1> ;		; EBX = Memory page address (physical!)
  3561                              <1> ;		; EAX = Swap disk (offset) address
  3562                              <1> ;		; EBP = virtual address (page fault address)
  3563                              <1> ;	call	swap_in
  3564                              <1> ;	pop	ebp
  3565                              <1> ;	jc      short pfh_err_retn
  3566                              <1> ;	xchg	ecx, ebx
  3567                              <1> ;		; EBX = physical address of the page table entry
  3568                              <1> ;		; ECX = new page
  3569                              <1> pfh_gpte_1:
  3570 00002816 08D1                <1> 	or	cl, dl	; lower 3 bits are used as U/S, R/W, P flags
  3571 00002818 890B                <1> 	mov	[ebx], ecx ; Let's put the new page table entry here !
  3572                              <1> pfh_cpp_ok:
  3573                              <1> ; 24/12/2021
  3574                              <1> ; ('add_to_swap_queue' procedure call has been disabled)
  3575                              <1> ;
  3576                              <1> ;	; 20/07/2015
  3577                              <1> ;	mov	ebx, cr2
  3578                              <1> ;	call 	add_to_swap_queue
  3579                              <1> 	;
  3580                              <1> 	; The new PTE (which contains the new page) will be added to 
  3581                              <1> 	; the swap queue, here. 
  3582                              <1> 	; (Later, if memory will become insufficient, 
  3583                              <1> 	; one page will be swapped out which is at the head of 
  3584                              <1> 	; the swap queue by using FIFO and access check methods.)
  3585                              <1> 	;
  3586 0000281A 31C0                <1> 	xor	eax, eax  ; 0
  3587                              <1> 	;
  3588                              <1> pfh_err_retn:
  3589 0000281C 59                  <1> 	pop	ecx
  3590 0000281D 5A                  <1> 	pop	edx
  3591 0000281E 5B                  <1> 	pop	ebx
  3592 0000281F C3                  <1> 	retn 
  3593                              <1> 	
  3594                              <1> copy_page:
  3595                              <1> 	; 17/07/2022
  3596                              <1> 	; 24/12/2021 - Retro UNIX 386 v1.1
  3597                              <1> 	; 16/04/2021
  3598                              <1> 	; 19/04/2020 - Retro UNIX 386 v2
  3599                              <1> 	; 22/09/2015
  3600                              <1> 	; 21/09/2015
  3601                              <1> 	; 19/09/2015
  3602                              <1> 	; 07/09/2015
  3603                              <1> 	; 31/08/2015
  3604                              <1> 	; 20/07/2015
  3605                              <1> 	; 05/05/2015
  3606                              <1> 	; 03/05/2015
  3607                              <1> 	; 18/04/2015
  3608                              <1> 	; 12/04/2015
  3609                              <1> 	; 30/10/2014
  3610                              <1> 	; 18/10/2014 (Retro UNIX 386 v1 - beginning)
  3611                              <1> 	;
  3612                              <1> 	; INPUT -> 
  3613                              <1> 	;	EBX = Virtual (linear) address of source page
  3614                              <1> 	;	     (Page fault address)
  3615                              <1> 	; OUTPUT ->
  3616                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF THE ALLOCATED PAGE
  3617                              <1> 	;	(corresponding PAGE TABLE ENTRY is mapped/set)
  3618                              <1> 	;	EAX = 0 (CF = 1) 
  3619                              <1> 	;		if there is not a free page to be allocated
  3620                              <1> 	;	(page content of the source page will be copied
  3621                              <1> 	;	onto the target/new page) 	
  3622                              <1> 	;
  3623                              <1> 	; Modified Registers -> ecx, ebx (except EAX)
  3624                              <1> 	;
  3625                              <1> 
  3626                              <1> 	; 19/04/2020 - Retro UNIX 386 v2
  3627                              <1> 	; INPUT: 
  3628                              <1> 	;	EBX = Virtual (linear) address of source page
  3629                              <1> 	;	     (Page fault address)
  3630                              <1> 	; OUTPUT:
  3631                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF THE ALLOCATED PAGE
  3632                              <1> 	;	(corresponding PAGE TABLE ENTRY is mapped/set)
  3633                              <1> 	;	EAX = 0 (CF = 1) 
  3634                              <1> 	;		if there is not a free page to be allocated
  3635                              <1> 	;	(page content of the source page will be copied
  3636                              <1> 	;	onto the target/new page) 	
  3637                              <1> 	;
  3638                              <1> 	; Modified Registers -> ecx, ebx (except EAX) ; 16/04/2021
  3639                              <1> 	
  3640 00002820 56                  <1> 	push	esi ; *
  3641 00002821 57                  <1> 	push	edi ; **
  3642                              <1> 	; 16/04/2021
  3643                              <1> 	; 19/04/2020 - Retro UNIX 386 v2
  3644                              <1> 	;push	ebx ; ***
  3645                              <1> 	;push	ecx ; ****
  3646 00002822 31F6                <1> 	xor 	esi, esi
  3647 00002824 C1EB0C              <1> 	shr	ebx, 12 ; shift 12 bits right to get PDE & PTE numbers
  3648 00002827 89D9                <1> 	mov	ecx, ebx ; save page fault address (as 12 bit shifted)
  3649 00002829 C1EB08              <1> 	shr	ebx, 8	 ; shift 8 bits right and then
  3650 0000282C 80E3FC              <1> 	and	bl, 0FCh ; mask lower 2 bits to get PDE offset	
  3651 0000282F 89DF                <1> 	mov 	edi, ebx ; save it for the parent of current process
  3652 00002831 031D[35660000]      <1> 	add	ebx, [u.pgdir] ; EBX points to the relevant page dir entry 
  3653 00002837 8B03                <1> 	mov	eax, [ebx] ; physical (base) address of the page table
  3654 00002839 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear attribute bits 	
  3655 0000283D 89CB                <1> 	mov	ebx, ecx   ; (restore higher 20 bits of page fault address)
  3656 0000283F 81E3FF030000        <1> 	and	ebx, 3FFh  ; mask PDE# bits, the result is PTE# (0 to 1023)
  3657                              <1> 	;shl	bx, 2	   ; shift 2 bits left to get PTE offset
  3658                              <1> 	; 17/07/2022
  3659 00002845 C1E302              <1> 	shl	ebx, 2
  3660 00002848 01C3                <1> 	add	ebx, eax   ; EBX points to the relevant page table entry 
  3661                              <1> 	; 07/09/2015
  3662 0000284A 66F7030002          <1>         test    word [ebx], PTE_DUPLICATED ; (Does current process share this
  3663                              <1> 				     ; read only page as a child process?)	
  3664 0000284F 7509                <1> 	jnz	short cpp_0 ; yes
  3665 00002851 8B0B                <1> 	mov	ecx, [ebx] ; PTE value
  3666 00002853 6681E100F0          <1> 	and	cx, PTE_A_CLEAR ; 0F000h  ; clear page attributes
  3667 00002858 EB31                <1> 	jmp	short cpp_1
  3668                              <1> cpp_0:
  3669 0000285A 89FE                <1> 	mov	esi, edi
  3670 0000285C 0335[39660000]      <1> 	add	esi, [u.ppgdir] ; the parent's page directory entry
  3671 00002862 8B06                <1> 	mov	eax, [esi] ; physical (base) address of the page table
  3672 00002864 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear attribute bits
  3673 00002868 89CE                <1> 	mov	esi, ecx   ; (restore higher 20 bits of page fault address)	
  3674 0000286A 81E6FF030000        <1> 	and	esi, 3FFh  ; mask PDE# bits, the result is PTE# (0 to 1023)
  3675                              <1> 	;shl	si, 2	   ; shift 2 bits left to get PTE offset
  3676                              <1> 	; 17/07/2022
  3677 00002870 C1E602              <1> 	shl	esi, 2
  3678 00002873 01C6                <1> 	add	esi, eax   ; EDX points to the relevant page table entry  	
  3679 00002875 8B0E                <1> 	mov	ecx, [esi] ; PTE value of the parent process
  3680                              <1> 	; 21/09/2015
  3681 00002877 8B03                <1> 	mov	eax, [ebx] ; PTE value of the child process
  3682 00002879 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear page attributes	
  3683                              <1> 	;
  3684 0000287D F6C101              <1> 	test	cl, PTE_A_PRESENT ; is it a present/valid page ?
  3685 00002880 7424                <1> 	jz	short cpp_3 ; the parent's page is not same page  	
  3686                              <1> 	;
  3687 00002882 6681E100F0          <1> 	and	cx, PTE_A_CLEAR ; 0F000h ; clear page attributes
  3688 00002887 39C8                <1> 	cmp	eax, ecx   ; Same page?	
  3689 00002889 751B                <1> 	jne	short cpp_3 ; Parent page and child page are not same 
  3690                              <1> 			    ; Convert child's page to writable page
  3691                              <1> cpp_1:
  3692 0000288B E837FCFFFF          <1> 	call	allocate_page
  3693 00002890 721A                <1> 	jc	short cpp_4 ; 'insufficient memory' error
  3694 00002892 21F6                <1> 	and	esi, esi    ; check ESI is valid or not
  3695 00002894 7405                <1> 	jz	short cpp_2
  3696                              <1> 		; Convert read only page to writable page 
  3697                              <1> 		;(for the parent of the current process)
  3698                              <1> 	;and	word [esi], PTE_A_CLEAR ; 0F000h
  3699                              <1> 	; 22/09/2015
  3700 00002896 890E                <1> 	mov	[esi], ecx
  3701 00002898 800E07              <1> 	or	byte [esi], PTE_A_PRESENT + PTE_A_WRITE + PTE_A_USER
  3702                              <1> 				 ; 1+2+4 = 7
  3703                              <1> cpp_2:
  3704 0000289B 89C7                <1> 	mov	edi, eax ; new page address of the child process
  3705                              <1> 	; 07/09/2015
  3706 0000289D 89CE                <1> 	mov	esi, ecx ; the page address of the parent process
  3707 0000289F B900040000          <1> 	mov	ecx, PAGE_SIZE / 4
  3708 000028A4 F3A5                <1> 	rep	movsd ; 31/08/2015
  3709                              <1> cpp_3:		
  3710 000028A6 0C07                <1> 	or	al, PTE_A_PRESENT + PTE_A_WRITE + PTE_A_USER ; 1+2+4 = 7
  3711 000028A8 8903                <1> 	mov	[ebx], eax ; Update PTE
  3712 000028AA 28C0                <1> 	sub	al, al ; clear attributes
  3713                              <1> cpp_4:
  3714                              <1> 	; 16/04/2021
  3715                              <1> 	; 19/04/2020 - Retro UNIX 386 v2
  3716                              <1> 	;pop	ecx ; ****
  3717                              <1> 	;pop	ebx ; ***
  3718 000028AC 5F                  <1> 	pop	edi ; **
  3719 000028AD 5E                  <1> 	pop	esi ; *
  3720 000028AE C3                  <1> 	retn
  3721                              <1> 
  3722                              <1> ;; 28/04/2015
  3723                              <1> ;; 24/10/2014
  3724                              <1> ;; 21/10/2014 (Retro UNIX 386 v1 - beginning)
  3725                              <1> ;; SWAP_PAGE_QUEUE (4096 bytes)
  3726                              <1> ;;
  3727                              <1> ;;   0000   0001   0002   0003   ....   1020   1021   1022   1023	
  3728                              <1> ;; +------+------+------+------+-    -+------+------+------+------+
  3729                              <1> ;; |  pg1 |  pg2 |  pg3 |  pg4 | .... |pg1021|pg1022|pg1023|pg1024|
  3730                              <1> ;; +------+------+------+------+-    -+------+------+------+------+    
  3731                              <1> ;;
  3732                              <1> ;; [swpq_last] = 0 to 4096 (step 4) -> the last position on the queue
  3733                              <1> ;;
  3734                              <1> ;; Method:
  3735                              <1> ;;	Swap page queue is a list of allocated pages with physical
  3736                              <1> ;;	addresses (system mode virtual adresses = physical addresses).
  3737                              <1> ;;	It is used for 'swap_in' and 'swap_out' procedures.
  3738                              <1> ;;	When a new page is being allocated, swap queue is updated
  3739                              <1> ;;	by 'swap_queue_shift' procedure, header of the queue (offset 0)
  3740                              <1> ;;	is checked for 'accessed' flag. If the 1st page on the queue
  3741                              <1> ;;	is 'accessed' or 'read only', it is dropped from the list;
  3742                              <1> ;;	other pages from the 2nd to the last (in [swpq_last]) shifted
  3743                              <1> ;; 	to head then the 2nd page becomes the 1st and '[swpq_last]' 
  3744                              <1> ;;	offset value becomes it's previous offset value - 4.
  3745                              <1> ;;	If the 1st page of the swap page queue is not 'accessed'	
  3746                              <1> ;;	the queue/list is not shifted.
  3747                              <1> ;;	After the queue/list shift, newly allocated page is added
  3748                              <1> ;;	to the tail of the queue at the [swpq_count*4] position.
  3749                              <1> ;;	But, if [swpq_count] > 1023, the newly allocated page
  3750                              <1> ;;	will not be added to the tail of swap page queue.  		 
  3751                              <1> ;;	
  3752                              <1> ;;	During 'swap_out' procedure, swap page queue is checked for
  3753                              <1> ;;	the first non-accessed, writable page in the list, 
  3754                              <1> ;;	from the head to the tail. The list is shifted to left 
  3755                              <1> ;;	(to the head) till a non-accessed page will be found in the list.
  3756                              <1> ;;	Then, this page	is swapped out (to disk) and then it is dropped
  3757                              <1> ;;	from the list by a final swap queue shift. [swpq_count] value
  3758                              <1> ;;	is changed. If all pages on the queue' are 'accessed', 
  3759                              <1> ;;	'insufficient memory' error will be returned ('swap_out' 
  3760                              <1> ;;	procedure will be failed)...
  3761                              <1> ;;
  3762                              <1> ;;	Note: If the 1st page of the queue is an 'accessed' page,
  3763                              <1> ;;	'accessed' flag of the page will be reset (0) and that page
  3764                              <1> ;;	(PTE) will be added to the tail of the queue after
  3765                              <1> ;;	the check, if [swpq_count] < 1023. If [swpq_count] = 1024
  3766                              <1> ;;	the queue will be rotated and the PTE in the head will be
  3767                              <1> ;;	added to the tail after resetting 'accessed' bit. 
  3768                              <1> ;;
  3769                              <1> ;;
  3770                              <1> ;;	
  3771                              <1> ;; SWAP DISK/FILE (with 4096 bytes swapped page blocks)
  3772                              <1> ;;
  3773                              <1> ;;  00000000  00000004  00000008  0000000C   ...   size-8    size-4
  3774                              <1> ;; +---------+---------+---------+---------+-- --+---------+---------+
  3775                              <1> ;; |descriptr| page(1) | page(2) | page(3) | ... |page(n-1)| page(n) |
  3776                              <1> ;; +---------+---------+---------+---------+-- --+---------+---------+    
  3777                              <1> ;;
  3778                              <1> ;; [swpd_next] = the first free block address in swapped page records
  3779                              <1> ;;    		 for next free block search by 'swap_out' procedure.
  3780                              <1> ;; [swpd_size] = swap disk/file size in sectors (512 bytes)
  3781                              <1> ;;		 NOTE: max. possible swap disk size is 1024 GB
  3782                              <1> ;; 		 (entire swap space must be accessed by using
  3783                              <1> ;;		 31 bit offset address) 
  3784                              <1> ;; [swpd_free] = free block (4096 bytes) count in swap disk/file space
  3785                              <1> ;; [swpd_start] = absolute/start address of the swap disk/file
  3786                              <1> ;;		  0 for file, or beginning sector of the swap partition
  3787                              <1> ;; [swp_drv] = logical drive description table addr. of swap disk/file
  3788                              <1> ;;
  3789                              <1> ;; 					
  3790                              <1> ;; Method:
  3791                              <1> ;;	When the memory (ram) becomes insufficient, page allocation
  3792                              <1> ;;	procedure swaps out a page from memory to the swap disk 
  3793                              <1> ;;	(partition) or swap file to get a new free page at the memory.
  3794                              <1> ;;	Swapping out is performed by using swap page queue.
  3795                              <1> ;;
  3796                              <1> ;; 	Allocation block size of swap disk/file is equal to page size
  3797                              <1> ;;	(4096 bytes). Swapping address (in sectors) is recorded
  3798                              <1> ;;	into relevant page file entry as 31 bit physical (logical)
  3799                              <1> ;;	offset address as 1 bit shifted to left for present flag (0).
  3800                              <1> ;;	Swapped page address is between 1 and swap disk/file size - 4.	  
  3801                              <1> ;;	Absolute physical (logical) address of the swapped page is 
  3802                              <1> ;;	calculated by adding offset value to the swap partition's 
  3803                              <1> ;;	start address. If the swap device (disk) is a virtual disk 
  3804                              <1> ;;	or it is a file, start address of the swap disk/volume is 0, 
  3805                              <1> ;;	and offset value is equal to absolute (physical or logical)
  3806                              <1> ;;	address/position. (It has not to be ZERO if the swap partition 
  3807                              <1> ;;	is in a partitioned virtual hard disk.) 
  3808                              <1> ;;
  3809                              <1> ;;	Note: Swap addresses are always specified/declared in sectors, 
  3810                              <1> ;;	not in bytes or	in blocks/zones/clusters (4096 bytes) as unit.
  3811                              <1> ;;
  3812                              <1> ;;	Swap disk/file allocation is mapped via 'Swap Allocation Table'
  3813                              <1> ;;	at memory as similar to 'Memory Allocation Table'.
  3814                              <1> ;;
  3815                              <1> ;;	Every bit of Swap Allocation Table repsesents one swap block
  3816                              <1> ;;	(equal to page size) respectively. Bit 0 of the S.A.T. byte 0
  3817                              <1> ;;	is reserved for swap disk/file block 0 as descriptor block
  3818                              <1> ;;	(also for compatibility with PTE). If bit value is ZERO,
  3819                              <1> ;;	it means relevant (respective) block is in use, and, 
  3820                              <1> ;;	of course, if bit value is 1, it means relevant (respective)
  3821                              <1> ;;      swap disk/file block is free.
  3822                              <1> ;;	For example: bit 1 of the byte 128 repsesents block 1025 
  3823                              <1> ;;	(128*8+1) or sector (offset) 8200 on the swap disk or
  3824                              <1> ;;	byte (offset/position) 4198400 in the swap file. 
  3825                              <1> ;;	4GB swap space is represented via 128KB Swap Allocation Table.
  3826                              <1> ;;	Initial layout of Swap Allocation Table is as follows:
  3827                              <1> ;;	------------------------------------------------------------
  3828                              <1> ;;	0111111111111111111111111 .... 11111111111111111111111111111
  3829                              <1> ;;	------------------------------------------------------------
  3830                              <1> ;;	(0 is reserved block, 1s represent free blocks respectively.)
  3831                              <1> ;;	(Note: Allocation cell/unit of the table is bit, not byte)
  3832                              <1> ;;
  3833                              <1> ;;	..............................................................
  3834                              <1> ;;
  3835                              <1> ;;	'swap_out' procedure checks 'free_swap_blocks' count at first,
  3836                              <1> ;;	then it searches Swap Allocation Table if free count is not
  3837                              <1> ;;	zero. From begining the [swpd_next] dword value, the first bit 
  3838                              <1> ;;	position with value of 1 on the table is converted to swap
  3839                              <1> ;;	disk/file offset address, in sectors (not 4096 bytes block).
  3840                              <1> ;;	'ldrv_write' procedure is called with ldrv (logical drive
  3841                              <1> ;;	number of physical swap disk or virtual swap disk)
  3842                              <1> ;;	number, sector offset (not absolute sector -LBA- number),
  3843                              <1> ;;	and sector count (8, 512*8 = 4096) and buffer adress
  3844                              <1> ;;	(memory page). That will be a direct disk write procedure.
  3845                              <1> ;;	(for preventing late memory allocation, significant waiting). 
  3846                              <1> ;;	If disk write procedure returns with error or free count of 
  3847                              <1> ;;	swap blocks is ZERO, 'swap_out' procedure will return with
  3848                              <1> ;;	'insufficient memory error' (cf=1). 
  3849                              <1> ;;
  3850                              <1> ;;	(Note: Even if free swap disk/file blocks was not zero,
  3851                              <1> ;;	any disk write error will not be fixed by 'swap_out' procedure,
  3852                              <1> ;;	in other words, 'swap_out' will not check the table for other
  3853                              <1> ;;	free blocks after a disk write error. It will return to 
  3854                              <1> ;;	the caller with error (CF=1) which means swapping is failed. 
  3855                              <1> ;;
  3856                              <1> ;;	After writing the page on to swap disk/file address/sector,
  3857                              <1> ;;	'swap_out' procedure returns with that swap (offset) sector
  3858                              <1> ;;	address (cf=0). 
  3859                              <1> ;;
  3860                              <1> ;;	..............................................................
  3861                              <1> ;;
  3862                              <1> ;;	'swap_in' procedure loads addressed (relevant) swap disk or
  3863                              <1> ;;	file sectors at specified memory page. Then page allocation
  3864                              <1> ;;	procedure updates relevant page table entry with 'present' 
  3865                              <1> ;;	attribute. If swap disk or file reading fails there is nothing
  3866                              <1> ;;	to do, except to terminate the process which is the owner of
  3867                              <1> ;;	the swapped page.
  3868                              <1> ;;
  3869                              <1> ;;	'swap_in' procedure sets the relevant/respective bit value
  3870                              <1> ;;	in the Swap Allocation Table (as free block). 'swap_in' also
  3871                              <1> ;;	updates [swpd_first] pointer if it is required.
  3872                              <1> ;;
  3873                              <1> ;;	..............................................................	 
  3874                              <1> ;;
  3875                              <1> ;;	Note: If [swap_enabled] value is ZERO, that means there is not
  3876                              <1> ;;	a swap disk or swap file in use... 'swap_in' and 'swap_out'
  3877                              <1> ;;	procedures ans 'swap page que' procedures will not be active...
  3878                              <1> ;;	'Insufficient memory' error will be returned by 'swap_out'
  3879                              <1> ;;	and 'general protection fault' will be returned by 'swap_in'
  3880                              <1> ;;	procedure, if it is called mistakenly (a wrong value in a PTE).		
  3881                              <1> ;;
  3882                              <1> 
  3883                              <1> ; 24/12/2021
  3884                              <1> ; ('swap_in' procedure call is disabled)
  3885                              <1> 
  3886                              <1> ;swap_in:
  3887                              <1> 	; 31/08/2015
  3888                              <1> 	; 20/07/2015
  3889                              <1> 	; 28/04/2015
  3890                              <1> 	; 18/04/2015
  3891                              <1> 	; 24/10/2014 (Retro UNIX 386 v1 - beginning)
  3892                              <1> 	;
  3893                              <1> 	; INPUT -> 
  3894                              <1> 	;	EBX = PHYSICAL (real/flat) ADDRESS OF THE MEMORY PAGE
  3895                              <1> 	;	EBP = VIRTUAL (LINEAR) ADDRESS (page fault address)
  3896                              <1> 	;	EAX = Offset Address for the swapped page on the
  3897                              <1> 	;	      swap disk or in the swap file.
  3898                              <1> 	;
  3899                              <1> 	; OUTPUT ->
  3900                              <1> 	;	EAX = 0 if loading at memory has been successful
  3901                              <1> 	;
  3902                              <1> 	;	CF = 1 -> swap disk reading error (disk/file not present
  3903                              <1> 	;		  or sector not present or drive not ready
  3904                              <1> 	;	     EAX = Error code
  3905                              <1> 	;	     [u.error] = EAX 
  3906                              <1> 	;		       = The last error code for the process
  3907                              <1> 	;		         (will be reset after returning to user)	  
  3908                              <1> 	;
  3909                              <1> 	; Modified Registers -> EAX
  3910                              <1> 	;
  3911                              <1> 
  3912                              <1> ;       cmp     dword [swp_drv], 0
  3913                              <1> ;	jna	short swpin_dnp_err
  3914                              <1> ;
  3915                              <1> ;	cmp	eax, [swpd_size]
  3916                              <1> ;	jnb	short swpin_snp_err
  3917                              <1> ;
  3918                              <1> ;	push	esi
  3919                              <1> ;	push	ebx
  3920                              <1> ;	push	ecx
  3921                              <1> ;	mov	esi, [swp_drv]	
  3922                              <1> ;	mov	ecx, PAGE_SIZE / LOGIC_SECT_SIZE  ; 8 !
  3923                              <1> ;		; Note: Even if corresponding physical disk's sector 
  3924                              <1> ;		; size different than 512 bytes, logical disk sector
  3925                              <1> ;		; size is 512 bytes and disk reading procedure
  3926                              <1> ;		; will be performed for reading 4096 bytes
  3927                              <1> ;		; (2*2048, 8*512). 
  3928                              <1> ;	; ESI = Logical disk description table address
  3929                              <1> ;	; EBX = Memory page (buffer) address (physical!)
  3930                              <1> ;	; EAX = Sector adress (offset address, logical sector number)
  3931                              <1> ;	; ECX = Sector count ; 8 sectors
  3932                              <1> ;	push	eax
  3933                              <1> ;	call	logical_disk_read
  3934                              <1> ;	pop	eax
  3935                              <1> ;	jnc	short swpin_read_ok
  3936                              <1> ;	;
  3937                              <1> ;	mov	eax, SWP_DISK_READ_ERR ; drive not ready or read error
  3938                              <1> ;	mov	[u.error], eax
  3939                              <1> ;	jmp	short swpin_retn
  3940                              <1> ;	;
  3941                              <1> ;swpin_read_ok:
  3942                              <1> ;	; EAX = Offset address (logical sector number)
  3943                              <1> ;	call	unlink_swap_block  ; Deallocate swap block	
  3944                              <1> ;	;
  3945                              <1> ;	; EBX = Memory page (buffer) address (physical!)
  3946                              <1> ;	; 20/07/2015
  3947                              <1> ;	mov	ebx, ebp ; virtual address (page fault address)
  3948                              <1> ;       and     bx, ~PAGE_OFF ; ~0FFFh ; reset bits, 0 to 11
  3949                              <1> ;	mov	bl, [u.uno] ; current process number
  3950                              <1> ;	; EBX = Virtual (Linear) address & process number combination
  3951                              <1> ;	call	swap_queue_shift
  3952                              <1> ;	; eax = 0 ; 10/06/2016 (if ebx input > 0, eax output = 0)
  3953                              <1> ;	;sub	eax, eax  ; 0 ; Error Code = 0  (no error)
  3954                              <1> ;	; zf = 1
  3955                              <1> ;swpin_retn:
  3956                              <1> ;	pop	ecx
  3957                              <1> ;	pop	ebx
  3958                              <1> ;	pop	esi
  3959                              <1> ;	retn
  3960                              <1> ;
  3961                              <1> ;swpin_dnp_err:
  3962                              <1> ;	mov	eax, SWP_DISK_NOT_PRESENT_ERR
  3963                              <1> ;swpin_err_retn:
  3964                              <1> ;	mov	[u.error], eax
  3965                              <1> ;	stc
  3966                              <1> ;	retn
  3967                              <1> ;
  3968                              <1> ;swpin_snp_err:
  3969                              <1> ;	mov	eax, SWP_SECTOR_NOT_PRESENT_ERR
  3970                              <1> ;	jmp	short swpin_err_retn
  3971                              <1> 
  3972                              <1> ; 24/12/2021
  3973                              <1> ; ('swap_out' procedure call is disabled)
  3974                              <1> 
  3975                              <1> ;swap_out:
  3976                              <1> 	; 10/06/2016
  3977                              <1> 	; 07/06/2016
  3978                              <1>         ; 23/05/2016
  3979                              <1> 	; 19/05/2016 - TRDOS 386 (TRDOS v2.0)
  3980                              <1> 	; 24/10/2014 - 31/08/2015 (Retro UNIX 386 v1)
  3981                              <1> 	;
  3982                              <1> 	; INPUT -> 
  3983                              <1> 	;	none
  3984                              <1> 	;
  3985                              <1> 	; OUTPUT ->
  3986                              <1> 	;	EAX = Physical page address (which is swapped out
  3987                              <1> 	;	      for allocating a new page)
  3988                              <1> 	;	CF = 1 -> swap disk writing error (disk/file not present
  3989                              <1> 	;		  or sector not present or drive not ready
  3990                              <1> 	;	     EAX = Error code
  3991                              <1> 	;	     [u.error] = EAX 
  3992                              <1> 	;		       = The last error code for the process
  3993                              <1> 	;		         (will be reset after returning to user)	  
  3994                              <1> 	;
  3995                              <1> 	; Modified Registers -> none (except EAX)
  3996                              <1> 	;
  3997                              <1> 
  3998                              <1> ;	cmp 	word [swpq_count], 1
  3999                              <1> ;       jc      swpout_im_err ; 'insufficient memory'
  4000                              <1> ;
  4001                              <1> ;       ;cmp    dword [swp_drv], 1
  4002                              <1> ;	;jc	short swpout_dnp_err ; 'swap disk/file not present'
  4003                              <1> ;
  4004                              <1> ;       cmp     dword [swpd_free], 1
  4005                              <1> ;       jc      swpout_nfspc_err ; 'no free space on swap disk'
  4006                              <1> ;
  4007                              <1> ;	push	ebx ; *
  4008                              <1> ;swpout_1:
  4009                              <1> ;	; 10/06/2016
  4010                              <1> ;	xor	ebx, ebx ; shift the queue and return a PTE value
  4011                              <1> ;	call	swap_queue_shift
  4012                              <1> ;	and	eax, eax	; 0 = empty queue (improper entries)
  4013                              <1> ;       jz      swpout_npts_err        ; There is not any proper PTE
  4014                              <1> ;				       ; pointer in the swap queue
  4015                              <1> ;	; EAX = PTE value of the page
  4016                              <1> ;	; EBX = PTE address of the page
  4017                              <1> ;	and	ax, PTE_A_CLEAR ; 0F000h ; clear attribute bits
  4018                              <1> ;	;
  4019                              <1> ;	; 07/06/2016
  4020                              <1> ;	; 19/05/2016
  4021                              <1> ;	; check this page is in timer events or not
  4022                              <1> ;	
  4023                              <1> ;swpout_timer_page_0:
  4024                              <1> ;	push	edx ; **
  4025                              <1> ;
  4026                              <1> ;	; 07/06/2016
  4027                              <1> ;	cmp	byte [timer_events], 0 
  4028                              <1> ;	jna	short swpout_2
  4029                              <1> ;	;
  4030                              <1> ;	mov	dl, [timer_events]
  4031                              <1> ;
  4032                              <1> ;	push	ecx ; ***
  4033                              <1> ;	push	ebx ; ****
  4034                              <1> ;	mov	ebx, timer_set ; beginning address of timer event
  4035                              <1> ;			       ; structures 
  4036                              <1> ;swpout_timer_page_1:
  4037                              <1> ;	mov	cl, [ebx]
  4038                              <1> ;	or	cl, cl ; 0 = free, >0 = process number
  4039                              <1> ;	jz	short swpout_timer_page_3
  4040                              <1> ;	mov	ecx, [ebx+12] ; response (signal return) address
  4041                              <1> ;	and	cx, PTE_A_CLEAR ; clear offset part (right 12 bits)
  4042                              <1> ;				; of the response byte address, to
  4043                              <1> ;				; get beginning of the page address)
  4044                              <1> ;	cmp	eax, ecx
  4045                              <1> ;	jne	short swpout_timer_page_2 ; not same page
  4046                              <1> ;	
  4047                              <1> ;	; !same page!
  4048                              <1> ;	;
  4049                              <1> ;	; NOTE: // 19/05/2016 // - TRDOS 386 feature only ! -
  4050                              <1> ;	; This page will be used by the kernel to put timer event
  4051                              <1> ;	; response (signal return) byte at the requested address;
  4052                              <1> ;	; in order to prevent a possible wrong write (while
  4053                              <1> ;	; this page is swapped out) on physical memory,
  4054                              <1> ;	; we must protect this page against to be swapped out!
  4055                              <1> ;	;
  4056                              <1> ;	pop	ebx ; ****
  4057                              <1> ;	pop	ecx ; ***
  4058                              <1> ;	pop	edx ; **
  4059                              <1> ;	jmp	short swpout_1	; do not swap out this page !
  4060                              <1> ; 
  4061                              <1> ;swpout_timer_page_2:
  4062                              <1> ;	; 07/06/2016
  4063                              <1> ;	dec	dl
  4064                              <1> ;	jz	short swpout_timer_page_4
  4065                              <1> ;swpout_timer_page_3:
  4066                              <1> ;	;cmp	ebx, timer_set + 240 ; last timer event (15*16) 
  4067                              <1> ;	;jnb	short swpout_timer_page_4
  4068                              <1> ;	add	ebx, 16
  4069                              <1> ;	jmp	short swpout_timer_page_1	
  4070                              <1> ;
  4071                              <1> ;swpout_timer_page_4:
  4072                              <1> ;	pop	ebx ; ****
  4073                              <1> ;	pop	ecx ; ***
  4074                              <1> ;swpout_2:
  4075                              <1> ;	mov	edx, ebx	       ; Page table entry address	
  4076                              <1> ;	mov	ebx, eax	       ; Buffer (Page) Address				
  4077                              <1> ;	;
  4078                              <1> ;	call	link_swap_block
  4079                              <1> ;	jnc	short swpout_3	       ; It may not be needed here	
  4080                              <1> ;				       ; because [swpd_free] value
  4081                              <1> ;				       ; was checked at the beginging. 	
  4082                              <1> ;	pop	edx ; **
  4083                              <1> ;	pop	ebx ; *
  4084                              <1> ;	jmp	short swpout_nfspc_err 
  4085                              <1> ;swpout_3:
  4086                              <1> ;	test	eax, 80000000h ; test bit 31 (this may not be needed!)
  4087                              <1> ;	jnz	short swpout_nfspc_err  ; 10/06/2016 (bit 31 = 1 !)
  4088                              <1> ;	;	
  4089                              <1> ;	push	esi ; **
  4090                              <1> ;	push	ecx ; ***
  4091                              <1> ;	push	eax ; sector address ; (31 bit !, bit 31 = 0)
  4092                              <1> ;	mov	esi, [swp_drv]	
  4093                              <1> ;	mov	ecx, PAGE_SIZE / LOGIC_SECT_SIZE  ; 8 !
  4094                              <1> ;		; Note: Even if corresponding physical disk's sector 
  4095                              <1> ;		; size different than 512 bytes, logical disk sector
  4096                              <1> ;		; size is 512 bytes and disk writing procedure
  4097                              <1> ;		; will be performed for writing 4096 bytes
  4098                              <1> ;		; (2*2048, 8*512). 
  4099                              <1> ;	; ESI = Logical disk description table address
  4100                              <1> ;	; EBX = Buffer (Page) address
  4101                              <1> ;	; EAX = Sector adress (offset address, logical sector number)
  4102                              <1> ;	; ECX = Sector count ; 8 sectors
  4103                              <1> ;	; edx = PTE address
  4104                              <1> ;	call	logical_disk_write
  4105                              <1> ;	; edx = PTE address
  4106                              <1> ;	pop	ecx ; sector address	
  4107                              <1> ;	jnc	short swpout_write_ok
  4108                              <1> ;	;
  4109                              <1> ;	;; call	unlink_swap_block ; this block must be left as 'in use'
  4110                              <1> ;swpout_dw_err:
  4111                              <1> ;	mov	eax, SWP_DISK_WRITE_ERR ; drive not ready or write error
  4112                              <1> ;	mov	[u.error], eax
  4113                              <1> ;	jmp	short swpout_retn
  4114                              <1> ;	;
  4115                              <1> ;swpout_write_ok:
  4116                              <1> ;	; EBX = Buffer (page) address
  4117                              <1> ;	; EDX = Page Table Entry address
  4118                              <1> ;	; ECX = Swap disk sector (file block) address (31 bit)
  4119                              <1> ;	shl 	ecx, 1  ; 31 bit sector address from bit 1 to bit 31 
  4120                              <1> ;	mov 	[edx], ecx 
  4121                              <1> ;		; bit 0 = 0 (swapped page)
  4122                              <1> ;	mov	eax, ebx
  4123                              <1> ;swpout_retn:
  4124                              <1> ;	pop	ecx ; ***
  4125                              <1> ;	pop	esi ; **
  4126                              <1> ;	pop	ebx ; *
  4127                              <1> ;	retn
  4128                              <1> ;
  4129                              <1> ;;swpout_dnp_err:
  4130                              <1> ;;	mov	eax, SWP_DISK_NOT_PRESENT_ERR ; disk not present
  4131                              <1> ;;	jmp	short swpout_err_retn
  4132                              <1> ;swpout_nfspc_err:
  4133                              <1> ;	mov	eax, SWP_NO_FREE_SPACE_ERR ; no free space
  4134                              <1> ;swpout_err_retn:
  4135                              <1> ;	mov	[u.error], eax
  4136                              <1> ;	;stc
  4137                              <1> ;	retn
  4138                              <1> ;swpout_npts_err:
  4139                              <1> ;	mov	eax, SWP_NO_PAGE_TO_SWAP_ERR
  4140                              <1> ;	pop	ebx
  4141                              <1> ;	jmp	short swpout_err_retn
  4142                              <1> ;swpout_im_err:
  4143                              <1> ;	mov	eax, ERR_MINOR_IM ; insufficient (out of) memory
  4144                              <1> ;	jmp	short swpout_err_retn
  4145                              <1> 
  4146                              <1> ; 24/12/2021
  4147                              <1> ; ('swap_queue_shift' procedure call is disabled)
  4148                              <1> 
  4149                              <1> ;swap_queue_shift:
  4150                              <1> 	; 26/03/2017
  4151                              <1> 	; 10/06/2016
  4152                              <1> 	; 09/06/2016 - TRDOS 386 (TRDOS v2.0)
  4153                              <1> 	; 23/10/2014 - 20/07/2015 (Retro UNIX 386 v1)
  4154                              <1> 	;
  4155                              <1> 	; INPUT ->
  4156                              <1> 	;	EBX = Virtual (linear) address (bit 12 to 31) 
  4157                              <1> 	;	      and process number combination (bit 0 to 11)
  4158                              <1> 	;	EBX = 0 -> shift/drop from the head (offset 0)
  4159                              <1> 	;	
  4160                              <1> 	; OUTPUT ->
  4161                              <1> 	;	If EBX input > 0 
  4162                              <1> 	;	   the queue will be shifted 4 bytes (dword),
  4163                              <1> 	; 	   from the tail to the head, up to entry offset
  4164                              <1> 	; 	   which points to EBX input value or nothing
  4165                              <1> 	;	   to do if EBX value is not found on the queue.
  4166                              <1> 	;	   (The entry -with EBX value- will be removed
  4167                              <1> 	;	   from the queue if it is found.)
  4168                              <1> 	;
  4169                              <1> 	;	   EAX = 0		
  4170                              <1> 	;
  4171                              <1> 	;	If EBX input = 0
  4172                              <1> 	;	   the queue will be shifted 4 bytes (dword),
  4173                              <1> 	; 	   from the tail to the head, if the PTE address
  4174                              <1> 	;	   which is pointed in head of the queue is marked
  4175                              <1> 	;	   as "accessed" or it is marked as "non present".
  4176                              <1> 	;	   (If "accessed" flag of the PTE -which is pointed
  4177                              <1> 	;	   in the head- is set -to 1-, it will be reset
  4178                              <1> 	;	   -to 0- and then, the queue will be rotated 
  4179                              <1> 	;	   -without dropping pointer of the PTE from 
  4180                              <1> 	;	   the queue- for 4 bytes on head to tail direction.
  4181                              <1> 	;	   Pointer in the head will be moved into the tail,
  4182                              <1> 	;	   other PTEs will be shifted on head direction.)
  4183                              <1> 	;
  4184                              <1> 	;	   Swap queue will be shifted up to the first
  4185                              <1> 	;	   'present' or 'non accessed' page will be found
  4186                              <1> 	;	   (as pointed) on the queue head (then it will be
  4187                              <1>         ;          removed/dropped from the queue).
  4188                              <1> 	;
  4189                              <1> 	;	   EAX (> 0) = PTE value of the page which is
  4190                              <1> 	;		 (it's pointer -virtual address-) dropped
  4191                              <1> 	;		 (removed) from swap queue.
  4192                              <1> 	;	   EBX = PTE address of the page (if EAX > 0)
  4193                              <1> 	;	         which is (it's pointer -virtual address-)
  4194                              <1> 	;		 dropped (removed) from swap queue.
  4195                              <1> 	;
  4196                              <1> 	;	   EAX = 0 -> empty swap queue ! 
  4197                              <1> 	;
  4198                              <1> 	; Modified Registers -> EAX, EBX
  4199                              <1> 	;
  4200                              <1> ;	movzx   eax, word [swpq_count]  ; Max. 1024
  4201                              <1> ;	and	ax, ax
  4202                              <1> ;	jz	short swpqs_retn
  4203                              <1> ;	push	edi
  4204                              <1> ;	push	esi
  4205                              <1> ;	push	ecx
  4206                              <1> ;	mov	esi, swap_queue
  4207                              <1> ;	mov	ecx, eax
  4208                              <1> ;	or	ebx, ebx
  4209                              <1> ;	jz	short swpqs_7
  4210                              <1> ;swpqs_1:
  4211                              <1> ;	lodsd
  4212                              <1> ;	cmp	eax, ebx
  4213                              <1> ;	je	short swpqs_2
  4214                              <1> ;	loop	swpqs_1
  4215                              <1> ;	; 10/06/2016
  4216                              <1> ;	sub	eax, eax 
  4217                              <1> ;	jmp	short swpqs_6
  4218                              <1> ;swpqs_2:
  4219                              <1> ;	mov	edi, esi
  4220                              <1> ;	sub 	edi, 4
  4221                              <1> ;swpqs_3:
  4222                              <1> ;	dec	word [swpq_count]
  4223                              <1> ;	jz	short swpqs_5
  4224                              <1> ;swpqs_4:
  4225                              <1> ;	dec 	ecx
  4226                              <1> ;	rep	movsd	; shift up (to the head)
  4227                              <1> ;swpqs_5:
  4228                              <1> ;	xor	eax, eax
  4229                              <1> ;	mov	[edi], eax
  4230                              <1> ;swpqs_6:
  4231                              <1> ;	pop	ecx
  4232                              <1> ;	pop	esi
  4233                              <1> ;	pop	edi
  4234                              <1> ;swpqs_retn:
  4235                              <1> ;	retn		
  4236                              <1> ;swpqs_7:
  4237                              <1> ;	mov	edi, esi ; head
  4238                              <1> ;	lodsd
  4239                              <1> ;	; 20/07/2015
  4240                              <1> ;	mov	ebx, eax
  4241                              <1> ;	and	ebx, ~PAGE_OFF ; ~0FFFh 
  4242                              <1> ;		      ; ebx = virtual address (at page boundary)	
  4243                              <1> ;	and	eax, PAGE_OFF ; 0FFFh
  4244                              <1> ;		      ; ax = process number (1 to 4095)
  4245                              <1> ;	cmp	al, [u.uno]
  4246                              <1> ;		; Max. 16 (nproc) processes for Retro UNIX 386 v1
  4247                              <1> ;	jne	short swpqs_8
  4248                              <1> ;	mov	eax, [u.pgdir]
  4249                              <1> ;	jmp	short swpqs_9
  4250                              <1> ;swpqs_8:
  4251                              <1> ;	; 09/06/2016
  4252                              <1> ;	cmp	byte [eax+p.stat-1], 0
  4253                              <1> ;	jna	short swpqs_3     ; free (or terminated) process
  4254                              <1> ;	cmp	byte [eax+p.stat-1], 2 ; waiting
  4255                              <1> ;	ja	short swpqs_3 	  ; zombie (3) or undefined ?	
  4256                              <1> ;
  4257                              <1> ;	;shl	ax, 2
  4258                              <1> ;	shl	al, 2
  4259                              <1> ;	mov 	eax, [eax+p.upage-4]
  4260                              <1> ;	or	eax, eax
  4261                              <1> ;	jz	short swpqs_3 ; invalid upage
  4262                              <1> ;	add	eax, u.pgdir - user
  4263                              <1> ;			 ; u.pgdir value for the process
  4264                              <1> ;			 ; is in [eax]
  4265                              <1> ;	mov	eax, [eax]
  4266                              <1> ;	and	eax, eax
  4267                              <1> ;	jz	short swpqs_3 ; invalid page directory
  4268                              <1> ;swpqs_9:
  4269                              <1> ;	push	edx
  4270                              <1> ;	; eax = page directory
  4271                              <1> ;	; ebx = virtual address
  4272                              <1> ;	call	get_pte
  4273                              <1> ;	mov	ebx, edx	; PTE address
  4274                              <1> ;	pop	edx
  4275                              <1> ;	; 10/06/2016
  4276                              <1> ;	jc	short swpqs_13 ; empty PDE
  4277                              <1> ;	; EAX = PTE value
  4278                              <1> ;	test	al, PTE_A_PRESENT ; bit 0 = 1
  4279                              <1> ;	jz	short swpqs_13  ; Drop non-present page
  4280                              <1> ;			        ; from the queue (head)
  4281                              <1> ;	test	al, PTE_A_WRITE	; bit 1 = 0 (read only)
  4282                              <1> ;	jz	short swpqs_13  ; Drop read only page
  4283                              <1> ;			        ; from the queue (head) 	
  4284                              <1> ;	;test	al, PTE_A_ACCESS ; bit 5 = 1 (Accessed)
  4285                              <1> ;	;jnz	short swpqs_11  ; present
  4286                              <1> ;			        ; accessed page
  4287                              <1> ;       btr     eax, PTE_A_ACCESS_BIT ; reset 'accessed' bit
  4288                              <1> ;	jc	short swpqs_11  ; accessed page
  4289                              <1> ;
  4290                              <1> ;	dec	ecx
  4291                              <1> ;	mov	[swpq_count], cx
  4292                              <1> ;       jz      short swpqs_10
  4293                              <1> ;		; esi = head + 4
  4294                              <1> ;		; edi = head
  4295                              <1> ;	rep	movsd	 ; n = 1 to k-1, [n - 1] = [n]
  4296                              <1> ;swpqs_10:
  4297                              <1> ;	mov	[edi], ecx ; 0
  4298                              <1> ;	jmp	short swpqs_6 ; 26/03/2017
  4299                              <1> ;
  4300                              <1> ;swpqs_11:
  4301                              <1> ;	mov	[ebx], eax     ; save changed attribute
  4302                              <1> ;	; Rotation (head -> tail)
  4303                              <1> ;	dec	ecx     ; entry count -> last entry number		
  4304                              <1> ;	jz	short swpqs_10
  4305                              <1> ;		; esi = head + 4
  4306                              <1> ;		; edi = head
  4307                              <1> ;	mov	eax, [edi] ; 20/07/2015
  4308                              <1> ;	rep	movsd	 ; n = 1 to k-1, [n - 1] = [n]
  4309                              <1> ;	mov	[edi], eax ; head -> tail ; [k] = [1]
  4310                              <1> ;
  4311                              <1> ;	mov	cx, [swpq_count]
  4312                              <1> ;
  4313                              <1> ;swpqs_12:
  4314                              <1> ;	mov	esi, swap_queue ; head
  4315                              <1> ;       jmp     swpqs_7
  4316                              <1> ;
  4317                              <1> ;swpqs_13:
  4318                              <1> ;	dec	ecx
  4319                              <1> ;	mov	[swpq_count], cx
  4320                              <1> ;       jz      swpqs_5
  4321                              <1> ;	jmp	short swpqs_12
  4322                              <1> 
  4323                              <1> ; 24/12/2021
  4324                              <1> ; ('add_to_swp_queue' procedure call is disabled)
  4325                              <1> 
  4326                              <1> ;add_to_swap_queue:
  4327                              <1> 	; 20/02/2017
  4328                              <1> 	; 20/07/2015
  4329                              <1> 	; 24/10/2014 (Retro UNIX 386 v1 - beginning)
  4330                              <1> 	;
  4331                              <1> 	; Adds new page to swap queue
  4332                              <1> 	; (page directories and page tables must not be added
  4333                              <1> 	; to swap queue)	
  4334                              <1> 	;
  4335                              <1> 	; INPUT ->
  4336                              <1> 	;	EBX = Linear (Virtual) addr for current process
  4337                              <1> 	;	[u.uno]
  4338                              <1> 	;	20/02/2017
  4339                              <1> 	;	(Linear address = CORE + user's virtual address)
  4340                              <1> 	;
  4341                              <1> 	; OUTPUT ->
  4342                              <1> 	;	EAX = [swpq_count]
  4343                              <1> 	;	      (after the PTE has been added)
  4344                              <1> 	;	EAX = 0 -> Swap queue is full, (1024 entries)
  4345                              <1> 	;	      the PTE could not be added.
  4346                              <1> 	;
  4347                              <1> 	; Modified Registers -> EAX
  4348                              <1> 	;
  4349                              <1> ;	push	ebx
  4350                              <1> ;       and     bx, ~PAGE_OFF ; ~0FFFh ; reset bits, 0 to 11
  4351                              <1> ;	mov	bl, [u.uno] ; current process number
  4352                              <1> ;	call	swap_queue_shift ; drop from the queue if
  4353                              <1> ;				 ; it is already on the queue
  4354                              <1> ;		; then add it to the tail of the queue
  4355                              <1> ;	movzx	eax, word [swpq_count]
  4356                              <1> ;	cmp	ax, 1024
  4357                              <1> ;	jb	short atsq_1
  4358                              <1> ;	sub	ax, ax
  4359                              <1> ;	pop	ebx
  4360                              <1> ;	retn
  4361                              <1> ;atsq_1:
  4362                              <1> ;	push	esi
  4363                              <1> ;	mov	esi, swap_queue
  4364                              <1> ;	and	ax, ax
  4365                              <1> ;	jz	short atsq_2
  4366                              <1> ;	shl	ax, 2	; convert to offset
  4367                              <1> ;	add	esi, eax
  4368                              <1> ;	shr	ax, 2
  4369                              <1> ;atsq_2:
  4370                              <1> ;	inc	ax
  4371                              <1> ;	mov	[esi], ebx ; Virtual address + [u.uno] combination
  4372                              <1> ;	mov	[swpq_count], ax
  4373                              <1> ;	pop	esi
  4374                              <1> ;	pop	ebx
  4375                              <1> ;	retn
  4376                              <1> 
  4377                              <1> ; 24/12/2021
  4378                              <1> ; ('unlink_swap_block' procedure call is disabled)
  4379                              <1> 
  4380                              <1> ;unlink_swap_block:
  4381                              <1> 	; 15/09/2015
  4382                              <1> 	; 30/04/2015
  4383                              <1> 	; 18/04/2015
  4384                              <1> 	; 24/10/2014 (Retro UNIX 386 v1 - beginning)
  4385                              <1> 	;
  4386                              <1> 	; INPUT -> 
  4387                              <1> 	;	EAX = swap disk/file offset address
  4388                              <1> 	;	      (bit 1 to bit 31)
  4389                              <1> 	; OUTPUT ->
  4390                              <1> 	;	[swpd_free] is increased
  4391                              <1> 	;	(corresponding SWAP DISK ALLOC. TABLE bit is SET)
  4392                              <1> 	;
  4393                              <1> 	; Modified Registers -> EAX
  4394                              <1> 	;
  4395                              <1> ;	push	ebx
  4396                              <1> ;	push	edx
  4397                              <1> ;	;
  4398                              <1> ;	shr	eax, SECTOR_SHIFT+1  ;3+1 ; shift sector address to 
  4399                              <1> ;				     ; 3 bits right
  4400                              <1> ;				     ; to get swap block/page number
  4401                              <1> ;	mov	edx, eax
  4402                              <1> ;	; 15/09/2015
  4403                              <1> ;	shr	edx, 3		     ; to get offset to S.A.T.
  4404                              <1> ;				     ; (1 allocation bit = 1 page)
  4405                              <1> ;				     ; (1 allocation bytes = 8 pages)
  4406                              <1> ;	and	dl, 0FCh 	     ; clear lower 2 bits
  4407                              <1> ;				     ; (to get 32 bit position)			
  4408                              <1> ;	;
  4409                              <1> ;	mov	ebx, swap_alloc_table ; Swap Allocation Table address
  4410                              <1> ;	add	ebx, edx
  4411                              <1> ;	and	eax, 1Fh	     ; lower 5 bits only
  4412                              <1> ;				     ; (allocation bit position)	 
  4413                              <1> ;	cmp 	eax, [swpd_next]     ; is the new free block addr. lower
  4414                              <1> ;				     ; than the address in 'swpd_next' ?
  4415                              <1> ;				     ; (next/first free block value)		
  4416                              <1> ;	jnb	short uswpbl_1	     ; no	
  4417                              <1> ;	mov	[swpd_next], eax     ; yes	
  4418                              <1> ;uswpbl_1:
  4419                              <1> ;	bts	[ebx], eax	     ; unlink/release/deallocate block
  4420                              <1> ;				     ; set relevant bit to 1.
  4421                              <1> ;				     ; set CF to the previous bit value	
  4422                              <1> ;	cmc			     ; complement carry flag	
  4423                              <1> ;	jc	short uswpbl_2	     ; do not increase swfd_free count
  4424                              <1> ;				     ; if the block is already deallocated
  4425                              <1> ;				     ; before.	
  4426                              <1> ;       inc     dword [swpd_free]
  4427                              <1> ;uswpbl_2:
  4428                              <1> ;	pop	edx
  4429                              <1> ;	pop	ebx
  4430                              <1> ;	retn
  4431                              <1> 
  4432                              <1> ; 24/12/2021
  4433                              <1> ; ('link_swap_block' procedure call is disabled)
  4434                              <1> 
  4435                              <1> ;link_swap_block:
  4436                              <1> 	; 01/07/2015
  4437                              <1> 	; 18/04/2015
  4438                              <1> 	; 24/10/2014 (Retro UNIX 386 v1 - beginning)
  4439                              <1> 	;
  4440                              <1> 	; INPUT -> none
  4441                              <1> 	;
  4442                              <1> 	; OUTPUT ->
  4443                              <1> 	;	EAX = OFFSET ADDRESS OF THE ALLOCATED BLOCK (4096 bytes)
  4444                              <1> 	;	      in sectors (corresponding 
  4445                              <1> 	;	      SWAP DISK ALLOCATION TABLE bit is RESET)
  4446                              <1> 	;
  4447                              <1> 	;	CF = 1 and EAX = 0 
  4448                              <1> 	; 		   if there is not a free block to be allocated	
  4449                              <1> 	;
  4450                              <1> 	; Modified Registers -> none (except EAX)
  4451                              <1> 	;
  4452                              <1> 
  4453                              <1> ;	;mov	eax, [swpd_free]
  4454                              <1> ;	;and	eax, eax
  4455                              <1> ;	;jz	short out_of_swpspc
  4456                              <1> ;	;
  4457                              <1> ;	push	ebx
  4458                              <1> ;	push	ecx
  4459                              <1> ;	;
  4460                              <1> ;	mov	ebx, swap_alloc_table ; Swap Allocation Table offset
  4461                              <1> ;	mov	ecx, ebx
  4462                              <1> ;	add	ebx, [swpd_next] ; Free block searching starts from here
  4463                              <1> ;				 ; next_free_swap_block >> 5
  4464                              <1> ;	add	ecx, [swpd_last] ; Free block searching ends here
  4465                              <1> ;				 ; (total_swap_blocks - 1) >> 5
  4466                              <1> ;lswbl_scan:
  4467                              <1> ;	cmp	ebx, ecx
  4468                              <1> ;	ja	short lswbl_notfound
  4469                              <1> ;	;
  4470                              <1> ;	bsf	eax, [ebx] ; Scans source operand for first bit set (1).
  4471                              <1> ;			   ; Clears ZF if a bit is found set (1) and 
  4472                              <1> ;			   ; loads the destination with an index to
  4473                              <1> ;			   ; first set bit. (0 -> 31) 
  4474                              <1> ;			   ; Sets ZF to 1 if no bits are found set.
  4475                              <1> ;	; 01/07/2015
  4476                              <1> ;	jnz	short lswbl_found ; ZF = 0 -> a free block has been found
  4477                              <1> ;			 ;
  4478                              <1> ;			 ; NOTE:  a Swap Disk Allocation Table bit 
  4479                              <1> ;			 ;	  with value of 1 means 
  4480                              <1> ;			 ;	  the corresponding page is free 
  4481                              <1> ;			 ;	  (Retro UNIX 386 v1 feaure only!)
  4482                              <1> ;	add	ebx, 4
  4483                              <1> ;			 ; We return back for searching next page block
  4484                              <1> ;			 ; NOTE: [swpd_free] is not ZERO; so, 
  4485                              <1> ;			 ;	 we always will find at least 1 free block here.
  4486                              <1> ;	jmp    	short lswbl_scan
  4487                              <1> ;	;
  4488                              <1> ;lswbl_notfound:	
  4489                              <1> ;	sub	ecx, swap_alloc_table
  4490                              <1> ;	mov	[swpd_next], ecx ; next/first free page = last page 
  4491                              <1> ;				 ; (unlink_swap_block procedure will change it)
  4492                              <1> ;	xor	eax, eax
  4493                              <1> ;	mov	[swpd_free], eax
  4494                              <1> ;	stc
  4495                              <1> ;lswbl_ok:
  4496                              <1> ;	pop	ecx
  4497                              <1> ;	pop	ebx
  4498                              <1> ;	retn
  4499                              <1> ;	;
  4500                              <1> ;;out_of_swpspc:
  4501                              <1> ;;	stc
  4502                              <1> ;;	retn
  4503                              <1> ;
  4504                              <1> ;lswbl_found:
  4505                              <1> ;	mov	ecx, ebx
  4506                              <1> ;	sub	ecx, swap_alloc_table
  4507                              <1> ;	mov	[swpd_next], ecx ; Set first free block searching start
  4508                              <1> ;				 ; address/offset (to the next)
  4509                              <1> ;       dec     dword [swpd_free] ; 1 block has been allocated (X = X-1) 
  4510                              <1> ;	;
  4511                              <1> ;	btr	[ebx], eax	 ; The destination bit indexed by the source value
  4512                              <1> ;				 ; is copied into the Carry Flag and then cleared
  4513                              <1> ;				 ; in the destination.
  4514                              <1> ;				 ;
  4515                              <1> ;				 ; Reset the bit which is corresponding to the 
  4516                              <1> ;				 ; (just) allocated block.
  4517                              <1> ;	shl	ecx, 5		 ; (block offset * 32) + block index
  4518                              <1> ;	add	eax, ecx	 ; = block number
  4519                              <1> ;	shl	eax, SECTOR_SHIFT ; 3, sector (offset) address of the block
  4520                              <1> ;				 ; 1 block =  8 sectors
  4521                              <1> ;	;
  4522                              <1> ;	; EAX = offset address of swap disk/file sector (beginning of the block)
  4523                              <1> ;	;
  4524                              <1> ;	; NOTE: The relevant page table entry will be updated
  4525                              <1> ;	;       according to this EAX value...
  4526                              <1> ;	;
  4527                              <1> ;	jmp	short lswbl_ok
  4528                              <1> 
  4529                              <1> ; 24/12/2021
  4530                              <1> ; ('logical_disk_read' procedure call is disabled)
  4531                              <1> 
  4532                              <1> ;logical_disk_read:
  4533                              <1> 	; 20/07/2015
  4534                              <1> 	; 09/03/2015 (temporary code here)
  4535                              <1> 	;
  4536                              <1> 	; INPUT ->
  4537                              <1> 	; 	ESI = Logical disk description table address
  4538                              <1> 	; 	EBX = Memory page (buffer) address (physical!)
  4539                              <1> 	; 	EAX = Sector adress (offset address, logical sector number)
  4540                              <1> 	; 	ECX = Sector count
  4541                              <1> 	;
  4542                              <1> 	;
  4543                              <1> ;	retn
  4544                              <1> 
  4545                              <1> ; 24/12/2021
  4546                              <1> ; ('logical_disk_write' procedure call is disabled)
  4547                              <1> 
  4548                              <1> ;logical_disk_write:
  4549                              <1> 	; 20/07/2015
  4550                              <1> 	; 09/03/2015 (temporary code here)
  4551                              <1> 	;
  4552                              <1> 	; INPUT ->
  4553                              <1> 	; 	ESI = Logical disk description table address
  4554                              <1> 	; 	EBX = Memory page (buffer) address (physical!)
  4555                              <1> 	; 	EAX = Sector adress (offset address, logical sector number)
  4556                              <1> 	; 	ECX = Sector count
  4557                              <1> 	;
  4558                              <1> ;	retn
  4559                              <1> 
  4560                              <1> get_physical_addr:
  4561                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4562                              <1> 	; 19/04/2020 - Retro UNIX 386 v2
  4563                              <1> 	; 18/10/2015
  4564                              <1> 	; 29/07/2015
  4565                              <1> 	; 20/07/2015
  4566                              <1> 	; 04/06/2015
  4567                              <1> 	; 20/05/2015
  4568                              <1> 	; 28/04/2015
  4569                              <1> 	; 18/04/2015
  4570                              <1> 	; Get physical address
  4571                              <1> 	;     (allocates a new page for user if it is not present)
  4572                              <1> 	;	
  4573                              <1> 	; (This subroutine is needed for mapping user's virtual 
  4574                              <1> 	; (buffer) address to physical address (of the buffer).)
  4575                              <1> 	; ('sys write', 'sys read' system calls...)
  4576                              <1> 	;
  4577                              <1> 	; INPUT ->
  4578                              <1> 	;	EBX = virtual address
  4579                              <1> 	;	u.pgdir = page directory (physical) address
  4580                              <1> 	;
  4581                              <1> 	; OUTPUT ->
  4582                              <1> 	;	EAX = physical address 
  4583                              <1> 	;	EBX = linear address	
  4584                              <1> 	;	EDX = physical address of the page frame
  4585                              <1> 	;	      (with attribute bits)
  4586                              <1> 	;	ECX = byte count within the page frame
  4587                              <1> 	;
  4588                              <1> 	; Modified Registers -> EAX, EBX, ECX, EDX
  4589                              <1> 	;
  4590                              <1> 
  4591                              <1> 	; 19/04/2020 - Retro UNIX386 v2
  4592 000028AF A1[35660000]        <1> 	mov	eax, [u.pgdir]
  4593                              <1> 
  4594                              <1> ifs_get_physical_addr: ; 19/04/2020 - Retro UNIX 386 v2
  4595                              <1> 	
  4596 000028B4 81C300004000        <1> 	add	ebx, CORE ; 18/10/2015
  4597                              <1> 	;
  4598                              <1> 	;mov	eax, [u.pgdir]
  4599 000028BA E81AFDFFFF          <1> 	call	get_pte
  4600                              <1> 		; EDX = Page table entry address (if CF=0)
  4601                              <1> 	        ;       Page directory entry address (if CF=1)
  4602                              <1> 		;       (Bit 0 value is 0 if PT is not present)
  4603                              <1> 		; EAX = Page table entry value (page address)
  4604                              <1> 		;	CF = 1 -> PDE not present or invalid ? 
  4605 000028BF 731C                <1> 	jnc	short gpa_1
  4606                              <1> 	;
  4607 000028C1 E801FCFFFF          <1> 	call	allocate_page
  4608 000028C6 724B                <1> 	jc	short gpa_im_err  ; 'insufficient memory' error
  4609                              <1> gpa_0:
  4610 000028C8 E86BFCFFFF          <1> 	call 	clear_page
  4611                              <1> 	; EAX = Physical (base) address of the allocated (new) page
  4612 000028CD 0C07                <1> 	or	al, PDE_A_PRESENT + PDE_A_WRITE + PDE_A_USER ; 4+2+1 = 7
  4613                              <1> 			   ; lower 3 bits are used as U/S, R/W, P flags
  4614                              <1> 			   ; (user, writable, present page)	
  4615 000028CF 8902                <1> 	mov	[edx], eax ; Let's put the new page directory entry here !
  4616 000028D1 A1[35660000]        <1> 	mov	eax, [u.pgdir]	
  4617 000028D6 E8FEFCFFFF          <1> 	call	get_pte
  4618 000028DB 7236                <1> 	jc	short gpa_im_err ; 'insufficient memory' error
  4619                              <1> gpa_1:
  4620                              <1> 	; EAX = PTE value, EDX = PTE address
  4621 000028DD A801                <1> 	test 	al, PTE_A_PRESENT
  4622 000028DF 750A                <1> 	jnz	short gpa_3
  4623 000028E1 09C0                <1> 	or	eax, eax
  4624 000028E3 7420                <1> 	jz	short gpa_4  ; Allocate a new page
  4625                              <1> 
  4626                              <1> ; 24/12/2021
  4627                              <1> ; ('reload_page' procedure call is disabled)
  4628 000028E5 EB2C                <1> 	jmp	short gpa_im_err
  4629                              <1> 
  4630                              <1> 	; 20/07/2015
  4631                              <1> ;	push	ebp
  4632                              <1> ;	mov	ebp, ebx ; virtual (linear) address
  4633                              <1> ;	; reload swapped page
  4634                              <1> ;	call	reload_page ; 28/04/2015
  4635                              <1> ;	pop	ebp
  4636                              <1> ;	jc	short gpa_retn
  4637                              <1> gpa_2:
  4638                              <1> ; 24/12/2021
  4639                              <1> ; ('add_to_swap_queue' procedure call is disabled)
  4640                              <1> 
  4641                              <1> 	; 20/07/2015
  4642                              <1> 	; 20/05/2015
  4643                              <1> 	; add this page to swap queue
  4644                              <1> ;	push	eax 
  4645                              <1> ;	; EBX = Linear (CORE+virtual) address ; 20/02/2017 
  4646                              <1> ;	call 	add_to_swap_queue
  4647                              <1> ;	pop	eax
  4648                              <1> 		; PTE address in EDX
  4649                              <1> 		; virtual address in EBX
  4650                              <1> 	; EAX = memory page address
  4651 000028E7 0C07                <1> 	or	al, PTE_A_PRESENT + PTE_A_USER + PTE_A_WRITE
  4652                              <1> 				  ; present flag, bit 0 = 1
  4653                              <1> 				  ; user flag, bit 2 = 1	
  4654                              <1> 				  ; writable flag, bit 1 = 1
  4655 000028E9 8902                <1> 	mov	[edx], eax  ; Update PTE value
  4656                              <1> gpa_3:
  4657                              <1> 	; 18/10/2015
  4658 000028EB 89D9                <1> 	mov	ecx, ebx
  4659 000028ED 81E1FF0F0000        <1> 	and	ecx, PAGE_OFF
  4660 000028F3 89C2                <1> 	mov 	edx, eax
  4661 000028F5 662500F0            <1> 	and	ax, PTE_A_CLEAR
  4662 000028F9 01C8                <1> 	add	eax, ecx
  4663 000028FB F7D9                <1> 	neg	ecx ; 1 -> -1 (0FFFFFFFFh), 4095 (0FFFh) -> -4095
  4664 000028FD 81C100100000        <1> 	add	ecx, PAGE_SIZE
  4665 00002903 F8                  <1> 	clc
  4666                              <1> gpa_retn:
  4667 00002904 C3                  <1> 	retn	
  4668                              <1> gpa_4:	
  4669 00002905 E8BDFBFFFF          <1> 	call	allocate_page
  4670 0000290A 7207                <1> 	jc	short gpa_im_err ; 'insufficient memory' error
  4671 0000290C E827FCFFFF          <1> 	call	clear_page
  4672 00002911 EBD4                <1> 	jmp	short gpa_2
  4673                              <1> 
  4674                              <1> gpa_im_err:	
  4675 00002913 B804000000          <1> 	mov	eax, ERR_MINOR_IM ; Insufficient memory (minor) error!
  4676                              <1> 				  ; Major error = 0 (No protection fault)	
  4677 00002918 C3                  <1> 	retn
  4678                              <1> 
  4679                              <1> ; 24/12/2021
  4680                              <1> ; ('reload_page' procedure call is disabled)
  4681                              <1> 
  4682                              <1> ;reload_page:
  4683                              <1> 	; 20/07/2015
  4684                              <1> 	; 28/04/2015 (Retro UNIX 386 v1 - beginning)
  4685                              <1> 	;
  4686                              <1> 	; Reload (Restore) swapped page at memory
  4687                              <1> 	;
  4688                              <1> 	; INPUT -> 
  4689                              <1> 	;	EBP = Virtual (linear) memory address
  4690                              <1> 	;	EAX = PTE value (swap disk sector address)
  4691                              <1> 	;	(Swap disk sector address = bit 1 to bit 31 of EAX)	
  4692                              <1> 	; OUTPUT ->
  4693                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS OF RELOADED PAGE
  4694                              <1> 	;
  4695                              <1> 	;	CF = 1 and EAX = error code
  4696                              <1> 	;
  4697                              <1> 	; Modified Registers -> none (except EAX)
  4698                              <1> 	;
  4699                              <1> ;	shr	eax, 1   ; Convert PTE value to swap disk address 
  4700                              <1> ;	push	ebx      ;
  4701                              <1> ;	mov	ebx, eax ; Swap disk (offset) address	
  4702                              <1> ;	call	allocate_page
  4703                              <1> ;	jc	short rlp_im_err
  4704                              <1> ;	xchg 	eax, ebx	
  4705                              <1> ;	; EBX = Physical memory (page) address
  4706                              <1> ;	; EAX = Swap disk (offset) address
  4707                              <1> ;	; EBP = Virtual (linear) memory address
  4708                              <1> ;	call	swap_in
  4709                              <1> ;	jc	short rlp_swp_err  ; (swap disk/file read error)
  4710                              <1> ;	mov	eax, ebx	
  4711                              <1> ;rlp_retn:
  4712                              <1> ;	pop	ebx
  4713                              <1> ;	retn
  4714                              <1> ;	
  4715                              <1> ;rlp_im_err:	
  4716                              <1> ;	mov	eax, ERR_MINOR_IM ; Insufficient memory (minor) error!
  4717                              <1> ;				  ; Major error = 0 (No protection fault)	
  4718                              <1> ;	jmp	short rlp_retn
  4719                              <1> ;
  4720                              <1> ;rlp_swp_err:
  4721                              <1> ;	mov 	eax, SWP_DISK_READ_ERR ; Swap disk read error !
  4722                              <1> ;	jmp	short rlp_retn
  4723                              <1> 
  4724                              <1> copy_page_dir:
  4725                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4726                              <1> 	; 19/09/2015
  4727                              <1> 	; temporary - 07/09/2015
  4728                              <1> 	; 07/09/2015 (Retro UNIX 386 v1 - beginning)
  4729                              <1> 	;
  4730                              <1> 	; INPUT -> 
  4731                              <1> 	;	[u.pgdir] = PHYSICAL (real/flat) ADDRESS of the parent's
  4732                              <1> 	;		    page directory.
  4733                              <1> 	; OUTPUT ->
  4734                              <1> 	;	EAX =  PHYSICAL (real/flat) ADDRESS of the child's
  4735                              <1> 	;	       page directory.
  4736                              <1> 	;	(New page directory with new page table entries.)
  4737                              <1> 	;	(New page tables with read only copies of the parent's
  4738                              <1> 	;	pages.)
  4739                              <1> 	;	EAX = 0 -> Error (CF = 1)
  4740                              <1> 	;
  4741                              <1> 	; Modified Registers -> none (except EAX)
  4742                              <1> 	;
  4743 00002919 E8A9FBFFFF          <1> 	call	allocate_page
  4744 0000291E 723E                <1> 	jc	short cpd_err
  4745                              <1> 	;
  4746 00002920 55                  <1> 	push	ebp ; 20/07/2015
  4747 00002921 56                  <1> 	push	esi
  4748 00002922 57                  <1> 	push	edi
  4749 00002923 53                  <1> 	push	ebx
  4750 00002924 51                  <1> 	push	ecx
  4751 00002925 8B35[35660000]      <1> 	mov	esi, [u.pgdir]
  4752 0000292B 89C7                <1> 	mov	edi, eax
  4753 0000292D 50                  <1> 	push	eax ; save child's page directory address
  4754                              <1> 	; copy PDE 0 from the parent's page dir to the child's page dir
  4755                              <1> 	; (use same system space for all user page tables) 
  4756 0000292E A5                  <1> 	movsd
  4757 0000292F BD00004000          <1> 	mov	ebp, 1024*4096 ; pass the 1st 4MB (system space)
  4758 00002934 B9FF030000          <1> 	mov	ecx, (PAGE_SIZE / 4) - 1 ; 1023
  4759                              <1> cpd_0:	
  4760 00002939 AD                  <1> 	lodsd
  4761                              <1> 	;or	eax, eax
  4762                              <1>         ;jnz	short cpd_1
  4763 0000293A A801                <1> 	test	al, PDE_A_PRESENT ;  bit 0 =  1
  4764 0000293C 7508                <1> 	jnz	short cpd_1
  4765                              <1>  	; (virtual address at the end of the page table)	
  4766 0000293E 81C500004000        <1> 	add	ebp, 1024*4096 ; page size * PTE count
  4767 00002944 EB0F                <1> 	jmp	short cpd_2
  4768                              <1> cpd_1:	
  4769 00002946 662500F0            <1> 	and	ax, PDE_A_CLEAR ; 0F000h ; clear attribute bits
  4770 0000294A 89C3                <1> 	mov	ebx, eax
  4771                              <1> 	; EBX = Parent's page table address
  4772 0000294C E81F000000          <1> 	call	copy_page_table
  4773 00002951 720C                <1> 	jc	short cpd_p_err
  4774                              <1> 	; EAX = Child's page table address
  4775 00002953 0C07                <1> 	or	al, PDE_A_PRESENT + PDE_A_WRITE + PDE_A_USER
  4776                              <1> 			 ; set bit 0, bit 1 and bit 2 to 1
  4777                              <1> 			 ; (present, writable, user)
  4778                              <1> cpd_2:
  4779 00002955 AB                  <1> 	stosd
  4780 00002956 E2E1                <1> 	loop	cpd_0
  4781                              <1> 	;
  4782 00002958 58                  <1> 	pop	eax  ; restore child's page directory address
  4783                              <1> cpd_3:
  4784 00002959 59                  <1> 	pop	ecx
  4785 0000295A 5B                  <1> 	pop	ebx
  4786 0000295B 5F                  <1> 	pop	edi
  4787 0000295C 5E                  <1> 	pop	esi
  4788 0000295D 5D                  <1> 	pop	ebp
  4789                              <1> cpd_err:
  4790 0000295E C3                  <1> 	retn
  4791                              <1> cpd_p_err:
  4792                              <1> 	; release the allocated pages missing (recover free space)
  4793 0000295F 58                  <1> 	pop	eax  ; the new page directory address (physical)
  4794 00002960 8B1D[35660000]      <1> 	mov	ebx, [u.pgdir] ; parent's page directory address 
  4795 00002966 E88CFCFFFF          <1> 	call 	deallocate_page_dir
  4796 0000296B 29C0                <1> 	sub	eax, eax ; 0
  4797 0000296D F9                  <1> 	stc
  4798 0000296E EBE9                <1> 	jmp	short cpd_3	
  4799                              <1> 
  4800                              <1> copy_page_table:
  4801                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4802                              <1> 	; 19/09/2015
  4803                              <1> 	; temporary - 07/09/2015
  4804                              <1> 	; 07/09/2015 (Retro UNIX 386 v1 - beginning)
  4805                              <1> 	;
  4806                              <1> 	; INPUT -> 
  4807                              <1> 	;	EBX = PHYSICAL (real/flat) ADDRESS of the parent's page table.
  4808                              <1> 	;	EBP = page table entry index (from 'copy_page_dir')
  4809                              <1> 	; OUTPUT ->
  4810                              <1> 	;	EAX = PHYSICAL (real/flat) ADDRESS of the child's page table.
  4811                              <1> 	;	EBP = (recent) page table index (for 'add_to_swap_queue')	
  4812                              <1> 	;	CF = 1 -> error 
  4813                              <1> 	;
  4814                              <1> 	; Modified Registers -> EBP (except EAX)
  4815                              <1> 	;
  4816 00002970 E852FBFFFF          <1> 	call	allocate_page
  4817 00002975 7244                <1> 	jc	short cpt_err
  4818                              <1> 	;
  4819 00002977 50                  <1> 	push	eax ; *
  4820                              <1> 	;push 	ebx
  4821 00002978 56                  <1> 	push	esi
  4822 00002979 57                  <1> 	push	edi
  4823 0000297A 52                  <1> 	push	edx
  4824 0000297B 51                  <1> 	push	ecx
  4825                              <1> 	;
  4826 0000297C 89DE                <1> 	mov	esi, ebx
  4827 0000297E 89C7                <1> 	mov	edi, eax
  4828 00002980 89C2                <1> 	mov	edx, eax
  4829 00002982 81C200100000        <1> 	add	edx, PAGE_SIZE 	
  4830                              <1> cpt_0:
  4831 00002988 AD                  <1> 	lodsd
  4832 00002989 A801                <1> 	test	al, PTE_A_PRESENT ;  bit 0 = 1
  4833                              <1> 	;jnz	short cpt_1 (*)
  4834                              <1> 	; 24/12/2021
  4835                              <1> 	;and	eax, eax (*)
  4836 0000298B 741E                <1> 	jz	short cpt_2  ; 24/12/2021
  4837                              <1> 	
  4838                              <1> ; 24/12/2021
  4839                              <1> ; ('reload_page' procedure call is disabled)
  4840                              <1> ;
  4841                              <1> ;	; ebp = virtual (linear) address of the memory page
  4842                              <1> ;	call	reload_page ; 28/04/2015
  4843                              <1> ;	jc	short cpt_p_err
  4844                              <1> cpt_1:
  4845 0000298D 662500F0            <1> 	and	ax, PTE_A_CLEAR ; 0F000h ; clear attribute bits
  4846 00002991 89C1                <1> 	mov	ecx, eax
  4847                              <1> 	; Allocate a new page for the child process
  4848 00002993 E82FFBFFFF          <1> 	call	allocate_page
  4849 00002998 721C                <1> 	jc	short cpt_p_err
  4850 0000299A 57                  <1> 	push	edi
  4851 0000299B 56                  <1> 	push	esi
  4852 0000299C 89CE                <1> 	mov	esi, ecx
  4853 0000299E 89C7                <1> 	mov	edi, eax
  4854 000029A0 B900040000          <1> 	mov	ecx, PAGE_SIZE/4
  4855 000029A5 F3A5                <1> 	rep	movsd	; copy page (4096 bytes)
  4856 000029A7 5E                  <1> 	pop	esi
  4857 000029A8 5F                  <1> 	pop	edi
  4858                              <1> 	; 
  4859                              <1> ; 24/12/2021
  4860                              <1> ; ('add_to_swap_queue' procedure call is disabled)	
  4861                              <1> ;
  4862                              <1> ;	push	ebx
  4863                              <1> ;	push	eax
  4864                              <1> ;	mov	ebx, ebp
  4865                              <1> ;	; ebx = virtual address of the memory page
  4866                              <1> ;	call	add_to_swap_queue
  4867                              <1> ;	pop	eax
  4868                              <1> ;	pop	ebx
  4869                              <1> 	;
  4870                              <1> 	;or	ax, PTE_A_USER+PTE_A_PRESENT 
  4871 000029A9 0C07                <1> 	or	al, PTE_A_USER+PTE_A_WRITE+PTE_A_PRESENT 
  4872                              <1> cpt_2:
  4873 000029AB AB                  <1> 	stosd  ; EDI points to child's PTE  	 
  4874                              <1> 	;
  4875 000029AC 81C500100000        <1> 	add	ebp, 4096 ; 20/07/2015 (next page)
  4876                              <1> 	;
  4877 000029B2 39D7                <1> 	cmp	edi, edx
  4878 000029B4 72D2                <1> 	jb	short cpt_0
  4879                              <1> cpt_p_err:
  4880 000029B6 59                  <1> 	pop	ecx
  4881 000029B7 5A                  <1> 	pop	edx
  4882 000029B8 5F                  <1> 	pop	edi
  4883 000029B9 5E                  <1> 	pop	esi
  4884                              <1> 	;pop	ebx
  4885 000029BA 58                  <1> 	pop	eax ; *
  4886                              <1> cpt_err:
  4887 000029BB C3                  <1> 	retn
  4888                              <1> 
  4889                              <1> ; /// End Of MEMORY MANAGEMENT FUNCTIONS ///
  4890                              <1> 
  4891                              <1> ;; Data:
  4892                              <1> 
  4893                              <1> ; 09/03/2015
  4894                              <1> ;swpq_count: dw 0 ; count of pages on the swap que
  4895                              <1> ;swp_drv:    dd 0 ; logical drive description table address of the swap drive/disk
  4896                              <1> ;swpd_size:  dd 0 ; size of swap drive/disk (volume) in sectors (512 bytes).
  4897                              <1> ;swpd_free:  dd 0 ; free page blocks (4096 bytes) on swap disk/drive (logical)
  4898                              <1> ;swpd_next:  dd 0 ; next free page block
  4899                              <1> ;swpd_last:  dd 0 ; last swap page block		 		
  2109                                  %include 'sysdefs.inc' ; 09/03/2015
  2110                              <1> ; Retro UNIX 386 v1.1 Kernel (v0.2.1.6) - SYSDEFS.INC
  2111                              <1> ; Last Modification: 15/07/2022
  2112                              <1> ;
  2113                              <1> ; ///////// RETRO UNIX 386 V1 SYSTEM DEFINITIONS ///////////////
  2114                              <1> ; (Modified from 
  2115                              <1> ;	Retro UNIX 8086 v1 system definitions in 'UNIX.ASM', 01/09/2014)
  2116                              <1> ; ((UNIX.ASM (RETRO UNIX 8086 V1 Kernel), 11/03/2013 - 01/09/2014))
  2117                              <1> ; 	UNIX.ASM (MASM 6.11) --> SYSDEFS.INC (NASM 2.11)
  2118                              <1> ; ----------------------------------------------------------------------------
  2119                              <1> ;
  2120                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2121                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2122                              <1> ; <Bell Laboratories (17/3/1972)>
  2123                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2124                              <1> ;
  2125                              <1> ; ****************************************************************************
  2126                              <1> 
  2127                              <1> nproc 	equ	16  ; number of processes
  2128                              <1> nfiles 	equ	50
  2129                              <1> ntty	equ     8   ; 8+1 -> 8 (10/05/2013)
  2130                              <1> ;nbuf	equ	6   ; number of buffers (04/02/2016)
  2131                              <1> nbuf	equ	8   ; 15/07/2022 
  2132                              <1> 
  2133                              <1> ;csgmnt	equ	2000h	; 26/05/2013 (segment of process 1)
  2134                              <1> ;core	equ 	0  	    ; 19/04/2013	
  2135                              <1> ;ecore	equ	32768 - 64  ; 04/06/2013 (24/05/2013)
  2136                              <1> 	; (if total size of argument list and arguments is 128 bytes)
  2137                              <1> 	; maximum executable file size = 32768-(64+40+128-6) = 32530 bytes
  2138                              <1> 	; maximum stack size = 40 bytes (+6 bytes for 'IRET' at 32570)	
  2139                              <1> 	; initial value of user's stack pointer = 32768-64-128-2 = 32574
  2140                              <1> 	; 	(sp=32768-args_space-2 at the beginning of execution)
  2141                              <1> 	; argument list offset = 32768-64-128 = 32576 (if it is 128 bytes)
  2142                              <1> 	; 'u' structure offset (for the '/core' dump file) = 32704
  2143                              <1> 	; '/core' dump file size = 32768 bytes
  2144                              <1>  
  2145                              <1> ; 08/03/2014 
  2146                              <1> ;sdsegmnt equ	6C0h  ; 256*16 bytes (swap data segment size for 16 processes)		 	 
  2147                              <1> ; 19/04/2013 Retro UNIX 8086 v1 feature only !
  2148                              <1> ;;sdsegmnt equ 	740h  ; swap data segment (for user structures and registers)
  2149                              <1> 
  2150                              <1> ; 30/08/2013
  2151                              <1> time_count equ 4 ; 10 --> 4 01/02/2014
  2152                              <1> 
  2153                              <1> ; 05/02/2014
  2154                              <1> ; process status
  2155                              <1> ;SFREE 	equ 0
  2156                              <1> ;SRUN	equ 1
  2157                              <1> ;SWAIT	equ 2
  2158                              <1> ;SZOMB	equ 3
  2159                              <1> ;SSLEEP	equ 4 ; Retro UNIX 8086 V1 extension (for sleep and wakeup)
  2160                              <1> 
  2161                              <1> ; 09/03/2015
  2162                              <1> userdata equ 80000h ; user structure data address for current user ; temporary
  2163                              <1> swap_queue equ 90000h - 2000h ; swap queue address ; temporary
  2164                              <1> swap_alloc_table equ 0D0000h  ;  swap allocation table address ; temporary
  2165                              <1> 
  2166                              <1> ; 17/09/2015
  2167                              <1> ESPACE equ 48 ; [u.usp] (at 'sysent') - [u.sp] value for error return
  2168                              <1> 
  2169                              <1> ; 21/09/2015 (36) 
  2170                              <1> ; 01/07/2015 (35)
  2171                              <1> ; 14/07/2013 (0-34)
  2172                              <1> ; UNIX v1 system calls
  2173                              <1> _rele 	equ 0
  2174                              <1> _exit 	equ 1
  2175                              <1> _fork 	equ 2
  2176                              <1> _read 	equ 3
  2177                              <1> _write	equ 4
  2178                              <1> _open	equ 5
  2179                              <1> _close 	equ 6
  2180                              <1> _wait 	equ 7
  2181                              <1> _creat 	equ 8
  2182                              <1> _link 	equ 9
  2183                              <1> _unlink	equ 10
  2184                              <1> _exec	equ 11
  2185                              <1> _chdir	equ 12
  2186                              <1> _time 	equ 13
  2187                              <1> _mkdir 	equ 14
  2188                              <1> _chmod	equ 15
  2189                              <1> _chown	equ 16
  2190                              <1> _break	equ 17
  2191                              <1> _stat	equ 18
  2192                              <1> _seek	equ 19
  2193                              <1> _tell 	equ 20
  2194                              <1> _mount	equ 21
  2195                              <1> _umount	equ 22
  2196                              <1> _setuid	equ 23
  2197                              <1> _getuid	equ 24
  2198                              <1> _stime	equ 25
  2199                              <1> _quit	equ 26	
  2200                              <1> _intr	equ 27
  2201                              <1> _fstat	equ 28
  2202                              <1> _emt 	equ 29
  2203                              <1> _mdate 	equ 30
  2204                              <1> _stty 	equ 31
  2205                              <1> _gtty	equ 32
  2206                              <1> _ilgins	equ 33
  2207                              <1> _sleep	equ 34 ; Retro UNIX 8086 v1 feature only !
  2208                              <1> _msg	equ 35 ; Retro UNIX 386 v1 feature only !
  2209                              <1> _geterr	equ 36 ; Retro UNIX 386 v1 feature only !
  2210                              <1> 
  2211                              <1> %macro sys 1-4
  2212                              <1>     ; 13/04/2015
  2213                              <1>     ; Retro UNIX 386 v1 system call.		
  2214                              <1>     mov eax, %1
  2215                              <1>     %if %0 >= 2   
  2216                              <1>         mov ebx, %2
  2217                              <1>         %if %0 >= 3    
  2218                              <1>             mov ecx, %3
  2219                              <1>             %if %0 = 4
  2220                              <1>                mov edx, %4   
  2221                              <1>             %endif
  2222                              <1>         %endif
  2223                              <1>     %endif
  2224                              <1>     int 30h	   
  2225                              <1> %endmacro
  2226                              <1> 
  2227                              <1> ; 13/05/2015 - ERROR CODES
  2228                              <1> ERR_FILE_NOT_OPEN  equ 10 ; 'file not open !' error
  2229                              <1> ERR_FILE_ACCESS    equ 11 ; 'permission denied !' error
  2230                              <1> ; 14/05/2015
  2231                              <1> ERR_DIR_ACCESS     equ 11 ; 'permission denied !' error
  2232                              <1> ERR_FILE_NOT_FOUND equ 12 ; 'file not found !' error
  2233                              <1> ERR_TOO_MANY_FILES equ 13 ; 'too many open files !' error
  2234                              <1> ERR_DIR_EXISTS     equ 14 ; 'directory already exists !' error 	
  2235                              <1> ; 16/05/2015		
  2236                              <1> ERR_DRV_NOT_RDY    equ 15 ; 'drive not ready !' error
  2237                              <1> ; 18/05/2015
  2238                              <1> ERR_DEV_NOT_RDY    equ 15 ; 'device not ready !' error
  2239                              <1> ERR_DEV_ACCESS     equ 11 ; 'permission denied !' error 
  2240                              <1> ERR_DEV_NOT_OPEN   equ 10 ; 'device not open !' error	
  2241                              <1> ; 07/06/2015
  2242                              <1> ERR_FILE_EOF	   equ 16 ; 'end of file !' error
  2243                              <1> ERR_DEV_VOL_SIZE   equ 16 ; 'out of volume' error
  2244                              <1> ; 09/06/2015
  2245                              <1> ERR_DRV_READ	   equ 17 ; 'disk read error !'
  2246                              <1> ERR_DRV_WRITE	   equ 18 ; 'disk write error !'
  2247                              <1> ; 16/06/2015
  2248                              <1> ERR_NOT_DIR	   equ 19 ; 'not a (valid) directory !' error
  2249                              <1> ERR_FILE_SIZE	   equ 20 ; 'file size error !'	
  2250                              <1> ; 22/06/2015
  2251                              <1> ERR_NOT_SUPERUSER  equ 11 ; 'permission denied !' error
  2252                              <1> ERR_NOT_OWNER      equ 11 ; 'permission denied !' error
  2253                              <1> ERR_NOT_FILE       equ 11 ; 'permission denied !' error	
  2254                              <1> ; 23/06/2015
  2255                              <1> ERR_FILE_EXISTS    equ 14 ; 'file already exists !' error
  2256                              <1> ERR_DRV_NOT_SAME   equ 21 ; 'not same drive !' error
  2257                              <1> ERR_DIR_NOT_FOUND  equ 12 ; 'directory not found !' error
  2258                              <1> ERR_NOT_EXECUTABLE equ 22 ; 'not executable file !' error
  2259                              <1> ; 27/06/2015
  2260                              <1> ERR_INV_PARAMETER  equ 23 ; 'invalid parameter !' error
  2261                              <1> ERR_INV_DEV_NAME   equ 24 ; 'invalid device name !' error
  2262                              <1> ; 29/06/2015
  2263                              <1> ERR_TIME_OUT	   equ 25 ; 'time out !' error			
  2264                              <1> ERR_DEV_NOT_RESP   equ 25 ; 'device not responding !' error
  2265                              <1> ; 08/02/2022 
  2266                              <1> ; (error numbers from TRDOS 386 v2.0 'sysdefs.s')
  2267                              <1> ; 10/10/2016
  2268                              <1> ERR_INV_FILE_NAME  equ 26 ; 'invalid file name !' error
  2269                              <1> ; 18/05/2016
  2270                              <1> ERR_MISC	   equ 27 ; miscellaneous/other errors
  2271                              <1> ; 15/10/2016
  2272                              <1> ERR_INV_FORMAT	   equ 28 ; 'invalid format !' error
  2273                              <1> ERR_INV_DATA	   equ 29 ; 'invalid data !' error
  2274                              <1> ; 16/10/2016
  2275                              <1> ERR_DISK_WRITE	   equ 30 ; 'disk write protected !'
  2276                              <1> ; 08/02/2022
  2277                              <1> ERR_INV_FS	   equ 28  ;'invalid fs/superblock !' error
  2278                              <1> 
  2279                              <1> ; 13/06/2022
  2280                              <1> ; printer errors
  2281                              <1> ERR_PRN_NOT_RDY	   equ 15 ; 'device not ready !' error
  2282                              <1> ERR_PRN_TIMEOUT	   equ 25 ; 'time out !' error
  2283                              <1> ERR_PRN_PAPER	   equ 31 ; 'out of paper !' error
  2284                              <1> ERR_PRN_IO	   equ 32 ; 'io error !' error
  2285                              <1> ERR_PRN_BUSY	   equ 34 ; 'busy !' error
  2286                              <1> 
  2287                              <1> ; 26/08/2015
  2288                              <1> ; 24/07/2015
  2289                              <1> ; 24/06/2015
  2290                              <1> MAX_ARG_LEN	   equ 256 ; max. length of sys exec arguments
  2291                              <1> ; 01/07/2015
  2292                              <1> MAX_MSG_LEN	   equ 255 ; max. msg length for 'sysmsg'
  2293                              <1> ; 24/12/2021
  2294                              <1> ERR_INV_FUNC	   equ 1  ; 'invalid system call !' error	 					 		
  2110                                  %include 'u0.s'        ; 15/03/2015
  2111                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.6) - SYS0.INC
  2112                              <1> ; Last Modification: 17/07/2022
  2113                              <1> ; ----------------------------------------------------------------------------
  2114                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2115                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2116                              <1> ;
  2117                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2118                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2119                              <1> ; <Bell Laboratories (17/3/1972)>
  2120                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2121                              <1> ;
  2122                              <1> ; Retro UNIX 8086 v1 - U0.ASM (28/07/2014) //// UNIX v1 -> u0.s
  2123                              <1> ;
  2124                              <1> ; ****************************************************************************
  2125                              <1> 
  2126                              <1> sys_init:
  2127                              <1> 	; 26/02/2022
  2128                              <1> 	; 08/01/2022
  2129                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2130                              <1> 	; 18/10/2015
  2131                              <1> 	; 28/08/2015
  2132                              <1> 	; 24/08/2015
  2133                              <1> 	; 14/08/2015
  2134                              <1> 	; 24/07/2015 
  2135                              <1> 	; 02/07/2015
  2136                              <1> 	; 01/07/2015
  2137                              <1> 	; 23/06/2015
  2138                              <1> 	; 15/04/2015
  2139                              <1> 	; 13/03/2015
  2140                              <1> 	; 11/03/2015 (Retro UNIX 386 v1 - Beginning)
  2141                              <1> 	; 28/07/2014 (Retro UNIX 8086 v1)
  2142                              <1> 	;
  2143                              <1> 	;call	ldrv_init ; Logical drive description tables initialization
  2144                              <1> 	;
  2145                              <1> 	; 14/02/2014
  2146                              <1> 	; 14/07/2013
  2147                              <1> 	;;mov	ax, 41
  2148                              <1> 	; 24/12/2021
  2149                              <1> 	;xor	eax, eax
  2150                              <1> 	;mov	al, 41
  2151                              <1> 	;mov	[rootdir], ax
  2152                              <1> 	;mov	[u.cdir], ax
  2153                              <1> 	;;and	al, 1 ; 15/04/2015
  2154                              <1> 	;inc	al  ; ax = 1
  2155 000029BC B001                <1> 	mov	al, 1
  2156 000029BE A2[2B660000]        <1> 	mov	[u.uno], al
  2157                              <1> 	;mov	[mpid], ax
  2158                              <1> 	;mov	[p.pid], ax
  2159 000029C3 A2[CA650000]        <1> 	mov	[mpid], al
  2160 000029C8 A2[F4620000]        <1> 	mov	[p.pid], al	
  2161 000029CD A2[54630000]        <1> 	mov	[p.stat], al ; SRUN, 05/02/2014
  2162                              <1> 	; 24/12/2021
  2163 000029D2 B029                <1> 	mov	al, 41
  2164                              <1> 	;mov	[rootdir], ax
  2165                              <1> 	;mov	[u.cdir], ax
  2166 000029D4 A2[CC650000]        <1> 	mov	[rootdir], al
  2167 000029D9 A2[E0650000]        <1> 	mov	[u.cdir], al
  2168                              <1> 	;
  2169 000029DE B004                <1> 	mov	al, time_count ; 30/08/2013
  2170 000029E0 A2[1E660000]        <1> 	mov	[u.quant], al ; 14/07/2013
  2171                              <1> 	; 02/07/2015
  2172 000029E5 A1[18620000]        <1> 	mov	eax, [k_page_dir]
  2173                              <1> 	;sub	eax, eax
  2174 000029EA A3[35660000]        <1> 	mov	[u.pgdir], eax ; reset
  2175                              <1> 	; 18/10/2015
  2176                              <1> 	;mov	[u.ppgdir], eax ; 0
  2177                              <1> 	; 26/02/2022
  2178                              <1>  	;call	epoch
  2179                              <1> 	;mov	[s.time], eax ; 13/03/2015
  2180                              <1> 	; 17/07/2013
  2181 000029EF E881060000          <1> 	call 	bf_init ; buffer initialization
  2182                              <1> 	; 26/02/2022
  2183                              <1> 	; (save sysinit time on sb0)
  2184 000029F4 E829030000          <1> 	call	epoch
  2185 000029F9 A3[38780000]        <1> 	mov	[s.time], eax ; 13/03/2015
  2186                              <1> 	; 23/06/2015
  2187 000029FE E8C4FAFFFF          <1> 	call	allocate_page
  2188                              <1> 	;;jc	error
  2189                              <1> 	;jc	panic   ; jc short panic (01/07/2015)
  2190                              <1> 	; 24/12/2021
  2191 00002A03 7305                <1> 	jnc	short sysinit_1
  2192 00002A05 E989000000          <1> 	jmp	panic
  2193                              <1> sysinit_1:
  2194 00002A0A A3[2C660000]        <1> 	mov	[u.upage], eax ; user structure page	
  2195 00002A0F A3[64630000]        <1> 	mov	[p.upage], eax
  2196                              <1> 	;
  2197 00002A14 E81FFBFFFF          <1> 	call	clear_page
  2198                              <1> 	;
  2199                              <1> 	; 14/08/2015
  2200 00002A19 FA                  <1> 	cli
  2201                              <1> 	; 14/03/2015
  2202                              <1> 	; 17/01/2014
  2203 00002A1A E8D0010000          <1> 	call	sp_init ; serial port initialization
  2204                              <1> 	; 14/08/2015
  2205 00002A1F FB                  <1> 	sti
  2206                              <1> 	;
  2207                              <1> 	; 30/06/2015
  2208                              <1> 	;mov	esi, kernel_init_ok_msg
  2209                              <1> 	;call 	print_msg
  2210                              <1> 	;
  2211 00002A20 30DB                <1> 	xor	bl, bl ; video page 0
  2212                              <1> vp_clr_nxt:  ; clear video pages (reset cursor positions)
  2213 00002A22 E8410F0000          <1> 	call 	vp_clr  ; 17/07/2013
  2214 00002A27 FEC3                <1> 	inc	bl
  2215 00002A29 80FB08              <1> 	cmp	bl, 8
  2216 00002A2C 72F4                <1> 	jb	short vp_clr_nxt
  2217                              <1> 	;
  2218                              <1> 	; 24/07/2015
  2219                              <1> 	;push    KDATA
  2220                              <1>         ;push    esp
  2221                              <1> 	;mov	[tss.esp0], esp
  2222                              <1>         ;mov     word [tss.ss0], KDATA
  2223                              <1> 	;
  2224                              <1> 	; 08/01/2022
  2225                              <1> 	; 24/08/2015
  2226                              <1> 	;; temporary (01/07/2015)
  2227                              <1> 	;mov	byte [u.quant], time_count ; 4 
  2228                              <1> 			       ; it is not needed here !
  2229                              <1> 	;;inc	byte [u.kcall] ; 'the caller is kernel' sign
  2230 00002A2E FE0D[D3650000]      <1> 	dec 	byte [sysflg] ; FFh = ready for system call
  2231                              <1> 			      ; 0 = executing a system call
  2232                              <1> 	;;sys 	_msg, kernel_init_ok_msg, 255, 0
  2233                              <1> 	;
  2234                              <1> 	;;; 06/08/2015
  2235                              <1> 	;;;call	getch ; wait for a key stroke
  2236                              <1> 	;;mov 	ecx, 0FFFFFFFh	
  2237                              <1> ;;sys_init_msg_wait:
  2238                              <1> ;;	push 	ecx
  2239                              <1> ;;	mov	al, 1
  2240                              <1> ;;	mov 	ah, [ptty] ; active (current) video page
  2241                              <1> ;;	call	getc_n
  2242                              <1> ;;	pop	ecx
  2243                              <1> ;;	jnz	short sys_init_msg_ok
  2244                              <1> ;;	loop	sys_init_msg_wait
  2245                              <1> 	;
  2246                              <1> ;;sys_init_msg_ok:
  2247                              <1> 	; 28/08/2015 (initial settings for the 1st 'rswap')
  2248 00002A34 6A10                <1> 	push	KDATA ; ss
  2249 00002A36 54                  <1> 	push	esp
  2250 00002A37 9C                  <1> 	pushfd
  2251 00002A38 6A08                <1> 	push	KCODE ; cs
  2252 00002A3A 68[672A0000]        <1> 	push	init_exec ; eip
  2253 00002A3F 8925[D4650000]      <1> 	mov	[u.sp], esp
  2254 00002A45 1E                  <1> 	push	ds
  2255 00002A46 06                  <1> 	push	es
  2256 00002A47 0FA0                <1> 	push	fs
  2257 00002A49 0FA8                <1> 	push	gs	
  2258 00002A4B 60                  <1> 	pushad
  2259 00002A4C 8925[D8650000]      <1> 	mov	[u.usp], esp
  2260 00002A52 E8AD1B0000          <1> 	call	wswap ; save current user (u) structure, user registers
  2261                              <1> 		      ; and interrupt return components (for IRET)
  2262 00002A57 61                  <1> 	popad
  2263 00002A58 6658                <1> 	pop	ax ; gs
  2264 00002A5A 6658                <1> 	pop	ax ; fs
  2265 00002A5C 6658                <1> 	pop	ax ; es
  2266 00002A5E 6658                <1> 	pop	ax ; ds	
  2267 00002A60 58                  <1> 	pop	eax ; eip (init_exec)
  2268 00002A61 6658                <1> 	pop	ax ; cs (KCODE)
  2269 00002A63 58                  <1> 	pop	eax ; E-FLAGS
  2270 00002A64 58                  <1> 	pop	eax ; esp
  2271 00002A65 6658                <1> 	pop	ax ; ss (KDATA)
  2272                              <1> 	;
  2273                              <1> 	; 08/01/2022 ([u.ppgdir] is zero already)
  2274                              <1> 	;xor	eax, eax ; 0
  2275                              <1> 	;mov	[u.ppgdir], eax ; reset (to zero) for '/etc/init'
  2276                              <1> 	;
  2277                              <1> 	; 02/07/2015
  2278                              <1> 	; [u.pgdir ] = [k_page_dir]
  2279                              <1> 	; [u.ppgdir] = 0 (page dir of the parent process)
  2280                              <1> 	;     (The caller is os kernel sign for 'sysexec')
  2281                              <1> init_exec:
  2282                              <1> 	; 13/03/2013
  2283                              <1> 	; 24/07/2013
  2284 00002A67 BB[892A0000]        <1> 	mov	ebx, init_file
  2285 00002A6C B9[812A0000]        <1> 	mov	ecx, init_argp
  2286                              <1> 	; EBX contains 'etc/init' asciiz file name address  
  2287                              <1> 	; ECX contains address of argument list pointer
  2288                              <1> 	;
  2289                              <1> 	;dec 	byte [sysflg] ; FFh = ready for system call
  2290                              <1> 			      ; 0 = executing a system call
  2291                              <1> 	sys	_exec  ; execute file
  2212                              <2> 
  2213                              <2> 
  2214 00002A71 B80B000000          <2>  mov eax, %1
  2215                              <2>  %if %0 >= 2
  2216                              <2>  mov ebx, %2
  2217                              <2>  %if %0 >= 3
  2218                              <2>  mov ecx, %3
  2219                              <2>  %if %0 = 4
  2220                              <2>  mov edx, %4
  2221                              <2>  %endif
  2222                              <2>  %endif
  2223                              <2>  %endif
  2224 00002A76 CD30                <2>  int 30h
  2292 00002A78 7319                <1> 	jnc	short panic
  2293                              <1> 	;
  2294 00002A7A BE[305F0000]        <1> 	mov	esi, etc_init_err_msg
  2295                              <1> 	; 08/01/2022
  2296                              <1> 	;call 	print_msg
  2297 00002A7F EB17                <1> 	jmp	short key_to_reboot
  2298                              <1> 
  2299                              <1> ;align 4
  2300                              <1> init_argp:
  2301 00002A81 [892A0000]00000000  <1> 	dd 	init_file, 0  ; 23/06/2015 (dw -> dd)
  2302                              <1> init_file:
  2303                              <1> 	; 24/08/2015
  2304 00002A89 2F6574632F696E6974- <1> 	db 	'/etc/init', 0
  2304 00002A92 00                  <1>
  2305                              <1> panic:
  2306                              <1> 	; 13/03/2015 (Retro UNIX 386 v1)
  2307                              <1> 	; 07/03/2014 (Retro UNIX 8086 v1)
  2308 00002A93 BE[155F0000]        <1> 	mov 	esi, panic_msg
  2309                              <1> key_to_reboot: ; 08/01/2022 (Retro UNIX 386 v1.1)
  2310 00002A98 E819000000          <1> 	call 	print_msg
  2311                              <1> ;key_to_reboot:
  2312                              <1> 	; 15/11/2015
  2313 00002A9D E8C62B0000          <1> 	call 	getch 
  2314                              <1> 		; wait for a character from the current tty
  2315                              <1> 	;
  2316 00002AA2 B00A                <1> 	mov	al, 0Ah
  2317 00002AA4 8A1D[46620000]      <1> 	mov	bl, [ptty] ; [active_page]
  2318 00002AAA B407                <1> 	mov	ah, 07h ; Black background, 
  2319                              <1> 			; light gray forecolor
  2320 00002AAC E8F1E8FFFF          <1> 	call 	write_tty
  2321 00002AB1 E990E5FFFF          <1> 	jmp	cpu_reset 
  2322                              <1> 
  2323                              <1> print_msg:
  2324                              <1> 	; 01/07/2015
  2325                              <1> 	; 13/03/2015 (Retro UNIX 386 v1)
  2326                              <1> 	; 07/03/2014 (Retro UNIX 8086 v1)
  2327                              <1> 	; (Modified registers: EAX, EBX, ECX, EDX, ESI, EDI)
  2328                              <1> 	;
  2329                              <1> 	;
  2330 00002AB6 AC                  <1> 	lodsb
  2331                              <1> pmsg1:
  2332 00002AB7 56                  <1> 	push 	esi
  2333 00002AB8 0FB61D[46620000]    <1> 	movzx	ebx, byte [ptty]
  2334 00002ABF B407                <1> 	mov	ah, 07h ; Black background, light gray forecolor
  2335 00002AC1 E8DCE8FFFF          <1> 	call 	write_tty
  2336 00002AC6 5E                  <1> 	pop	esi
  2337 00002AC7 AC                  <1> 	lodsb
  2338 00002AC8 20C0                <1> 	and 	al, al
  2339 00002ACA 75EB                <1> 	jnz 	short pmsg1
  2340 00002ACC C3                  <1> 	retn
  2341                              <1> 	
  2342                              <1> ctrlbrk:
  2343                              <1> 	; 04/02/2022
  2344                              <1> 	; 01/02/2022
  2345                              <1> 	; 12/11/2015
  2346                              <1> 	; 13/03/2015 (Retro UNIX 386 v1)
  2347                              <1> 	; 06/12/2013 (Retro UNIX 8086 v1)
  2348                              <1> 	;
  2349                              <1> 	; INT 1Bh (control+break) handler
  2350                              <1> 	;
  2351                              <1>       	; Retro Unix 8086 v1 feature only!
  2352                              <1>       	;
  2353 00002ACD 66833D[20660000]00  <1> 	cmp 	word [u.intr], 0
  2354 00002AD5 764B                <1> 	jna 	short cbrk4
  2355                              <1> cbrk0:
  2356                              <1> 	; 12/11/2015
  2357                              <1> 	; 06/12/2013
  2358 00002AD7 66833D[22660000]00  <1> 	cmp 	word [u.quit], 0
  2359 00002ADF 7441                <1> 	jz	short cbrk4
  2360                              <1> 	;
  2361                              <1> 	; 20/09/2013	
  2362                              <1> 	;push 	ax
  2363                              <1> 	; 01/02/2022
  2364 00002AE1 50                  <1> 	push	eax
  2365                              <1> 
  2366                              <1> 	; 04/02/2022
  2367                              <1> 	; (repetitive ctrl+brk check) 
  2368 00002AE2 66A1[22660000]      <1> 	mov	ax, [u.quit]
  2369 00002AE8 6640                <1> 	inc	ax ; 0FFFFh -> 0
  2370 00002AEA 7435                <1> 	jz	short cbrk3
  2371                              <1> 
  2372                              <1> 	; 20/09/2013
  2373 00002AEC A0[46620000]        <1> 	mov	al, [ptty]
  2374                              <1> 	;
  2375                              <1> 	; 12/11/2015
  2376                              <1> 	;
  2377                              <1> 	; ctrl+break (EOT, CTRL+D) from serial port
  2378                              <1> 	; or ctrl+break from console (pseudo) tty
  2379                              <1> 	; (!redirection!)
  2380                              <1> 	;
  2381 00002AF1 3C08                <1> 	cmp	al, 8 ; serial port tty nums > 7
  2382 00002AF3 7211                <1>         jb      short cbrk1 ; console (pseudo) tty
  2383                              <1> 	;	
  2384                              <1> 	; Serial port interrupt handler sets [ptty]
  2385                              <1> 	; to the port's tty number (as temporary).
  2386                              <1> 	;
  2387                              <1> 	; If active process is using a stdin or 
  2388                              <1> 	; stdout redirection (by the shell),
  2389                              <1>         ; console tty keyboard must be available
  2390                              <1> 	; to terminate running process,
  2391                              <1> 	; in order to prevent a deadlock. 
  2392                              <1> 	;
  2393 00002AF5 52                  <1> 	push	edx
  2394 00002AF6 0FB615[2B660000]    <1> 	movzx	edx, byte [u.uno]
  2395 00002AFD 3A82[33630000]      <1> 	cmp     al, [edx+p.ttyc-1] ; console tty (rw)
  2396 00002B03 5A                  <1> 	pop	edx
  2397 00002B04 7412                <1> 	je	short cbrk2
  2398                              <1> cbrk1:
  2399 00002B06 FEC0                <1> 	inc 	al  ; [u.ttyp] : 1 based tty number
  2400                              <1> 	; 06/12/2013
  2401 00002B08 3A05[0C660000]      <1> 	cmp	al, [u.ttyp] ; recent open tty (r)
  2402 00002B0E 7408                <1> 	je	short cbrk2	
  2403 00002B10 3A05[0D660000]      <1>         cmp     al, [u.ttyp+1] ; recent open tty (w)
  2404 00002B16 7509                <1> 	jne	short cbrk3	
  2405                              <1> cbrk2:
  2406                              <1> 	;; 06/12/2013
  2407                              <1> 	;mov	ax, [u.quit]
  2408                              <1> 	;and	ax, ax
  2409                              <1> 	;jz	short cbrk3
  2410                              <1> 	;
  2411                              <1> 	;xor	ax, ax ; 0
  2412                              <1> 	;dec	ax
  2413                              <1> 	; 01/02/2022
  2414 00002B18 31C0                <1> 	xor	eax, eax ; 0
  2415 00002B1A 48                  <1> 	dec	eax ; 0FFFFFFFFh
  2416                              <1> 	; 0FFFFh = 'ctrl+brk' keystroke
  2417 00002B1B 66A3[22660000]      <1> 	mov	[u.quit], ax
  2418                              <1> cbrk3:
  2419                              <1> 	;pop	ax
  2420                              <1> 	; 01/02/2022
  2421 00002B21 58                  <1> 	pop	eax
  2422                              <1> cbrk4:
  2423 00002B22 C3                  <1> 	retn
  2424                              <1> 
  2425                              <1> com2_int:
  2426                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2427                              <1> 	; 07/11/2015 
  2428                              <1> 	; 24/10/2015
  2429                              <1> 	; 23/10/2015
  2430                              <1> 	; 14/03/2015 (Retro UNIX 386 v1 - Beginning)
  2431                              <1> 	; 28/07/2014 (Retro UNIX 8086 v1)
  2432                              <1> 	; < serial port 2 interrupt handler >
  2433                              <1> 	;
  2434 00002B23 890424              <1> 	mov 	[esp], eax ; overwrite call return address
  2435                              <1> 	;;push	eax
  2436                              <1> 	; 08/01/2022
  2437 00002B26 29C0                <1> 	sub	eax, eax
  2438 00002B28 B009                <1> 	mov	al, 9
  2439                              <1> 	;mov	ax, 9
  2440 00002B2A EB07                <1> 	jmp	short comm_int
  2441                              <1> com1_int:
  2442                              <1> 	; 07/11/2015
  2443                              <1> 	; 24/10/2015
  2444 00002B2C 890424              <1> 	mov 	[esp], eax ; overwrite call return address
  2445                              <1> 	; 23/10/2015
  2446                              <1> 	;push	eax
  2447                              <1> 	; 08/01/2022
  2448 00002B2F 29C0                <1> 	sub	eax, eax
  2449 00002B31 B008                <1> 	mov	al, 8
  2450                              <1> 	;mov	ax, 8
  2451                              <1> comm_int:
  2452                              <1> 	; 08/01/2022
  2453                              <1> 	; 20/11/2015
  2454                              <1> 	; 18/11/2015
  2455                              <1> 	; 17/11/2015
  2456                              <1> 	; 16/11/2015
  2457                              <1> 	; 09/11/2015
  2458                              <1> 	; 08/11/2015
  2459                              <1> 	; 07/11/2015
  2460                              <1> 	; 06/11/2015 (serial4.asm, 'serial')
  2461                              <1> 	; 01/11/2015
  2462                              <1> 	; 26/10/2015
  2463                              <1> 	; 23/10/2015
  2464 00002B33 53                  <1> 	push	ebx
  2465 00002B34 56                  <1> 	push	esi
  2466 00002B35 57                  <1> 	push	edi
  2467 00002B36 1E                  <1> 	push 	ds
  2468 00002B37 06                  <1> 	push 	es
  2469                              <1> 	; 18/11/2015
  2470 00002B38 0F20DB              <1> 	mov	ebx, cr3
  2471 00002B3B 53                  <1> 	push	ebx ; ****
  2472                              <1> 	;
  2473 00002B3C 51                  <1> 	push	ecx ; ***
  2474 00002B3D 52                  <1> 	push	edx ; **
  2475                              <1> 	;
  2476 00002B3E BB10000000          <1> 	mov	ebx, KDATA
  2477 00002B43 8EDB                <1> 	mov	ds, bx
  2478 00002B45 8EC3                <1> 	mov	es, bx
  2479                              <1> 	;
  2480 00002B47 8B0D[18620000]      <1> 	mov	ecx, [k_page_dir]
  2481 00002B4D 0F22D9              <1> 	mov	cr3, ecx
  2482                              <1> 	; 20/11/2015
  2483                              <1> 	; Interrupt identification register
  2484 00002B50 66BAFA02            <1> 	mov	dx, 2FAh ; COM2
  2485                              <1> 	;
  2486 00002B54 3C08                <1> 	cmp 	al, 8 
  2487 00002B56 7702                <1> 	ja 	short com_i0
  2488                              <1> 	;
  2489                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1)
  2490                              <1> 	; 20/11/2015
  2491                              <1> 	; 17/11/2015
  2492                              <1> 	; 16/11/2015
  2493                              <1> 	; 15/11/2015
  2494                              <1> 	; 24/10/2015
  2495                              <1> 	; 14/03/2015 (Retro UNIX 386 v1 - Beginning)
  2496                              <1> 	; 28/07/2014 (Retro UNIX 8086 v1)
  2497                              <1> 	; < serial port 1 interrupt handler >
  2498                              <1> 	;
  2499 00002B58 FEC6                <1> 	inc	dh ; 3FAh ; COM1 Interrupt id. register
  2500                              <1> com_i0:
  2501                              <1> 	;push	eax ; *
  2502                              <1> 	; 07/11/2015
  2503 00002B5A A2[86620000]        <1> 	mov 	byte [ccomport], al
  2504                              <1> 	; 09/11/2015
  2505                              <1> 	;movzx	ebx, ax ; 8 or 9
  2506                              <1> 	; 08/01/2022
  2507 00002B5F 89C3                <1> 	mov	ebx, eax ; 8 or 9
  2508                              <1> 	; 17/11/2015
  2509                              <1>  	; reset request for response status
  2510 00002B61 88A3[7C620000]      <1> 	mov	[ebx+req_resp-8], ah ; 0
  2511                              <1> 	;
  2512                              <1> 	; 20/11/2015
  2513 00002B67 EC                  <1> 	in	al, dx		; read interrupt id. register
  2514 00002B68 EB00                <1> 	JMP	$+2	   	; I/O DELAY
  2515 00002B6A 2404                <1> 	and	al, 4		; received data available?	
  2516 00002B6C 7470                <1> 	jz	short com_eoi	; (transmit. holding reg. empty)
  2517                              <1> 	;
  2518                              <1> 	; 20/11/2015
  2519 00002B6E 80EA02              <1> 	sub	dl, 3FAh-3F8h	; data register (3F8h, 2F8h)
  2520 00002B71 EC                  <1> 	in	al, dx     	; read character
  2521                              <1> 	;JMP	$+2	   	; I/O DELAY
  2522                              <1> 	; 08/11/2015
  2523                              <1> 	; 07/11/2015
  2524 00002B72 89DE                <1> 	mov	esi, ebx 
  2525 00002B74 89DF                <1> 	mov	edi, ebx
  2526 00002B76 81C6[80620000]      <1> 	add 	esi, rchar - 8 ; points to last received char
  2527 00002B7C 81C7[82620000]      <1> 	add	edi, schar - 8 ; points to last sent char
  2528 00002B82 8806                <1> 	mov	[esi], al ; received char (current char)
  2529                              <1> 	; query
  2530 00002B84 20C0                <1> 	and	al, al
  2531 00002B86 7527                <1> 	jnz	short com_i2
  2532                              <1>    	; response
  2533                              <1> 	; 17/11/2015
  2534                              <1> 	; set request for response status
  2535 00002B88 FE83[7C620000]      <1>         inc     byte [ebx+req_resp-8] ; 1 
  2536                              <1> 	;
  2537 00002B8E 6683C205            <1> 	add	dx, 3FDh-3F8h	; (3FDh, 2FDh)
  2538 00002B92 EC                  <1> 	in	al, dx	   	; read line status register 
  2539 00002B93 EB00                <1> 	JMP	$+2	   	; I/O DELAY
  2540 00002B95 2420                <1> 	and	al, 20h	   	; transmitter holding reg. empty?
  2541 00002B97 7445                <1> 	jz	short com_eoi 	; no
  2542 00002B99 B0FF                <1> 	mov 	al, 0FFh   	; response			
  2543 00002B9B 6683EA05            <1> 	sub	dx, 3FDh-3F8h 	; data port (3F8h, 2F8h)
  2544 00002B9F EE                  <1> 	out	dx, al	   	; send on serial port
  2545                              <1> 	; 17/11/2015
  2546 00002BA0 803F00              <1> 	cmp 	byte [edi], 0   ; query ? (schar)
  2547 00002BA3 7502                <1> 	jne 	short com_i1    ; no
  2548 00002BA5 8807                <1> 	mov	[edi], al 	; 0FFh (responded)
  2549                              <1> com_i1:
  2550                              <1> 	; 17/11/2015
  2551                              <1> 	; reset request for response status (again)
  2552 00002BA7 FE8B[7C620000]      <1>         dec     byte [ebx+req_resp-8] ; 0 
  2553 00002BAD EB2F                <1> 	jmp	short com_eoi
  2554                              <1> com_i2:	
  2555                              <1> 	; 08/11/2015
  2556 00002BAF 3CFF                <1> 	cmp 	al, 0FFh	; (response ?)
  2557 00002BB1 7417                <1> 	je	short com_i3	; (check for response signal)
  2558                              <1> 	; 07/11/2015
  2559 00002BB3 3C04                <1> 	cmp	al, 04h	; EOT
  2560 00002BB5 751C                <1> 	jne	short com_i4	
  2561                              <1> 	; EOT = 04h (End of Transmit) - 'CTRL + D'
  2562                              <1> 	;(an EOT char is supposed as a ctrl+brk from the terminal)
  2563                              <1> 	; 08/11/2015
  2564                              <1> 		; ptty -> tty 0 to 7 (pseudo screens)
  2565 00002BB7 861D[46620000]      <1> 	xchg	bl, [ptty]  ; tty number (8 or 9)
  2566 00002BBD E80BFFFFFF          <1> 	call 	ctrlbrk
  2567 00002BC2 861D[46620000]      <1> 	xchg	[ptty], bl ; (restore ptty value and BL value)
  2568                              <1> 	;mov	al, 04h ; EOT
  2569                              <1> 	; 08/11/2015
  2570 00002BC8 EB09                <1> 	jmp	short com_i4	
  2571                              <1> com_i3:
  2572                              <1> 	; 08/11/2015
  2573                              <1> 	; If 0FFh has been received just after a query
  2574                              <1> 	; (schar, ZERO), it is a response signal.
  2575                              <1> 	; 17/11/2015
  2576 00002BCA 803F00              <1>         cmp     byte [edi], 0 ; query ? (schar)
  2577 00002BCD 7704                <1> 	ja	short com_i4 ; no
  2578                              <1> 	; reset query status (schar)
  2579 00002BCF 8807                <1> 	mov	[edi], al ; 0FFh
  2580 00002BD1 FEC0                <1> 	inc	al ; 0
  2581                              <1> com_i4:
  2582                              <1> 	; 27/07/2014
  2583                              <1> 	; 09/07/2014
  2584 00002BD3 D0E3                <1> 	shl	bl, 1	
  2585 00002BD5 81C3[48620000]      <1> 	add	ebx, ttychr
  2586                              <1> 	; 23/07/2014 (always overwrite)
  2587                              <1> 	;;cmp	word [ebx], 0
  2588                              <1> 	;;ja	short com_eoi
  2589                              <1> 	;
  2590 00002BDB 668903              <1> 	mov	[ebx], ax   ; Save ascii code
  2591                              <1> 			    ; scan code = 0
  2592                              <1> com_eoi:
  2593                              <1> 	;mov	al, 20h
  2594                              <1> 	;out	20h, al	   ; end of interrupt
  2595                              <1> 	;
  2596                              <1> 	; 07/11/2015
  2597                              <1>       	;pop	eax ; *
  2598 00002BDE A0[86620000]        <1> 	mov	al, byte [ccomport] ; current COM port
  2599                              <1> 	; al = tty number (8 or 9)
  2600 00002BE3 E8F61A0000          <1>         call	wakeup
  2601                              <1> com_iret:
  2602                              <1> 	; 23/10/2015
  2603 00002BE8 5A                  <1> 	pop	edx ; **
  2604 00002BE9 59                  <1> 	pop	ecx ; ***
  2605                              <1> 	; 18/11/2015
  2606                              <1> 	;pop	eax ; ****
  2607                              <1> 	;mov	cr3, eax
  2608                              <1> 	;jmp	iiret
  2609 00002BEA E995DDFFFF          <1> 	jmp	iiretp
  2610                              <1> 
  2611                              <1> ;iiretp: ; 01/09/2015
  2612                              <1> ;	; 28/08/2015
  2613                              <1> ;	pop	eax ; (*) page directory
  2614                              <1> ;	mov	cr3, eax
  2615                              <1> ;iiret:
  2616                              <1> ;	; 22/08/2014
  2617                              <1> ;	mov	al, 20h ; END OF INTERRUPT COMMAND TO 8259
  2618                              <1> ;	out	20h, al	; 8259 PORT
  2619                              <1> ;	;
  2620                              <1> ;	pop	es
  2621                              <1> ;	pop	ds
  2622                              <1> ;	pop	edi
  2623                              <1> ;	pop	esi
  2624                              <1> ;	pop	ebx ; 29/08/2014
  2625                              <1> ;	pop 	eax
  2626                              <1> ;	iretd
  2627                              <1> 
  2628                              <1> sp_init:
  2629                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2630                              <1> 	; 07/11/2015
  2631                              <1> 	; 29/10/2015
  2632                              <1> 	; 26/10/2015
  2633                              <1> 	; 23/10/2015
  2634                              <1> 	; 29/06/2015
  2635                              <1> 	; 14/03/2015 (Retro UNIX 386 v1 - 115200 baud)
  2636                              <1> 	; 28/07/2014 (Retro UNIX 8086 v1 - 9600 baud)
  2637                              <1> 	; Initialization of Serial Port Communication Parameters
  2638                              <1> 	; (COM1 base port address = 3F8h, COM1 Interrupt = IRQ 4)
  2639                              <1> 	; (COM2 base port address = 2F8h, COM1 Interrupt = IRQ 3)
  2640                              <1> 	;
  2641                              <1> 	; ((Modified registers: EAX, ECX, EDX, EBX))
  2642                              <1> 	;
  2643                              <1> 	; INPUT:  (29/06/2015)
  2644                              <1> 	;	AL = 0 for COM1
  2645                              <1> 	;	     1 for COM2
  2646                              <1> 	;	AH = Communication parameters	
  2647                              <1> 	;
  2648                              <1> 	;  (*) Communication parameters (except BAUD RATE):
  2649                              <1> 	;	Bit	4	3	2	1	0
  2650                              <1> 	;		-PARITY--   STOP BIT  -WORD LENGTH-	 		 
  2651                              <1> 	;  this one -->	00 = none    0 = 1 bit  11 = 8 bits
  2652                              <1> 	;		01 = odd     1 = 2 bits	10 = 7 bits
  2653                              <1> 	;		11 = even
  2654                              <1> 	;  Baud rate setting bits: (29/06/2015)
  2655                              <1> 	;		Retro UNIX 386 v1 feature only !
  2656                              <1> 	;	Bit	7    6    5  | Baud rate
  2657                              <1> 	;		------------------------
  2658                              <1> 	;	value	0    0    0  | Default (Divisor = 1)
  2659                              <1> 	;		0    0    1  | 9600 (12)
  2660                              <1> 	;		0    1    0  | 19200 (6) 
  2661                              <1> 	;		0    1	  1  | 38400 (3) 
  2662                              <1> 	;		1    0	  0  | 14400 (8)
  2663                              <1> 	;		1    0	  1  | 28800 (4)
  2664                              <1> 	;		1    1    0  | 57600 (2)
  2665                              <1> 	;		1    1    1  | 115200 (1) 	
  2666                              <1> 	
  2667                              <1> 	; References:	
  2668                              <1> 	; (1) IBM PC-XT Model 286 BIOS Source Code
  2669                              <1> 	;     RS232.ASM --- 10/06/1985 COMMUNICATIONS BIOS (RS232)
  2670                              <1> 	; (2) Award BIOS 1999 - ATORGS.ASM
  2671                              <1> 	; (3) http://wiki.osdev.org/Serial_Ports
  2672                              <1> 	;
  2673                              <1> 	; Set communication parameters for COM1 (= 03h)	
  2674                              <1> 	;
  2675 00002BEF BB[82620000]        <1> 	mov	ebx, com1p		; COM1 parameters  
  2676 00002BF4 66BAF803            <1> 	mov	dx, 3F8h		; COM1
  2677                              <1> 	; 29/10/2015
  2678 00002BF8 66B90103            <1> 	mov	cx, 301h  ; divisor = 1 (115200 baud)
  2679 00002BFC E84F000000          <1> 	call	sp_i3	; call A4	
  2680 00002C01 A880                <1> 	test	al, 80h
  2681 00002C03 740E                <1> 	jz	short sp_i0 ; OK..
  2682                              <1> 		; Error !
  2683                              <1> 	;mov	dx, 3F8h
  2684 00002C05 80EA05              <1> 	sub	dl, 5 ; 3FDh -> 3F8h
  2685                              <1> 	;mov	cx, 30Eh  ; divisor = 12 (9600 baud)
  2686                              <1> 	; 08/01/2022
  2687 00002C08 B10E                <1> 	mov	cl, 0Eh ; cx = 30Eh, divisor = 12 (9600 baud)
  2688 00002C0A E841000000          <1> 	call	sp_i3	; call A4	
  2689 00002C0F A880                <1> 	test	al, 80h
  2690 00002C11 7508                <1> 	jnz	short sp_i1
  2691                              <1> sp_i0:
  2692                              <1>         ; (Note: Serial port interrupts will be disabled here...)	
  2693                              <1>         ; (INT 14h initialization code disables interrupts.)
  2694                              <1> 	;
  2695 00002C13 C603E3              <1> 	mov	byte [ebx], 0E3h ; 11100011b
  2696 00002C16 E8BF000000          <1> 	call	sp_i5 ; 29/06/2015
  2697                              <1> sp_i1:
  2698 00002C1B 43                  <1> 	inc	ebx
  2699 00002C1C 66BAF802            <1> 	mov	dx, 2F8h		; COM2
  2700                              <1> 	; 29/10/2015
  2701                              <1> 	;mov	cx, 301h  ; divisor = 1 (115200 baud)
  2702                              <1> 	; 08/01/2022
  2703 00002C20 B101                <1> 	mov	cl, 01h ; cx = 301h, divisor = 1 (115200 baud)
  2704 00002C22 E829000000          <1> 	call	sp_i3	; call A4	
  2705 00002C27 A880                <1> 	test	al, 80h
  2706 00002C29 740E                <1> 	jz	short sp_i2 ; OK..
  2707                              <1> 		; Error !
  2708                              <1> 	;mov	dx, 2F8h
  2709 00002C2B 80EA05              <1> 	sub	dl, 5 ; 2FDh -> 2F8h
  2710                              <1> 	;mov	cx, 30Eh  ; divisor = 12 (9600 baud)
  2711                              <1> 	; 08/01/2022
  2712 00002C2E B10E                <1> 	mov	cl, 0Eh ; cx = 30Eh, divisor = 12 (9600 baud)
  2713 00002C30 E81B000000          <1> 	call	sp_i3	; call A4	
  2714 00002C35 A880                <1> 	test	al, 80h
  2715 00002C37 7516                <1> 	jnz	short sp_i7
  2716                              <1> sp_i2:
  2717 00002C39 C603E3              <1> 	mov	byte [ebx], 0E3h ; 11100011b
  2718                              <1> sp_i6:
  2719                              <1> 	;; COM2 - enabling IRQ 3
  2720                              <1> 	; 08/01/2022
  2721 00002C3C B4F7                <1> 	mov	ah, 0F7h ; enable IRQ 3 (COM2)
  2722                              <1> 	; 07/11/2015
  2723                              <1> 	; 26/10/2015
  2724                              <1> 	;pushf
  2725                              <1> 	;cli
  2726                              <1> 	;;
  2727                              <1> 	;;mov	dx, 2FCh   		; modem control register
  2728                              <1> 	;mov	dl, 0FCh ; 08/01/2022
  2729                              <1> 	;in	al, dx 	   		; read register
  2730                              <1> 	;JMP	$+2	   		; I/O DELAY
  2731                              <1> 	;or	al, 8      		; enable bit 3 (OUT2)
  2732                              <1> 	;out	dx, al     		; write back to register
  2733                              <1> 	;JMP	$+2	   		; I/O DELAY
  2734                              <1> 	;;mov	dx, 2F9h   		; interrupt enable register
  2735                              <1> 	;mov	dl, 0F9h ; 08/01/2022
  2736                              <1> 	;in	al, dx     		; read register
  2737                              <1> 	;JMP	$+2	   		; I/O DELAY
  2738                              <1> 	;;or	al, 1      		; receiver data interrupt enable and
  2739                              <1> 	;or	al, 3	   		; transmitter empty interrupt enable
  2740                              <1> 	;out	dx, al 	   		; write back to register
  2741                              <1> 	;JMP	$+2        		; I/O DELAY
  2742                              <1> 	;in	al, 21h    		; read interrupt mask register
  2743                              <1> 	;JMP	$+2	   		; I/O DELAY
  2744                              <1> 	;and	al, 0F7h   		; enable IRQ 3 (COM2)
  2745                              <1> 	;out	21h, al    		; write back to register
  2746                              <1> 	;
  2747                              <1> 	; 08/01/2022
  2748 00002C3E 9C                  <1> 	pushf
  2749 00002C3F E8AA000000          <1> 	call	sp_i8
  2750                              <1> 	; 23/10/2015
  2751 00002C44 B8[232B0000]        <1> 	mov 	eax, com2_int
  2752 00002C49 A3[D4300000]        <1> 	mov	[com2_irq3], eax
  2753                              <1> 	; 26/10/2015
  2754 00002C4E 9D                  <1> 	popf	
  2755                              <1> sp_i7:
  2756 00002C4F C3                  <1> 	retn
  2757                              <1> 
  2758                              <1> sp_i3:
  2759                              <1> ;A4:  	;-----	INITIALIZE THE COMMUNICATIONS PORT
  2760                              <1> 	; 28/10/2015
  2761 00002C50 FEC2                <1> 	inc	dl	; 3F9h (2F9h)	; 3F9h, COM1 Interrupt enable register 
  2762 00002C52 B000                <1> 	mov	al, 0
  2763 00002C54 EE                  <1> 	out	dx, al			; disable serial port interrupt
  2764 00002C55 EB00                <1> 	JMP	$+2			; I/O DELAY
  2765 00002C57 80C202              <1> 	add	dl, 2 	; 3FBh (2FBh)	; COM1 Line control register (3FBh)
  2766 00002C5A B080                <1> 	mov	al, 80h			
  2767 00002C5C EE                  <1> 	out	dx, al			; SET DLAB=1 ; divisor latch access bit
  2768                              <1> 	;-----	SET BAUD RATE DIVISOR
  2769                              <1> 	; 26/10/2015
  2770 00002C5D 80EA03              <1> 	sub 	dl, 3   ; 3F8h (2F8h)	; register for least significant byte
  2771                              <1> 					; of the divisor value
  2772 00002C60 88C8                <1> 	mov	al, cl	; 1
  2773 00002C62 EE                  <1> 	out	dx, al			; 1 = 115200 baud (Retro UNIX 386 v1)
  2774                              <1> 					; 2 = 57600 baud
  2775                              <1> 					; 3 = 38400 baud
  2776                              <1> 					; 6 = 19200 baud
  2777                              <1> 					; 12 = 9600 baud (Retro UNIX 8086 v1)
  2778 00002C63 EB00                <1> 	JMP	$+2			; I/O DELAY
  2779 00002C65 28C0                <1> 	sub	al, al
  2780 00002C67 FEC2                <1> 	inc	dl      ; 3F9h (2F9h)	; register for most significant byte
  2781                              <1> 					; of the divisor value
  2782 00002C69 EE                  <1> 	out	dx, al ; 0
  2783 00002C6A EB00                <1> 	JMP	$+2			; I/O DELAY
  2784                              <1> 	;	
  2785 00002C6C 88E8                <1> 	mov	al, ch ; 3		; 8 data bits, 1 stop bit, no parity
  2786                              <1> 	;and	al, 1Fh ; Bits 0,1,2,3,4	
  2787 00002C6E 80C202              <1> 	add	dl, 2	; 3FBh (2FBh)	; Line control register
  2788 00002C71 EE                  <1> 	out	dx, al			
  2789 00002C72 EB00                <1> 	JMP	$+2			; I/O DELAY
  2790                              <1> 	; 29/10/2015
  2791 00002C74 FECA                <1> 	dec 	dl 	; 3FAh (2FAh)	; FIFO Control register (16550/16750)
  2792 00002C76 30C0                <1> 	xor	al, al			; 0
  2793 00002C78 EE                  <1> 	out	dx, al			; Disable FIFOs (reset to 8250 mode)
  2794 00002C79 EB00                <1> 	JMP	$+2	
  2795                              <1> sp_i4:
  2796                              <1> ;A18:	;-----	COMM PORT STATUS ROUTINE
  2797                              <1> 	; 29/06/2015 (line status after modem status)
  2798 00002C7B 80C204              <1> 	add	dl, 4	; 3FEh (2FEh)	; Modem status register
  2799                              <1> sp_i4s:
  2800 00002C7E EC                  <1> 	in	al, dx			; GET MODEM CONTROL STATUS
  2801 00002C7F EB00                <1> 	JMP	$+2			; I/O DELAY
  2802 00002C81 88C4                <1> 	mov	ah, al			; PUT IN (AH) FOR RETURN
  2803 00002C83 FECA                <1> 	dec	dl	; 3FDh (2FDh)	; POINT TO LINE STATUS REGISTER
  2804                              <1> 					; dx = 3FDh for COM1, 2FDh for COM2
  2805 00002C85 EC                  <1> 	in	al, dx			; GET LINE CONTROL STATUS
  2806                              <1> 	; AL = Line status, AH = Modem status
  2807 00002C86 C3                  <1> 	retn
  2808                              <1> 
  2809                              <1> sp_status:
  2810                              <1> 	; 29/06/2015
  2811                              <1> 	; 27/06/2015 (Retro UNIX 386 v1)
  2812                              <1> 	; Get serial port status
  2813 00002C87 66BAFE03            <1> 	mov	dx, 3FEh		; Modem status register (COM1)
  2814 00002C8B 28C6                <1> 	sub	dh, al			; dh = 2 for COM2 (al = 1)
  2815                              <1> 					; dx = 2FEh for COM2
  2816 00002C8D EBEF                <1> 	jmp	short sp_i4s
  2817                              <1> 
  2818                              <1> sp_setp: ; Set serial port communication parameters
  2819                              <1> 	; 08/01/2022
  2820                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2821                              <1> 	; 07/11/2015
  2822                              <1> 	; 29/10/2015
  2823                              <1> 	; 29/06/2015
  2824                              <1> 	; Retro UNIX 386 v1 feature only !	
  2825                              <1> 	;
  2826                              <1> 	; INPUT:
  2827                              <1> 	;	AL = 0 for COM1
  2828                              <1> 	;	     1 for COM2
  2829                              <1> 	;	AH = Communication parameters (*)
  2830                              <1> 	; OUTPUT:
  2831                              <1> 	;	CL = Line status
  2832                              <1> 	;	CH = Modem status
  2833                              <1> 	;   If cf = 1 -> Error code in [u.error]
  2834                              <1> 	;		 'invalid parameter !' 
  2835                              <1> 	;		 	 or
  2836                              <1> 	;		 'device not ready !' error
  2837                              <1> 	;	
  2838                              <1> 	;  (*) Communication parameters (except BAUD RATE):
  2839                              <1> 	;	Bit	4	3	2	1	0
  2840                              <1> 	;		-PARITY--   STOP BIT  -WORD LENGTH-	 		 
  2841                              <1> 	;  this one -->	00 = none    0 = 1 bit  11 = 8 bits
  2842                              <1> 	;		01 = odd     1 = 2 bits	10 = 7 bits
  2843                              <1> 	;		11 = even
  2844                              <1> 	;  Baud rate setting bits: (29/06/2015)
  2845                              <1> 	;		Retro UNIX 386 v1 feature only !
  2846                              <1> 	;	Bit	7    6    5  | Baud rate
  2847                              <1> 	;		------------------------
  2848                              <1> 	;	value	0    0    0  | Default (Divisor = 1)
  2849                              <1> 	;		0    0    1  | 9600 (12)
  2850                              <1> 	;		0    1    0  | 19200 (6) 
  2851                              <1> 	;		0    1	  1  | 38400 (3) 
  2852                              <1> 	;		1    0	  0  | 14400 (8)
  2853                              <1> 	;		1    0	  1  | 28800 (4)
  2854                              <1> 	;		1    1    0  | 57600 (2)
  2855                              <1> 	;		1    1    1  | 115200 (1) 
  2856                              <1> 	;
  2857                              <1> 	; (COM1 base port address = 3F8h, COM1 Interrupt = IRQ 4)
  2858                              <1> 	; (COM2 base port address = 2F8h, COM1 Interrupt = IRQ 3)
  2859                              <1> 	;
  2860                              <1> 	; ((Modified registers: EAX, ECX, EDX, EBX))
  2861                              <1> 	;
  2862 00002C8F 66BAF803            <1> 	mov	dx, 3F8h
  2863 00002C93 BB[82620000]        <1> 	mov	ebx, com1p ; COM1 control byte offset
  2864 00002C98 3C01                <1> 	cmp	al, 1
  2865 00002C9A 7770                <1> 	ja 	short sp_invp_err
  2866 00002C9C 7203                <1> 	jb	short sp_setp1 ;  COM1 (AL = 0)
  2867 00002C9E FECE                <1> 	dec	dh ; 2F8h
  2868 00002CA0 43                  <1> 	inc	ebx ; COM2 control byte offset
  2869                              <1> sp_setp1:
  2870                              <1> 	; 29/10/2015
  2871 00002CA1 8823                <1> 	mov	[ebx], ah
  2872 00002CA3 0FB6CC              <1> 	movzx 	ecx, ah
  2873 00002CA6 C0E905              <1> 	shr	cl, 5 ; -> baud rate index
  2874 00002CA9 80E41F              <1> 	and	ah, 1Fh ; communication parameters except baud rate
  2875 00002CAC 8A81[1B2D0000]      <1> 	mov	al, [ecx+b_div_tbl]
  2876 00002CB2 6689C1              <1> 	mov	cx, ax
  2877 00002CB5 E896FFFFFF          <1> 	call	sp_i3
  2878 00002CBA 6689C1              <1> 	mov	cx, ax ; CL = Line status, CH = Modem status
  2879 00002CBD A880                <1> 	test	al, 80h
  2880 00002CBF 740F                <1> 	jz	short sp_setp2
  2881 00002CC1 C603E3              <1>         mov     byte [ebx], 0E3h ; Reset to initial value (11100011b)
  2882                              <1> stp_dnr_err:
  2883 00002CC4 C705[31660000]0F00- <1> 	mov	dword [u.error], ERR_DEV_NOT_RDY ; 'device not ready !'
  2883 00002CCC 0000                <1>
  2884                              <1> 	; CL = Line status, CH = Modem status
  2885 00002CCE F9                  <1> 	stc
  2886 00002CCF C3                  <1> 	retn
  2887                              <1> sp_setp2:
  2888 00002CD0 80FE02              <1> 	cmp	dh, 2 ; COM2 (2F?h)
  2889                              <1>         ;jna	sp_i6
  2890                              <1> 		      ; COM1 (3F?h)
  2891                              <1> 	; 24/12/2021
  2892 00002CD3 7705                <1> 	ja	short sp_i5
  2893 00002CD5 E962FFFFFF          <1> 	jmp	sp_i6
  2894                              <1> sp_i5: 
  2895                              <1> 	; 08/01/2022
  2896 00002CDA B4EF                <1> 	mov	ah, 0EFh ; enable IRQ 4 (COM1)
  2897                              <1> 	; 07/11/2015
  2898                              <1> 	; 26/10/2015
  2899                              <1> 	; 29/06/2015
  2900                              <1> 	;
  2901                              <1> 	;; COM1 - enabling IRQ 4
  2902                              <1> 	;pushf
  2903                              <1> 	;cli
  2904                              <1> 	;;mov	dx, 3FCh   		; modem control register
  2905                              <1> 	;mov	dl, 0FCh ; 08/01/2022
  2906                              <1> 	;in	al, dx 	   		; read register
  2907                              <1> 	;JMP	$+2			; I/O DELAY
  2908                              <1> 	;or	al, 8      		; enable bit 3 (OUT2)
  2909                              <1> 	;out	dx, al     		; write back to register
  2910                              <1> 	;JMP	$+2			; I/O DELAY
  2911                              <1> 	;;mov	dx, 3F9h   		; interrupt enable register
  2912                              <1> 	;mov	dl, 0F9h ; 08/01/2022
  2913                              <1> 	;in	al, dx     		; read register
  2914                              <1> 	;JMP	$+2			; I/O DELAY
  2915                              <1> 	;;or	al, 1      		; receiver data interrupt enable and
  2916                              <1> 	;or	al, 3	   		; transmitter empty interrupt enable
  2917                              <1> 	;out	dx, al 	   		; write back to register
  2918                              <1> 	;JMP	$+2        		; I/O DELAY
  2919                              <1> 	;in	al, 21h    		; read interrupt mask register
  2920                              <1> 	;JMP	$+2			; I/O DELAY
  2921                              <1> 	;and	al, 0EFh   		; enable IRQ 4 (COM1)
  2922                              <1> 	;out	21h, al    		; write back to register
  2923                              <1> 	;
  2924                              <1> 	; 08/01/2022
  2925 00002CDC 9C                  <1> 	pushf
  2926 00002CDD E80C000000          <1> 	call	sp_i8
  2927                              <1> 	; 23/10/2015
  2928 00002CE2 B8[2C2B0000]        <1> 	mov 	eax, com1_int
  2929 00002CE7 A3[D0300000]        <1> 	mov	[com1_irq4], eax
  2930                              <1> 	; 26/10/2015
  2931 00002CEC 9D                  <1> 	popf
  2932 00002CED C3                  <1> 	retn
  2933                              <1> 
  2934                              <1> sp_i8:
  2935                              <1> 	; 08/01/2022
  2936                              <1> 	;pushf
  2937 00002CEE FA                  <1> 	cli
  2938                              <1> 	;
  2939                              <1> 	;mov	dx, 2FCh  ; 3FCh	; modem control register
  2940 00002CEF B2FC                <1> 	mov	dl, 0FCh
  2941 00002CF1 EC                  <1> 	in	al, dx 	   		; read register
  2942 00002CF2 EB00                <1> 	JMP	$+2	   		; I/O DELAY
  2943 00002CF4 0C08                <1> 	or	al, 8      		; enable bit 3 (OUT2)
  2944 00002CF6 EE                  <1> 	out	dx, al     		; write back to register
  2945 00002CF7 EB00                <1> 	JMP	$+2	   		; I/O DELAY
  2946                              <1> 	;mov	dx, 2F9h  ; 3F9h 	; interrupt enable register
  2947 00002CF9 B2F9                <1> 	mov	dl, 0F9h
  2948 00002CFB EC                  <1> 	in	al, dx     		; read register
  2949 00002CFC EB00                <1> 	JMP	$+2	   		; I/O DELAY
  2950                              <1> 	;or	al, 1      		; receiver data interrupt enable and
  2951 00002CFE 0C03                <1> 	or	al, 3	   		; transmitter empty interrupt enable
  2952 00002D00 EE                  <1> 	out	dx, al 	   		; write back to register
  2953 00002D01 EB00                <1> 	JMP	$+2        		; I/O DELAY
  2954 00002D03 E421                <1> 	in	al, 21h    		; read interrupt mask register
  2955 00002D05 EB00                <1> 	JMP	$+2	   		; I/O DELAY
  2956                              <1> 	;and	al, 0F7h  ; 0EFh	; enable IRQ 3 (COM2)
  2957 00002D07 20E0                <1> 	and	al, ah	; 0F7h or 0EFh 
  2958 00002D09 E621                <1> 	out	21h, al    		; write back to register
  2959                              <1> 	;
  2960                              <1> 	;popf	
  2961 00002D0B C3                  <1> 	retn
  2962                              <1> 
  2963                              <1> sp_invp_err:
  2964 00002D0C C705[31660000]1700- <1> 	mov	dword [u.error], ERR_INV_PARAMETER ; 'invalid parameter !' 
  2964 00002D14 0000                <1>
  2965 00002D16 31C9                <1> 	xor	ecx, ecx
  2966 00002D18 49                  <1> 	dec	ecx ; 0FFFFh
  2967 00002D19 F9                  <1> 	stc
  2968 00002D1A C3                  <1> 	retn
  2969                              <1> 
  2970                              <1> ; 29/10/2015
  2971                              <1> b_div_tbl: ; Baud rate divisor table (115200/divisor)
  2972 00002D1B 010C0603080401      <1> 	db	1, 12, 6, 3, 8, 4, 1
  2973                              <1> 
  2974                              <1> ; Retro UNIX 8086 v1 - UNIX.ASM (01/09/2014) 
  2975                              <1> epoch:
  2976                              <1> 	; 17/07/2022
  2977                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2978                              <1> 	; 15/03/2015 (Retro UNIX 386 v1 - 32 bit version)
  2979                              <1> 	; 09/04/2013 (Retro UNIX 8086 v1 - UNIX.ASM)
  2980                              <1> 	; 'epoch' procedure prototype: 
  2981                              <1> 	; 	            UNIXCOPY.ASM, 10/03/2013
  2982                              <1> 	; 14/11/2012
  2983                              <1> 	; unixboot.asm (boot file configuration)
  2984                              <1> 	; version of "epoch" procedure in "unixproc.asm"
  2985                              <1> 	; 21/7/2012
  2986                              <1> 	; 15/7/2012
  2987                              <1> 	; 14/7/2012		
  2988                              <1> 	; Erdogan Tan - RETRO UNIX v0.1
  2989                              <1> 	; compute current date and time as UNIX Epoch/Time
  2990                              <1> 	; UNIX Epoch: seconds since 1/1/1970 00:00:00
  2991                              <1> 	;
  2992                              <1>         ;  ((Modified registers: EAX, EDX, ECX, EBX))  
  2993                              <1> 	;
  2994 00002D22 E818010000          <1> 	call 	get_rtc_time		; Return Current Time
  2995 00002D27 86E9                <1>         xchg 	ch,cl
  2996 00002D29 66890D[885F0000]    <1>         mov 	[hour], cx
  2997 00002D30 86F2                <1>         xchg 	dh,dl
  2998 00002D32 668915[8A5F0000]    <1>         mov 	[second], dx
  2999                              <1> 	;
  3000 00002D39 E832010000          <1>         call 	get_rtc_date		; Return Current Date
  3001 00002D3E 86E9                <1>         xchg 	ch,cl
  3002 00002D40 66890D[845F0000]    <1>         mov 	[year], cx
  3003 00002D47 86F2                <1>         xchg 	dh,dl
  3004 00002D49 668915[865F0000]    <1>         mov 	[month], dx
  3005                              <1> 	;
  3006 00002D50 66B93030            <1> 	mov 	cx, 3030h
  3007                              <1> 	;
  3008 00002D54 A0[885F0000]        <1> 	mov 	al, [hour] ; Hour
  3009                              <1>         	; AL <= BCD number)
  3010 00002D59 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3011                              <1> 					; AH = AL / 10h
  3012                              <1> 					; AL = AL MOD 10h
  3013 00002D5B D50A                <1>         aad 	; AX= AH*10+AL
  3014 00002D5D A2[885F0000]        <1> 	mov 	[hour], al
  3015 00002D62 A0[895F0000]        <1> 	mov 	al, [hour+1] ; Minute
  3016                              <1>         	; AL <= BCD number)
  3017 00002D67 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3018                              <1> 					; AH = AL / 10h
  3019                              <1> 					; AL = AL MOD 10h
  3020 00002D69 D50A                <1>         aad 	; AX= AH*10+AL
  3021 00002D6B A2[895F0000]        <1> 	mov 	[minute], al
  3022 00002D70 A0[8A5F0000]        <1> 	mov 	al, [second] ; Second
  3023                              <1>         	; AL <= BCD number)
  3024 00002D75 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3025                              <1> 					; AH = AL / 10h
  3026                              <1> 					; AL = AL MOD 10h
  3027 00002D77 D50A                <1>         aad 	; AX= AH*10+AL
  3028 00002D79 A2[8A5F0000]        <1> 	mov 	[second], al
  3029 00002D7E 66A1[845F0000]      <1> 	mov 	ax, [year] ; Year (century)
  3030                              <1>  	;push 	ax
  3031                              <1> 	; 08/01/2022
  3032 00002D84 50                  <1> 	push	eax
  3033                              <1> 	   	; AL <= BCD number)
  3034 00002D85 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3035                              <1> 					; AH = AL / 10h
  3036                              <1> 					; AL = AL MOD 10h
  3037 00002D87 D50A                <1>         aad 	; AX= AH*10+AL
  3038 00002D89 B464                <1> 	mov 	ah, 100
  3039 00002D8B F6E4                <1> 	mul 	ah
  3040 00002D8D 66A3[845F0000]      <1> 	mov 	[year], ax
  3041                              <1> 	;pop	ax
  3042                              <1> 	; 08/01/2022
  3043 00002D93 58                  <1> 	pop	eax
  3044 00002D94 88E0                <1> 	mov	al, ah
  3045                              <1>         	; AL <= BCD number)
  3046 00002D96 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3047                              <1> 					; AH = AL / 10h
  3048                              <1> 					; AL = AL MOD 10h
  3049 00002D98 D50A                <1>         aad 	; AX= AH*10+AL
  3050 00002D9A 660105[845F0000]    <1> 	add 	[year], ax
  3051 00002DA1 A0[865F0000]        <1> 	mov 	al, [month] ; Month
  3052                              <1>            	; AL <= BCD number)
  3053 00002DA6 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3054                              <1> 					; AH = AL / 10h
  3055                              <1> 					; AL = AL MOD 10h
  3056 00002DA8 D50A                <1>         aad 	; AX= AH*10+AL
  3057 00002DAA A2[865F0000]        <1> 	mov 	[month], al	
  3058 00002DAF A0[875F0000]        <1>         mov     al, [month+1]      	; Day
  3059                              <1>            	; AL <= BCD number)
  3060 00002DB4 D410                <1>         db 	0D4h,10h		; Undocumented inst. AAM
  3061                              <1> 					; AH = AL / 10h
  3062                              <1> 					; AL = AL MOD 10h
  3063 00002DB6 D50A                <1>         aad 	; AX= AH*10+AL
  3064 00002DB8 A2[875F0000]        <1>         mov     [day], al
  3065                              <1> 	
  3066                              <1> convert_to_epoch:
  3067                              <1> 	; 17/07/2022
  3068                              <1> 	; 15/03/2015 (Retro UNIX 386 v1 - 32 bit modification)
  3069                              <1> 	; 09/04/2013 (Retro UNIX 8086 v1)
  3070                              <1> 	;
  3071                              <1> 	; ((Modified registers: EAX, EDX, EBX)) 
  3072                              <1> 	;
  3073                              <1> 	; Derived from DALLAS Semiconductor
  3074                              <1> 	; Application Note 31 (DS1602/DS1603)
  3075                              <1> 	; 6 May 1998
  3076 00002DBD 29C0                <1> 	sub 	eax, eax
  3077 00002DBF 66A1[845F0000]      <1> 	mov 	ax, [year]
  3078 00002DC5 662DB207            <1> 	sub 	ax, 1970
  3079 00002DC9 BA6D010000          <1> 	mov 	edx, 365
  3080 00002DCE F7E2                <1> 	mul 	edx
  3081 00002DD0 31DB                <1> 	xor 	ebx, ebx
  3082 00002DD2 8A1D[865F0000]      <1> 	mov 	bl, [month]
  3083 00002DD8 FECB                <1> 	dec 	bl
  3084 00002DDA D0E3                <1> 	shl 	bl, 1
  3085                              <1> 	;sub	edx, edx
  3086 00002DDC 668B93[8C5F0000]    <1> 	mov 	dx, [EBX+DMonth]
  3087 00002DE3 8A1D[875F0000]      <1>         mov     bl, [day]
  3088 00002DE9 FECB                <1> 	dec 	bl
  3089 00002DEB 01D0                <1> 	add 	eax, edx
  3090 00002DED 01D8                <1> 	add 	eax, ebx
  3091                              <1> 			; EAX = days since 1/1/1970
  3092 00002DEF 668B15[845F0000]    <1> 	mov 	dx, [year]
  3093 00002DF6 6681EAB107          <1> 	sub 	dx, 1969
  3094                              <1> 	;shr 	dx, 1
  3095                              <1> 	;shr 	dx, 1		
  3096                              <1> 	; 17/07/2022
  3097 00002DFB C1EA02              <1> 	shr	edx, 2
  3098                              <1> 		; (year-1969)/4
  3099 00002DFE 01D0                <1> 	add 	eax, edx
  3100                              <1> 			; + leap days since 1/1/1970
  3101 00002E00 803D[865F0000]02    <1> 	cmp 	byte [month], 2	; if past february
  3102 00002E07 7610                <1> 	jna 	short cte1
  3103 00002E09 668B15[845F0000]    <1> 	mov 	dx, [year]
  3104 00002E10 6683E203            <1> 	and 	dx, 3 ; year mod 4
  3105 00002E14 7503                <1> 	jnz 	short cte1		
  3106                              <1> 			; and if leap year
  3107 00002E16 83C001              <1> 	add 	eax, 1 	; add this year's leap day (february 29)
  3108                              <1> cte1: 			; compute seconds since 1/1/1970
  3109 00002E19 BA18000000          <1> 	mov 	edx, 24
  3110 00002E1E F7E2                <1> 	mul	edx
  3111 00002E20 8A15[885F0000]      <1> 	mov 	dl, [hour]
  3112 00002E26 01D0                <1> 	add 	eax, edx
  3113                              <1> 		; EAX = hours since 1/1/1970 00:00:00
  3114                              <1> 	;mov	ebx, 60
  3115 00002E28 B33C                <1> 	mov	bl, 60
  3116 00002E2A F7E3                <1> 	mul	ebx
  3117 00002E2C 8A15[895F0000]      <1> 	mov 	dl, [minute]
  3118 00002E32 01D0                <1> 	add 	eax, edx
  3119                              <1> 		; EAX = minutes since 1/1/1970 00:00:00
  3120                              <1> 	;mov 	ebx, 60
  3121 00002E34 F7E3                <1> 	mul	ebx
  3122 00002E36 8A15[8A5F0000]      <1> 	mov 	dl, [second]
  3123 00002E3C 01D0                <1> 	add 	eax, edx
  3124                              <1>  		; EAX -> seconds since 1/1/1970 00:00:00
  3125 00002E3E C3                  <1> 	retn
  3126                              <1> 
  3127                              <1> get_rtc_time:
  3128                              <1> 	; 15/03/2015
  3129                              <1> 	; Derived from IBM PC-XT Model 286 BIOS Source Code
  3130                              <1> 	; BIOS2.ASM ---- 10/06/1985 BIOS INTERRUPT ROUTINES
  3131                              <1> 	; INT 1Ah
  3132                              <1> 	; (AH) = 02H  READ THE REAL TIME CLOCK AND RETURN WITH,	:
  3133                              <1> 	;       (CH) = HOURS IN BCD (00-23)			:
  3134                              <1> 	;       (CL) = MINUTES IN BCD (00-59)			:
  3135                              <1> 	;       (DH) = SECONDS IN BCD (00-59)			:
  3136                              <1> 	;       (DL) = DAYLIGHT SAVINGS ENABLE (00-01).		:
  3137                              <1> 	;								
  3138                              <1> RTC_20: 				; GET RTC TIME
  3139 00002E3F FA                  <1> 	cli
  3140 00002E40 E8DBDCFFFF          <1> 	CALL	UPD_IPR 		; CHECK FOR UPDATE IN PROCESS
  3141 00002E45 7227                <1> 	JC	short RTC_29		; EXIT IF ERROR (CY= 1)
  3142                              <1> 
  3143 00002E47 B000                <1> 	MOV	AL, CMOS_SECONDS 	; SET ADDRESS OF SECONDS
  3144 00002E49 E8BCDCFFFF          <1> 	CALL	CMOS_READ		; GET SECONDS
  3145 00002E4E 88C6                <1> 	MOV	DH, AL			; SAVE
  3146 00002E50 B00B                <1> 	MOV	AL, CMOS_REG_B		; ADDRESS ALARM REGISTER
  3147 00002E52 E8B3DCFFFF          <1> 	CALL	CMOS_READ		; READ CURRENT VALUE OF DSE BIT
  3148 00002E57 2401                <1> 	AND	AL, 00000001B		; MASK FOR VALID DSE BIT
  3149 00002E59 88C2                <1> 	MOV	DL, AL			; SET [DL] TO ZERO FOR NO DSE BIT
  3150 00002E5B B002                <1> 	MOV	AL, CMOS_MINUTES 	; SET ADDRESS OF MINUTES
  3151 00002E5D E8A8DCFFFF          <1> 	CALL	CMOS_READ		; GET MINUTES
  3152 00002E62 88C1                <1> 	MOV	CL, AL			; SAVE
  3153 00002E64 B004                <1> 	MOV	AL, CMOS_HOURS		; SET ADDRESS OF HOURS
  3154 00002E66 E89FDCFFFF          <1> 	CALL	CMOS_READ		; GET HOURS
  3155 00002E6B 88C5                <1> 	MOV	CH, AL			; SAVE
  3156 00002E6D F8                  <1> 	CLC				; SET CY= 0
  3157                              <1> RTC_29:
  3158 00002E6E FB                  <1> 	sti
  3159 00002E6F C3                  <1> 	RETn				; RETURN WITH RESULT IN CARRY FLAG
  3160                              <1> 
  3161                              <1> get_rtc_date:
  3162                              <1> 	; 15/03/2015
  3163                              <1> 	; Derived from IBM PC-XT Model 286 BIOS Source Code
  3164                              <1> 	; BIOS2.ASM ---- 10/06/1985 BIOS INTERRUPT ROUTINES
  3165                              <1> 	; INT 1Ah
  3166                              <1> 	; (AH) = 04H  READ THE DATE FROM THE REAL TIME CLOCK AND RETURN WITH,:
  3167                              <1> 	;      (CH) = CENTURY IN BCD (19 OR 20) 		       :
  3168                              <1> 	;      (CL) = YEAR IN BCD (00-99)			       :
  3169                              <1> 	;      (DH) = MONTH IN BCD (01-12)			       :
  3170                              <1> 	;      (DL) = DAY IN BCD (01-31).		
  3171                              <1> 	;
  3172                              <1> RTC_40: 				; GET RTC DATE
  3173 00002E70 FA                  <1> 	cli
  3174 00002E71 E8AADCFFFF          <1> 	CALL	UPD_IPR			; CHECK FOR UPDATE IN PROCESS
  3175 00002E76 7225                <1> 	JC	short RTC_49		; EXIT IF ERROR (CY= 1)
  3176                              <1> 
  3177 00002E78 B007                <1> 	MOV	AL, CMOS_DAY_MONTH	; ADDRESS DAY OF MONTH
  3178 00002E7A E88BDCFFFF          <1> 	CALL	CMOS_READ		; READ DAY OF MONTH
  3179 00002E7F 88C2                <1> 	MOV	DL, AL			; SAVE
  3180 00002E81 B008                <1> 	MOV	AL, CMOS_MONTH		; ADDRESS MONTH
  3181 00002E83 E882DCFFFF          <1> 	CALL	CMOS_READ		; READ MONTH
  3182 00002E88 88C6                <1> 	MOV	DH, AL			; SAVE
  3183 00002E8A B009                <1> 	MOV	AL, CMOS_YEAR		; ADDRESS YEAR
  3184 00002E8C E879DCFFFF          <1> 	CALL	CMOS_READ		; READ YEAR
  3185 00002E91 88C1                <1> 	MOV	CL, AL			; SAVE
  3186 00002E93 B032                <1> 	MOV	AL, CMOS_CENTURY 	; ADDRESS CENTURY LOCATION
  3187 00002E95 E870DCFFFF          <1> 	CALL	CMOS_READ		; GET CENTURY BYTE
  3188 00002E9A 88C5                <1> 	MOV	CH, AL			; SAVE
  3189 00002E9C F8                  <1> 	CLC				; SET CY=0
  3190                              <1> RTC_49:
  3191 00002E9D FB                  <1> 	sti
  3192 00002E9E C3                  <1> 	RETn				; RETURN WITH RESULTS IN CARRY FLAG
  3193                              <1> 
  3194                              <1> set_date_time:
  3195                              <1> convert_from_epoch:
  3196                              <1> 	; 02/06/2022
  3197                              <1> 	; 01/06/2022 (BugFix)
  3198                              <1> 	; 15/03/2015 (Retro UNIX 386 v1 - 32 bit version)
  3199                              <1> 	; 20/06/2013 (Retro UNIX 8086 v1)
  3200                              <1> 	; 'convert_from_epoch' procedure prototype: 
  3201                              <1> 	; 	            UNIXCOPY.ASM, 10/03/2013
  3202                              <1> 	;
  3203                              <1> 	; ((Modified registers: EAX, EDX, ECX, EBX))	
  3204                              <1> 	;
  3205                              <1> 	; Derived from DALLAS Semiconductor
  3206                              <1> 	; Application Note 31 (DS1602/DS1603)
  3207                              <1> 	; 6 May 1998
  3208                              <1> 	;
  3209                              <1> 	; INPUT:
  3210                              <1> 	; EAX = Unix (Epoch) Time
  3211                              <1> 	;
  3212 00002E9F 31D2                <1> 	xor 	edx, edx
  3213                              <1> 	; 02/06/2022
  3214 00002EA1 31C9                <1> 	xor	ecx, ecx
  3215 00002EA3 31DB                <1> 	xor	ebx, ebx
  3216                              <1> 	;mov 	ecx, 60
  3217 00002EA5 B13C                <1> 	mov	cl, 60
  3218 00002EA7 F7F1                <1> 	div	ecx
  3219                              <1> 	;mov 	[imin], eax  ; whole minutes
  3220                              <1> 			     ; since 1/1/1970
  3221                              <1> 	;mov 	[second], dx ; leftover seconds
  3222 00002EA9 8815[8A5F0000]      <1> 	mov	[second], dl ; 02/06/2022
  3223 00002EAF 29D2                <1> 	sub 	edx, edx
  3224 00002EB1 F7F1                <1> 	div	ecx
  3225                              <1> 	;mov 	[ihrs], eax  ; whole hours
  3226                              <1> 	;		     ; since 1/1/1970
  3227                              <1> 	;mov 	[minute], dx ; leftover minutes
  3228 00002EB3 8815[895F0000]      <1> 	mov	[minute], dl ; 02/06/2022
  3229 00002EB9 31D2                <1> 	xor	edx, edx
  3230                              <1> 	;mov 	cx, 24
  3231 00002EBB B118                <1> 	mov 	cl, 24
  3232 00002EBD F7F1                <1> 	div	ecx
  3233                              <1> 	;mov 	[iday], ax   ; whole days
  3234                              <1> 			     ; since 1/1/1970
  3235                              <1> 	;mov 	[hour], dx   ; leftover hours
  3236 00002EBF 8815[885F0000]      <1> 	mov	[hour], dl   ; 02/06/2022
  3237                              <1> 
  3238 00002EC5 05DB020000          <1> 	add 	eax, 365+366 ; whole day since
  3239                              <1> 			     ; 1/1/1968 	
  3240                              <1> 	;mov 	[iday], ax
  3241 00002ECA 50                  <1> 	push 	eax
  3242 00002ECB 29D2                <1> 	sub	edx, edx
  3243 00002ECD B9B5050000          <1> 	mov 	ecx, (4*365)+1 ; 4 years = 1461 days
  3244 00002ED2 F7F1                <1> 	div	ecx
  3245 00002ED4 59                  <1> 	pop 	ecx
  3246                              <1> 	;mov 	[lday], ax   ; count of quadyrs (4 years)
  3247                              <1> 	;push	dx
  3248                              <1> 	; 01/06/2022
  3249 00002ED5 52                  <1> 	push 	edx
  3250                              <1> 	;mov 	[qday], dx   ; days since quadyr began
  3251 00002ED6 6683FA3C            <1> 	cmp 	dx, 31+29    ; if past feb 29 then
  3252 00002EDA F5                  <1> 	cmc		     ; add this quadyr's leap day
  3253 00002EDB 83D000              <1> 	adc 	eax, 0	     ; to # of qadyrs (leap days)
  3254                              <1> 	;mov 	[lday], ax   ; since 1968			  
  3255                              <1> 	;mov 	cx, [iday]
  3256 00002EDE 91                  <1> 	xchg 	ecx, eax     ; ECX = lday, EAX = iday		  
  3257 00002EDF 29C8                <1> 	sub 	eax, ecx     ; iday - lday
  3258 00002EE1 B96D010000          <1> 	mov 	ecx, 365
  3259 00002EE6 31D2                <1> 	xor	edx, edx
  3260                              <1> 	; EAX = iday-lday, EDX = 0
  3261 00002EE8 F7F1                <1> 	div	ecx
  3262                              <1> 	;mov 	[iyrs], ax   ; whole years since 1968
  3263                              <1> 	;jday = iday - (iyrs*365) - lday
  3264                              <1> 	;mov	[jday], dx   ; days since 1/1 of current year
  3265                              <1> 	;add	eax, 1968
  3266 00002EEA 6605B007            <1> 	add 	ax, 1968     ; compute year
  3267 00002EEE 66A3[845F0000]      <1> 	mov 	[year], ax
  3268                              <1> 	;mov 	cx, dx
  3269                              <1> 	; 02/06/2022
  3270 00002EF4 89D1                <1> 	mov	ecx, edx
  3271                              <1> 	;mov 	dx, [qday]
  3272                              <1> 	;pop	dx
  3273                              <1> 	; 01/06/2022
  3274 00002EF6 5A                  <1> 	pop 	edx
  3275 00002EF7 6681FA6D01          <1> 	cmp 	dx, 365	     ; if qday <= 365 and qday >= 60	
  3276 00002EFC 7709                <1> 	ja 	short cfe1   ; jday = jday +1
  3277 00002EFE 6683FA3C            <1> 	cmp 	dx, 60       ; if past 2/29 and leap year then
  3278 00002F02 F5                  <1>         cmc		     ; add a leap day to the # of whole
  3279 00002F03 6683D100            <1> 	adc 	cx, 0        ; days since 1/1 of current year
  3280                              <1> cfe1:			
  3281                              <1> 	;mov 	[jday], cx
  3282                              <1> 	;mov 	bx, 12       ; estimate month
  3283                              <1> 	;sub	ebx, ebx
  3284                              <1> 	; 02/06/2022
  3285 00002F07 B30C                <1> 	mov	bl, 12
  3286 00002F09 66BA6E01            <1> 	mov 	dx, 366      ; mday, max. days since 1/1 is 365
  3287 00002F0D 6683E003            <1> 	and 	ax, 11b      ; year mod 4 (and dx, 3) 
  3288                              <1> cfe2:	; Month calculation  ; 0 to 11  (11 to 0)	
  3289                              <1> 	;cmp 	cx, dx       ; mday = # of days passed from 1/1
  3290                              <1> 	; 02/06/2022
  3291 00002F11 39D1                <1> 	cmp	ecx, edx 	 		
  3292 00002F13 7319                <1> 	jnb 	short cfe3
  3293                              <1> 	;dec 	bx           ; month = month - 1
  3294 00002F15 FECB                <1> 	dec	bl			
  3295                              <1> 	;shl 	bx, 1
  3296 00002F17 D0E3                <1> 	shl	bl, 1
  3297 00002F19 668B93[8C5F0000]    <1> 	mov 	dx, [ebx+DMonth] ; # elapsed days at 1st of month
  3298                              <1> 	;shr 	bx, 1        ; bx = month - 1 (0 to 11)
  3299                              <1> 	; 02/06/2022
  3300 00002F20 D0EB                <1> 	shr	bl, 1
  3301 00002F22 80FB01              <1> 	cmp	bl, 1
  3302                              <1> 	;cmp	bx, 1        ; if month > 2 and year mod 4  = 0	
  3303 00002F25 76EA                <1> 	jna 	short cfe2   ; then mday = mday + 1
  3304 00002F27 08C0                <1> 	or 	al, al       ; if past 2/29 and leap year then
  3305 00002F29 75E6                <1> 	jnz 	short cfe2   ; add leap day (to mday)
  3306                              <1> 	;inc 	dx           ; mday = mday + 1
  3307 00002F2B 42                  <1> 	inc	edx
  3308 00002F2C EBE3                <1> 	jmp 	short cfe2
  3309                              <1> cfe3:
  3310                              <1> 	;inc 	bx	     ; -> bx = month, 1 to 12
  3311                              <1> 	; 02/06/2022
  3312 00002F2E FEC3                <1> 	inc	bl
  3313                              <1> 	;mov 	[month], bx
  3314 00002F30 881D[865F0000]      <1> 	mov	[month], bl
  3315                              <1> 	;sub 	cx, dx	     ; day = jday - mday + 1	
  3316 00002F36 29D1                <1> 	sub	ecx, edx
  3317                              <1> 	;inc 	cx 			  
  3318 00002F38 FEC1                <1> 	inc	cl
  3319                              <1> 	;mov 	[day], cx
  3320 00002F3A 880D[875F0000]      <1> 	mov	[day], cl    ; 02/06/2022
  3321                              <1> 	
  3322                              <1> 	; eax, ebx, ecx, edx is changed at return
  3323                              <1> 	; output ->
  3324                              <1> 	; [year], [month], [day], [hour], [minute], [second]
  3325                              <1> 
  3326                              <1> 	; 01/06/2022 (BugFix)	
  3327                              <1> _set_date:
  3328 00002F40 66A1[845F0000]      <1> 	mov	ax, [year]
  3329 00002F46 B520                <1> 	mov	ch, 20h ; century (bcd)
  3330 00002F48 662DD007            <1> 	sub	ax, 2000
  3331 00002F4C 7306                <1> 	jnc	short set_date
  3332 00002F4E B519                <1> 	mov	ch, 19h ; century (bcd) 
  3333 00002F50 6683C064            <1> 	add	ax, 100	
  3334                              <1> 	; 01/06/2022
  3335                              <1> 	; 15/03/2015 (Retro UNIX 386 v1 - 32 bit version)
  3336                              <1> 	; 20/06/2013 (Retro UNIX 8086 v1)
  3337                              <1> set_date:
  3338                              <1>         ;mov	al, [year+1]
  3339                              <1> 	;aam 	; ah = al / 10, al = al mod 10
  3340                              <1> 	;db 	0D5h, 10h    ; Undocumented inst. AAD
  3341                              <1> 	;		     ; AL = AH * 10h + AL
  3342                              <1> 	;mov 	ch, al ; century (BCD)
  3343                              <1> 	;mov 	al, [year]
  3344                              <1> 	; al = year (0-99) ; 01/06/2022
  3345 00002F54 D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3346 00002F56 D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3347                              <1> 			     ; AL = AH * 10h + AL
  3348 00002F58 88C1                <1> 	mov 	cl, al ; year (BCD)
  3349 00002F5A A0[865F0000]        <1>         mov 	al, [month]
  3350 00002F5F D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3351 00002F61 D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3352                              <1> 			     ; AL = AH * 10h + AL
  3353 00002F63 88C6                <1> 	mov 	dh, al ; month (BCD)
  3354 00002F65 A0[875F0000]        <1> 	mov 	al, [day]
  3355 00002F6A D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3356 00002F6C D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3357                              <1> 			     ; AL = AH * 10h + AL
  3358                              <1> 	; 01/06/2022 (BugFix)
  3359 00002F6E 88C2                <1> 	mov 	dl, al ; day (BCD)
  3360                              <1> 
  3361                              <1> 	; Set real-time clock date
  3362 00002F70 E879000000          <1> 	call	set_rtc_date
  3363                              <1> set_time:
  3364                              <1>         ; Read real-time clock time 
  3365                              <1> 	; (get day light saving time bit status)
  3366 00002F75 FA                  <1>  	cli
  3367 00002F76 E8A5DBFFFF          <1> 	CALL	UPD_IPR 	; CHECK FOR UPDATE IN PROCESS
  3368                              <1> 	; cf = 1 -> al = 0
  3369 00002F7B 7207                <1>         jc      short stime1
  3370 00002F7D B00B                <1> 	MOV	AL, CMOS_REG_B	; ADDRESS ALARM REGISTER
  3371 00002F7F E886DBFFFF          <1> 	CALL	CMOS_READ	; READ CURRENT VALUE OF DSE BIT
  3372                              <1> stime1:
  3373 00002F84 FB                  <1> 	sti
  3374 00002F85 2401                <1> 	AND	AL, 00000001B	; MASK FOR VALID DSE BIT
  3375 00002F87 88C2                <1> 	MOV	DL, AL		; SET [DL] TO ZERO FOR NO DSE BIT
  3376                              <1> 	; DL = 1 or 0 (day light saving time)
  3377                              <1> 	;	
  3378 00002F89 A0[885F0000]        <1> 	mov 	al, [hour]
  3379 00002F8E D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3380 00002F90 D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3381                              <1> 			     ; AL = AH * 10h + AL
  3382 00002F92 88C5                <1> 	mov 	ch, al ; hour (BCD)
  3383 00002F94 A0[895F0000]        <1>         mov     al, [minute]
  3384 00002F99 D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3385 00002F9B D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3386                              <1> 			     ; AL = AH * 10h + AL
  3387 00002F9D 88C1                <1> 	mov 	cl, al       ; minute (BCD)
  3388 00002F9F A0[8A5F0000]        <1>         mov     al, [second]
  3389 00002FA4 D40A                <1> 	aam 	; ah = al / 10, al = al mod 10
  3390 00002FA6 D510                <1> 	db 	0D5h, 10h    ; Undocumented inst. AAD
  3391                              <1> 			     ; AL = AH * 10h + AL
  3392 00002FA8 88C6                <1> 	mov 	dh, al	     ; second (BCD)
  3393                              <1> 
  3394                              <1> 	; Set real-time clock time
  3395                              <1>  	; call	set_rtc_time
  3396                              <1> set_rtc_time:
  3397                              <1> 	; 15/04/2015 (257, POSTEQU.INC -> H EQU 256, X EQU H+1)
  3398                              <1> 	; 15/03/2015
  3399                              <1> 	; Derived from IBM PC-XT Model 286 BIOS Source Code
  3400                              <1> 	; BIOS2.ASM ---- 10/06/1985 BIOS INTERRUPT ROUTINES
  3401                              <1> 	; INT 1Ah
  3402                              <1> 	; (AH) = 03H  SET THE REAL TIME CLOCK USING,			:
  3403                              <1> 	;      (CH) = HOURS IN BCD (00-23)			       	:
  3404                              <1> 	;      (CL) = MINUTES IN BCD (00-59)			       	:
  3405                              <1> 	;      (DH) = SECONDS IN BCD (00-59)			       	:
  3406                              <1> 	;      (DL) = 01 IF DAYLIGHT SAVINGS ENABLE OPTION, ELSE 00.    :
  3407                              <1> 	;								:
  3408                              <1> 	;  NOTE: (DL)= 00 IF DAYLIGHT SAVINGS TIME ENABLE IS NOT ENABLED. :
  3409                              <1> 	;        (DL)= 01 ENABLES TWO SPECIAL UPDATES THE LAST SUNDAY IN  :
  3410                              <1> 	;         APRIL   (1:59:59 --> 3:00:00 AM) AND THE LAST SUNDAY IN :
  3411                              <1> 	;         OCTOBER (1:59:59 --> 1:00:00 AM) THE FIRST TIME.	  :
  3412                              <1> 	;
  3413                              <1> RTC_30: 				; SET RTC TIME
  3414 00002FAA FA                  <1> 	cli
  3415 00002FAB E870DBFFFF          <1> 	CALL	UPD_IPR 		; CHECK FOR UPDATE IN PROCESS
  3416 00002FB0 7305                <1> 	JNC	short RTC_35		; GO AROUND IF CLOCK OPERATING
  3417 00002FB2 E886000000          <1> 	CALL	RTC_STA 		; ELSE TRY INITIALIZING CLOCK
  3418                              <1> RTC_35:
  3419 00002FB7 88F4                <1> 	MOV	AH, DH			; GET TIME BYTE - SECONDS
  3420 00002FB9 B000                <1> 	MOV	AL, CMOS_SECONDS 	; ADDRESS SECONDS
  3421 00002FBB E89D000000          <1> 	CALL	CMOS_WRITE		; UPDATE SECONDS
  3422 00002FC0 88CC                <1> 	MOV	AH, CL			; GET TIME BYTE - MINUTES
  3423 00002FC2 B002                <1> 	MOV	AL, CMOS_MINUTES 	; ADDRESS MINUTES
  3424 00002FC4 E894000000          <1> 	CALL	CMOS_WRITE		; UPDATE MINUTES
  3425 00002FC9 88EC                <1> 	MOV	AH, CH			; GET TIME BYTE - HOURS
  3426 00002FCB B004                <1> 	MOV	AL, CMOS_HOURS		; ADDRESS HOURS
  3427 00002FCD E88B000000          <1> 	CALL	CMOS_WRITE		; UPDATE ADDRESS
  3428                              <1> 	;MOV	AX, X*CMOS_REG_B 	; ADDRESS ALARM REGISTER
  3429 00002FD2 66B80B0B            <1> 	MOV	AX, 257*CMOS_REG_B 	; 
  3430 00002FD6 E82FDBFFFF          <1> 	CALL	CMOS_READ		; READ CURRENT TIME
  3431 00002FDB 2462                <1> 	AND	AL, 01100010B		; MASK FOR VALID BIT POSITIONS
  3432 00002FDD 0C02                <1> 	OR	AL, 00000010B		; TURN ON 24 HOUR MODE
  3433 00002FDF 80E201              <1> 	AND	DL, 00000001B		; USE ONLY THE DSE BIT
  3434 00002FE2 08D0                <1> 	OR	AL, DL			; GET DAY LIGHT SAVINGS TIME BIT (OSE)
  3435 00002FE4 86E0                <1> 	XCHG	AH, AL			; PLACE IN WORK REGISTER AND GET ADDRESS
  3436 00002FE6 E872000000          <1> 	CALL	CMOS_WRITE		; SET NEW ALARM BITS
  3437 00002FEB F8                  <1> 	CLC				; SET CY= 0
  3438 00002FEC FB                  <1> 	sti
  3439 00002FED C3                  <1> 	RETn				; RETURN WITH CY= 0
  3440                              <1> 
  3441                              <1> set_rtc_date:
  3442                              <1> 	; 15/04/2015 (257, POSTEQU.INC -> H EQU 256, X EQU H+1)
  3443                              <1> 	; 15/03/2015
  3444                              <1> 	; Derived from IBM PC-XT Model 286 BIOS Source Code
  3445                              <1> 	; BIOS2.ASM ---- 10/06/1985 BIOS INTERRUPT ROUTINES
  3446                              <1> 	; INT 1Ah
  3447                              <1> 	; (AH) = 05H  SET THE DATE INTO THE REAL TIME CLOCK USING, :
  3448                              <1> 	;     (CH) = CENTURY IN BCD (19 OR 20)			   :
  3449                              <1> 	;     (CL) = YEAR IN BCD (00-99)			   :
  3450                              <1> 	;     (DH) = MONTH IN BCD (01-12)			   :
  3451                              <1> 	;     (DL) = DAY IN BCD (01-31).
  3452                              <1> 	;
  3453                              <1> RTC_50: 				; SET RTC DATE
  3454 00002FEE FA                  <1> 	cli
  3455 00002FEF E82CDBFFFF          <1> 	CALL	UPD_IPR 		; CHECK FOR UPDATE IN PROCESS
  3456 00002FF4 7305                <1> 	JNC	short RTC_55		; GO AROUND IF NO ERROR
  3457 00002FF6 E842000000          <1> 	CALL	RTC_STA 		; ELSE INITIALIZE CLOCK
  3458                              <1> RTC_55:
  3459 00002FFB 66B80600            <1> 	MOV	AX, CMOS_DAY_WEEK	; ADDRESS OF DAY OF WEEK BYTE
  3460 00002FFF E859000000          <1> 	CALL	CMOS_WRITE		; LOAD ZEROS TO DAY OF WEEK
  3461 00003004 88D4                <1> 	MOV	AH, DL			; GET DAY OF MONTH BYTE
  3462 00003006 B007                <1> 	MOV	AL, CMOS_DAY_MONTH	; ADDRESS DAY OF MONTH BYTE
  3463 00003008 E850000000          <1> 	CALL	CMOS_WRITE		; WRITE OF DAY OF MONTH REGISTER
  3464 0000300D 88F4                <1> 	MOV	AH, DH			; GET MONTH
  3465 0000300F B008                <1> 	MOV	AL, CMOS_MONTH		; ADDRESS MONTH BYTE
  3466 00003011 E847000000          <1> 	CALL	CMOS_WRITE		; WRITE MONTH REGISTER
  3467 00003016 88CC                <1> 	MOV	AH, CL			; GET YEAR BYTE
  3468 00003018 B009                <1> 	MOV	AL, CMOS_YEAR		; ADDRESS YEAR REGISTER
  3469 0000301A E83E000000          <1> 	CALL	CMOS_WRITE		; WRITE YEAR REGISTER
  3470 0000301F 88EC                <1> 	MOV	AH, CH			; GET CENTURY BYTE
  3471 00003021 B032                <1> 	MOV	AL, CMOS_CENTURY 	; ADDRESS CENTURY BYTE
  3472 00003023 E835000000          <1> 	CALL	CMOS_WRITE		; WRITE CENTURY LOCATION
  3473                              <1> 	;MOV	AX, X*CMOS_REG_B 	; ADDRESS ALARM REGISTER
  3474 00003028 66B80B0B            <1> 	MOV	AX, 257*CMOS_REG_B 	; 
  3475 0000302C E8D9DAFFFF          <1> 	CALL	CMOS_READ		; READ CURRENT SETTINGS
  3476 00003031 247F                <1> 	AND	AL, 07FH 		; CLEAR 'SET BIT'
  3477 00003033 86E0                <1> 	XCHG	AH, AL			; MOVE TO WORK REGISTER
  3478 00003035 E823000000          <1> 	CALL	CMOS_WRITE		; AND START CLOCK UPDATING
  3479 0000303A F8                  <1> 	CLC				; SET CY= 0
  3480 0000303B FB                  <1> 	sti
  3481 0000303C C3                  <1> 	RETn				; RETURN CY=0
  3482                              <1> 
  3483                              <1> 	; 15/03/2015
  3484                              <1> RTC_STA:				; INITIALIZE REAL TIME CLOCK
  3485 0000303D B426                <1> 	mov	ah, 26h
  3486 0000303F B00A                <1> 	mov	al, CMOS_REG_A		; ADDRESS REGISTER A AND LOAD DATA MASK
  3487 00003041 E817000000          <1> 	CALL	CMOS_WRITE		; INITIALIZE STATUS REGISTER A
  3488 00003046 B482                <1> 	mov	ah, 82h
  3489 00003048 B00B                <1> 	mov 	al, CMOS_REG_B		; SET "SET BIT" FOR CLOCK INITIALIZATION
  3490 0000304A E80E000000          <1> 	CALL	CMOS_WRITE		; AND 24 HOUR MODE TO REGISTER B
  3491 0000304F B00C                <1> 	MOV	AL, CMOS_REG_C		; ADDRESS REGISTER C
  3492 00003051 E8B4DAFFFF          <1> 	CALL	CMOS_READ		; READ REGISTER C TO INITIALIZE
  3493 00003056 B00D                <1> 	MOV	AL, CMOS_REG_D		; ADDRESS REGISTER D
  3494                              <1> 	;CALL	CMOS_READ		; READ REGISTER D TO INITIALIZE
  3495                              <1> 	;RETn
  3496                              <1> 	; 12/01/2022
  3497 00003058 E9ADDAFFFF          <1> 	jmp	CMOS_READ
  3498                              <1> 
  3499                              <1> 	; 15/03/2015
  3500                              <1> 	; IBM PC/XT Model 286 BIOS source code ----- 10/06/85 (test4.asm)
  3501                              <1> CMOS_WRITE:			; WRITE (AH) TO LOCATION (AL)
  3502 0000305D 9C                  <1> 	pushf			; SAVE INTERRUPT ENABLE STATUS AND FLAGS
  3503                              <1> 	;push	ax		; SAVE WORK REGISTER VALUES
  3504 0000305E D0C0                <1> 	rol	al, 1		; MOVE NMI BIT TO LOW POSITION
  3505 00003060 F9                  <1> 	stc			; FORCE NMI BIT ON IN CARRY FLAG
  3506 00003061 D0D8                <1> 	rcr	al, 1		; HIGH BIT ON TO DISABLE NMI - OLD IN CY
  3507 00003063 FA                  <1> 	cli			; DISABLE INTERRUPTS
  3508 00003064 E670                <1> 	out	CMOS_PORT, al	; ADDRESS LOCATION AND DISABLE NMI
  3509 00003066 88E0                <1> 	mov	al, ah		; GET THE DATA BYTE TO WRITE
  3510 00003068 E671                <1> 	out	CMOS_DATA, al	; PLACE IN REQUESTED CMOS LOCATION
  3511 0000306A B01E                <1> 	mov	al, CMOS_SHUT_DOWN*2 ; GET ADDRESS OF DEFAULT LOCATION
  3512 0000306C D0D8                <1> 	rcr	al, 1		; PUT ORIGINAL NMI MASK BIT INTO ADDRESS
  3513 0000306E E670                <1> 	out	CMOS_PORT, al	; SET DEFAULT TO READ ONLY REGISTER
  3514 00003070 90                  <1> 	nop			; I/O DELAY
  3515 00003071 E471                <1> 	in	al, CMOS_DATA	; OPEN STANDBY LATCH
  3516                              <1> 	;pop	ax		; RESTORE WORK REGISTERS
  3517 00003073 9D                  <1> 	popf	
  3518 00003074 C3                  <1> 	RETn
  3519                              <1> 
  3520                              <1> bf_init:
  3521                              <1> 	; 14/08/2015
  3522                              <1> 	; 02/07/2015
  3523                              <1> 	; 01/07/2015
  3524                              <1> 	; 15/04/2015 (Retro UNIX 386 v1 - Beginning)
  3525                              <1> 	; Buffer (pointer) initialization !
  3526                              <1> 	; 
  3527                              <1> 	; 17/07/2013 - 24/07/2013
  3528                              <1> 	; Retro UNIX 8086 v1 (U9.ASM)
  3529                              <1> 	; (Retro UNIX 8086 v1 feature only !)
  3530                              <1> 	;
  3531 00003075 BF[98650000]        <1> 	mov	edi, bufp 
  3532 0000307A B8[A4760000]        <1> 	mov	eax, buffer + (nbuf*520) 
  3533 0000307F 29D2                <1> 	sub	edx, edx
  3534 00003081 FECA                <1> 	dec	dl
  3535 00003083 31C9                <1> 	xor	ecx, ecx
  3536 00003085 49                  <1> 	dec	ecx
  3537                              <1> bi0:
  3538 00003086 2D08020000          <1> 	sub	eax, 520 ; 8 header + 512 data
  3539 0000308B AB                  <1> 	stosd
  3540 0000308C 89C6                <1> 	mov	esi, eax
  3541 0000308E 8916                <1> 	mov	[esi], edx ; 000000FFh
  3542                              <1> 			   ; Not a valid device sign
  3543 00003090 894E04              <1> 	mov	[esi+4], ecx ; 0FFFFFFFFh
  3544                              <1> 		      ; Not a valid block number sign 	 	
  3545 00003093 3D[64660000]        <1> 	cmp	eax, buffer
  3546 00003098 77EC                <1> 	ja	short bi0
  3547 0000309A B8[A4760000]        <1> 	mov	eax, sb0
  3548 0000309F AB                  <1> 	stosd
  3549 000030A0 B8[AC780000]        <1> 	mov	eax, sb1
  3550 000030A5 AB                  <1> 	stosd
  3551 000030A6 89C6                <1> 	mov	esi, eax ; offset sb1
  3552 000030A8 8916                <1> 	mov	[esi], edx ; 000000FFh
  3553                              <1> 			   ; Not a valid device sign
  3554 000030AA 894E04              <1> 	mov	[esi+4], ecx ; 0FFFFFFFFh
  3555                              <1> 		      ; Not a valid block number sign 	 
  3556                              <1> 	; 14/08/2015
  3557                              <1> 	;call 	rdev_init
  3558                              <1> 	;retn
  3559                              <1> 
  3560                              <1> rdev_init: ; root device, super block buffer initialization
  3561                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3562                              <1> 	; 14/08/2015
  3563                              <1> 	; Retro UNIX 386 v1 feature only !
  3564                              <1> 	;
  3565                              <1> 	; NOTE: Disk partitions (file systems), logical
  3566                              <1> 	; drive initialization, partition's start sector etc.
  3567                              <1> 	; will be coded here, later in 'ldrv_init'	
  3568                              <1> 
  3569 000030AD 0FB605[385D0000]    <1> 	movzx	eax, byte [boot_drv]
  3570                              <1> rdi_0:
  3571 000030B4 3C80                <1> 	cmp	al, 80h
  3572 000030B6 7202                <1> 	jb	short rdi_1
  3573 000030B8 2C7E                <1> 	sub	al, 7Eh ; 80h = 2 (hd0), 81h = 3 (hd1)
  3574                              <1> rdi_1:
  3575 000030BA A2[C4650000]        <1> 	mov	[rdev], al
  3576 000030BF BB[A4760000]        <1>         mov	ebx, sb0 ; super block buffer
  3577 000030C4 8903                <1> 	mov 	[ebx], eax
  3578 000030C6 B001                <1> 	mov	al, 1 ; eax = 1
  3579 000030C8 894304              <1> 	mov	[ebx+4], eax ; super block address on disk
  3580                              <1> 	;call 	diskio
  3581                              <1> 	;retn
  3582                              <1> 	; 24/12/2021
  3583 000030CB E911250000          <1> 	jmp	diskio
  3584                              <1> 
  3585                              <1> ; 23/10/2015
  3586                              <1> com1_irq4:
  3587 000030D0 [D8300000]          <1> 	dd	dummy_retn
  3588                              <1> com2_irq3:
  3589 000030D4 [D8300000]          <1> 	dd	dummy_retn
  3590                              <1> 
  3591                              <1> dummy_retn:
  3592 000030D8 C3                  <1> 	retn
  2111                                  %include 'u1.s'        ; 10/05/2015
  2112                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.6) - SYS1.INC
  2113                              <1> ; Last Modification: 17/07/2022
  2114                              <1> ; ----------------------------------------------------------------------------
  2115                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2116                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2117                              <1> ;
  2118                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2119                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2120                              <1> ; <Bell Laboratories (17/3/1972)>
  2121                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2122                              <1> ;
  2123                              <1> ; Retro UNIX 8086 v1 - U1.ASM (12/07/2014) //// UNIX v1 -> u1.s
  2124                              <1> ;
  2125                              <1> ; ****************************************************************************
  2126                              <1> 
  2127                              <1> unkni: ; / used for all system calls
  2128                              <1> sysent: ; < enter to system call >
  2129                              <1> 	; 08/01/2022
  2130                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2131                              <1> 	; 19/10/2015
  2132                              <1> 	; 21/09/2015
  2133                              <1> 	; 01/07/2015
  2134                              <1> 	; 19/05/2015
  2135                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2136                              <1> 	; 10/04/2013 - 18/01/2014 (Retro UNIX 8086 v1)
  2137                              <1> 	;
  2138                              <1> 	; 'unkni' or 'sysent' is sytem entry from various traps. 
  2139                              <1> 	; The trap type is determined and an indirect jump is made to 
  2140                              <1> 	; the appropriate system call handler. If there is a trap inside
  2141                              <1> 	; the system a jump to panic is made. All user registers are saved 
  2142                              <1> 	; and u.sp points to the end of the users stack. The sys (trap)
  2143                              <1> 	; instructor is decoded to get the the system code part (see
  2144                              <1> 	; trap instruction in the PDP-11 handbook) and from this 
  2145                              <1> 	; the indirect jump address is calculated. If a bad system call is
  2146                              <1> 	; made, i.e., the limits of the jump table are exceeded, 'badsys'
  2147                              <1> 	; is called. If the call is legitimate control passes to the
  2148                              <1> 	; appropriate system routine.
  2149                              <1> 	;
  2150                              <1> 	; Calling sequence:
  2151                              <1> 	;	Through a trap caused by any sys call outside the system.
  2152                              <1> 	; Arguments:
  2153                              <1> 	;	Arguments of particular system call.	
  2154                              <1> 	; ...............................................................
  2155                              <1> 	;	
  2156                              <1> 	; Retro UNIX 8086 v1 modification: 
  2157                              <1> 	;       System call number is in EAX register.
  2158                              <1> 	;
  2159                              <1> 	;       Other parameters are in EDX, EBX, ECX, ESI, EDI, EBP
  2160                              <1> 	;	registers depending of function details.
  2161                              <1>   	;
  2162                              <1> 	; 16/04/2015
  2163 000030D9 368925[D4650000]    <1>         mov     [ss:u.sp], esp ; Kernel stack points to return address
  2164                              <1> 	; save user registers
  2165 000030E0 1E                  <1> 	push	ds
  2166 000030E1 06                  <1> 	push	es
  2167 000030E2 0FA0                <1> 	push	fs
  2168 000030E4 0FA8                <1> 	push	gs
  2169 000030E6 60                  <1> 	pushad  ; eax, ecx, edx, ebx, esp -before pushad-, ebp, esi, edi
  2170                              <1> 	;
  2171                              <1> 	; ESPACE = esp - [ss:u.sp] ; 4*12 = 48 ; 17/09/2015
  2172                              <1> 	; 	(ESPACE is size of space in kernel stack 
  2173                              <1> 	;	for saving/restoring user registers.)
  2174                              <1> 	;
  2175 000030E7 50                  <1> 	push	eax ; 01/07/2015
  2176 000030E8 66B81000            <1> 	mov     ax, KDATA
  2177 000030EC 8ED8                <1>         mov     ds, ax
  2178 000030EE 8EC0                <1>         mov     es, ax
  2179 000030F0 8EE0                <1>         mov     fs, ax
  2180 000030F2 8EE8                <1>         mov     gs, ax
  2181 000030F4 A1[18620000]        <1> 	mov	eax, [k_page_dir]
  2182 000030F9 0F22D8              <1> 	mov	cr3, eax
  2183 000030FC 58                  <1> 	pop	eax ; 01/07/2015
  2184                              <1> 	; 19/10/2015
  2185 000030FD FC                  <1> 	cld
  2186                              <1> 	;
  2187 000030FE FE05[D3650000]      <1> 	inc	byte [sysflg]
  2188                              <1> 		; incb sysflg / indicate a system routine is in progress
  2189 00003104 FB                  <1>         sti 	; 18/01/2014
  2190                              <1> 	;jnz	panic ; 24/05/2013
  2191                              <1> 	; 24/12/2021
  2192 00003105 7405                <1> 	jz	short _1
  2193 00003107 E987F9FFFF          <1> 	jmp	panic
  2194                              <1> 		; beq 1f
  2195                              <1> 		; jmp panic ; / called if trap inside system
  2196                              <1> ;1:
  2197                              <1> _1:	; 24/12/2021
  2198                              <1> 	; 16/04/2015
  2199 0000310C A3[DC650000]        <1> 	mov	[u.r0], eax
  2200 00003111 8925[D8650000]      <1> 	mov	[u.usp], esp ; kernel stack points to user's registers
  2201                              <1> 	;
  2202                              <1> 		; mov $s.syst+2,clockp
  2203                              <1> 		; mov r0,-(sp) / save user registers 
  2204                              <1> 		; mov sp,u.r0 / pointer to bottom of users stack 
  2205                              <1> 			   ; / in u.r0
  2206                              <1> 		; mov r1,-(sp)
  2207                              <1> 		; mov r2,-(sp)
  2208                              <1> 		; mov r3,-(sp)
  2209                              <1> 		; mov r4,-(sp)
  2210                              <1> 		; mov r5,-(sp)
  2211                              <1> 		; mov ac,-(sp) / "accumulator" register for extended
  2212                              <1> 		             ; / arithmetic unit
  2213                              <1> 		; mov mq,-(sp) / "multiplier quotient" register for the
  2214                              <1> 		             ; / extended arithmetic unit
  2215                              <1> 		; mov sc,-(sp) / "step count" register for the extended
  2216                              <1> 		             ; / arithmetic unit
  2217                              <1> 		; mov sp,u.sp / u.sp points to top of users stack
  2218                              <1> 		; mov 18.(sp),r0 / store pc in r0
  2219                              <1> 		; mov -(r0),r0 / sys inst in r0      10400xxx
  2220                              <1> 		; sub $sys,r0 / get xxx code
  2221 00003117 C1E002              <1> 	shl	eax, 2
  2222                              <1> 		; asl r0 / multiply by 2 to jump indirect in bytes
  2223 0000311A 3D94000000          <1> 	cmp	eax, end_of_syscalls - syscalls
  2224                              <1> 		; cmp r0,$2f-1f / limit of table (35) exceeded
  2225                              <1> 	;jnb	short badsys
  2226                              <1> 		; bhis badsys / yes, bad system call
  2227                              <1> 	; 08/01/2022
  2228 0000311F 7205                <1> 	jb	short _2
  2229 00003121 E95D010000          <1> 	jmp	badsys
  2230                              <1> _2:
  2231                              <1> 	; 08/01/2022
  2232                              <1> 	;cmc
  2233                              <1> 	;pushf	
  2234                              <1> 	;push	eax
  2235 00003126 8B2D[D4650000]      <1>  	mov 	ebp, [u.sp] ; Kernel stack at the beginning of sys call
  2236                              <1> 	;mov	al, 0FEh ; 11111110b
  2237                              <1> 	;;adc	al, 0 ; al = al + cf
  2238                              <1> 	;and	[ebp+8], al ; flags (reset carry flag)
  2239 0000312C 806508FE            <1> 	and	byte [ebp+8], 0FEh ; 11111110b ; 25/12/2021
  2240                              <1> 		; bic $341,20.(sp) / set users processor priority to 0 
  2241                              <1> 				 ; / and clear carry bit
  2242                              <1> 	;pop	ebp ; eax
  2243 00003130 89C5                <1> 	mov	ebp, eax ; 25/12/2021
  2244                              <1> 	;popf
  2245                              <1>         ;;jc	badsys
  2246                              <1> 	; 24/12/2021
  2247                              <1> 	;jnc	short _3  ; 08/01/2022
  2248                              <1> 	;jmp	badsys
  2249                              <1> ;_3:
  2250 00003132 A1[DC650000]        <1> 	mov	eax, [u.r0]
  2251                              <1> 	; system call registers: EAX, EDX, ECX, EBX, ESI, EDI
  2252 00003137 FFA5[3D310000]      <1> 	jmp	dword [ebp+syscalls]
  2253                              <1> 		; jmp *1f(r0) / jump indirect thru table of addresses
  2254                              <1> 		            ; / to proper system routine.
  2255                              <1> syscalls: ; 1:
  2256                              <1> 	; 21/09/2015
  2257                              <1> 	; 01/07/2015
  2258                              <1> 	; 16/04/2015 (32 bit address modification) 
  2259 0000313D [4D320000]          <1> 	dd sysrele	; / 0
  2260 00003141 [F5320000]          <1> 	dd sysexit 	; / 1
  2261 00003145 [1F340000]          <1> 	dd sysfork 	; / 2
  2262 00003149 [25350000]          <1> 	dd sysread 	; / 3
  2263 0000314D [38350000]          <1> 	dd syswrite 	; / 4
  2264 00003151 [A1350000]          <1> 	dd sysopen 	; / 5
  2265 00003155 [CC360000]          <1> 	dd sysclose 	; / 6
  2266 00003159 [9A330000]          <1> 	dd syswait 	; / 7
  2267 0000315D [49360000]          <1> 	dd syscreat 	; / 8
  2268 00003161 [853A0000]          <1> 	dd syslink 	; / 9
  2269 00003165 [413B0000]          <1> 	dd sysunlink 	; / 10
  2270 00003169 [0B3C0000]          <1> 	dd sysexec 	; / 11
  2271 0000316D [8E420000]          <1> 	dd syschdir 	; / 12
  2272 00003171 [71430000]          <1> 	dd systime 	; / 13
  2273 00003175 [85360000]          <1> 	dd sysmkdir 	; / 14
  2274 00003179 [DE420000]          <1> 	dd syschmod 	; / 15
  2275 0000317D [41430000]          <1> 	dd syschown 	; / 16
  2276 00003181 [A4430000]          <1> 	dd sysbreak 	; / 17
  2277 00003185 [CB3F0000]          <1> 	dd sysstat 	; / 18
  2278 00003189 [74440000]          <1> 	dd sysseek 	; / 19
  2279 0000318D [86440000]          <1> 	dd systell 	; / 20
  2280 00003191 [BA4F0000]          <1> 	dd sysmount 	; / 21
  2281 00003195 [A5500000]          <1> 	dd sysumount 	; / 22
  2282 00003199 [02450000]          <1> 	dd syssetuid 	; / 23
  2283 0000319D [33450000]          <1> 	dd sysgetuid 	; / 24
  2284 000031A1 [80430000]          <1> 	dd sysstime 	; / 25
  2285 000031A5 [F6440000]          <1> 	dd sysquit 	; / 26
  2286 000031A9 [EA440000]          <1> 	dd sysintr 	; / 27
  2287 000031AD [A83F0000]          <1> 	dd sysfstat 	; / 28
  2288 000031B1 [E9360000]          <1> 	dd sysemt 	; / 29
  2289 000031B5 [35370000]          <1> 	dd sysmdate 	; / 30
  2290 000031B9 [8F370000]          <1> 	dd sysstty 	; / 31
  2291 000031BD [78390000]          <1> 	dd sysgtty 	; / 32
  2292 000031C1 [30370000]          <1> 	dd sysilgins 	; / 33
  2293 000031C5 [03580000]          <1> 	dd syssleep 	; 34 ; Retro UNIX 8086 v1 feature only !
  2294                              <1> 			     ; 11/06/2014
  2295 000031C9 [1A580000]          <1> 	dd sysmsg	; 35 ; Retro UNIX 386 v1 feature only !
  2296                              <1> 			     ; 01/07/2015
  2297 000031CD [F2580000]          <1> 	dd sysgeterr	; 36 ; Retro UNIX 386 v1 feature only !
  2298                              <1> 			     ; 21/09/2015 - get last error number
  2299                              <1> end_of_syscalls:
  2300                              <1> 
  2301                              <1> error:
  2302                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2303                              <1> 	; 17/09/2015
  2304                              <1> 	; 03/09/2015
  2305                              <1> 	; 01/09/2015
  2306                              <1> 	; 09/06/2015
  2307                              <1> 	; 13/05/2015
  2308                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2309                              <1> 	; 10/04/2013 - 07/08/2013 (Retro UNIX 8086 v1)
  2310                              <1> 	;
  2311                              <1> 	; 'error' merely sets the error bit off the processor status (c-bit)
  2312                              <1> 	; then falls right into the 'sysret', 'sysrele' return sequence.
  2313                              <1> 	;
  2314                              <1> 	; INPUTS -> none
  2315                              <1> 	; OUTPUTS ->
  2316                              <1> 	;	processor status - carry (c) bit is set (means error)
  2317                              <1> 	;
  2318                              <1> 	; 26/05/2013 (Stack pointer must be reset here! 
  2319                              <1> 	; 	      Because, jumps to error procedure
  2320                              <1> 	;	      disrupts push-pop nesting balance)
  2321                              <1> 	;
  2322 000031D1 8B2D[D4650000]      <1> 	mov	ebp, [u.sp] ; interrupt (system call) return (iretd) address
  2323 000031D7 804D0801            <1> 	or	byte [ebp+8], 1  ; set carry bit of flags register
  2324                              <1> 				 ; (system call will return with cf = 1)
  2325                              <1> 		; bis $1,20.(r1) / set c bit in processor status word below
  2326                              <1> 		               ; / users stack
  2327                              <1> 	; 17/09/2015
  2328 000031DB 83ED30              <1> 	sub	ebp, ESPACE ; 48 ; total size of stack frame ('sysdefs.inc')
  2329                              <1> 				 ; for saving/restoring user registers	
  2330                              <1> 	;cmp	ebp, [u.usp]
  2331                              <1> 	;je	short err0	
  2332 000031DE 892D[D8650000]      <1> 	mov	[u.usp], ebp
  2333                              <1> ;err0:
  2334                              <1> 	; 01/09/2015
  2335 000031E4 8B25[D8650000]      <1> 	mov	esp, [u.usp] 	    ; Retro Unix 8086 v1 modification!
  2336                              <1> 				    ; 10/04/2013
  2337                              <1> 				    ; (If an I/O error occurs during disk I/O,
  2338                              <1> 				    ; related procedures will jump to 'error'
  2339                              <1> 				    ; procedure directly without returning to 
  2340                              <1> 				    ; the caller procedure. So, stack pointer
  2341                              <1>                                     ; must be restored here.)
  2342                              <1> 	; 13/05/2015
  2343                              <1> 	; NOTE: (The last) error code is in 'u.error', it can be retrieved by
  2344                              <1> 	;	'get last error' system call later. 	
  2345                              <1> 
  2346                              <1> 	; 03/09/2015 - 09/06/2015 - 07/08/2013
  2347 000031EA C605[43660000]00    <1> 	mov 	byte [u.kcall], 0 ; namei_r, mkdir_w reset
  2348                              <1> 
  2349                              <1> sysret: ; < return from system call>
  2350                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2351                              <1> 	; 10/09/2015
  2352                              <1> 	; 29/07/2015
  2353                              <1> 	; 25/06/2015
  2354                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2355                              <1> 	; 10/04/2013 - 23/02/2014 (Retro UNIX 8086 v1)
  2356                              <1> 	;
  2357                              <1> 	; 'sysret' first checks to see if process is about to be 
  2358                              <1> 	; terminated (u.bsys). If it is, 'sysexit' is called.
  2359                              <1> 	; If not, following happens:	 
  2360                              <1> 	; 	1) The user's stack pointer is restored.
  2361                              <1> 	;	2) r1=0 and 'iget' is called to see if last mentioned
  2362                              <1> 	;	   i-node has been modified. If it has, it is written out
  2363                              <1> 	;	   via 'ppoke'.
  2364                              <1> 	;	3) If the super block has been modified, it is written out
  2365                              <1> 	;	   via 'ppoke'.				
  2366                              <1> 	;	4) If the dismountable file system's super block has been
  2367                              <1> 	;	   modified, it is written out to the specified device
  2368                              <1> 	;	   via 'ppoke'.
  2369                              <1> 	;	5) A check is made if user's time quantum (uquant) ran out
  2370                              <1> 	;	   during his execution. If so, 'tswap' is called to give
  2371                              <1> 	;	   another user a chance to run.
  2372                              <1> 	;	6) 'sysret' now goes into 'sysrele'. 
  2373                              <1> 	;	    (See 'sysrele' for conclusion.)		
  2374                              <1> 	;
  2375                              <1> 	; Calling sequence:
  2376                              <1> 	;	jump table or 'br sysret'
  2377                              <1> 	; Arguments: 
  2378                              <1> 	;	-	
  2379                              <1> 	; ...............................................................
  2380                              <1> 	;	
  2381                              <1> 	; ((AX=r1 for 'iget' input))
  2382                              <1> 	;	
  2383                              <1> 	;xor	ax, ax ; 04/05/2013
  2384                              <1> 	; 24/12/2021
  2385 000031F1 31C0                <1> 	xor	eax, eax
  2386                              <1> sysret0: ; 29/07/2015 (eax = 0, jump from sysexec)
  2387 000031F3 FEC0                <1> 	inc	al ; 04/05/2013
  2388 000031F5 3805[2A660000]      <1> 	cmp	[u.bsys], al ; 1
  2389                              <1> 		; tstb u.bsys / is a process about to be terminated because
  2390                              <1> 	;jnb	sysexit ; 04/05/2013
  2391                              <1> 	;	; bne sysexit / of an error? yes, go to sysexit
  2392                              <1> 	; 24/12/2021
  2393 000031FB 720F                <1> 	jb	short _3
  2394 000031FD C705[31660000]0100- <1> 	mov	dword [u.error], ERR_INV_FUNC ; 1 ; 'invalid system call !'
  2394 00003205 0000                <1>
  2395 00003207 E9E9000000          <1> 	jmp	sysexit
  2396                              <1> _3:
  2397                              <1> 	;mov	esp, [u.usp] ; 24/05/2013 (that is not needed here)
  2398                              <1> 		; mov u.sp,sp / no point stack to users stack
  2399 0000320C FEC8                <1> 	dec 	al ; mov ax, 0
  2400                              <1> 		; clr r1 / zero r1 to check last mentioned i-node
  2401 0000320E E8DA160000          <1> 	call	iget
  2402                              <1> 		; jsr r0,iget / if last mentioned i-node has been modified
  2403                              <1> 		            ; / it is written out
  2404                              <1> 	;xor 	ax, ax ; 0
  2405                              <1> 	; 24/12/2021
  2406 00003213 31C0                <1> 	xor	eax, eax
  2407 00003215 3805[D1650000]      <1> 	cmp	[smod], al ; 0
  2408                              <1> 		; tstb	smod / has the super block been modified
  2409 0000321B 7614                <1> 	jna	short sysret1
  2410                              <1> 		; beq	1f / no, 1f
  2411 0000321D A2[D1650000]        <1> 	mov	[smod], al ; 0
  2412                              <1> 		; clrb smod / yes, clear smod
  2413 00003222 BB[A4760000]        <1> 	mov	ebx, sb0 ;; 07/08//2013
  2414 00003227 66810B0002          <1>    	or	word [ebx], 200h ;;
  2415                              <1> 	;or	word [sb0], 200h ; write bit, bit 9
  2416                              <1> 		; bis $1000,sb0 / set write bit in I/O queue for super block
  2417                              <1> 		      	      ; / output
  2418                              <1> 	; AX = 0
  2419 0000322C E814230000          <1> 	call 	poke ; 07/08/2013
  2420                              <1> 	; call	ppoke
  2421                              <1> 	; AX = 0
  2422                              <1> 		; jsr r0,ppoke / write out modified super block to disk
  2423                              <1> sysret1: ;1:
  2424 00003231 3805[D2650000]      <1> 	cmp	[mmod], al ; 0
  2425                              <1> 		; tstb	mmod / has the super block for the dismountable file
  2426                              <1> 		           ; / system
  2427 00003237 7614                <1> 	jna	short sysrel0
  2428                              <1> 		; beq 1f / been modified?  no, 1f
  2429 00003239 A2[D2650000]        <1> 	mov	[mmod], al ; 0	
  2430                              <1> 		; clrb	mmod / yes, clear mmod
  2431                              <1>         ;mov    ax, [mntd]
  2432                              <1>         ;;mov   al, [mdev] ; 26/04/2013
  2433 0000323E BB[AC780000]        <1> 	mov	ebx, sb1 ;; 07/08//2013
  2434                              <1>         ;;mov	[ebx], al
  2435                              <1> 	;mov    [sb1], al
  2436                              <1> 		; movb	mntd,sb1 / set the I/O queue
  2437 00003243 66810B0002          <1> 	or	word [ebx], 200h
  2438                              <1> 	;or	word [sb1], 200h ; write bit, bit 9
  2439                              <1> 		; bis $1000,sb1 / set write bit in I/O queue for detached sb
  2440 00003248 E8F8220000          <1> 	call	poke ; 07/08/2013
  2441                              <1> 	;call	ppoke 
  2442                              <1> 		; jsr r0,ppoke / write it out to its device
  2443                              <1>         ;xor    al, al ; 26/04/2013       
  2444                              <1> ;1:
  2445                              <1> 		; tstb uquant / is the time quantum 0?
  2446                              <1> 		; bne 1f / no, don't swap it out
  2447                              <1> 
  2448                              <1> sysrele: ; < release >
  2449                              <1> 	; 14/10/2015
  2450                              <1> 	; 01/09/2015
  2451                              <1> 	; 24/07/2015
  2452                              <1> 	; 14/05/2015
  2453                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2454                              <1> 	; 10/04/2013 - 07/03/2014 (Retro UNIX 8086 v1)
  2455                              <1> 	;
  2456                              <1> 	; 'sysrele' first calls 'tswap' if the time quantum for a user is
  2457                              <1> 	;  zero (see 'sysret'). It then restores the user's registers and
  2458                              <1> 	; turns off the system flag. It then checked to see if there is
  2459                              <1> 	; an interrupt from the user by calling 'isintr'. If there is, 
  2460                              <1> 	; the output gets flashed (see isintr) and interrupt action is
  2461                              <1> 	; taken by a branch to 'intract'. If there is no interrupt from
  2462                              <1> 	; the user, a rti is made.
  2463                              <1> 	;
  2464                              <1> 	; Calling sequence:
  2465                              <1> 	;	Fall through a 'bne' in 'sysret' & ?
  2466                              <1> 	; Arguments:
  2467                              <1> 	;	-	
  2468                              <1> 	; ...............................................................
  2469                              <1> 	;	
  2470                              <1> 	; 23/02/2014 (swapret)
  2471                              <1> 	; 22/09/2013
  2472                              <1> sysrel0: ;1:
  2473 0000324D 803D[1E660000]00    <1> 	cmp	byte [u.quant], 0 ; 16/05/2013
  2474                              <1> 		; tstb uquant / is the time quantum 0?
  2475 00003254 7705                <1>         ja      short swapret
  2476                              <1> 		; bne 1f / no, don't swap it out
  2477                              <1> sysrelease: ; 07/12/2013 (jump from 'clock')
  2478 00003256 E828130000          <1> 	call	tswap
  2479                              <1> 		; jsr r0,tswap / yes, swap it out
  2480                              <1> ;
  2481                              <1> ; Retro Unix 8086 v1 feature: return from 'swap' to 'swapret' address.
  2482                              <1> swapret: ;1:
  2483                              <1> 	; 10/09/2015
  2484                              <1> 	; 01/09/2015
  2485                              <1> 	; 14/05/2015
  2486                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - 32 bit, pm modifications)
  2487                              <1> 	; 26/05/2013 (Retro UNIX 8086 v1)
  2488                              <1> 	; cli
  2489                              <1> 	; 24/07/2015
  2490                              <1> 	;
  2491                              <1> 	;; 'esp' must be already equal to '[u.usp]' here ! 
  2492                              <1> 	;; mov	esp, [u.usp]
  2493                              <1> 
  2494                              <1> 	; 22/09/2013
  2495 0000325B E8FA140000          <1> 	call	isintr
  2496                              <1> 	; 20/10/2013
  2497 00003260 7405                <1> 	jz	short sysrel1
  2498 00003262 E877000000          <1> 	call	intract
  2499                              <1> 		; jsr r0,isintr / is there an interrupt from the user
  2500                              <1> 		;     br intract / yes, output gets flushed, take interrupt
  2501                              <1> 		               ; / action
  2502                              <1> sysrel1:
  2503 00003267 FA                  <1> 	cli ; 14/10/2015
  2504 00003268 FE0D[D3650000]      <1> 	dec	byte [sysflg]
  2505                              <1> 		; decb sysflg / turn system flag off
  2506 0000326E A1[35660000]        <1> 	mov     eax, [u.pgdir]
  2507 00003273 0F22D8              <1> 	mov	cr3, eax  ; 1st PDE points to Kernel Page Table 0 (1st 4 MB)
  2508                              <1> 			  ; (others are different than kernel page tables) 
  2509                              <1> 	; 10/09/2015
  2510 00003276 61                  <1> 	popad ; edi, esi, ebp, temp (icrement esp by 4), ebx, edx, ecx, eax
  2511                              <1> 		; mov (sp)+,sc / restore user registers
  2512                              <1> 		; mov (sp)+,mq
  2513                              <1> 		; mov (sp)+,ac
  2514                              <1> 		; mov (sp)+,r5
  2515                              <1> 		; mov (sp)+,r4
  2516                              <1> 		; mov (sp)+,r3
  2517                              <1> 		; mov (sp)+,r2
  2518                              <1> 	;
  2519 00003277 A1[DC650000]        <1> 	mov	eax, [u.r0]  ; ((return value in EAX))
  2520 0000327C 0FA9                <1> 	pop	gs
  2521 0000327E 0FA1                <1> 	pop	fs
  2522 00003280 07                  <1> 	pop	es
  2523 00003281 1F                  <1> 	pop	ds
  2524 00003282 CF                  <1> 	iretd	
  2525                              <1> 		; rti / no, return from interrupt
  2526                              <1> 
  2527                              <1> badsys:
  2528                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2529                              <1> 	; (Major Modification: 'core' dumping procedure in
  2530                              <1>         ;       original UNIX v1 and Retro UNIX 8086 v1
  2531                              <1> 	;	has been changed to print 'Invalid System Call !'
  2532                              <1> 	;	message on the user's console tty.)
  2533                              <1> 	; (EIP, EAX values will be shown on screen with error message)
  2534                              <1> 	; (EIP = Return address just after the system call -INT 30h-)
  2535                              <1> 	; (EAX = Function number)  
  2536                              <1> 	;
  2537 00003283 FE05[2A660000]      <1> 	inc	byte [u.bsys]
  2538                              <1> 	;
  2539 00003289 8B1D[D4650000]      <1> 	mov	ebx, [u.sp] ; esp at the beginning of 'sysent'
  2540 0000328F 8B03                <1> 	mov	eax, [ebx] ; EIP (return address, not 'INT 30h' address)
  2541 00003291 E83AE4FFFF          <1> 	call	dwordtohex
  2542 00003296 8915[785F0000]      <1> 	mov	[bsys_msg_eip], edx
  2543 0000329C A3[7C5F0000]        <1> 	mov	[bsys_msg_eip+4], eax
  2544 000032A1 A1[DC650000]        <1> 	mov	eax, [u.r0]
  2545 000032A6 E825E4FFFF          <1> 	call	dwordtohex
  2546 000032AB 8915[685F0000]      <1> 	mov	[bsys_msg_eax], edx
  2547 000032B1 A3[6C5F0000]        <1> 	mov	[bsys_msg_eax+4], eax
  2548                              <1> 	; 24/12/2021
  2549                              <1> 	;xor	eax, eax
  2550                              <1> 	;mov	dword [u.base], badsys_msg ; "Invalid System Call !"
  2551                              <1> 	;mov	ebx, [u.fofp]
  2552                              <1> 	;mov	[ebx], eax
  2553                              <1> 	;;mov	eax, 1 ; inode number of console tty (for user)	
  2554                              <1> 	;inc	eax
  2555                              <1> 	;mov	dword [u.count], BSYS_M_SIZE
  2556                              <1> 		; writei
  2557                              <1> 		; INPUTS ->
  2558                              <1> 		;    r1 - inode number
  2559                              <1> 		;    u.count - byte count to be written
  2560                              <1> 		;    u.base - points to user buffer
  2561                              <1> 		;    u.fofp - points to word with current file offset
  2562                              <1> 		; OUTPUTS ->
  2563                              <1> 		;    u.count - cleared
  2564                              <1> 		;    u.nread - accumulates total bytes passed back	
  2565                              <1> 		;
  2566                              <1> 		; ((Modified registers: EDX, EBX, ECX, ESI, EDI, EBP)) 	
  2567                              <1> 	;call	writei
  2568                              <1> 	;;mov	eax, 1
  2569                              <1> 	;jmp	sysexit
  2570                              <1> 
  2571                              <1> 	; 24/12/2021 - Retro UNIX 386 v1.1
  2572 000032B6 BE[495F0000]        <1> 	mov	esi, badsys_msg ; "Invalid System Call !"
  2573 000032BB 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  2574 000032C2 8A83[33630000]      <1> 	mov	al, [ebx+p.ttyc-1] ; current/console tty
  2575 000032C8 C605[47620000]0F    <1> 	mov	byte [ccolor], 0Fh ; white (message) color
  2576 000032CF A2[30660000]        <1> 	mov 	[u.ttyn], al ; current (active) tty (for user)
  2577 000032D4 E8FE250000          <1> 	call	print_cmsg
  2578                              <1> 	;mov	dword [u.error], ERR_INV_FUNC ; 1 ; 'invalid system call !'
  2579 000032D9 E9F3FEFFFF          <1> 	jmp	error
  2580                              <1> 
  2581                              <1> 		; incb u.bsys / turn on the user's bad-system flag
  2582                              <1> 		; mov $3f,u.namep / point u.namep to "core\0\0"
  2583                              <1> 		; jsr r0,namei / get the i-number for the core image file
  2584                              <1> 		; br 1f / error
  2585                              <1> 		; neg r1 / negate the i-number to open the core image file
  2586                              <1> 		       ; / for writing
  2587                              <1> 		; jsr r0,iopen / open the core image file
  2588                              <1> 		; jsr r0,itrunc / free all associated blocks
  2589                              <1> 		; br 2f
  2590                              <1> ;1:
  2591                              <1> 		; mov $17,r1 / put i-node mode (17) in r1
  2592                              <1> 		; jsr r0,maknod / make an i-node
  2593                              <1> 		; mov u.dirbuf,r1 / put i-node number in r1
  2594                              <1> ;2:
  2595                              <1> 		; mov $core,u.base / move address core to u.base
  2596                              <1> 		; mov $ecore-core,u.count / put the byte count in u.count
  2597                              <1> 		; mov $u.off,u.fofp / more user offset to u.fofp
  2598                              <1> 		; clr u.off / clear user offset
  2599                              <1> 		; jsr r0,writei / write out the core image to the user
  2600                              <1> 		; mov $user,u.base / pt. u.base to user
  2601                              <1> 		; mov $64.,u.count / u.count = 64
  2602                              <1> 		; jsr r0,writei / write out all the user parameters
  2603                              <1> 		; neg r1 / make i-number positive
  2604                              <1> 		; jsr r0,iclose / close the core image file
  2605                              <1> 		; br sysexit /
  2606                              <1> ;3:
  2607                              <1> 		; <core\0\0>
  2608                              <1> 
  2609                              <1> intract: ; / interrupt action
  2610                              <1> 	; 14/10/2015
  2611                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2612                              <1> 	; 09/05/2013 - 07/12/2013 (Retro UNIX 8086 v1)
  2613                              <1> 	;
  2614                              <1> 	; Retro UNIX 8086 v1 modification !
  2615                              <1> 	; (Process/task switching and quit routine by using
  2616                              <1> 	; Retro UNIX 8086 v1 keyboard interrupt output.))
  2617                              <1> 	;
  2618                              <1> 	; input -> 'u.quit'  (also value of 'u.intr' > 0)
  2619                              <1> 	; output -> If value of 'u.quit' = FFFFh ('ctrl+brk' sign)
  2620                              <1> 	;		'intract' will jump to 'sysexit'.
  2621                              <1> 	;	    Intract will return to the caller 
  2622                              <1> 	;		if value of 'u.quit' <> FFFFh. 	 
  2623                              <1> 	; 14/10/2015
  2624 000032DE FB                  <1> 	sti
  2625                              <1> 	; 07/12/2013	
  2626 000032DF 66FF05[22660000]    <1> 	inc 	word [u.quit]
  2627 000032E6 7408                <1> 	jz	short intrct0 ; FFFFh -> 0
  2628 000032E8 66FF0D[22660000]    <1> 	dec	word [u.quit]
  2629                              <1> 	; 16/04/2015
  2630 000032EF C3                  <1> 	retn
  2631                              <1> intrct0:	
  2632 000032F0 58                  <1> 	pop	eax ; call intract -> retn
  2633                              <1> 	;
  2634 000032F1 31C0                <1> 	xor 	eax, eax
  2635 000032F3 FEC0                <1> 	inc	al  ; mov ax, 1
  2636                              <1> ;;;
  2637                              <1> 	; UNIX v1 original 'intract' routine... 
  2638                              <1> 	; / interrupt action
  2639                              <1> 		;cmp *(sp),$rti / are you in a clock interrupt?
  2640                              <1> 		; bne 1f / no, 1f
  2641                              <1> 		; cmp (sp)+,(sp)+ / pop clock pointer
  2642                              <1> 	; 1: / now in user area
  2643                              <1> 		; mov r1,-(sp) / save r1
  2644                              <1> 		; mov u.ttyp,r1 
  2645                              <1> 			; / pointer to tty buffer in control-to r1
  2646                              <1> 		; cmpb 6(r1),$177
  2647                              <1> 			; / is the interrupt char equal to "del"
  2648                              <1> 		; beq 1f / yes, 1f
  2649                              <1> 		; clrb 6(r1) 
  2650                              <1> 		        ; / no, clear the byte 
  2651                              <1> 			; / (must be a quit character)
  2652                              <1> 		; mov (sp)+,r1 / restore r1
  2653                              <1> 		; clr u.quit / clear quit flag
  2654                              <1> 		; bis $20,2(sp) 
  2655                              <1> 		    	; / set trace for quit (sets t bit of 
  2656                              <1> 			; / ps-trace trap)
  2657                              <1> 		; rti   ;  / return from interrupt
  2658                              <1> 	; 1: / interrupt char = del
  2659                              <1> 		; clrb 6(r1) / clear the interrupt byte 
  2660                              <1> 			   ; / in the buffer
  2661                              <1> 		; mov (sp)+,r1 / restore r1
  2662                              <1> 		; cmp u.intr,$core / should control be 
  2663                              <1> 				; / transferred to loc core?
  2664                              <1> 		; blo 1f
  2665                              <1> 		; jmp *u.intr / user to do rti yes, 
  2666                              <1> 				; / transfer to loc core
  2667                              <1> 	; 1:
  2668                              <1> 		; sys 1 / exit
  2669                              <1> 
  2670                              <1> sysexit: ; <terminate process>
  2671                              <1> 	; 17/07/2022
  2672                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2673                              <1> 	; 01/09/2015
  2674                              <1> 	; 31/08/2015
  2675                              <1> 	; 14/05/2015
  2676                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2677                              <1> 	; 19/04/2013 - 14/02/2014 (Retro UNIX 8086 v1)
  2678                              <1> 	;
  2679                              <1> 	; 'sysexit' terminates a process. First each file that
  2680                              <1> 	; the process has opened is closed by 'flose'. The process
  2681                              <1> 	; status is then set to unused. The 'p.pid' table is then
  2682                              <1> 	; searched to find children of the dying process. If any of
  2683                              <1> 	; children are zombies (died by not waited for), they are
  2684                              <1> 	; set free. The 'p.pid' table is then searched to find the
  2685                              <1> 	; dying process's parent. When the parent is found, it is
  2686                              <1> 	; checked to see if it is free or it is a zombie. If it is
  2687                              <1> 	; one of these, the dying process just dies. If it is waiting
  2688                              <1> 	; for a child process to die, it notified that it doesn't 
  2689                              <1> 	; have to wait anymore by setting it's status from 2 to 1
  2690                              <1> 	; (waiting to active). It is awakened and put on runq by
  2691                              <1> 	; 'putlu'. The dying process enters a zombie state in which
  2692                              <1> 	; it will never be run again but stays around until a 'wait'
  2693                              <1> 	; is completed by it's parent process. If the parent is not
  2694                              <1> 	; found, process just dies. This means 'swap' is called with
  2695                              <1> 	; 'u.uno=0'. What this does is the 'wswap' is not called
  2696                              <1> 	; to write out the process and 'rswap' reads the new process
  2697                              <1> 	; over the one that dies..i.e., the dying process is 
  2698                              <1> 	; overwritten and destroyed.	
  2699                              <1>  	;
  2700                              <1> 	; Calling sequence:
  2701                              <1> 	;	sysexit or conditional branch.
  2702                              <1> 	; Arguments:
  2703                              <1> 	;	-	
  2704                              <1> 	; ...............................................................
  2705                              <1> 	;	
  2706                              <1> 	; Retro UNIX 8086 v1 modification: 
  2707                              <1> 	;       System call number (=1) is in EAX register.
  2708                              <1> 	;
  2709                              <1> 	;       Other parameters are in EDX, EBX, ECX, ESI, EDI, EBP
  2710                              <1> 	;       registers depending of function details.
  2711                              <1> 	;
  2712                              <1> 	; ('swap' procedure is mostly different than original UNIX v1.)
  2713                              <1> 	;
  2714                              <1> ; / terminate process
  2715                              <1> 	; AX = 1
  2716                              <1> 	;dec 	ax ; 0
  2717                              <1> 	; 24/12/2021
  2718 000032F5 48                  <1> 	dec	eax ; 0
  2719                              <1> 	;dec 	ax ; 0
  2720 000032F6 66A3[20660000]      <1> 	mov	[u.intr], ax ; 0
  2721                              <1> 		; clr u.intr / clear interrupt control word
  2722                              <1> 		; clr r1 / clear r1
  2723                              <1> 	; AX = 0
  2724                              <1> sysexit_1: ; 1:
  2725                              <1> 	; AX = File descriptor
  2726                              <1> 		; / r1 has file descriptor (index to u.fp list)
  2727                              <1> 		; / Search the whole list
  2728 000032FC E8680D0000          <1> 	call	fclose
  2729                              <1> 		; jsr r0,fclose / close all files the process opened
  2730                              <1> 	;; ignore error return
  2731                              <1> 		; br .+2 / ignore error return
  2732                              <1> 	;inc	ax
  2733 00003301 FEC0                <1> 	inc	al
  2734                              <1> 		; inc r1 / increment file descriptor
  2735                              <1> 	;cmp	ax, 10
  2736 00003303 3C0A                <1> 	cmp	al, 10
  2737                              <1> 		; cmp r1,$10. / end of u.fp list?
  2738 00003305 72F5                <1> 	jb	short sysexit_1
  2739                              <1> 		; blt 1b / no, go back
  2740 00003307 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; 01/09/2015
  2741                              <1> 		; movb	u.uno,r1 / yes, move dying process's number to r1
  2742 0000330E 88A3[53630000]      <1> 	mov	[ebx+p.stat-1], ah ; 0, SFREE, 05/02/2014
  2743                              <1> 		; clrb p.stat-1(r1) / free the process
  2744                              <1> 	;shl	bx, 1
  2745 00003314 D0E3                <1> 	shl	bl, 1
  2746                              <1> 		; asl r1 / use r1 for index into the below tables
  2747 00003316 668B8B[F2620000]    <1> 	mov	cx, [ebx+p.pid-2]
  2748                              <1> 		; mov p.pid-2(r1),r3 / move dying process's name to r3
  2749 0000331D 668B93[12630000]    <1> 	mov	dx, [ebx+p.ppid-2]
  2750                              <1> 		; mov p.ppid-2(r1),r4 / move its parents name to r4
  2751                              <1> 	; xor 	bx, bx ; 0
  2752 00003324 30DB                <1> 	xor	bl, bl ; 0
  2753                              <1> 		; clr r2
  2754 00003326 31F6                <1> 	xor	esi, esi ; 0
  2755                              <1> 		; clr r5 / initialize reg
  2756                              <1> sysexit_2: ; 1:
  2757                              <1> 	        ; / find children of this dying process, 
  2758                              <1> 		; / if they are zombies, free them
  2759                              <1> 	;add	bx, 2
  2760 00003328 80C302              <1> 	add	bl, 2
  2761                              <1> 		; add $2,r2 / search parent process table 
  2762                              <1> 		          ; / for dying process's name
  2763 0000332B 66398B[12630000]    <1> 	cmp	[ebx+p.ppid-2], cx
  2764                              <1> 		; cmp p.ppid-2(r2),r3 / found it?
  2765 00003332 7513                <1> 	jne	short sysexit_4
  2766                              <1> 		; bne 3f / no
  2767                              <1> 	;shr	bx, 1
  2768 00003334 D0EB                <1> 	shr	bl, 1
  2769                              <1> 		; asr r2 / yes, it is a parent
  2770 00003336 80BB[53630000]03    <1> 	cmp	byte [ebx+p.stat-1], 3 ; SZOMB, 05/02/2014
  2771                              <1> 		; cmpb p.stat-1(r2),$3 / is the child of this 
  2772                              <1> 				     ; / dying process a zombie
  2773 0000333D 7506                <1> 	jne	short sysexit_3 
  2774                              <1> 		; bne 2f / no
  2775 0000333F 88A3[53630000]      <1> 	mov	[ebx+p.stat-1], ah ; 0, SFREE, 05/02/2014
  2776                              <1> 		; clrb p.stat-1(r2) / yes, free the child process
  2777                              <1> sysexit_3: ; 2:
  2778                              <1> 	;shr	bx, 1
  2779 00003345 D0E3                <1> 	shl	bl, 1
  2780                              <1> 		; asl r2
  2781                              <1> sysexit_4: ; 3:
  2782                              <1> 		; / search the process name table 
  2783                              <1> 		; / for the dying process's parent
  2784 00003347 663993[F2620000]    <1> 	cmp	[ebx+p.pid-2], dx ; 17/09/2013	
  2785                              <1> 		; cmp p.pid-2(r2),r4 / found it?
  2786 0000334E 7502                <1> 	jne	short sysexit_5
  2787                              <1> 		; bne 3f / no
  2788 00003350 89DE                <1> 	mov	esi, ebx
  2789                              <1> 		; mov r2,r5 / yes, put index to p.pid table (parents
  2790                              <1> 		          ; / process # x2) in r5
  2791                              <1> sysexit_5: ; 3:
  2792                              <1> 	;cmp	bx, nproc + nproc
  2793 00003352 80FB20              <1> 	cmp	bl, nproc + nproc
  2794                              <1> 		; cmp r2,$nproc+nproc / has whole table been searched?
  2795 00003355 72D1                <1> 	jb	short sysexit_2
  2796                              <1> 		; blt 1b / no, go back
  2797                              <1> 		; mov r5,r1 / yes, r1 now has parents process # x2
  2798 00003357 21F6                <1> 	and	esi, esi ; r5=r1
  2799 00003359 7430                <1> 	jz	short sysexit_6
  2800                              <1> 		; beq 2f / no parent has been found. 
  2801                              <1> 		       ; / The process just dies
  2802                              <1> 	;shr	si, 1
  2803                              <1> 	; 17/07/2022
  2804 0000335B D1EE                <1> 	shr	esi, 1
  2805                              <1> 		; asr r1 / set up index to p.stat
  2806 0000335D 8A86[53630000]      <1> 	mov	al, [esi+p.stat-1]
  2807                              <1> 		; movb p.stat-1(r1),r2 / move status of parent to r2
  2808 00003363 20C0                <1> 	and	al, al
  2809 00003365 7424                <1> 	jz	short sysexit_6
  2810                              <1> 		; beq 2f / if its been freed, 2f
  2811 00003367 3C03                <1> 	cmp	al, 3
  2812                              <1> 		; cmp r2,$3 / is parent a zombie?
  2813 00003369 7420                <1> 	je	short sysexit_6
  2814                              <1> 		; beq 2f / yes, 2f
  2815                              <1> 	; BH = 0
  2816 0000336B 8A1D[2B660000]      <1> 	mov	bl, [u.uno]
  2817                              <1> 		; movb u.uno,r3 / move dying process's number to r3
  2818 00003371 C683[53630000]03    <1> 	mov	byte [ebx+p.stat-1], 3  ; SZOMB, 05/02/2014
  2819                              <1> 		; movb $3,p.stat-1(r3) / make the process a zombie
  2820                              <1> 	; 05/02/2014
  2821 00003378 3C01                <1> 	cmp	al, 1 ; SRUN
  2822 0000337A 740F                <1> 	je	short sysexit_6
  2823                              <1> 	;cmp	al, 2
  2824                              <1> 		; cmp r2,$2 / is the parent waiting for 
  2825                              <1> 			  ; / this child to die
  2826                              <1> 	;jne	short sysexit_6	
  2827                              <1> 		; bne 2f / yes, notify parent not to wait any more
  2828                              <1> 	; 05/02/2014
  2829                              <1> 	; p.stat = 2 --> waiting
  2830                              <1> 	; p.stat = 4 --> sleeping
  2831 0000337C C686[53630000]01    <1> 	mov	byte [esi+p.stat-1], 1 ; SRUN ; 05/02/2014
  2832                              <1> 	;dec	byte [esi+p.stat-1]
  2833                              <1> 		; decb	p.stat-1(r1) / awaken it by putting it (parent)
  2834 00003383 6689F0              <1> 	mov	ax, si ; r1  (process number in AL)
  2835                              <1> 	; 
  2836                              <1> 	;mov	ebx, runq + 4
  2837                              <1> 		; mov $runq+4,r2 / on the runq
  2838 00003386 E8CF120000          <1> 	call	putlu
  2839                              <1> 		; jsr r0, putlu
  2840                              <1> sysexit_6: ; 2:
  2841                              <1> 	; 31/08/2015
  2842                              <1> 		; / the process dies
  2843 0000338B C605[2B660000]00    <1> 	mov	byte [u.uno], 0
  2844                              <1> 		; clrb u.uno / put zero as the process number, 
  2845                              <1> 	           ; / so "swap" will
  2846 00003392 E8F6110000          <1> 	call	swap
  2847                              <1> 		; jsr r0,swap / overwrite process with another process
  2848                              <1> hlt_sys:
  2849                              <1> 	;sti ; 18/01/2014
  2850                              <1> hlts0:
  2851 00003397 F4                  <1> 	hlt
  2852 00003398 EBFD                <1> 	jmp	short hlts0
  2853                              <1> 		; 0 / and thereby kill it; halt?
  2854                              <1> 
  2855                              <1> 
  2856                              <1> syswait: ; < wait for a processs to die >
  2857                              <1> 	; 09/02/2022
  2858                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1)
  2859                              <1> 	; 17/09/2015
  2860                              <1> 	; 02/09/2015
  2861                              <1> 	; 01/09/2015
  2862                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - Beginning)
  2863                              <1> 	; 24/05/2013 - 05/02/2014 (Retro UNIX 8086 v1)
  2864                              <1> 	;
  2865                              <1> 	; 'syswait' waits for a process die. 
  2866                              <1> 	; It works in following way:
  2867                              <1> 	;    1) From the parent process number, the parent's 
  2868                              <1> 	; 	process name is found. The p.ppid table of parent
  2869                              <1> 	;	names is then searched for this process name.
  2870                              <1> 	;	If a match occurs, r2 contains child's process
  2871                              <1> 	;	number. The child status is checked to see if it is
  2872                              <1> 	;	a zombie, i.e; dead but not waited for (p.stat=3)
  2873                              <1> 	;	If it is, the child process is freed and it's name
  2874                              <1> 	;	is put in (u.r0). A return is then made via 'sysret'.
  2875                              <1> 	;	If the child is not a zombie, nothing happens and
  2876                              <1> 	;	the search goes on through the p.ppid table until
  2877                              <1> 	;	all processes are checked or a zombie is found.
  2878                              <1> 	;    2) If no zombies are found, a check is made to see if
  2879                              <1> 	;	there are any children at all. If there are none,
  2880                              <1> 	;	an error return is made. If there are, the parent's
  2881                              <1> 	;	status is set to 2 (waiting for child to die),
  2882                              <1> 	;	the parent is swapped out, and a branch to 'syswait'
  2883                              <1> 	;	is made to wait on the next process.
  2884                              <1> 	;
  2885                              <1> 	; Calling sequence:
  2886                              <1> 	;	?
  2887                              <1> 	; Arguments:
  2888                              <1> 	;	-
  2889                              <1> 	; Inputs: - 
  2890                              <1> 	; Outputs: if zombie found, it's name put in u.r0.	
  2891                              <1> 	; ...............................................................
  2892                              <1> 	;				
  2893                              <1> 	
  2894                              <1> ; / wait for a process to die
  2895                              <1> 
  2896                              <1> syswait_0:
  2897 0000339A 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; 01/09/2015
  2898                              <1> 		; movb u.uno,r1 / put parents process number in r1
  2899 000033A1 D0E3                <1> 	shl	bl, 1
  2900                              <1> 	;shl	bx, 1
  2901                              <1> 		; asl r1 / x2 to get index into p.pid table
  2902 000033A3 668B83[F2620000]    <1> 	mov	ax, [ebx+p.pid-2]
  2903                              <1> 		; mov p.pid-2(r1),r1 / get the name of this process
  2904 000033AA 31F6                <1> 	xor	esi, esi
  2905                              <1> 		; clr r2
  2906 000033AC 31C9                <1> 	xor	ecx, ecx ; 30/10/2013
  2907                              <1> 	;xor 	cl, cl
  2908                              <1> 		; clr r3 / initialize reg 3
  2909                              <1> syswait_1: ; 1:
  2910                              <1> 	; 09/02/2022
  2911 000033AE 46                  <1> 	inc	esi
  2912 000033AF 46                  <1> 	inc	esi
  2913                              <1> 	;add	si, 2
  2914                              <1> 		; add $2,r2 / use r2 for index into p.ppid table
  2915                              <1> 			  ; / search table of parent processes 
  2916                              <1> 			  ; / for this process name
  2917 000033B0 663B86[12630000]    <1> 	cmp	ax, [esi+p.ppid-2]
  2918                              <1> 		; cmp p.ppid-2(r2),r1 / r2 will contain the childs 
  2919                              <1> 			            ; / process number
  2920 000033B7 7531                <1> 	jne	short syswait_3
  2921                              <1> 		;bne 3f / branch if no match of parent process name
  2922                              <1> 	;inc	cx
  2923 000033B9 FEC1                <1> 	inc	cl
  2924                              <1> 		;inc r3 / yes, a match, r3 indicates number of children
  2925                              <1> 	; 09/02/2022
  2926 000033BB D1EE                <1> 	shr	esi, 1
  2927                              <1> 	;shr	si, 1
  2928                              <1> 		; asr r2 / r2/2 to get index to p.stat table
  2929                              <1> 	; The possible states ('p.stat' values) of a process are:
  2930                              <1> 	;	0 = free or unused
  2931                              <1> 	;	1 = active
  2932                              <1> 	;	2 = waiting for a child process to die
  2933                              <1> 	;	3 = terminated, but not yet waited for (zombie).	
  2934 000033BD 80BE[53630000]03    <1> 	cmp	byte [esi+p.stat-1], 3 ; SZOMB, 05/02/2014
  2935                              <1> 		; cmpb p.stat-1(r2),$3 / is the child process a zombie?
  2936 000033C4 7522                <1> 	jne	short syswait_2
  2937                              <1> 		; bne 2f / no, skip it
  2938 000033C6 88BE[53630000]      <1> 	mov	[esi+p.stat-1], bh ; 0
  2939                              <1> 		; clrb p.stat-1(r2) / yes, free it
  2940                              <1> 	; 09/02/2022
  2941 000033CC D1E6                <1> 	shl	esi, 1
  2942                              <1> 	;shl	si, 1
  2943                              <1> 		; asl r2 / r2x2 to get index into p.pid table
  2944 000033CE 0FB786[F2620000]    <1> 	movzx	eax, word [esi+p.pid-2]
  2945 000033D5 A3[DC650000]        <1> 	mov	[u.r0], eax
  2946                              <1> 		; mov p.pid-2(r2),*u.r0 
  2947                              <1> 			      ; / put childs process name in (u.r0)
  2948                              <1> 	;
  2949                              <1> 	; Retro UNIX 386 v1 modification ! (17/09/2015)
  2950                              <1> 	;
  2951                              <1> 	; Parent process ID -p.ppid- field (of the child process)
  2952                              <1> 	; must be cleared in order to prevent infinitive 'syswait'
  2953                              <1> 	; system call loop from the application/program if it calls
  2954                              <1> 	; 'syswait' again (mistakenly) while there is not a zombie
  2955                              <1> 	; or running child process to wait. ('forktest.s', 17/09/2015)
  2956                              <1> 	;
  2957                              <1> 	; Note: syswait will return with error if there is not a
  2958                              <1> 	;       zombie or running process to wait.	
  2959                              <1> 	;
  2960                              <1> 	;sub	ax, ax
  2961                              <1> 	; 08/01/2022
  2962 000033DA 29C0                <1> 	sub	eax, eax
  2963 000033DC 668986[12630000]    <1> 	mov 	[esi+p.ppid-2], ax ; 0 ; 17/09/2015
  2964 000033E3 E90BFEFFFF          <1> 	jmp	sysret0 ; ax = 0
  2965                              <1> 	;
  2966                              <1> 	;jmp	sysret
  2967                              <1> 		; br sysret1 / return cause child is dead
  2968                              <1> syswait_2: ; 2:
  2969                              <1> 	; 09/02/2022
  2970 000033E8 D1E6                <1> 	shl	esi, 1
  2971                              <1> 	;shl	si, 1
  2972                              <1> 		; asl r2 / r2x2 to get index into p.ppid table
  2973                              <1> syswait_3: ; 3:
  2974 000033EA 6683FE20            <1> 	cmp	si, nproc+nproc
  2975                              <1> 		; cmp r2,$nproc+nproc / have all processes been checked?
  2976 000033EE 72BE                <1> 	jb	short syswait_1
  2977                              <1> 		; blt 1b / no, continue search
  2978                              <1> 	;and	cx, cx
  2979 000033F0 20C9                <1> 	and	cl, cl
  2980                              <1> 		; tst r3 / one gets here if there are no children 
  2981                              <1> 		       ; / or children that are still active
  2982                              <1> 	; 30/10/2013
  2983 000033F2 7515                <1> 	jnz	short syswait_4
  2984                              <1> 	;jz	error
  2985                              <1> 		; beq error1 / there are no children, error
  2986 000033F4 890D[DC650000]      <1> 	mov	[u.r0], ecx ; 0
  2987                              <1> 	; 09/02/2022
  2988 000033FA C705[31660000]1B00- <1> 	mov	dword [u.error], ERR_MISC ; 27
  2988 00003402 0000                <1>
  2989                              <1> 			; miscellaneous/other errors
  2990 00003404 E9C8FDFFFF          <1> 	jmp	error
  2991                              <1> syswait_4:
  2992 00003409 8A1D[2B660000]      <1> 	mov	bl, [u.uno]
  2993                              <1> 		; movb u.uno,r1 / there are children so put 
  2994                              <1> 			      ; / parent process number in r1
  2995 0000340F FE83[53630000]      <1> 	inc	byte [ebx+p.stat-1] ; 2, SWAIT, 05/02/2014
  2996                              <1> 		; incb p.stat-1(r1) / it is waiting for 
  2997                              <1> 				  ; / other children to die
  2998                              <1> 	; 04/11/2013
  2999 00003415 E873110000          <1> 	call	swap
  3000                              <1> 		; jsr r0,swap / swap it out, because it's waiting
  3001 0000341A E97BFFFFFF          <1> 	jmp	syswait_0
  3002                              <1> 		; br syswait / wait on next process
  3003                              <1> 
  3004                              <1> sysfork: ; < create a new process >
  3005                              <1> 	; 26/02/2022
  3006                              <1> 	; 25/02/2022
  3007                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1)
  3008                              <1> 	; 18/09/2015
  3009                              <1> 	; 04/09/2015
  3010                              <1> 	; 02/09/2015
  3011                              <1> 	; 01/09/2015
  3012                              <1> 	; 28/08/2015
  3013                              <1> 	; 14/05/2015
  3014                              <1> 	; 10/05/2015
  3015                              <1> 	; 09/05/2015
  3016                              <1> 	; 06/05/2015 (Retro UNIX 386 v1 - Beginning)
  3017                              <1> 	; 24/05/2013 - 14/02/2014 (Retro UNIX 8086 v1)
  3018                              <1> 	;
  3019                              <1> 	; 'sysfork' creates a new process. This process is referred
  3020                              <1> 	; to as the child process. This new process core image is
  3021                              <1> 	; a copy of that of the caller of 'sysfork'. The only
  3022                              <1> 	; distinction is the return location and the fact that (u.r0)
  3023                              <1> 	; in the old process (parent) contains the process id (p.pid)
  3024                              <1> 	; of the new process (child). This id is used by 'syswait'.
  3025                              <1> 	; 'sysfork' works in the following manner: 	
  3026                              <1> 	;    1) The process status table (p.stat) is searched to find
  3027                              <1> 	;	a process number that is unused. If none are found
  3028                              <1> 	;	an error occurs.
  3029                              <1> 	;    2) when one is found, it becomes the child process number
  3030                              <1> 	;	and it's status (p.stat) is set to active.
  3031                              <1> 	;    3) If the parent had a control tty, the interrupt 
  3032                              <1> 	;	character in that tty buffer is cleared.
  3033                              <1> 	;    4) The child process is put on the lowest priority run 
  3034                              <1> 	;	queue via 'putlu'.
  3035                              <1> 	;    5) A new process name is gotten from 'mpid' (actually 
  3036                              <1> 	;	it is a unique number) and is put in the child's unique
  3037                              <1> 	;	identifier; process id (p.pid).
  3038                              <1> 	;    6) The process name of the parent is then obtained and
  3039                              <1> 	;	placed in the unique identifier of the parent process
  3040                              <1> 	;	name is then put in 'u.r0'.	
  3041                              <1> 	;    7) The child process is then written out on disk by
  3042                              <1> 	;	'wswap',i.e., the parent process is copied onto disk
  3043                              <1> 	;	and the child is born. (The child process is written 
  3044                              <1> 	;	out on disk/drum with 'u.uno' being the child process
  3045                              <1> 	;	number.)
  3046                              <1> 	;    8) The parent process number is then restored to 'u.uno'.
  3047                              <1> 	;    9) The child process name is put in 'u.r0'.
  3048                              <1> 	;   10) The pc on the stack sp + 18 is incremented by 2 to
  3049                              <1> 	;	create the return address for the parent process.
  3050                              <1> 	;   11) The 'u.fp' list as then searched to see what files
  3051                              <1> 	;	the parent has opened. For each file the parent has
  3052                              <1> 	;	opened, the corresponding 'fsp' entry must be updated
  3053                              <1> 	;	to indicate that the child process also has opened
  3054                              <1> 	;	the file. A branch to 'sysret' is then made.	 			 				
  3055                              <1> 	;
  3056                              <1> 	; Calling sequence:
  3057                              <1> 	;	from shell ?
  3058                              <1> 	; Arguments:
  3059                              <1> 	;	-
  3060                              <1> 	; Inputs: -
  3061                              <1> 	; Outputs: *u.r0 - child process name
  3062                              <1> 	; ...............................................................
  3063                              <1> 	;	
  3064                              <1> 	; Retro UNIX 8086 v1 modification: 
  3065                              <1> 	;	AX = r0 = PID (>0) (at the return of 'sysfork')
  3066                              <1> 	;	= process id of child a parent process returns
  3067                              <1> 	;	= process id of parent when a child process returns
  3068                              <1> 	;
  3069                              <1> 	;       In original UNIX v1, sysfork is called and returns as
  3070                              <1> 	;	in following manner: (with an example: c library, fork)
  3071                              <1> 	;	
  3072                              <1> 	;	1:
  3073                              <1> 	;		sys	fork
  3074                              <1> 	;			br 1f  / child process returns here
  3075                              <1> 	;		bes	2f     / parent process returns here
  3076                              <1> 	;		/ pid of new process in r0
  3077                              <1> 	;		rts	pc
  3078                              <1> 	;	2: / parent process condionally branches here
  3079                              <1> 	;		mov	$-1,r0 / pid = -1 means error return
  3080                              <1> 	;		rts	pc
  3081                              <1> 	;
  3082                              <1> 	;	1: / child process brances here
  3083                              <1> 	;		clr	r0   / pid = 0 in child process
  3084                              <1> 	;		rts	pc
  3085                              <1> 	;
  3086                              <1> 	;	In UNIX v7x86 (386) by Robert Nordier (1999)
  3087                              <1> 	;		// pid = fork();
  3088                              <1> 	;		//
  3089                              <1> 	;		// pid == 0 in child process; 
  3090                              <1> 	;		// pid == -1 means error return
  3091                              <1> 	;		// in child, 
  3092                              <1> 	;		//	parents id is in par_uid if needed
  3093                              <1> 	;		
  3094                              <1> 	;		_fork:
  3095                              <1> 	;			mov	$.fork,eax
  3096                              <1> 	;			int	$0x30
  3097                              <1> 	;			jmp	1f
  3098                              <1> 	;			jnc	2f
  3099                              <1> 	;			jmp	cerror
  3100                              <1> 	;		1:
  3101                              <1> 	;			mov	eax,_par_uid
  3102                              <1> 	;			xor	eax,eax
  3103                              <1> 	;		2:
  3104                              <1> 	;			ret
  3105                              <1> 	;
  3106                              <1> 	;	In Retro UNIX 8086 v1,
  3107                              <1> 	;	'sysfork' returns in following manner:
  3108                              <1> 	;	
  3109                              <1> 	;		mov	ax, sys_fork
  3110                              <1> 	;		mov	bx, offset @f ; routine for child
  3111                              <1> 	;		int	20h
  3112                              <1> 	;		jc	error
  3113                              <1> 	;		
  3114                              <1> 	;	; Routine for parent process here (just after 'jc')
  3115                              <1> 	;		mov	word ptr [pid_of_child], ax
  3116                              <1> 	;		jmp	next_routine_for_parent	
  3117                              <1> 	;
  3118                              <1> 	;	@@: ; routine for child process here				
  3119                              <1> 	;		....	
  3120                              <1> 	;	NOTE: 'sysfork' returns to specified offset
  3121                              <1> 	;	       for child process by using BX input.
  3122                              <1> 	;	      (at first, parent process will return then 
  3123                              <1> 	;	      child process will return -after swapped in-
  3124                              <1> 	;	      'syswait' is needed in parent process
  3125                              <1> 	;	      if return from child process will be waited for.)
  3126                              <1> 	;	  				
  3127                              <1> 	
  3128                              <1> ; / create a new process
  3129                              <1> 	; EBX = return address for child process 
  3130                              <1> 	     ; (Retro UNIX 8086 v1 modification !)
  3131 0000341F 31F6                <1> 	xor 	esi, esi
  3132                              <1> 		; clr r1
  3133                              <1> sysfork_1: ; 1: / search p.stat table for unused process number
  3134 00003421 46                  <1> 	inc	esi
  3135                              <1> 		; inc r1
  3136 00003422 80BE[53630000]00    <1> 	cmp	byte [esi+p.stat-1], 0 ; SFREE, 05/02/2014
  3137                              <1> 		; tstb p.stat-1(r1) / is process active, unused, dead
  3138 00003429 760B                <1> 	jna	short sysfork_2	
  3139                              <1> 		; beq 1f / it's unused so branch
  3140 0000342B 6683FE10            <1> 	cmp	si, nproc
  3141                              <1> 		; cmp r1,$nproc / all processes checked
  3142 0000342F 72F0                <1> 	jb	short sysfork_1
  3143                              <1> 		; blt 1b / no, branch back
  3144                              <1> 	;
  3145                              <1> 	; Retro UNIX 8086 v1. modification:
  3146                              <1> 	;	Parent process returns from 'sysfork' to address 
  3147                              <1> 	;	which is just after 'sysfork' system call in parent
  3148                              <1> 	;	process. Child process returns to address which is put
  3149                              <1> 	;	in BX register by parent process for 'sysfork'. 
  3150                              <1> 	;
  3151                              <1> 		;add $2,18.(sp) / add 2 to pc when trap occured, points
  3152                              <1> 		             ; / to old process return
  3153                              <1> 		; br error1 / no room for a new process
  3154                              <1> sysfork_0:
  3155 00003431 E99BFDFFFF          <1> 	jmp	error
  3156                              <1> sysfork_2: ; 1:
  3157 00003436 E88CF0FFFF          <1> 	call	allocate_page
  3158                              <1> 	;jc	error
  3159                              <1> 	; 08/01/2022
  3160 0000343B 72F4                <1> 	jc	short sysfork_0
  3161                              <1> 
  3162 0000343D 50                  <1> 	push	eax   ; UPAGE (user structure page) address
  3163                              <1> 	; Retro UNIX 386 v1 modification!
  3164 0000343E E87BF2FFFF          <1> 	call	duplicate_page_dir
  3165                              <1> 		; EAX = New page directory 
  3166 00003443 7308                <1> 	jnc	short sysfork_3
  3167 00003445 58                  <1> 	pop	eax   ; UPAGE (user structure page) address
  3168 00003446 E842F2FFFF          <1> 	call 	deallocate_page
  3169                              <1> 	;jmp	error
  3170                              <1> 	; 08/01/2022
  3171 0000344B EBE4                <1> 	jmp	short sysfork_0 ; error
  3172                              <1> sysfork_3:
  3173                              <1> 	; Retro UNIX 386 v1 modification !
  3174 0000344D 56                  <1> 	push	esi
  3175 0000344E E8B1110000          <1> 	call	wswap ; save current user (u) structure, user registers
  3176                              <1> 		      ; and interrupt return components (for IRET)
  3177 00003453 8705[35660000]      <1> 	xchg	eax, [u.pgdir] ; page directory of the child process
  3178 00003459 A3[39660000]        <1> 	mov	[u.ppgdir], eax ; page directory of the parent process
  3179 0000345E 5E                  <1> 	pop	esi
  3180 0000345F 58                  <1> 	pop	eax   ; UPAGE (user structure page) address
  3181                              <1> 		; [u.usp] = esp
  3182 00003460 89F7                <1> 	mov	edi, esi
  3183                              <1> 	;shl	di, 2
  3184                              <1> 	; 08/01/2022
  3185 00003462 C1E702              <1> 	shl	edi, 2
  3186 00003465 8987[60630000]      <1> 	mov	[edi+p.upage-4], eax ; memory page for 'user' struct
  3187 0000346B A3[2C660000]        <1> 	mov	[u.upage], eax ; memory page for 'user' struct (child)
  3188                              <1> 	; 28/08/2015
  3189 00003470 0FB605[2B660000]    <1> 	movzx	eax, byte [u.uno] ; parent process number
  3190                              <1> 		; movb u.uno,-(sp) / save parent process number
  3191 00003477 89C7                <1> 	mov	edi, eax
  3192 00003479 50                  <1>         push	eax ; ** 
  3193 0000347A 8A87[33630000]      <1> 	mov     al, [edi+p.ttyc-1] ; console tty (parent)
  3194                              <1> 		; 18/09/2015
  3195 00003480 8886[33630000]      <1> 	mov     [esi+p.ttyc-1], al ; set child's console tty
  3196                              <1> 	; 26/02/2022 (p.waitc is not used)
  3197                              <1> 	;mov	[esi+p.waitc-1], ah ; 0 ; reset child's wait channel
  3198                              <1> 	; 25/02/2022 (BugFix)
  3199                              <1> 	;mov	[esi+p.ttyc-1], ax ; al - set child's console tty
  3200                              <1> 	;			   ; ah - reset child's wait channel	
  3201 00003486 89F0                <1> 	mov	eax, esi
  3202 00003488 A2[2B660000]        <1> 	mov	[u.uno], al ; child process number
  3203                              <1> 		;movb r1,u.uno / set child process number to r1
  3204 0000348D FE86[53630000]      <1>         inc     byte [esi+p.stat-1] ; 1, SRUN, 05/02/2014
  3205                              <1> 		; incb p.stat-1(r1) / set p.stat entry for child 
  3206                              <1> 				; / process to active status
  3207                              <1> 		; mov u.ttyp,r2 / put pointer to parent process' 
  3208                              <1> 			      ; / control tty buffer in r2
  3209                              <1>                 ; beq 2f / branch, if no such tty assigned
  3210                              <1> 		; clrb 6(r2) / clear interrupt character in tty buffer
  3211                              <1> 	; 2:
  3212 00003493 53                  <1> 	push	ebx  ; * return address for the child process
  3213                              <1> 		     ; * Retro UNIX 8086 v1 feature only !	
  3214                              <1> 	; (Retro UNIX 8086 v1 modification!)
  3215                              <1> 		; mov $runq+4,r2
  3216 00003494 E8C1110000          <1> 	call	putlu 
  3217                              <1>  		; jsr r0,putlu / put child process on lowest priority 
  3218                              <1> 			   ; / run queue
  3219                              <1> 	; 08/01/2022
  3220 00003499 D1E6                <1> 	shl	esi, 1
  3221                              <1> 	;shl	si, 1
  3222                              <1> 		; asl r1 / multiply r1 by 2 to get index 
  3223                              <1> 		       ; / into p.pid table
  3224 0000349B 66FF05[CA650000]    <1> 	inc	word [mpid]
  3225                              <1> 		; inc mpid / increment m.pid; get a new process name
  3226 000034A2 66A1[CA650000]      <1> 	mov	ax, [mpid]
  3227 000034A8 668986[F2620000]    <1> 	mov	[esi+p.pid-2], ax
  3228                              <1> 		;mov mpid,p.pid-2(r1) / put new process name 
  3229                              <1> 				    ; / in child process' name slot
  3230 000034AF 5A                  <1> 	pop	edx  ; * return address for the child process
  3231                              <1> 		     ; * Retro UNIX 8086 v1 feature only !	
  3232 000034B0 5B                  <1>   	pop	ebx  ; **
  3233                              <1> 	;mov	ebx, [esp] ; ** parent process number
  3234                              <1> 		; movb (sp),r2 / put parent process number in r2
  3235                              <1> 	; 08/01/2022
  3236 000034B1 D1E3                <1> 	shl	ebx, 1
  3237                              <1> 	;shl 	bx, 1
  3238                              <1> 		; asl r2 / multiply by 2 to get index into below tables
  3239                              <1> 	;movzx eax, word [ebx+p.pid-2]
  3240 000034B3 668B83[F2620000]    <1> 	mov	ax, [ebx+p.pid-2]
  3241                              <1> 		; mov p.pid-2(r2),r2 / get process name of parent
  3242                              <1> 				   ; / process
  3243 000034BA 668986[12630000]    <1> 	mov	[esi+p.ppid-2], ax
  3244                              <1> 		; mov r2,p.ppid-2(r1) / put parent process name 
  3245                              <1> 			  ; / in parent process slot for child
  3246 000034C1 A3[DC650000]        <1> 	mov	[u.r0], eax	
  3247                              <1> 		; mov r2,*u.r0 / put parent process name on stack 
  3248                              <1> 			     ; / at location where r0 was saved
  3249 000034C6 8B2D[D4650000]      <1> 	mov 	ebp, [u.sp] ; points to return address (EIP for IRET)
  3250 000034CC 895500              <1> 	mov	[ebp], edx ; *, CS:EIP -> EIP
  3251                              <1> 			   ; * return address for the child process
  3252                              <1> 		; mov $sysret1,-(sp) /
  3253                              <1> 		; mov sp,u.usp / contents of sp at the time when 
  3254                              <1> 			      ; / user is swapped out
  3255                              <1> 		; mov $sstack,sp / point sp to swapping stack space
  3256                              <1> 	; 04/09/2015 - 01/09/2015
  3257                              <1> 	; [u.usp] = esp
  3258 000034CF 68[F1310000]        <1> 	push	sysret ; ***
  3259 000034D4 8925[D8650000]      <1> 	mov	[u.usp], esp ; points to 'sysret' address (***)
  3260                              <1> 			     ; (for child process)	
  3261 000034DA 31C0                <1> 	xor 	eax, eax
  3262 000034DC 66A3[0C660000]      <1> 	mov 	[u.ttyp], ax ; 0
  3263                              <1> 	;
  3264 000034E2 E81D110000          <1> 	call	wswap ; Retro UNIX 8086 v1 modification !
  3265                              <1> 		;jsr r0,wswap / put child process out on drum
  3266                              <1> 		;jsr r0,unpack / unpack user stack
  3267                              <1> 		;mov u.usp,sp / restore user stack pointer
  3268                              <1> 		; tst (sp)+ / bump stack pointer
  3269                              <1> 	; Retro UNIX 386 v1 modification !
  3270 000034E7 58                  <1> 	pop	eax ; ***
  3271                              <1> 	; 08/01/2022
  3272 000034E8 D1E3                <1> 	shl	ebx, 1
  3273                              <1> 	;shl 	bx, 1
  3274 000034EA 8B83[60630000]      <1> 	mov     eax, [ebx+p.upage-4] ; UPAGE address ; 14/05/2015
  3275 000034F0 E838110000          <1> 	call	rswap ; restore parent process 'u' structure, 
  3276                              <1> 		      ; registers and return address (for IRET)
  3277                              <1> 		;movb (sp)+,u.uno / put parent process number in u.uno
  3278 000034F5 0FB705[CA650000]    <1>         movzx   eax, word [mpid]
  3279 000034FC A3[DC650000]        <1> 	mov	[u.r0], eax
  3280                              <1> 		; mov mpid,*u.r0 / put child process name on stack 
  3281                              <1> 			       ; / where r0 was saved
  3282                              <1> 		; add $2,18.(sp) / add 2 to pc on stack; gives parent
  3283                              <1> 			          ; / process return
  3284                              <1> 	;xor	ebx, ebx
  3285 00003501 31F6                <1> 	xor     esi, esi
  3286                              <1> 		;clr r1
  3287                              <1> sysfork_4: ; 1: / search u.fp list to find the files 
  3288                              <1> 	      ; / opened by the parent process
  3289                              <1> 	; 01/09/2015
  3290                              <1> 	;xor	bh, bh
  3291                              <1> 	;mov 	bl, [esi+u.fp]
  3292 00003503 8A86[E2650000]      <1> 	mov 	al, [esi+u.fp]
  3293                              <1> 		; movb u.fp(r1),r2 / get an open file for this process
  3294                              <1>         ;or	bl, bl
  3295 00003509 08C0                <1> 	or	al, al
  3296 0000350B 740C                <1> 	jz	short sysfork_5	
  3297                              <1> 		; beq 2f / file has not been opened by parent, 
  3298                              <1> 		       ; / so branch
  3299 0000350D B40A                <1> 	mov	ah, 10 ; Retro UNIX 386 v1 fsp structure size = 10 bytes
  3300 0000350F F6E4                <1> 	mul	ah
  3301                              <1> 	;;movzx	ebx, ax
  3302                              <1> 	;mov	bx, ax
  3303 00003511 89C3                <1> 	mov	ebx, eax ; 08/01/2022
  3304                              <1> 	;shl	bx, 3
  3305                              <1> 		; asl r2 / multiply by 8
  3306                              <1>        		; asl r2 / to get index into fsp table
  3307                              <1>        		; asl r2
  3308 00003513 FE83[A2630000]      <1>   	inc     byte [ebx+fsp-2]
  3309                              <1> 		; incb fsp-2(r2) / increment number of processes
  3310                              <1> 			     ; / using file, because child will now be
  3311                              <1> 			     ; / using this file
  3312                              <1> sysfork_5: ; 2:
  3313 00003519 46                  <1>         inc     esi
  3314                              <1> 		; inc r1 / get next open file
  3315 0000351A 6683FE0A            <1>         cmp     si, 10
  3316                              <1> 		; cmp r1,$10. / 10. files is the maximum number which
  3317                              <1> 			  ; / can be opened
  3318 0000351E 72E3                <1> 	jb	short sysfork_4	
  3319                              <1> 		; blt 1b / check next entry
  3320 00003520 E9CCFCFFFF          <1> 	jmp	sysret
  3321                              <1> 		; br sysret1
  3322                              <1> 
  3323                              <1> sysread: ; < read from file >
  3324                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3325                              <1> 	; 13/05/2015
  3326                              <1> 	; 11/05/2015 (Retro UNIX 386 v1 - Beginning)
  3327                              <1> 	; 23/05/2013 (Retro UNIX 8086 v1)
  3328                              <1> 	;
  3329                              <1> 	; 'sysread' is given a buffer to read into and the number of
  3330                              <1> 	; characters to be read. If finds the file from the file
  3331                              <1> 	; descriptor located in *u.r0 (r0). This file descriptor
  3332                              <1> 	; is returned from a successful open call (sysopen).
  3333                              <1> 	; The i-number of file is obtained via 'rw1' and the data
  3334                              <1> 	; is read into core via 'readi'.
  3335                              <1> 	;
  3336                              <1> 	; Calling sequence:
  3337                              <1> 	;	sysread; buffer; nchars
  3338                              <1> 	; Arguments:
  3339                              <1> 	;	buffer - location of contiguous bytes where 
  3340                              <1> 	;		 input will be placed.
  3341                              <1> 	;	nchars - number of bytes or characters to be read.
  3342                              <1> 	; Inputs: *u.r0 - file descriptor (& arguments)
  3343                              <1> 	; Outputs: *u.r0 - number of bytes read.	
  3344                              <1> 	; ...............................................................
  3345                              <1> 	;				
  3346                              <1> 	; Retro UNIX 8086 v1 modification: 
  3347                              <1> 	;       'sysread' system call has three arguments; so,
  3348                              <1> 	;	* 1st argument, file descriptor is in BX register
  3349                              <1> 	;	* 2nd argument, buffer address/offset in CX register
  3350                              <1> 	;	* 3rd argument, number of bytes is in DX register
  3351                              <1> 	;
  3352                              <1> 	;	AX register (will be restored via 'u.r0') will return
  3353                              <1> 	;	to the user with number of bytes read. 
  3354                              <1> 	;
  3355 00003525 E840000000          <1> 	call	rw1
  3356                              <1> 	;jc	error ; 13/05/2015, ax < 1
  3357                              <1> 	;	; jsr r0,rw1 / get i-number of file to be read into r1
  3358                              <1>        	; 24/12/2021
  3359 0000352A 7239                <1> 	jc	short sysread_err
  3360 0000352C F6C480              <1> 	test	ah, 80h
  3361                              <1> 		; tst r1 / negative i-number?
  3362 0000352F 752A                <1> 	jnz	short rw3 ; 24/12/2021
  3363                              <1> 	;jnz	error
  3364                              <1> 		; ble error1 / yes, error 1 to read
  3365                              <1> 			   ; / it should be positive
  3366 00003531 E88B150000          <1> 	call	readi
  3367                              <1> 		; jsr r0,readi / read data into core
  3368 00003536 EB14                <1> 	jmp	short rw0
  3369                              <1> 		; br 1f
  3370                              <1> 
  3371                              <1> syswrite: ; < write to file >
  3372                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3373                              <1> 	; 13/05/2015
  3374                              <1> 	; 11/05/2015 (Retro UNIX 386 v1 - Beginning)
  3375                              <1> 	; 23/05/2013 (Retro UNIX 8086 v1)
  3376                              <1> 	;
  3377                              <1> 	; 'syswrite' is given a buffer to write onto an output file
  3378                              <1> 	; and the number of characters to write. If finds the file
  3379                              <1> 	; from the file descriptor located in *u.r0 (r0). This file 
  3380                              <1> 	; descriptor is returned from a successful open or create call
  3381                              <1> 	; (sysopen or syscreat). The i-number of file is obtained via
  3382                              <1> 	; 'rw1' and buffer is written on the output file via 'write'.
  3383                              <1> 	;
  3384                              <1> 	; Calling sequence:
  3385                              <1> 	;	syswrite; buffer; nchars
  3386                              <1> 	; Arguments:
  3387                              <1> 	;	buffer - location of contiguous bytes to be writtten.
  3388                              <1> 	;	nchars - number of characters to be written.
  3389                              <1> 	; Inputs: *u.r0 - file descriptor (& arguments)
  3390                              <1> 	; Outputs: *u.r0 - number of bytes written.	
  3391                              <1> 	; ...............................................................
  3392                              <1> 	;				
  3393                              <1> 	; Retro UNIX 8086 v1 modification: 
  3394                              <1> 	;       'syswrite' system call has three arguments; so,
  3395                              <1> 	;	* 1st argument, file descriptor is in BX register
  3396                              <1> 	;	* 2nd argument, buffer address/offset in CX register
  3397                              <1> 	;	* 3rd argument, number of bytes is in DX register
  3398                              <1> 	;
  3399                              <1> 	;	AX register (will be restored via 'u.r0') will return
  3400                              <1> 	;	to the user with number of bytes written. 
  3401                              <1> 	;
  3402 00003538 E82D000000          <1> 	call	rw1
  3403                              <1> 	;jc	error ; 13/05/2015, ax < 1
  3404                              <1> 	;	; jsr r0,rw1 / get i-number in r1 of file to write
  3405                              <1>        	; 24/12/2021
  3406 0000353D 7226                <1> 	jc	short syswrite_err
  3407 0000353F F6C480              <1>         test	ah, 80h
  3408                              <1> 		; tst r1 / positive i-number ?
  3409 00003542 7417                <1>         jz	short rw3 ; 13/05/2015
  3410                              <1> 	;jz	error
  3411                              <1> 		; bge error1 / yes, error 1 
  3412                              <1> 			   ; / negative i-number means write
  3413 00003544 66F7D8              <1>         neg	ax
  3414                              <1> 		; neg r1 / make it positive
  3415 00003547 E863170000          <1> 	call	writei
  3416                              <1>         	; jsr r0,writei / write data
  3417                              <1> rw0: ; 1:
  3418 0000354C A1[04660000]        <1>         mov	eax, [u.nread]
  3419 00003551 A3[DC650000]        <1> 	mov	[u.r0], eax
  3420                              <1> 		; mov u.nread,*u.r0 / put no. of bytes transferred
  3421                              <1> 				  ; / into (u.r0)
  3422 00003556 E996FCFFFF          <1> 	jmp	sysret
  3423                              <1>         	; br sysret1
  3424                              <1> 
  3425                              <1> rw3: 
  3426                              <1> 	; 13/05/2015
  3427 0000355B C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS ; permission denied !
  3427 00003563 0000                <1>
  3428                              <1> 	;stc
  3429                              <1> 	;retn
  3430                              <1> 	; 24/12/2021 (BugFix)
  3431                              <1> sysread_err:
  3432                              <1> syswrite_err:
  3433 00003565 E967FCFFFF          <1> 	jmp	error
  3434                              <1> 
  3435                              <1> rw1:	
  3436                              <1> 	; 14/05/2015
  3437                              <1> 	; 13/05/2015
  3438                              <1> 	; 11/05/2015 (Retro UNIX 386 v1 - Beginning)
  3439                              <1> 	; 23/05/2013 - 24/05/2013 (Retro UNIX 8086 v1)
  3440                              <1> 	; System call registers: bx, cx, dx (through 'sysenter')
  3441                              <1> 	;
  3442                              <1> 	;mov	[u.base], ecx 	; buffer address/offset 
  3443                              <1> 				;(in the user's virtual memory space)
  3444                              <1> 	;mov	[u.count], edx 
  3445                              <1> 		; jsr r0,arg; u.base / get buffer pointer
  3446                              <1>         	; jsr r0,arg; u.count / get no. of characters
  3447                              <1> 	;;mov	eax, ebx ; file descriptor
  3448                              <1> 		; mov *u.r0,r1 / put file descriptor 
  3449                              <1> 		             ; / (index to u.fp table) in r1
  3450                              <1> 	; 13/05/2015
  3451 0000356A C705[DC650000]0000- <1> 	mov	dword [u.r0], 0 ; r/w transfer count = 0 (reset)
  3451 00003572 0000                <1>
  3452                              <1> 	;
  3453                              <1> 	;; call	getf
  3454                              <1>         ; eBX = File descriptor
  3455 00003574 E8330B0000          <1> 	call	getf1 ; calling point in 'getf' from 'rw1'
  3456                              <1> 		; jsr r0,getf / get i-number of the file in r1
  3457                              <1> 	; AX = I-number of the file ; negative i-number means write
  3458                              <1> 	; 13/05/2015
  3459 00003579 6683F801            <1> 	cmp 	ax, 1
  3460 0000357D 7217                <1> 	jb	short rw2
  3461                              <1> 	;
  3462 0000357F 890D[FC650000]      <1> 	mov	[u.base], ecx 	; buffer address/offset 
  3463                              <1> 				;(in the user's virtual memory space)
  3464 00003585 8915[00660000]      <1> 	mov	[u.count], edx 
  3465                              <1> 	; 14/05/2015
  3466 0000358B C705[31660000]0000- <1>         mov     dword [u.error], 0 ; reset the last error code
  3466 00003593 0000                <1>
  3467 00003595 C3                  <1> 	retn
  3468                              <1>         	; rts r0
  3469                              <1> rw2:
  3470                              <1> 	; 13/05/2015
  3471 00003596 C705[31660000]0A00- <1> 	mov	dword [u.error], ERR_FILE_NOT_OPEN ; file not open !
  3471 0000359E 0000                <1>
  3472 000035A0 C3                  <1> 	retn
  3473                              <1> 
  3474                              <1> sysopen: ;<open file>
  3475                              <1> 	; 09/01/2022
  3476                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3477                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3478                              <1> 	; 22/05/2013 - 27/05/2013 (Retro UNIX 8086 v1)
  3479                              <1> 	;
  3480                              <1> 	; 'sysopen' opens a file in following manner:
  3481                              <1> 	;    1) The second argument in a sysopen says whether to
  3482                              <1> 	;	open the file ro read (0) or write (>0).
  3483                              <1> 	;    2) I-node of the particular file is obtained via 'namei'.
  3484                              <1> 	;    3) The file is opened by 'iopen'.
  3485                              <1> 	;    4) Next housekeeping is performed on the fsp table
  3486                              <1> 	;	and the user's open file list - u.fp.
  3487                              <1> 	;	a) u.fp and fsp are scanned for the next available slot.
  3488                              <1> 	;	b) An entry for the file is created in the fsp table.
  3489                              <1> 	;	c) The number of this entry is put on u.fp list.
  3490                              <1> 	;	d) The file descriptor index to u.fp list is pointed
  3491                              <1> 	;	   to by u.r0.
  3492                              <1> 	;
  3493                              <1> 	; Calling sequence:
  3494                              <1> 	;	sysopen; name; mode
  3495                              <1> 	; Arguments:
  3496                              <1> 	;	name - file name or path name
  3497                              <1> 	;	mode - 0 to open for reading
  3498                              <1> 	;	       1 to open for writing
  3499                              <1> 	; Inputs: (arguments)
  3500                              <1> 	; Outputs: *u.r0 - index to u.fp list (the file descriptor)
  3501                              <1> 	;		  is put into r0's location on the stack.	
  3502                              <1> 	; ...............................................................
  3503                              <1> 	;				
  3504                              <1> 	; Retro UNIX 8086 v1 modification: 
  3505                              <1> 	;       'sysopen' system call has two arguments; so,
  3506                              <1> 	;	* 1st argument, name is pointed to by BX register
  3507                              <1> 	;	* 2nd argument, mode is in CX register
  3508                              <1> 	;
  3509                              <1> 	;	AX register (will be restored via 'u.r0') will return
  3510                              <1> 	;	to the user with the file descriptor/number 
  3511                              <1> 	;	(index to u.fp list).
  3512                              <1> 	;
  3513                              <1> 	;call	arg2
  3514                              <1> 	; * name - 'u.namep' points to address of file/path name
  3515                              <1> 	;          in the user's program segment ('u.segmnt')
  3516                              <1> 	;          with offset in BX register (as sysopen argument 1).
  3517                              <1> 	; * mode - sysopen argument 2 is in CX register 
  3518                              <1> 	;          which is on top of stack.
  3519                              <1> 	;
  3520                              <1> 	; jsr r0,arg2 / get sys args into u.namep and on stack
  3521                              <1> 	;
  3522                              <1>        	; system call registers: ebx, ecx (through 'sysenter')
  3523                              <1> 
  3524 000035A1 891D[F4650000]      <1> 	mov	[u.namep], ebx
  3525                              <1> 	; 24/12/2021 (cx -> ecx)
  3526 000035A7 51                  <1> 	push	ecx ; * 
  3527 000035A8 E8300B0000          <1> 	call	namei
  3528                              <1> 		; jsr r0,namei / i-number of file in r1
  3529                              <1>      	;and	ax, ax
  3530                              <1> 	;jz	error ; File not found
  3531 000035AD 7239                <1> 	jc	short fnotfound ; 14/05/2015
  3532                              <1> 	;jc	error ; 27/05/2013
  3533                              <1> 		; br  error2 / file not found
  3534                              <1>    	; 24/12/2021
  3535                              <1> 	;pop	edx ; * ; mode
  3536                              <1> 	;push	edx ; *
  3537 000035AF 8B1424              <1> 	mov	edx, [esp] ; *
  3538                              <1> 	; edx = open mode (0 or 1)
  3539                              <1> 	;or	dx, dx
  3540 000035B2 08D2                <1> 	or	dl, dl
  3541                              <1> 		; tst (sp) / is mode = 0 (2nd arg of call; 
  3542                              <1> 		         ; / 0 means, open for read)
  3543 000035B4 7403                <1> 	jz	short sysopen_0
  3544                              <1> 		; beq 1f / yes, leave i-number positive
  3545                              <1> syscreat_0: ; 27/12/2015
  3546 000035B6 66F7D8              <1> 	neg	ax
  3547                              <1>         	; neg r1 / open for writing so make i-number negative
  3548                              <1> sysopen_0: ;1:
  3549 000035B9 E8891B0000          <1> 	call	iopen
  3550                              <1> 		;jsr r0,iopen / open file whose i-number is in r1
  3551 000035BE 5A                  <1> 	pop	edx ; * ; mode ; 24/12/2021
  3552                              <1> 	;and	dx, dx
  3553 000035BF 20D2                <1> 	and	dl, dl
  3554                              <1>         	; tst (sp)+ / pop the stack and test the mode
  3555 000035C1 7403                <1> 	jz	short sysopen_2
  3556                              <1>         	; beq op1 / is open for read op1
  3557                              <1> sysopen_1: ;op0:
  3558 000035C3 66F7D8              <1> 	neg	ax
  3559                              <1>         	; neg r1 
  3560                              <1> 	;; NOTE: iopen always make i-number positive.
  3561                              <1> 	;; Here i-number becomes negative again. [22/05/2013]
  3562                              <1> sysopen_2: ;op1:
  3563 000035C6 31F6                <1>         xor     esi, esi
  3564                              <1>         	; clr r2 / clear registers
  3565 000035C8 31DB                <1>         xor     ebx, ebx
  3566                              <1> 		; clr r3
  3567                              <1> sysopen_3: ;1: / scan the list of entries in fsp table
  3568 000035CA 389E[E2650000]      <1>         cmp     [esi+u.fp], bl ; 0
  3569                              <1> 		; tstb u.fp(r2) / test the entry in the u.fp list
  3570 000035D0 7625                <1>         jna      short sysopen_4
  3571                              <1> 		; beq 1f / if byte in list is 0 branch
  3572 000035D2 46                  <1>         inc     esi
  3573                              <1> 		; inc r2 / bump r2 so next byte can be checked
  3574 000035D3 6683FE0A            <1>         cmp     si, 10  ; OPENFILES
  3575                              <1> 		; cmp r2,$10. / reached end of list?
  3576 000035D7 72F1                <1> 	jb	short sysopen_3
  3577                              <1> 		; blt 1b / no, go back
  3578                              <1> toomanyf:
  3579                              <1> 	; 14/05/2015
  3580 000035D9 C705[31660000]0D00- <1> 	mov	dword [u.error], ERR_TOO_MANY_FILES ; too many open files !
  3580 000035E1 0000                <1>
  3581 000035E3 E9E9FBFFFF          <1> 	jmp	error
  3582                              <1>         	; br error2 / yes, error (no files open)
  3583                              <1> fnotfound: 
  3584                              <1> 	; 14/05/2015
  3585 000035E8 C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND ; file not found !
  3585 000035F0 0000                <1>
  3586 000035F2 E9DAFBFFFF          <1> 	jmp	error
  3587                              <1> 
  3588                              <1> sysopen_4: ; 1:
  3589 000035F7 6683BB[A4630000]00  <1>         cmp     word [ebx+fsp], 0
  3590                              <1> 		; tst fsp(r3) / scan fsp entries
  3591 000035FF 760D                <1>         jna     short sysopen_5
  3592                              <1> 		; beq 1f / if 0 branch
  3593                              <1> 	; 14/05/2015 - Retro UNIX 386 v1 modification !
  3594 00003601 6683C30A            <1>         add     bx, 10 ; fsp structure size = 10 bytes/entry
  3595                              <1> 		; add $8.,r3 / add 8 to r3 
  3596                              <1> 			; / to bump it to next entry mfsp table
  3597 00003605 6681FBF401          <1>         cmp     bx, nfiles*10
  3598                              <1> 		; cmp r3,$[nfiles*8.] / done scanning
  3599 0000360A 72EB                <1> 	jb	short sysopen_4
  3600                              <1>        		; blt 1b / no, back
  3601                              <1> 	;jmp	error
  3602                              <1>         ;	; br error2 / yes, error
  3603                              <1> 	; 24/12/2021
  3604 0000360C EBCB                <1> 	jmp	short toomanyf
  3605                              <1> 
  3606                              <1> sysopen_5: ; 1: / r2 has index to u.fp list; r3, has index to fsp table
  3607 0000360E 668983[A4630000]    <1>         mov     [ebx+fsp], ax
  3608                              <1> 		; mov r1,fsp(r3) / put i-number of open file 
  3609                              <1> 			; / into next available entry in fsp table,
  3610                              <1> 	; 09/01/2022
  3611                              <1> 	;mov	di, [cdev] ; word ? byte ?
  3612                              <1>         ;mov	[ebx+fsp+2], di ; device number
  3613                              <1> 		; mov cdev,fsp+2(r3) / put # of device in next word
  3614                              <1> 	;xor	edi, edi
  3615                              <1>         ;mov	[ebx+fsp+4], edi ; offset pointer (0)
  3616                              <1> 	;	; clr fsp+4(r3)
  3617                              <1>         ;mov	[ebx+fsp+8], di ; open count (0), deleted flag (0)
  3618                              <1>        	;	; clr fsp+6(r3) / clear the next two words
  3619 00003615 31C0                <1> 	xor	eax, eax
  3620 00003617 8983[A8630000]      <1> 	mov	[ebx+fsp+4], eax ; offset pointer (0)
  3621 0000361D 668983[AC630000]    <1> 	mov	[ebx+fsp+8], ax ; open count (0), deleted flag (0)
  3622                              <1> 
  3623 00003624 A0[C3650000]        <1> 	mov	al, [cdev]
  3624 00003629 668983[A6630000]    <1> 	mov	[ebx+fsp+2], ax ; device number
  3625                              <1> 
  3626 00003630 89D8                <1>   	mov	eax, ebx
  3627 00003632 B30A                <1> 	mov	bl, 10
  3628 00003634 F6F3                <1> 	div	bl 
  3629                              <1> 		; asr r3
  3630                              <1> 		; asr r3 / divide by 8 
  3631                              <1> 		; asr r3 ; / to get number of the fsp entry-1
  3632 00003636 FEC0                <1> 	inc	al
  3633                              <1>         	; inc r3 / add 1 to get fsp entry number
  3634 00003638 8886[E2650000]      <1>         mov     [esi+u.fp], al
  3635                              <1> 		; movb r3,u.fp(r2) / move entry number into 
  3636                              <1> 			; / next available slot in u.fp list
  3637 0000363E 8935[DC650000]      <1>         mov     [u.r0], esi
  3638                              <1> 		; mov r2,*u.r0 / move index to u.fp list 
  3639                              <1> 			     ; / into r0 loc on stack
  3640 00003644 E9A8FBFFFF          <1>         jmp	sysret
  3641                              <1> 		; br sysret2
  3642                              <1> 
  3643                              <1> 	;
  3644                              <1> 	; 'fsp' table (10 bytes/entry)
  3645                              <1> 	; bit 15				   bit 0
  3646                              <1> 	; ---|-------------------------------------------
  3647                              <1> 	; r/w|		i-number of open file
  3648                              <1> 	; ---|-------------------------------------------
  3649                              <1> 	;		   device number
  3650                              <1> 	; -----------------------------------------------
  3651                              <1> 	; offset pointer, r/w pointer to file (bit 0-15)
  3652                              <1> 	; -----------------------------------------------
  3653                              <1> 	; offset pointer, r/w pointer to file (bit 16-31)
  3654                              <1> 	; ----------------------|------------------------
  3655                              <1> 	;  flag that says file 	| number of processes
  3656                              <1> 	;   has been deleted	| that have file open 
  3657                              <1> 	; ----------------------|------------------------
  3658                              <1> 	;
  3659                              <1> 
  3660                              <1> syscreat: ; < create file >
  3661                              <1> 	; 24/12/2021
  3662                              <1> 	; 27/12/2015 (Retro UNIX 386 v1.1)
  3663                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3664                              <1> 	; 27/05/2013 (Retro UNIX 8086 v1)
  3665                              <1> 	;
  3666                              <1> 	; 'syscreat' called with two arguments; name and mode.
  3667                              <1> 	; u.namep points to name of the file and mode is put
  3668                              <1> 	; on the stack. 'namei' is called to get i-number of the file.		
  3669                              <1> 	; If the file aready exists, it's mode and owner remain 
  3670                              <1> 	; unchanged, but it is truncated to zero length. If the file
  3671                              <1> 	; did not exist, an i-node is created with the new mode via
  3672                              <1> 	; 'maknod' whether or not the file already existed, it is
  3673                              <1> 	; open for writing. The fsp table is then searched for a free
  3674                              <1> 	; entry. When a free entry is found, proper data is placed
  3675                              <1> 	; in it and the number of this entry is put in the u.fp list.
  3676                              <1> 	; The index to the u.fp (also know as the file descriptor)
  3677                              <1> 	; is put in the user's r0. 			
  3678                              <1> 	;
  3679                              <1> 	; Calling sequence:
  3680                              <1> 	;	syscreate; name; mode
  3681                              <1> 	; Arguments:
  3682                              <1> 	;	name - name of the file to be created
  3683                              <1> 	;	mode - mode of the file to be created
  3684                              <1> 	; Inputs: (arguments)
  3685                              <1> 	; Outputs: *u.r0 - index to u.fp list 
  3686                              <1> 	;		   (the file descriptor of new file)
  3687                              <1> 	; ...............................................................
  3688                              <1> 	;				
  3689                              <1> 	; Retro UNIX 8086 v1 modification: 
  3690                              <1> 	;       'syscreate' system call has two arguments; so,
  3691                              <1> 	;	* 1st argument, name is pointed to by BX register
  3692                              <1> 	;	* 2nd argument, mode is in CX register
  3693                              <1> 	;
  3694                              <1> 	;	AX register (will be restored via 'u.r0') will return
  3695                              <1> 	;	to the user with the file descriptor/number 
  3696                              <1> 	;	(index to u.fp list).
  3697                              <1> 	;
  3698                              <1> 	;call	arg2
  3699                              <1> 	; * name - 'u.namep' points to address of file/path name
  3700                              <1> 	;          in the user's program segment ('u.segmnt')
  3701                              <1> 	;          with offset in BX register (as sysopen argument 1).
  3702                              <1> 	; * mode - sysopen argument 2 is in CX register 
  3703                              <1> 	;          which is on top of stack.
  3704                              <1> 	;
  3705                              <1>         	; jsr r0,arg2 / put file name in u.namep put mode 
  3706                              <1> 			    ; / on stack
  3707 00003649 891D[F4650000]      <1> 	mov	[u.namep], ebx ; file name address
  3708                              <1> 	;push	cx ; mode
  3709                              <1> 	; 24/12/2021
  3710 0000364F 51                  <1> 	push	ecx ; cx = mode (permission flags)
  3711 00003650 E8880A0000          <1> 	call 	namei        	
  3712                              <1> 		; jsr r0,namei / get the i-number
  3713                              <1>         ;and	ax, ax
  3714                              <1> 	;jz	short syscreat_2	       	
  3715 00003655 721B                <1> 	jc	short syscreat_2
  3716                              <1> 		; br  2f / if file doesn't exist 2f
  3717                              <1> 	; 27/12/2015
  3718 00003657 6683F829            <1> 	cmp	ax, 41 ; device inode ?
  3719                              <1>         ;jb	syscreat_0 ; yes
  3720                              <1> 	; 24/12/2021
  3721 0000365B 7305                <1> 	jnb	short syscreat_1
  3722 0000365D E954FFFFFF          <1> 	jmp	syscreat_0
  3723                              <1> syscreat_1:
  3724 00003662 66F7D8              <1> 	neg 	ax
  3725                              <1>         	; neg r1 / if file already exists make i-number 
  3726                              <1> 		       ; / negative (open for writing)
  3727 00003665 E8DD1A0000          <1> 	call	iopen
  3728                              <1>         	; jsr r0,iopen /
  3729 0000366A E8AA130000          <1> 	call	itrunc
  3730                              <1>         	; jsr r0,itrunc / truncate to 0 length
  3731                              <1> 	;pop	cx ; pop mode (did not exist in original Unix v1 !?)
  3732                              <1> 	; 04/12/2021
  3733 0000366F 59                  <1> 	pop	ecx
  3734                              <1> 	; 08/01/2022
  3735 00003670 EB0E                <1> 	jmp	short syscreat_3
  3736                              <1>         ;jmp	sysopen_1
  3737                              <1>         	; br op0
  3738                              <1> syscreat_2: ; 2: / file doesn't exist
  3739                              <1> 	;pop	ax
  3740                              <1>         ;	; mov (sp)+,r1 / put the mode in r1
  3741                              <1> 	; 24/12/2021
  3742 00003672 58                  <1> 	pop	eax  ; ax = mode (permission flags)
  3743 00003673 30E4                <1> 	xor	ah, ah	
  3744                              <1>         	; bic $!377,r1 / clear upper byte
  3745 00003675 E86F0D0000          <1> 	call 	maknod
  3746                              <1>         	; jsr r0,maknod / make an i-node for this file
  3747 0000367A 66A1[0E660000]      <1> 	mov	ax, [u.dirbuf]
  3748                              <1>         	; mov u.dirbuf,r1 / put i-number 
  3749                              <1> 			        ; / for this new file in r1
  3750                              <1> syscreat_3:
  3751 00003680 E93EFFFFFF          <1>         jmp     sysopen_1
  3752                              <1>         	; br op0 / open the file
  3753                              <1> 
  3754                              <1> sysmkdir: ; < make directory >
  3755                              <1> 	; 26/02/2022
  3756                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3757                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3758                              <1> 	; 27/05/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  3759                              <1> 	;
  3760                              <1> 	; 'sysmkdir' creates an empty directory whose name is
  3761                              <1> 	; pointed to by arg 1. The mode of the directory is arg 2.	
  3762                              <1> 	; The special entries '.' and '..' are not present.
  3763                              <1> 	; Errors are indicated if the directory already exists or		
  3764                              <1> 	; user is not the super user. 
  3765                              <1> 	;
  3766                              <1> 	; Calling sequence:
  3767                              <1> 	;	sysmkdir; name; mode
  3768                              <1> 	; Arguments:
  3769                              <1> 	;	name - points to the name of the directory
  3770                              <1> 	;	mode - mode of the directory
  3771                              <1> 	; Inputs: (arguments)
  3772                              <1> 	; Outputs: -
  3773                              <1> 	;    (sets 'directory' flag to 1; 
  3774                              <1> 	;    'set user id on execution' and 'executable' flags to 0)
  3775                              <1> 	; ...............................................................
  3776                              <1> 	;				
  3777                              <1> 	; Retro UNIX 8086 v1 modification: 
  3778                              <1> 	;       'sysmkdir' system call has two arguments; so,
  3779                              <1> 	;	* 1st argument, name is pointed to by BX register
  3780                              <1> 	;	* 2nd argument, mode is in CX register
  3781                              <1> 	;
  3782                              <1> 		
  3783                              <1> ; / make a directory
  3784                              <1> 
  3785                              <1> 	;call	arg2
  3786                              <1> 	; * name - 'u.namep' points to address of file/path name
  3787                              <1> 	;          in the user's program segment ('u.segmnt')
  3788                              <1> 	;          with offset in BX register (as sysopen argument 1).
  3789                              <1> 	; * mode - sysopen argument 2 is in CX register 
  3790                              <1> 	;          which is on top of stack.
  3791                              <1> 
  3792                              <1> 		; jsr r0,arg2 / put file name in u.namep put mode 
  3793                              <1> 			    ; / on stack
  3794 00003685 891D[F4650000]      <1> 	mov	[u.namep], ebx
  3795                              <1> 	;push	cx ; mode
  3796                              <1> 	; 24/12/2021
  3797 0000368B 51                  <1> 	push	ecx ; cx = mode
  3798 0000368C E84C0A0000          <1> 	call	namei
  3799                              <1>         	; jsr r0,namei / get the i-number
  3800                              <1>         	;     br .+4 / if file not found branch around error
  3801                              <1>         ;xor 	ax, ax
  3802                              <1> 	;jnz	error
  3803 00003691 731B                <1> 	jnc	short dir_exists ; 14/05/2015
  3804                              <1> 	;jnc	error	
  3805                              <1> 		; br  error2 / directory already exists (error)
  3806 00003693 803D[28660000]00    <1> 	cmp	byte [u.uid], 0 ; 02/08/2013
  3807                              <1>         	;tstb u.uid / is user the super user
  3808                              <1> 	;jna	short dir_access_err ; 14/05/2015
  3809                              <1> 	;;jna	error
  3810                              <1> 	; 26/02/2022 (BugFix)
  3811 0000369A 7721                <1> 	ja	short dir_access_err
  3812                              <1>         	;bne error2 / no, not allowed
  3813                              <1> 	;pop	ax
  3814                              <1>         ;	;mov (sp)+,r1 / put the mode in r1
  3815                              <1> 	; 24/12/2021
  3816 0000369C 58                  <1> 	pop	eax  ; ax = mode
  3817 0000369D 6683E0CF            <1> 	and	ax, 0FFCFh ; 1111111111001111b
  3818                              <1>         	;bic $!317,r1 / all but su and ex
  3819                              <1> 	;or	ax, 4000h ; 1011111111111111b
  3820 000036A1 80CC40              <1> 	or	ah, 40h ; Set bit 14 to 1
  3821                              <1>         	;bis $40000,r1 / directory flag
  3822 000036A4 E8400D0000          <1> 	call	maknod
  3823                              <1>         	;jsr r0,maknod / make the i-node for the directory
  3824                              <1> ;sysclose_sysret: ; 26/02/2022
  3825 000036A9 E943FBFFFF          <1> 	jmp	sysret
  3826                              <1>         	;br sysret2 /
  3827                              <1> dir_exists:
  3828                              <1> 	; 14/05/2015
  3829 000036AE C705[31660000]0E00- <1> 	mov	dword [u.error], ERR_DIR_EXISTS ; dir. already exists !
  3829 000036B6 0000                <1>
  3830 000036B8 E914FBFFFF          <1> 	jmp	error
  3831                              <1> dir_access_err:
  3832                              <1> 	; 14/05/2015
  3833 000036BD C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_DIR_ACCESS ; permission denied !
  3833 000036C5 0000                <1>
  3834 000036C7 E905FBFFFF          <1> 	jmp	error
  3835                              <1> 
  3836                              <1> sysclose: ;<close file>
  3837                              <1> 	; 26/02/2022
  3838                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3839                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3840                              <1> 	; 22/05/2013 - 26/05/2013 (Retro UNIX 8086 v1)
  3841                              <1> 	;
  3842                              <1> 	; 'sysclose', given a file descriptor in 'u.r0', closes the
  3843                              <1> 	; associated file. The file descriptor (index to 'u.fp' list)
  3844                              <1> 	; is put in r1 and 'fclose' is called.
  3845                              <1> 	;
  3846                              <1> 	; Calling sequence:
  3847                              <1> 	;	sysclose
  3848                              <1> 	; Arguments:
  3849                              <1> 	;	-  
  3850                              <1> 	; Inputs: *u.r0 - file descriptor
  3851                              <1> 	; Outputs: -
  3852                              <1> 	; ...............................................................
  3853                              <1> 	;				
  3854                              <1> 	; Retro UNIX 8086 v1 modification:
  3855                              <1> 	;	 The user/application program puts file descriptor
  3856                              <1> 	;        in BX register as 'sysclose' system call argument.
  3857                              <1> 	; 	 (argument transfer method 1)
  3858                              <1> 
  3859                              <1> 	; / close the file
  3860                              <1> 	
  3861 000036CC 89D8                <1> 	mov 	eax, ebx
  3862 000036CE E896090000          <1> 	call 	fclose
  3863                              <1> 		; mov *u.r0,r1 / move index to u.fp list into r1
  3864                              <1> 		; jsr r0,fclose / close the file
  3865                              <1>                	; br error2 / unknown file descriptor
  3866                              <1> 		; br sysret2
  3867                              <1> 	; 14/05/2015
  3868                              <1> 	;jnc	sysret
  3869                              <1> 	; 04/12/2021
  3870 000036D3 7205                <1> 	jc	short sysclose_err
  3871 000036D5 E917FBFFFF          <1> 	jmp	sysret
  3872                              <1> 	; 26/02/2022
  3873                              <1> 	;jnc	short sysclose_sysret
  3874                              <1> sysclose_err:
  3875 000036DA C705[31660000]0A00- <1> 	mov	dword [u.error], ERR_FILE_NOT_OPEN ; file not open !
  3875 000036E2 0000                <1>
  3876 000036E4 E9E8FAFFFF          <1> 	jmp	error
  3877                              <1> 
  3878                              <1> sysemt:
  3879                              <1> 	; 26/02/2022
  3880                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3881                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3882                              <1> 	; 10/12/2013 - 20/04/2014 (Retro UNIX 8086 v1)
  3883                              <1> 	;
  3884                              <1> 	; Retro UNIX 8086 v1 modification: 
  3885                              <1> 	;	'Enable Multi Tasking'  system call instead 
  3886                              <1> 	;	of 'Emulator Trap' in original UNIX v1 for PDP-11.
  3887                              <1> 	;
  3888                              <1> 	; Retro UNIX 8086 v1 feature only!
  3889                              <1> 	;	Using purpose: Kernel will start without time-out
  3890                              <1> 	;	(internal clock/timer) functionality.
  3891                              <1> 	;	Then etc/init will enable clock/timer for
  3892                              <1> 	;	multi tasking. (Then it will not be disabled again
  3893                              <1> 	;	except hardware reset/restart.)
  3894                              <1> 	;
  3895                              <1> 
  3896 000036E9 803D[28660000]00    <1> 	cmp	byte [u.uid], 0 ; root ?
  3897                              <1> 	;;ja	error
  3898                              <1> 	;ja	badsys ; 14/05/2015
  3899                              <1> 	; 24/12/2021
  3900 000036F0 7605                <1> 	jna	short emt_0 
  3901 000036F2 E98CFBFFFF          <1> 	jmp	badsys
  3902                              <1> emt_0:
  3903                              <1> 	; 24/12/2021
  3904                              <1> 	;cli
  3905 000036F7 21DB                <1> 	and	ebx, ebx
  3906 000036F9 7429                <1> 	jz	short emt_2
  3907                              <1> 	; Enable multi tasking -time sharing-
  3908 000036FB B8[A2460000]        <1> 	mov	eax, clock
  3909                              <1> 	; 26/02/2022
  3910 00003700 BA[2C0A0000]        <1> 	mov	edx, rtci_default ; disable rtc (digital) printing
  3911                              <1> emt_1:
  3912 00003705 A3[F1060000]        <1> 	mov	[x_timer], eax
  3913                              <1> 	; 26/02/2022 (Temporary)
  3914 0000370A 8915[F5060000]      <1> 	mov	[x_rtci], edx
  3915 00003710 B306                <1> 	mov	bl, 6  ; timer interrupt page, video page 6
  3916 00003712 E851020000          <1> 	call	wttyc  ; clear video page
  3917 00003717 B307                <1> 	mov	bl, 7  ; rtc interrupt page, video page 7
  3918 00003719 E84A020000          <1> 	call	wttyc  ; clear video page
  3919                              <1> 	;
  3920 0000371E FB                  <1> 	sti
  3921 0000371F E9CDFAFFFF          <1> 	jmp	sysret
  3922                              <1> emt_2:
  3923                              <1> 	; Disable multi tasking -time sharing-
  3924 00003724 B8[FD060000]        <1> 	mov	eax, u_timer ; enable timer tick printing
  3925                              <1> 	; 26/02/2022
  3926 00003729 BA[330A0000]        <1> 	mov	edx, rtc_p   ; enable rtc (digital) printing
  3927                              <1> 	;
  3928 0000372E EBD5                <1> 	jmp	short emt_1
  3929                              <1> 
  3930                              <1> 	; Original UNIX v1 'sysemt' routine
  3931                              <1> ;sysemt:
  3932                              <1>         ;
  3933                              <1> 	;jsr    r0,arg; 30 / put the argument of the sysemt call 
  3934                              <1> 			 ; / in loc 30
  3935                              <1>         ;cmp    30,$core / was the argument a lower address 
  3936                              <1> 			; / than core
  3937                              <1>         ;blo    1f / yes, rtssym
  3938                              <1>         ;cmp    30,$ecore / no, was it higher than "core" 
  3939                              <1> 			; / and less than "ecore"
  3940                              <1>         ;blo    2f / yes, sysret2
  3941                              <1> ;1:
  3942                              <1>         ;mov    $rtssym,30
  3943                              <1> ;2:
  3944                              <1>         ;br     sysret2
  3945                              <1> 
  3946                              <1> sysilgins:
  3947                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  3948                              <1> 	; 03/06/2013
  3949                              <1> 	; Retro UNIX 8086 v1 modification: 
  3950                              <1> 	;	not a valid system call ! (not in use)
  3951                              <1> 	;
  3952 00003730 E94EFBFFFF          <1> 	jmp	badsys
  3953                              <1> 	;jmp	error
  3954                              <1> 	;;jmp 	sysret
  3955                              <1> 
  3956                              <1> 	; Original UNIX v1 'sysemt' routine
  3957                              <1> ;sysilgins: / calculate proper illegal instruction trap address
  3958                              <1>         ;jsr    r0,arg; 10 / take address from sysilgins call
  3959                              <1> 			  ;/ put it in loc 8.,
  3960                              <1>         ;cmp    10,$core / making it the illegal instruction 
  3961                              <1> 		       ; / trap address
  3962                              <1>         ;blo    1f / is the address a user core address?  
  3963                              <1> 		; / yes, go to 2f
  3964                              <1>         ;cmp    10,$ecore
  3965                              <1>         ;blo    2f
  3966                              <1> ;1:
  3967                              <1>         ;mov    $fpsym,10 / no, make 'fpsum' the illegal 
  3968                              <1> 		    ; / instruction trap address for the system
  3969                              <1> ;2:
  3970                              <1>         ;br     sysret2 / return to the caller via 'sysret'
  3971                              <1> 
  3972                              <1> sysmdate: ; < change the modification time of a file >
  3973                              <1> 	; 23/02/2022 (Retro UNIX 386 v1 feature/modification)
  3974                              <1> 	;	(ECX input)
  3975                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3976                              <1> 	; 16/05/2015 (Retro UNIX 386 v1 - Beginning)
  3977                              <1> 	; 03/06/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  3978                              <1> 	;
  3979                              <1> 	; 'sysmdate' is given a file name. It gets inode of this 
  3980                              <1> 	; file into core. The user is checked if he is the owner 
  3981                              <1> 	; or super user. If he is neither an error occurs.
  3982                              <1> 	; 'setimod' is then called to set the i-node modification
  3983                              <1> 	; byte and the modification time, but the modification time
  3984                              <1> 	; is overwritten by whatever get put on the stack during
  3985                              <1> 	; a 'systime' system call. This calls are restricted to
  3986                              <1> 	; the super user.		
  3987                              <1> 	;
  3988                              <1> 	; Calling sequence:
  3989                              <1> 	;	sysmdate; name
  3990                              <1> 	; Arguments:
  3991                              <1> 	;	name - points to the name of file
  3992                              <1> 	; Inputs: (arguments)
  3993                              <1> 	; Outputs: -
  3994                              <1> 	; ...............................................................
  3995                              <1> 	;				
  3996                              <1> 	; Retro UNIX 8086 v1 modification: 
  3997                              <1> 	;	 The user/application program puts address 
  3998                              <1> 	;	 of the file name in BX register 
  3999                              <1> 	;	 as 'sysmdate' system call argument.
  4000                              <1> 	;
  4001                              <1> ; / change the modification time of a file
  4002                              <1> 		; jsr r0,arg; u.namep / point u.namep to the file name
  4003 00003735 891D[F4650000]      <1>         mov	[u.namep], ebx
  4004                              <1> 	; 23/02/2022 - (Retro UNIX 386 v1 modification on unix v1 code)
  4005 0000373B 890D[60620000]      <1> 	mov	[p_time], ecx ; save new modification time to be set 
  4006 00003741 E897090000          <1> 	call	namei
  4007                              <1> 		; jsr r0,namei / get its i-number
  4008                              <1> 	;;jc	error       
  4009                              <1> 	;	; br error2 / no, such file
  4010                              <1> 	;jc	fnotfound ; file not found !
  4011                              <1> 	; 24/12/2021
  4012 00003746 7305                <1> 	jnc	short mdate_0
  4013 00003748 E99BFEFFFF          <1> 	jmp	fnotfound
  4014                              <1> mdate_0:
  4015 0000374D E89B110000          <1> 	call	iget
  4016                              <1> 		; jsr r0,iget / get i-node into core
  4017 00003752 A0[28660000]        <1> 	mov	al, [u.uid]
  4018 00003757 3A05[D7620000]      <1> 	cmp	al, [i.uid]
  4019                              <1>         	; cmpb u.uid,i.uid / is user same as owner
  4020 0000375D 7413                <1> 	je	short mdate_1
  4021                              <1>         	; beq 1f / yes
  4022 0000375F 20C0                <1> 	and	al, al
  4023                              <1> 		; tstb u.uid / no, is user the super user
  4024                              <1> 	;jnz	error
  4025                              <1> 		; bne error2 / no, error
  4026 00003761 740F                <1> 	jz	short mdate_1
  4027 00003763 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS ; permission denied !
  4027 0000376B 0000                <1>
  4028                              <1> sysstty_err:	; 04/02/2022
  4029 0000376D E95FFAFFFF          <1> 	jmp	error
  4030                              <1> mdate_1: ;1:
  4031 00003772 E880120000          <1> 	call	setimod
  4032                              <1>         	; jsr r0,setimod / fill in modification data,
  4033                              <1> 		               ; / time etc.
  4034 00003777 BE[60620000]        <1> 	mov	esi, p_time
  4035 0000377C BF[EE620000]        <1> 	mov	edi, i.mtim
  4036 00003781 A5                  <1> 	movsd
  4037                              <1> 		; mov 4(sp),i.mtim / move present time to
  4038                              <1>         	; mov 2(sp),i.mtim+2 / modification time
  4039 00003782 E96AFAFFFF          <1>         jmp	sysret
  4040                              <1> 		; br sysret2
  4041                              <1> 
  4042                              <1> 	; 04/02/2022
  4043                              <1> sysstty_err_s:
  4044 00003787 880D[DC650000]      <1> 	mov	byte [u.r0], cl ; serial port's tty number
  4045 0000378D EBDE                <1> 	jmp	short sysstty_err
  4046                              <1> 
  4047                              <1> sysstty: ; < set tty status and mode >
  4048                              <1> 	; 26/02/2022
  4049                              <1> 	; 04/02/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  4050                              <1> 	; 02/02/2022 (Retro UNIX 386 v1, Kernel v0.2.0.18)
  4051                              <1> 	; 01/02/2022 (Retro UNIX 386 v1) -clear screen-
  4052                              <1> 	; 17/11/2015
  4053                              <1> 	; 12/11/2015
  4054                              <1> 	; 29/10/2015
  4055                              <1> 	; 17/10/2015
  4056                              <1> 	; 13/10/2015
  4057                              <1> 	; 29/06/2015
  4058                              <1> 	; 27/06/2015 (Retro UNIX 386 v1 - Beginning)
  4059                              <1> 	; 02/06/2013 - 12/07/2014 (Retro UNIX 8086 v1)
  4060                              <1> 	;
  4061                              <1> 	; 'sysstty' sets the status and mode of the typewriter 
  4062                              <1> 	; whose file descriptor is in (u.r0).
  4063                              <1> 	;
  4064                              <1> 	; Calling sequence:
  4065                              <1> 	;	sysstty; arg
  4066                              <1> 	; Arguments:
  4067                              <1> 	;	arg - address of 3 consequitive words that contain
  4068                              <1> 	;	      the source of status data	
  4069                              <1> 	; Inputs: ((*u.r0 - file descriptor & argument))
  4070                              <1> 	; Outputs: ((status in address which is pointed to by arg))
  4071                              <1> 	; ...............................................................
  4072                              <1> 	;	
  4073                              <1> 	; Retro UNIX 8086 v1 modification: 
  4074                              <1> 	;	'sysstty' system call will set the tty
  4075                              <1> 	;	(clear keyboard buffer and set cursor position)
  4076                              <1> 	;	 in following manner:
  4077                              <1> 	;   NOTE: All of tty setting functions are here (16/01/2014)
  4078                              <1> 	;
  4079                              <1> 	; Inputs:
  4080                              <1> 	;	BX = 0 --> means
  4081                              <1> 	;	   If CL = FFh (& DX <> 0FFFFh) ; 01/02/2022
  4082                              <1> 	;	      set cursor position for console tty, only 
  4083                              <1> 	;	      CH will be ignored (char. will not be written)	
  4084                              <1> 	;	   If CH = 0 (& DX <> 0FFFFh & CL < FFh) ; 01/02/20222
  4085                              <1> 	;	      set console tty for (current) process
  4086                              <1> 	;	      CL = tty number (0 to 9)
  4087                              <1> 	;	      (If CH = 0, character will not be written)			
  4088                              <1> 	;          If CH > 0 (CL < FFh)	
  4089                              <1> 	;             CL = tty number (0 to 9)
  4090                              <1> 	;	      CH = character will be written
  4091                              <1> 	;	        at requested cursor position (in DX)	
  4092                              <1> 	;	   DX = cursor position for tty number 0 to 7.	
  4093                              <1>   	;		(only tty number 0 to 7) 
  4094                              <1> 	;          DL = communication parameters (for serial ports) 
  4095                              <1> 	;	        (only for COM1 and COM2 serial ports)
  4096                              <1> 	;	   DH < 0FFh -> DL is valid, initialize serial port
  4097                              <1> 	;			or set cursor position	
  4098                              <1> 	;	   DH = 0FFh -> DL is not valid
  4099                              <1> 	;		do not set serial port parameters 
  4100                              <1> 	;		or do not set cursor position
  4101                              <1> 	;
  4102                              <1> 	;	BX > 0 --> points to name of tty
  4103                              <1> 	;    	   CH > 0 -->
  4104                              <1> 	;		CH = character will be written in current 
  4105                              <1> 	;            	cursor position (for tty number from 0 to 7)
  4106                              <1> 	;	     	or character will be sent to serial port
  4107                              <1> 	;	     	(for tty number 8 or 9)
  4108                              <1> 	;		CL = color of the character if tty number < 8.
  4109                              <1> 	;    	   CH = 0 --> Do not write a character, 
  4110                              <1> 	;		set mode (tty 8 to 9) or 
  4111                              <1> 	;		set current cursor positions (tty 0 to 7) only.
  4112                              <1> 	;   	   DX = cursor position for tty number 0 to 7.
  4113                              <1> 	;    	   DH = FFh --> Do not set cursor pos (or comm. params.)
  4114                              <1> 	;		(DL is not valid)
  4115                              <1> 	;	   DL = communication parameters 
  4116                              <1> 	;		for tty number 8 or 9 (COM1 or COM2).
  4117                              <1> 	;
  4118                              <1> 	;	01/02/2022 - Retro UNIX 386 v1 - 2022 modification
  4119                              <1> 	;	(30/01/2022 - Retro UNIX 8086 - 2022 modification)
  4120                              <1> 	;	If CH = 0 & DX = 0FFFFh -> 
  4121                              <1> 	;	   clear screen (video page) & set cursor pos to 0,0.
  4122                              <1> 	;	   (for tty number 0 to 7, CL <= 7)
  4123                              <1> 	;	   (if CL = 0FFh -> clear console tty)	
  4124                              <1> 	;
  4125                              <1> 	; Outputs:
  4126                              <1> 	;	cf = 0 -> OK
  4127                              <1> 	;	     AL = tty number (0 to 9)
  4128                              <1> 	;	     AH = line status if tty number is 8 or 9
  4129                              <1> 	;	     AH = process number (of the caller) 	
  4130                              <1> 	;	cf = 1 means error (requested tty is not ready)
  4131                              <1> 	;	     AH = FFh if the tty is locked 
  4132                              <1> 	;		  (owned by another process)
  4133                              <1> 	;	        = process number (of the caller) 
  4134                              <1> 	;		  (if < FFh and tty number < 8)
  4135                              <1> 	;	     AL = tty number (0FFh if it does not exist)
  4136                              <1> 	;	     AH = line status if tty number is 8 or 9
  4137                              <1> 	;	NOTE: Video page will be cleared if cf = 0.
  4138                              <1> 	;	
  4139                              <1> 
  4140                              <1> 	; 27/06/2015 (32 bit modifications)
  4141                              <1> 	; 14/01/2014
  4142 0000378F 31C0                <1> 	xor 	eax, eax
  4143 00003791 6648                <1> 	dec	ax ; 17/10/2015
  4144 00003793 A3[DC650000]        <1> 	mov	[u.r0], eax ; 0FFFFh
  4145                              <1> 	;;;
  4146                              <1> 	; 01/02/2022
  4147 00003798 FEC1                <1> 	inc	cl  ; 0FFh -> 0, 7 -> 8
  4148 0000379A 39C2                <1> 	cmp	edx, eax
  4149                              <1> 	;cmp	dx, ax ; 0FFFFh
  4150 0000379C 7521                <1> 	jne	short sysstty_18
  4151                              <1> 	; clear video page
  4152                              <1> 	; (CH must be 0)
  4153 0000379E 08ED                <1> 	or	ch, ch
  4154 000037A0 75CB                <1> 	jnz	short sysstty_err ; invalid parameters
  4155 000037A2 80F908              <1> 	cmp	cl, 8 ; > tty7 (serial port?)
  4156 000037A5 77C6                <1> 	ja	short sysstty_err ; invalid parameters
  4157 000037A7 20C9                <1> 	and	cl, cl
  4158 000037A9 7514                <1> 	jnz	short sysstty_18 ; actual tty (video page) num + 1
  4159 000037AB 0FB635[2B660000]    <1> 	movzx	esi, byte [u.uno]
  4160 000037B2 8A8E[33630000]      <1> 	mov	cl, byte [esi+p.ttyc-1] ; current/console tty
  4161 000037B8 80F907              <1> 	cmp	cl, 7
  4162 000037BB 77CA                <1> 	ja	short sysstty_err_s ; serial port !	 
  4163                              <1> 	; here CL contains (actual) tty number (tty0 to tty7) 
  4164 000037BD FEC1                <1> 	inc	cl  ; 0 -> 1, 7 -> 8 
  4165                              <1> sysstty_18:
  4166 000037BF FEC9                <1> 	dec	cl  ; 8 -> 7, 1 -> 0
  4167                              <1> 	; cl = video page (tty) number		
  4168                              <1> 	;;;
  4169 000037C1 21DB                <1> 	and	ebx, ebx
  4170                              <1> 	;jnz	sysstty_6
  4171                              <1> 	; 01/02/2022
  4172 000037C3 7405                <1> 	jz	short sysstty_19
  4173 000037C5 E9C2000000          <1> 	jmp	sysstty_6
  4174                              <1> sysstty_19:
  4175                              <1> 	; set console tty
  4176                              <1> 	; 29/10/2015
  4177                              <1> 	; 17/01/2014 
  4178 000037CA 80F909              <1> 	cmp	cl, 9
  4179 000037CD 7613                <1> 	jna	short sysstty_0
  4180                              <1> 	; 17/11/2015
  4181 000037CF 80F9FF              <1> 	cmp	cl, 0FFh
  4182 000037D2 7202                <1> 	jb	short sysstty_13
  4183 000037D4 88CD                <1> 	mov	ch, cl ; force CH value to FFh 
  4184                              <1> sysstty_13:
  4185 000037D6 8A1D[2B660000]      <1> 	mov	bl, [u.uno] ; process number
  4186 000037DC 8A8B[33630000]      <1> 	mov	cl, [ebx+p.ttyc-1] ; current/console tty
  4187                              <1> sysstty_0:
  4188                              <1> 	; 29/06/2015
  4189                              <1> 	;push	dx
  4190                              <1> 	;push	cx
  4191                              <1> 	; 01/02/2022
  4192 000037E2 52                  <1> 	push	edx
  4193 000037E3 51                  <1> 	push	ecx
  4194 000037E4 30D2                <1> 	xor 	dl, dl	; sysstty call sign
  4195 000037E6 88C8                <1> 	mov	al, cl
  4196 000037E8 A2[DC650000]        <1> 	mov	[u.r0], al ; tty number (0 to 9)
  4197 000037ED E8EF190000          <1> 	call	ottyp
  4198                              <1> 	; 01/02/2022
  4199 000037F2 59                  <1> 	pop	ecx
  4200 000037F3 5A                  <1> 	pop	edx
  4201                              <1> 	;pop	cx
  4202                              <1> 	;pop	dx
  4203                              <1> 	;
  4204 000037F4 7220                <1> 	jc	short sysstty_pd_err
  4205                              <1> 	;
  4206                              <1> 	; 26/02/2022 (Bug! BugFix)
  4207                              <1> 	; (ebx = ?, modified in ottyp, it may be > 255)
  4208                              <1> 	;
  4209 000037F6 80F908              <1> 	cmp	cl, 8
  4210 000037F9 720C                <1> 	jb	short sysstty_2
  4211                              <1> 	;
  4212 000037FB 80FEFF              <1> 	cmp	dh, 0FFh
  4213 000037FE 7407                <1> 	je	short sysstty_2
  4214                              <1> 		; set communication parameters for serial ports
  4215                              <1> 
  4216                              <1> ; 01/02/2022
  4217                              <1> ;	; 29/10/2015
  4218                              <1> ;	mov	ah, dl ; communication parameters
  4219                              <1> ;		; ah = 0E3h = 11100011b = 115200 baud,
  4220                              <1> ;		;			 THRE int + RDA int 
  4221                              <1> ;		; ah = 23h = 00100011b = 9600 baud,
  4222                              <1> ;		;			 THRE int + RDA int 
  4223                              <1> ;	sub	al, al ; 0
  4224                              <1> ;	; 12/07/2014
  4225                              <1> ;	cmp	cl, 9
  4226                              <1> ;	jb	short sysstty_1
  4227                              <1> ;	inc	al
  4228                              <1> ;sysstty_1:
  4229                              <1> ;	; 01/02/2022
  4230                              <1> ;	push	ecx
  4231                              <1> ;	;push	cx
  4232                              <1> ;	; 29/06/2015	
  4233                              <1> ;	call 	sp_setp ; Set serial port communication parameters
  4234                              <1> ;	mov	[u.r0+1], cx ; Line status (ah)
  4235                              <1> ;			     ; Modem status (EAX bits 16 to 23)
  4236                              <1> ;	; 01/02/2022
  4237                              <1> ;	pop	ecx	
  4238                              <1> ;	;pop	cx
  4239                              <1> ;       jc      short sysstty_tmout_err ; 29/10/2015
  4240                              <1> 
  4241                              <1> 	; 01/02/2022
  4242 00003800 E830010000          <1> 	call	sysstty_scp
  4243 00003805 7276                <1>         jc      short sysstty_tmout_err ; 29/10/2015
  4244                              <1> 
  4245                              <1> sysstty_2:
  4246                              <1> 	; 17/01/2014
  4247 00003807 20ED                <1> 	and	ch, ch 	; set cursor position 
  4248                              <1> 			; or comm. parameters ONLY
  4249 00003809 7527                <1> 	jnz	short sysstty_3
  4250                              <1> 	; 01/02/2022
  4251 0000380B 6683FAFF            <1> 	cmp	dx, 0FFFFh
  4252 0000380F 7214                <1> 	jb	short sysstty_20
  4253                              <1> 	; clear screen (video page)
  4254 00003811 E93B010000          <1> 	jmp	sysstty_14
  4255                              <1> 
  4256                              <1> sysstty_pd_err: ; 29/06/2015
  4257                              <1> 	; 'permission denied !' error
  4258 00003816 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_NOT_OWNER
  4258 0000381E 0000                <1>
  4259 00003820 E9ACF9FFFF          <1> 	jmp	error
  4260                              <1> 
  4261                              <1> sysstty_20:
  4262 00003825 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  4263 0000382C 888B[33630000]      <1> 	mov	[ebx+p.ttyc-1], cl ; console tty
  4264                              <1> sysstty_3:
  4265                              <1> 	; 16/01/2014
  4266 00003832 88E8                <1> 	mov	al, ch ; character ; 0 to FFh
  4267                              <1> 	; 17/11/2015
  4268 00003834 B507                <1> 	mov 	ch, 7  ; Default color (light gray)
  4269 00003836 38E9                <1> 	cmp	cl, ch ; 7 (tty number)
  4270                              <1> 	;jna	sysstty_9
  4271                              <1> 	; 01/02/2022
  4272 00003838 7705                <1> 	ja	short sysstty_12
  4273 0000383A E9C5000000          <1> 	jmp	sysstty_9
  4274                              <1> 
  4275                              <1> sysstty_12:
  4276                              <1> 	;; BX = 0, CL = 8 or CL = 9
  4277                              <1> 	; (Set specified serial port as console tty port)
  4278                              <1> 	; CH = character to be written
  4279                              <1> 	; 15/04/2014
  4280                              <1> 	; CH = 0 --> initialization only
  4281                              <1> 	; AL = character
  4282                              <1> 	; 26/06/2014
  4283 0000383F 880D[30660000]      <1> 	mov	[u.ttyn], cl
  4284                              <1> 	; 12/07/2014
  4285 00003845 88CC                <1> 	mov	ah, cl ; tty number (8 or 9)
  4286                              <1> 	; 02/02/2022
  4287 00003847 FEC0                <1> 	inc	al  ; 0FFh -> 0, 0 -> 1
  4288 00003849 740B                <1> 	jz	short sysstty_4 ; al = ch = 0	
  4289 0000384B FEC8                <1> 	dec	al  ; 1 -> 0	
  4290                              <1> 	;and	al, al
  4291 0000384D 7407                <1> 	jz	short sysstty_4 ; al = ch = 0
  4292                              <1>  	; 04/07/2014
  4293 0000384F E89B1E0000          <1> 	call 	sndc
  4294                              <1> 	; 12/07/2014
  4295 00003854 EB0C                <1> 	jmp	short sysstty_5
  4296                              <1> 
  4297                              <1> sysstty_4:
  4298                              <1> 	; 12/07/2014
  4299                              <1> 	;xchg 	ah, al ; al = 0 -> al = ah, ah = 0
  4300 00003856 88E0                <1> 	mov	al, ah ; 29/06/2015
  4301 00003858 2C08                <1> 	sub	al, 8
  4302                              <1> 	; 27/06/2015
  4303 0000385A E828F4FFFF          <1> 	call	sp_status ; get serial port status
  4304                              <1> 	; AL = Line status, AH = Modem status
  4305                              <1> 	; 12/11/2015
  4306 0000385F 3C80                <1> 	cmp	al, 80h
  4307 00003861 F5                  <1> 	cmc
  4308                              <1> sysstty_5:
  4309 00003862 66A3[DD650000]      <1> 	mov	[u.r0+1], ax ; ah = line status
  4310                              <1> 		; EAX bits 16-23 = modem status	
  4311 00003868 9C                  <1> 	pushf
  4312 00003869 30D2                <1> 	xor	dl, dl ; sysstty call sign
  4313 0000386B A0[30660000]        <1> 	mov	al, [u.ttyn] ; 26/06/2014
  4314 00003870 E88F1A0000          <1> 	call	cttyp
  4315 00003875 9D                  <1> 	popf
  4316                              <1> 	;jnc	sysret ; time out error 
  4317                              <1> 	; 01/02/2022
  4318 00003876 7205                <1> 	jc	short sysstty_tmout_err
  4319 00003878 E974F9FFFF          <1> 	jmp	sysret
  4320                              <1> 
  4321                              <1> sysstty_tmout_err:
  4322 0000387D C705[31660000]1900- <1> 	mov	dword [u.error], ERR_TIME_OUT
  4322 00003885 0000                <1>
  4323 00003887 E945F9FFFF          <1> 	jmp	error
  4324                              <1> 
  4325                              <1> sysstty_6:
  4326                              <1> 	;push	dx
  4327                              <1> 	;push	cx
  4328                              <1> 	; 01/02/2022
  4329 0000388C 52                  <1> 	push	edx
  4330 0000388D 51                  <1> 	push	ecx
  4331 0000388E 891D[F4650000]      <1> 	mov	[u.namep], ebx
  4332 00003894 E844080000          <1> 	call	namei
  4333                              <1> 	; 01/02/2022
  4334 00003899 59                  <1> 	pop	ecx
  4335 0000389A 5A                  <1> 	pop	edx
  4336                              <1> 	;pop	cx
  4337                              <1> 	;pop	dx
  4338 0000389B 7258                <1> 	jc	short sysstty_inv_dn
  4339                              <1> 	;
  4340 0000389D 6683F813            <1> 	cmp	ax, 19  ; inode number of /dev/COM2
  4341 000038A1 7752                <1> 	ja	short sysstty_inv_dn ; 27/06/2015
  4342                              <1> 	;
  4343 000038A3 3C0A                <1> 	cmp	al, 10 ; /dev/tty0 .. /dev/tty7
  4344                              <1> 		       ; /dev/COM1, /dev/COM2
  4345 000038A5 7204                <1> 	jb	short sysstty_7
  4346 000038A7 2C0A                <1> 	sub	al, 10
  4347 000038A9 EB11                <1> 	jmp	short sysstty_8
  4348                              <1> 
  4349                              <1> sysstty_7:
  4350 000038AB 3C01                <1> 	cmp	al, 1 ; /dev/tty
  4351 000038AD 7546                <1> 	jne	short sysstty_inv_dn ; 27/06/2015
  4352 000038AF 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  4353 000038B6 8A83[33630000]      <1> 	mov	al, [ebx+p.ttyc-1] ; console tty
  4354                              <1> sysstty_8:
  4355                              <1> 	; 26/02/2022
  4356                              <1> 	; (ebx < 256)	
  4357 000038BC A2[DC650000]        <1> 	mov	[u.r0], al
  4358                              <1> 	; 01/02/2022
  4359                              <1> 	;push	dx
  4360                              <1> 	;push	ax
  4361                              <1> 	;push	cx
  4362 000038C1 52                  <1> 	push	edx
  4363 000038C2 50                  <1> 	push	eax
  4364 000038C3 51                  <1> 	push	ecx	
  4365 000038C4 E818190000          <1> 	call	ottyp
  4366 000038C9 59                  <1> 	pop	ecx
  4367 000038CA 58                  <1> 	pop	eax
  4368 000038CB 5A                  <1> 	pop	edx
  4369                              <1> 	;pop	cx
  4370                              <1> 	;pop	ax
  4371                              <1> 	;pop	dx
  4372                              <1>         ;jc	sysstty_pd_err ; 'permission denied !'
  4373                              <1> 	; 01/02/2022
  4374 000038CC 7305                <1> 	jnc	short sysstty_21
  4375 000038CE E943FFFFFF          <1> 	jmp	sysstty_pd_err ; 'permission denied !'
  4376                              <1> sysstty_21:
  4377                              <1> 	; 29/10/2015
  4378 000038D3 86E9                <1> 	xchg 	ch, cl
  4379                              <1> 		; cl = character, ch = color code
  4380 000038D5 86C1                <1> 	xchg	al, cl
  4381                              <1> 		; al = character, cl = tty number
  4382 000038D7 80F907              <1> 	cmp	cl, 7
  4383                              <1> 	;ja	sysstty_12
  4384                              <1> 	; 01/02/2022
  4385 000038DA 7628                <1> 	jna	short sysstty_16
  4386                              <1> ;;
  4387 000038DC 80FEFF              <1> 	cmp	dh, 0FFh
  4388 000038DF 740B                <1> 	je	short sysstty_22 ; do not set comm. parameters
  4389                              <1> 
  4390                              <1> ; 01/02/2022
  4391                              <1> ;	; 29/10/2015
  4392                              <1> ;	mov	ah, dl ; communication parameters
  4393                              <1> ;		; ah = 0E3h = 11100011b = 115200 baud,
  4394                              <1> ;		;			 THRE int + RDA int 
  4395                              <1> ;		; ah = 23h = 00100011b = 9600 baud,
  4396                              <1> ;		;			 THRE int + RDA int 
  4397                              <1> ;	sub	al, al ; 0
  4398                              <1> ;	; 12/07/2014
  4399                              <1> ;	cmp	cl, 9
  4400                              <1> ;	jb	short sysstty_1
  4401                              <1> ;	inc	al
  4402                              <1> ;sysstty_1:
  4403                              <1> ;	; 01/02/2022
  4404                              <1> ;	push	ecx
  4405                              <1> ;	;push	cx
  4406                              <1> ;	; 29/06/2015	
  4407                              <1> ;	call 	sp_setp ; Set serial port communication parameters
  4408                              <1> ;	mov	[u.r0+1], cx ; Line status (ah)
  4409                              <1> ;			     ; Modem status (EAX bits 16 to 23)
  4410                              <1> ;	; 01/02/2022
  4411                              <1> ;	pop	ecx	
  4412                              <1> ;	;pop	cx
  4413                              <1> ;       jc      short sysstty_tmout_err ; 29/10/2015
  4414                              <1> 
  4415                              <1> 	; 02/02/2022
  4416 000038E1 88C5                <1> 	mov	ch, al ; save char
  4417                              <1> 	; 01/02/2022
  4418 000038E3 E84D000000          <1> 	call	sysstty_scp
  4419 000038E8 7293                <1>         jc      short sysstty_tmout_err ; 29/10/2015
  4420                              <1> 	; 02/02/2022
  4421 000038EA 88E8                <1> 	mov	al, ch ; restore char
  4422                              <1> sysstty_22:
  4423                              <1> 	; 01/02/2022
  4424 000038EC 08ED                <1> 	or	ch, ch
  4425 000038EE 7437                <1> 	jz	short sysstty_11 ; do not send char to terminal
  4426                              <1> 	; send char to (serial port) terminal
  4427                              <1> 	; al = character
  4428                              <1> 	; cl = tty number (8 or 9)
  4429 000038F0 E94AFFFFFF          <1> 	jmp	sysstty_12 ; (tty8 or tty9)
  4430                              <1> 
  4431                              <1> sysstty_inv_dn: 
  4432                              <1> 	; 27/06/2015
  4433                              <1> 	; Invalid device name (not a tty) ! error
  4434                              <1> 	; (Device is not a tty or device name not found)
  4435 000038F5 C705[31660000]1800- <1> 	mov	dword [u.error], ERR_INV_DEV_NAME
  4435 000038FD 0000                <1>
  4436 000038FF E9CDF8FFFF          <1> 	jmp	error 
  4437                              <1> 
  4438                              <1> sysstty_16:
  4439                              <1> 	; 26/02/2022
  4440                              <1> 	; 16/01/2014
  4441                              <1> 	;xor	bh, bh
  4442                              <1> 	; 02/02/2022
  4443                              <1> sysstty_9: 	; tty 0 to tty 7
  4444                              <1> 	; al = character
  4445                              <1> 	; ch = color/attribute ; 01/02/2022
  4446                              <1> 	;
  4447                              <1> 	; 26/02/2022 (BugFix)
  4448                              <1> 	; (ebx may be > 255 here!? due to 'ottyp')
  4449 00003904 29DB                <1> 	sub	ebx, ebx ; *
  4450 00003906 80FEFF              <1> 	cmp	dh, 0FFh ; Do not set cursor position
  4451 00003909 740B                <1> 	je	short sysstty_10
  4452                              <1> 	; 02/02/2022
  4453 0000390B 51                  <1> 	push	ecx
  4454 0000390C 50                  <1> 	push	eax
  4455                              <1> 	;push	cx
  4456                              <1> 	;push	ax	
  4457                              <1> 	;movzx	ebx, cl
  4458 0000390D 88CB                <1> 	mov	bl, cl ; (tty number = video page number)
  4459 0000390F E898DBFFFF          <1> 	call	set_cpos
  4460                              <1> 	;pop	ax
  4461                              <1> 	;pop	cx
  4462                              <1> 	; 02/02/2022
  4463 00003914 58                  <1> 	pop	eax
  4464 00003915 59                  <1> 	pop	ecx
  4465                              <1> sysstty_10: 
  4466                              <1> 	; 29/10/2015
  4467 00003916 08C0                <1> 	or	al, al ; character
  4468 00003918 740D                <1> 	jz      short sysstty_11 ; al = 0
  4469                              <1> 	; 17/11/2015
  4470 0000391A 3CFF                <1> 	cmp	al, 0FFh
  4471 0000391C 7309                <1> 	jnb	short sysstty_11
  4472                              <1> 		; ch > 0 and ch < FFh
  4473                              <1> 	; write a character at current cursor position
  4474 0000391E 88EC                <1> 	mov	ah, ch ; color/attribute
  4475                              <1> 	; 12/07/2014
  4476                              <1> 	;push	cx
  4477                              <1> 	; 02/02/2022
  4478 00003920 51                  <1> 	push	ecx
  4479 00003921 E86EDCFFFF          <1> 	call	write_c_current
  4480                              <1> 	;pop	cx
  4481                              <1> 	; 02/02/2022
  4482 00003926 59                  <1> 	pop	ecx
  4483                              <1> sysstty_11:
  4484                              <1> 	; 14/01/2014
  4485 00003927 30D2                <1> 	xor	dl, dl ; sysstty call sign
  4486                              <1> 	; 18/01/2014
  4487                              <1> 	;movzx	eax, cl ; 27/06/2015
  4488 00003929 88C8                <1> 	mov	al, cl
  4489 0000392B E8D4190000          <1> 	call	cttyp
  4490 00003930 E9BCF8FFFF          <1> 	jmp	sysret
  4491                              <1> 
  4492                              <1> sysstty_scp:
  4493                              <1> 	; 02/02/2022
  4494                              <1> 	; set communication parameters (for COM1 or COM2)
  4495                              <1> 	; 01/02/2022
  4496                              <1> 	;
  4497                              <1> 	; 29/10/2015
  4498 00003935 88D4                <1> 	mov	ah, dl ; communication parameters
  4499                              <1> 		; ah = 0E3h = 11100011b = 115200 baud,
  4500                              <1> 		;			 THRE int + RDA int 
  4501                              <1> 		; ah = 23h = 00100011b = 9600 baud,
  4502                              <1> 		;			 THRE int + RDA int 
  4503 00003937 28C0                <1> 	sub	al, al ; 0
  4504                              <1> 	; 12/07/2014
  4505 00003939 80F909              <1> 	cmp	cl, 9
  4506 0000393C 7202                <1> 	jb	short sysstty_1
  4507 0000393E FEC0                <1> 	inc	al
  4508                              <1> sysstty_1:
  4509                              <1> 	; 02/02/2022
  4510 00003940 52                  <1> 	push	edx
  4511                              <1> 	; 01/02/2022
  4512 00003941 51                  <1> 	push	ecx
  4513                              <1> 	;push	cx
  4514                              <1> 	; 29/06/2015	
  4515 00003942 E848F3FFFF          <1> 	call 	sp_setp ; Set serial port communication parameters
  4516 00003947 66890D[DD650000]    <1> 	mov	[u.r0+1], cx ; Line status (ah)
  4517                              <1> 			     ; Modem status (EAX bits 16 to 23)
  4518                              <1> 	; 01/02/2022
  4519 0000394E 59                  <1> 	pop	ecx	
  4520                              <1> 	;pop	cx
  4521 0000394F 5A                  <1> 	pop	edx ; 02/02/2022
  4522                              <1> 	; 01/02/2022
  4523                              <1> 	; if cf = 1 -> sysstty_tmout_err
  4524 00003950 C3                  <1> 	retn
  4525                              <1> 
  4526                              <1> sysstty_14:
  4527                              <1> 	; 26/02/2022
  4528                              <1> 	; 02/02/2022
  4529                              <1> 	; ch = 0
  4530                              <1> 	; cl = video page
  4531                              <1> 	;
  4532                              <1> 	; dx = 0FFFFh
  4533                              <1> 	; clear screen (video page)
  4534                              <1> 	;
  4535                              <1> 
  4536                              <1> 	; 02/02/2022
  4537                              <1> 	; clear screen
  4538                              <1> 	;
  4539                              <1> 	; (modified registers: eax, ebx, ecx, edx, esi, edi)
  4540                              <1> 	; clear video page
  4541                              <1> 
  4542                              <1> 	; 26/02/2022
  4543 00003951 88CB                <1> 	mov 	bl, cl ; CL = tty number (0 to 7)
  4544                              <1> 
  4545                              <1> 	; clear video page
  4546 00003953 E810000000          <1> 	call	wttyc ; 26/02/2022
  4547                              <1> 
  4548                              <1> 	; 26/02/2022
  4549 00003958 88D8                <1> 	mov	al, bl
  4550 0000395A 8A25[2B660000]      <1> 	mov	ah, [u.uno]
  4551 00003960 66A3[DC650000]      <1> 	mov	[u.r0], ax
  4552 00003966 EBBF                <1> 	jmp	short sysstty_11
  4553                              <1> 
  4554                              <1> vp_clr:	; 27/02/2022
  4555                              <1> wttyc:
  4556                              <1> 	; 23/02/2022
  4557                              <1> 	; (clear video page)
  4558                              <1> 	; INPUT:
  4559                              <1> 	;  bl = video page (0 to 7)
  4560                              <1> 	;
  4561                              <1> 	; Modified registers: eax, ecx, edx, esi, edi
  4562                              <1> 
  4563                              <1> 	;xor	dx, dx ; column 0, row 0
  4564                              <1> 	;;inc	dx ; 0 ; 23/02/2022
  4565                              <1> 	;
  4566                              <1> ;	movzx	ebx, cl
  4567                              <1> ;	mov 	bl, cl ; CL = tty number (0 to 7) ; 23/02/2022
  4568                              <1> 
  4569                              <1> ;	shl 	bl, 1 
  4570                              <1> ;	mov 	al, byte ptr [ebx+ttyl]
  4571                              <1> ;		; AL = lock value (0 or process number)
  4572                              <1> ;	or	al, al
  4573                              <1> ;	jz	short @f
  4574                              <1> ;	cmp	al, byte ptr [u.uno] ; process number
  4575                              <1> ;	jne	short sysstty_15
  4576                              <1> ;		; only the owner can clear its video page
  4577                              <1> ;	xor	al, al ; 0
  4578                              <1> ;@@:
  4579                              <1> ;	;mov	bl, cl		
  4580                              <1> ;	shr	bl, 1 
  4581                              <1> 
  4582 00003968 30C0                <1> 	xor	al, al	; 0
  4583 0000396A B407                <1> 	mov 	ah, 07h	; attribute/color (default)
  4584                              <1> 
  4585                              <1> 	; scroll_up input:
  4586                              <1> 	;
  4587                              <1> 	; al = line count (0 or 1) ((0 == clear video page))
  4588                              <1> 	; 	((al = 1 for write_tty (putc) procedure))
  4589                              <1> 	; ah = attribute to be used on blanked line
  4590                              <1> 	; bl = video page number (0 to 7)
  4591                              <1> 
  4592 0000396C E8C1DBFFFF          <1> 	call	scroll_up ; clear video page (al=0)
  4593                              <1> 
  4594                              <1> 	; (modified registers: eax, ecx, edx, esi, edi)
  4595                              <1> 
  4596                              <1> 	; bl = video page number (0 to 7)
  4597                              <1> 	;xor	dx, dx ; column 0, row 0
  4598                              <1> 	; 02/02/2022
  4599 00003971 31D2                <1> 	xor	edx, edx
  4600                              <1> 	; 26/02/2022
  4601                              <1> 	;call	set_cpos
  4602                              <1> 	;retn
  4603 00003973 E934DBFFFF          <1> 	jmp	set_cpos
  4604                              <1> 
  4605                              <1> 	;mov	al, bl
  4606                              <1> 	;mov	ah, [u.uno]
  4607                              <1> 	;mov	[u.r0], ax
  4608                              <1> 	;jmp	short sysstty_11
  4609                              <1> 
  4610                              <1> ;sysstty_15:
  4611                              <1> ;	; 30/01/2022
  4612                              <1> ;	; permission (denied) error
  4613                              <1> ;	;xor	dl, dl ; sysstty call sign
  4614                              <1> ;	mov	al, cl
  4615                              <1> ;	sub	ah, ah ; 0
  4616                              <1> ;	call	cttyp
  4617                              <1> ;	jmp	error
  4618                              <1> 
  4619                              <1> ; Original UNIX v1 'sysstty' routine:
  4620                              <1> ; gtty:
  4621                              <1> ;sysstty: / set mode of typewriter; 3 consequtive word arguments
  4622                              <1>         ;jsr    r0,gtty / r1 will have offset to tty block, 
  4623                              <1> 	; 		/ r2 has source
  4624                              <1>         ;mov    r2,-(sp)
  4625                              <1>         ;mov    r1,-(sp) / put r1 and r2 on the stack
  4626                              <1> ;1: / flush the clist wait till typewriter is quiescent
  4627                              <1>         ;mov    (sp),r1 / restore r1 to tty block offset
  4628                              <1>         ;movb   tty+3(r1),0f / put cc offset into getc argument
  4629                              <1>         ;mov    $240,*$ps / set processor priority to 5
  4630                              <1>         ;jsr    r0,getc; 0:../ put character from clist in r1
  4631                              <1>         ;       br .+4 / list empty, skip branch
  4632                              <1>         ;br     1b / get another character until list is empty
  4633                              <1>         ;mov    0b,r1 / move cc offset to r1
  4634                              <1>         ;inc    r1 / bump it for output clist
  4635                              <1>         ;tstb   cc(r1) / is it 0
  4636                              <1>         ;beq    1f / yes, no characters to output
  4637                              <1>  	;mov    r1,0f / no, put offset in sleep arg
  4638                              <1>         ;jsr    r0,sleep; 0:.. / put tty output process to sleep
  4639                              <1>         ;br     1b / try to calm it down again
  4640                              <1> ;1:
  4641                              <1>         ;mov    (sp)+,r1
  4642                              <1>         ;mov    (sp)+,r2 / restore registers
  4643                              <1> 	;mov    (r2)+,r3 / put reader control status in r3
  4644                              <1>         ;beq    1f / if 0, 1f
  4645                              <1>         ;mov    r3,rcsr(r1) / move r.c. status to reader
  4646                              <1>         ;                   / control status register
  4647                              <1> ;1:
  4648                              <1>         ;mov    (r2)+,r3 / move pointer control status to r3
  4649                              <1>         ;beq    1f / if 0 1f
  4650                              <1>         ;mov    r3,tcsr(r1) / move p.c. status to printer 
  4651                              <1> 	;		    / control status reg
  4652                              <1> ;1:
  4653                              <1>         ;mov    (r2)+,tty+4(r1) / move to flag byte of tty block
  4654                              <1>         ;jmp     sysret2 / return to user
  4655                              <1> 
  4656                              <1> sysgtty: ; < get tty status >
  4657                              <1> 	; 26/02/2022
  4658                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4659                              <1> 	;	    ((32 bit reg push/pop))
  4660                              <1> 	; 23/11/2015
  4661                              <1> 	; 29/10/2015
  4662                              <1> 	; 17/10/2015
  4663                              <1> 	; 28/06/2015 (Retro UNIX 386 v1 - Beginning)
  4664                              <1> 	; 30/05/2013 - 12/07/2014 (Retro UNIX 8086 v1)
  4665                              <1> 	;
  4666                              <1> 	; 'sysgtty' gets the status of tty in question. 
  4667                              <1> 	; It stores in the three words addressed by it's argument
  4668                              <1> 	; the status of the typewriter whose file descriptor
  4669                              <1> 	; in (u.r0).
  4670                              <1> 	;
  4671                              <1> 	; Calling sequence:
  4672                              <1> 	;	sysgtty; arg
  4673                              <1> 	; Arguments:
  4674                              <1> 	;	arg - address of 3 words destination of the status
  4675                              <1> 	; Inputs: ((*u.r0 - file descriptor))
  4676                              <1> 	; Outputs: ((status in address which is pointed to by arg))
  4677                              <1> 	; ...............................................................
  4678                              <1> 	;	
  4679                              <1> 	; Retro UNIX 8086 v1 modification: 
  4680                              <1> 	;	'sysgtty' system call will return status of tty
  4681                              <1> 	;	(keyboard, serial port and video page status)
  4682                              <1> 	;	 in following manner:
  4683                              <1> 	;
  4684                              <1> 	; Inputs:
  4685                              <1> 	;	BX = 0 --> means 
  4686                              <1> 	;	     CH = 0 -->	'return status of the console tty' 
  4687                              <1> 	;	                 for (current) process
  4688                              <1> 	;	     CL = 0 --> return keyboard status (tty 0 to 9)
  4689                              <1> 	;	     CL = 1 --> return video page status (tty 0 to 7)
  4690                              <1> 	;	     CL = 1 --> return serial port status (tty 8 & 9)		
  4691                              <1> 	;	     CH > 0 -->	tty number + 1
  4692                              <1> 	;
  4693                              <1> 	;	BX > 0 --> points to name of tty
  4694                              <1> 	;	     CL = 0 --> return keyboard status
  4695                              <1> 	;	     CL = 1 --> return video page status
  4696                              <1> 	;	     CH = undefined		 
  4697                              <1> 	;
  4698                              <1> 	; Outputs:
  4699                              <1> 	;	cf = 0 ->
  4700                              <1> 	;
  4701                              <1> 	;	     AL = tty number from 0 to 9
  4702                              <1> 	;		  (0 to 7 is also the video page of the tty)	
  4703                              <1> 	;	     AH = 0 if the tty is free/unused
  4704                              <1> 	;	     AH = the process number of the caller 
  4705                              <1>  	;	     AH = FFh if the tty is locked by another process
  4706                              <1> 	;
  4707                              <1> 	;	  (if calling is for serial port status)
  4708                              <1> 	;	     BX = serial port status if tty number is 8 or 9
  4709                              <1> 	;		  (BH = modem status, BL = Line status)
  4710                              <1> 	;	     CX = 0FFFFh (if data is ready)
  4711                              <1> 	;	     CX = 0 (if data is not ready or undefined)		
  4712                              <1> 	;
  4713                              <1> 	;	  (if calling is for keyboard status)
  4714                              <1> 	;	     BX = current character in tty/keyboard buffer
  4715                              <1> 	;		  (BH = scan code, BL = ascii code)
  4716                              <1> 	;		  (BX=0 if there is not a waiting character)
  4717                              <1> 	;	     CX  is undefined
  4718                              <1> 	;
  4719                              <1> 	;	  (if calling is for video page status)	
  4720                              <1> 	;	     BX = cursor position on the video page
  4721                              <1> 	;		  if tty number < 8
  4722                              <1> 	;		  (BH = row, BL = column)
  4723                              <1> 	;	     CX = current character (in cursor position)
  4724                              <1> 	;		  on the video page of the tty 
  4725                              <1> 	;		  if tty number < 8
  4726                              <1> 	;		  (CH = color, CL = character)
  4727                              <1> 	;	
  4728                              <1> 	;	cf = 1 means error (requested tty is not ready)
  4729                              <1> 	;
  4730                              <1> 	;	     AH = FFh if the caller is not owner of
  4731                              <1> 	;		  specified tty or console tty
  4732                              <1> 	;	     AL = tty number (0FFh if it does not exist)
  4733                              <1> 	;	     BX, CX are undefined if cf = 1
  4734                              <1> 	;
  4735                              <1> 	;	  (If tty number is 8 or 9)
  4736                              <1> 	;	     AL = tty number 
  4737                              <1> 	;	     AH = the process number of the caller 
  4738                              <1> 	;	     BX = serial port status
  4739                              <1> 	;  		 (BH = modem status, BL = Line status)
  4740                              <1> 	;	     CX = 0
  4741                              <1> 	;
  4742                              <1> 		
  4743                              <1> gtty:   ; get (requested) tty number
  4744                              <1> 	; 26/02/2022
  4745                              <1> 	; 17/10/2015
  4746                              <1> 	; 28/06/2015 (Retro UNIX 386 v1 - 32 bit modifications)
  4747                              <1> 	; 30/05/2013 - 12/07/2014
  4748                              <1> 	; Retro UNIX 8086 v1 modification ! 
  4749                              <1> 	;
  4750                              <1> 	; ((Modified regs: eAX, eBX, eCX, eDX, eSI, eDI, eBP))
  4751                              <1> 	;
  4752                              <1> 	; 28/06/2015 (32 bit modifications)
  4753                              <1> 	; 16/01/2014
  4754 00003978 31C0                <1> 	xor 	eax, eax
  4755 0000397A 6648                <1> 	dec	ax ; 17/10/2015
  4756 0000397C A3[DC650000]        <1> 	mov 	[u.r0], eax ; 0FFFFh
  4757 00003981 80F901              <1> 	cmp	cl, 1
  4758 00003984 760F                <1> 	jna	short sysgtty_0
  4759                              <1> sysgtty_invp:
  4760                              <1> 	; 28/06/2015
  4761 00003986 C705[31660000]1700- <1>         mov     dword [u.error], ERR_INV_PARAMETER ; 'invalid parameter !' 
  4761 0000398E 0000                <1>
  4762 00003990 E93CF8FFFF          <1> 	jmp	error
  4763                              <1> sysgtty_0:	
  4764 00003995 21DB                <1> 	and	ebx, ebx
  4765 00003997 742E                <1> 	jz	short sysgtty_1
  4766                              <1> 	;
  4767 00003999 891D[F4650000]      <1> 	mov	[u.namep], ebx
  4768                              <1> 	;push	cx ; 23/11/2015
  4769 0000399F 51                  <1> 	push	ecx ; 24/12/2021
  4770 000039A0 E838070000          <1> 	call	namei
  4771 000039A5 59                  <1> 	pop	ecx
  4772                              <1> 	;pop	cx ; 23/11/2015
  4773 000039A6 7210                <1> 	jc 	short sysgtty_inv_dn ; 28/06/2015
  4774                              <1> 	;
  4775 000039A8 6683F801            <1> 	cmp	ax, 1
  4776 000039AC 7622                <1> 	jna	short sysgtty_2
  4777                              <1> 	; 26/02/2022
  4778 000039AE 20E4                <1> 	and	ah, ah
  4779 000039B0 7506                <1> 	jnz	short sysgtty_inv_dn
  4780                              <1> 	;sub	ax, 10
  4781 000039B2 2C0A                <1> 	sub	al, 10
  4782 000039B4 3C09                <1> 	cmp	al, 9
  4783                              <1> 	;cmp	ax, 9
  4784                              <1> 	;ja	short sysgtty_inv_dn
  4785                              <1> 	;mov	ch, al
  4786                              <1> 	;jmp	short sysgtty_4
  4787                              <1> 	; 23/11/2015
  4788 000039B6 7629                <1> 	jna	short sysgtty_4
  4789                              <1> sysgtty_inv_dn: 
  4790                              <1> 	; 28/06/2015
  4791                              <1> 	; Invalid device name (not a tty) ! error
  4792                              <1> 	; (Device is not a tty or device name not found)
  4793 000039B8 C705[31660000]1800- <1> 	mov	dword [u.error], ERR_INV_DEV_NAME
  4793 000039C0 0000                <1>
  4794 000039C2 E90AF8FFFF          <1> 	jmp	error 
  4795                              <1> sysgtty_1:
  4796                              <1> 	; 16/01/2014
  4797 000039C7 80FD0A              <1> 	cmp	ch, 10
  4798 000039CA 77BA                <1> 	ja	short sysgtty_invp ; 28/06/2015
  4799 000039CC FECD                <1> 	dec	ch ; 0 -> FFh (negative)
  4800 000039CE 790F                <1> 	jns	short sysgtty_3 ; not negative
  4801                              <1> 	;
  4802                              <1> sysgtty_2:
  4803                              <1> 	; get tty number of console tty
  4804 000039D0 8A25[2B660000]      <1> 	mov	ah, [u.uno]
  4805                              <1>  	; 28/06/2015
  4806 000039D6 0FB6DC              <1> 	movzx 	ebx, ah
  4807 000039D9 8AAB[33630000]      <1> 	mov	ch, [ebx+p.ttyc-1]
  4808                              <1> sysgtty_3:
  4809 000039DF 88E8                <1> 	mov	al, ch
  4810                              <1> sysgtty_4:
  4811 000039E1 A2[DC650000]        <1> 	mov	[u.r0], al
  4812                              <1>  	; 28/06/2015
  4813                              <1> 	;cmp	al, 9
  4814                              <1> 	;ja	short sysgtty_invp
  4815 000039E6 8B2D[D8650000]      <1> 	mov	ebp, [u.usp]
  4816                              <1> 	; 23/11/2015
  4817 000039EC 20C9                <1> 	and	cl, cl
  4818 000039EE 7432                <1> 	jz	short sysgtty_6 ; keyboard status
  4819 000039F0 3C08                <1> 	cmp	al, 8 ; cmp ch, 8
  4820 000039F2 722E                <1> 	jb	short sysgtty_6 ; video page status
  4821                              <1> 	; serial port status
  4822                              <1> 	; 12/07/2014
  4823                              <1> 	;mov	dx, 0
  4824                              <1> 	;je	short sysgtty_5
  4825                              <1> 	;inc	dl
  4826                              <1> ;sysgtty_5:
  4827                              <1> 	; 28/06/2015
  4828 000039F4 2C08                <1> 	sub	al, 8
  4829 000039F6 E88CF2FFFF          <1> 	call	sp_status ; serial (COM) port (line) status
  4830                              <1> 	; AL = Line status, AH = Modem status
  4831 000039FB 66894510            <1> 	mov	[ebp+16], ax ; serial port status (in EBX)
  4832 000039FF 8A25[2B660000]      <1> 	mov	ah, [u.uno]
  4833 00003A05 8825[DD650000]      <1>         mov     [u.r0+1], ah
  4834                              <1> 	; 24/12/2021
  4835 00003A0B 66C745180000        <1> 	mov	word [ebp+24], 0 ; data status (0 = not ready)
  4836                              <1> 				; (in ECX)
  4837 00003A11 A880                <1> 	test	al, 80h
  4838 00003A13 7561                <1> 	jnz	short sysgtty_dnr_err ; 29/06/2015
  4839 00003A15 A801                <1> 	test	al, 1
  4840                              <1> 	;jz	sysret
  4841 00003A17 7404                <1> 	jz	short sysgtty_10
  4842 00003A19 66FF4D18            <1> 	dec	word [ebp+24] ; data status (FFFFh = ready)
  4843                              <1> sysgtty_10:
  4844 00003A1D E9CFF7FFFF          <1> 	jmp	sysret
  4845                              <1> sysgtty_6:
  4846 00003A22 A2[30660000]        <1> 	mov	[u.ttyn], al ; tty number
  4847                              <1> 	;movzx	ebx, al
  4848 00003A27 88C3                <1> 	mov 	bl, al ; tty number (0 to 9)
  4849 00003A29 D0E3                <1> 	shl 	bl, 1  ; aligned to word
  4850                              <1> 	; 22/04/2014 - 29/06/2015
  4851 00003A2B 81C3[64620000]      <1>         add     ebx, ttyl
  4852 00003A31 8A23                <1>  	mov	ah, [ebx]
  4853 00003A33 3A25[2B660000]      <1> 	cmp	ah, [u.uno]
  4854 00003A39 7404                <1> 	je	short sysgtty_7
  4855 00003A3B 20E4                <1> 	and	ah, ah
  4856                              <1> 	;jz	short sysgtty_7
  4857 00003A3D 7506                <1> 	jnz	short sysgtty_8
  4858                              <1> 	;mov	ah, 0FFh
  4859                              <1> sysgtty_7:
  4860 00003A3F 8825[DD650000]      <1>         mov     [u.r0+1], ah
  4861                              <1> sysgtty_8:
  4862 00003A45 08C9                <1> 	or	cl, cl
  4863 00003A47 7510                <1> 	jnz	short sysgtty_9
  4864 00003A49 B001                <1> 	mov	al, 1  ; test a key is available
  4865 00003A4B E8221C0000          <1> 	call	getc
  4866 00003A50 66894510            <1> 	mov	[ebp+16], ax ; bx, character
  4867 00003A54 E998F7FFFF          <1> 	jmp	sysret
  4868                              <1> sysgtty_9:
  4869 00003A59 8A1D[30660000]      <1> 	mov	bl, [u.ttyn]
  4870                              <1> 	; bl = video page number
  4871 00003A5F E87F1D0000          <1> 	call 	get_cpos
  4872                              <1> 	; dx = cursor position
  4873 00003A64 66895510            <1> 	mov	[ebp+16], dx ; bx
  4874                              <1> 	;mov	bl, [u.ttyn]
  4875                              <1> 	; bl = video page number
  4876 00003A68 E8871D0000          <1> 	call	read_ac_current
  4877                              <1> 	; ax = character and attribute/color
  4878 00003A6D 66894518            <1> 	mov	[ebp+24], ax ; cx
  4879 00003A71 E97BF7FFFF          <1> 	jmp	sysret
  4880                              <1> sysgtty_dnr_err:
  4881                              <1> 	; 'device not responding !' error	
  4882                              <1> 	;mov 	dword [u.error], ERR_TIME_OUT ; 25
  4883 00003A76 C705[31660000]1900- <1> 	mov 	dword [u.error], ERR_DEV_NOT_RESP ; 25
  4883 00003A7E 0000                <1>
  4884 00003A80 E94CF7FFFF          <1> 	jmp	error	
  4885                              <1> 
  4886                              <1> ; Original UNIX v1 'sysgtty' routine:
  4887                              <1> ; sysgtty:
  4888                              <1>         ;jsr    r0,gtty / r1 will have offset to tty block,
  4889                              <1> 	;	       / r2 has destination
  4890                              <1>         ;mov    rcsr(r1),(r2)+ / put reader control status 
  4891                              <1> 	;                     / in 1st word of dest
  4892                              <1>         ;mov    tcsr(r1),(r2)+ / put printer control status
  4893                              <1> 	;                     / in 2nd word of dest
  4894                              <1>         ;mov    tty+4(r1),(r2)+ / put mode in 3rd word
  4895                              <1>         ;jmp    sysret2 / return to user
  4896                              <1> 	
  4897                              <1> ; Original UNIX v1 'gtty' routine:
  4898                              <1> ; gtty:
  4899                              <1>         ;jsr    r0,arg; u.off / put first arg in u.off
  4900                              <1>         ;mov    *u.r0,r1 / put file descriptor in r1
  4901                              <1>         ;jsr    r0,getf / get the i-number of the file
  4902                              <1>         ;tst    r1 / is it open for reading
  4903                              <1>         ;bgt    1f / yes
  4904                              <1>         ;neg    r1 / no, i-number is negative, 
  4905                              <1> 	;          / so make it positive
  4906                              <1> ;1:
  4907                              <1>         ;sub    $14.,r1 / get i-number of tty0
  4908                              <1>         ;cmp    r1,$ntty-1 / is there such a typewriter
  4909                              <1>         ;bhis   error9 / no, error
  4910                              <1>         ;asl    r1 / 0%2
  4911                              <1>         ;asl    r1 / 0%4 / yes
  4912                              <1>         ;asl    r1 / 0%8 / multiply by 8 so r1 points to 
  4913                              <1> 	;	       ; / tty block
  4914                              <1>         ;mov    u.off,r2 / put argument in r2
  4915                              <1>         ;rts    r0 / return
  2112                                  %include 'u2.s'        ; 11/05/2015
  2113                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.3) - SYS2.INC
  2114                              <1> ; Last Modification: 15/05/2022
  2115                              <1> ; ----------------------------------------------------------------------------
  2116                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2117                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2118                              <1> ;
  2119                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2120                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2121                              <1> ; <Bell Laboratories (17/3/1972)>
  2122                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2123                              <1> ;
  2124                              <1> ; Retro UNIX 8086 v1 - U2.ASM (24/03/2014) //// UNIX v1 -> u2.s
  2125                              <1> ;
  2126                              <1> ; ****************************************************************************
  2127                              <1> 
  2128                              <1> syslink:
  2129                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2130                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  2131                              <1> 	; 19/06/2013 (Retro UNIX 8086 v1)
  2132                              <1> 	;
  2133                              <1> 	; 'syslink' is given two arguments, name 1 and name 2.
  2134                              <1> 	; name 1 is a file that already exists. name 2 is the name
  2135                              <1> 	; given to the entry that will go in the current directory.
  2136                              <1> 	; name2 will then be a link to the name 1 file. The i-number
  2137                              <1> 	; in the name 2 entry of current directory is the same
  2138                              <1> 	; i-number for the name 1 file.
  2139                              <1> 	;
  2140                              <1> 	; Calling sequence:
  2141                              <1> 	;	syslink; name 1; name 2
  2142                              <1> 	; Arguments:
  2143                              <1> 	;	name 1 - file name to which link will be created.
  2144                              <1> 	;	name 2 - name of entry in current directory that
  2145                              <1> 	;		 links to name 1.
  2146                              <1> 	; Inputs: -
  2147                              <1> 	; Outputs: -
  2148                              <1> 	; ...............................................................
  2149                              <1> 	;	
  2150                              <1> 	; Retro UNIX 8086 v1 modification: 
  2151                              <1> 	;       'syslink' system call has two arguments; so,
  2152                              <1> 	;	* 1st argument, name 1 is pointed to by BX register
  2153                              <1> 	;	* 2nd argument, name 2 is pointed to by CX register
  2154                              <1> 	;
  2155                              <1> 		; / name1, name2
  2156                              <1> 		;jsr r0,arg2 / u.namep has 1st arg u.off has 2nd
  2157 00003A85 891D[F4650000]      <1> 	mov	[u.namep], ebx
  2158 00003A8B 51                  <1> 	push	ecx
  2159 00003A8C E84C060000          <1> 	call	namei
  2160                              <1> 		; jsr r0,namei / find the i-number associated with
  2161                              <1> 			     ; / the 1st path name
  2162                              <1>      	;;and	ax, ax
  2163                              <1> 	;;jz	error ; File not found
  2164                              <1> 	;jc	error 
  2165                              <1> 		; br error9 / cannot be found
  2166 00003A91 730F                <1> 	jnc	short syslink0
  2167                              <1> 	;pop 	ecx
  2168                              <1> 	; 'file not found !' error
  2169 00003A93 C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND ; 12
  2169 00003A9B 0000                <1>
  2170 00003A9D E92FF7FFFF          <1> 	jmp	error
  2171                              <1> syslink0:
  2172 00003AA2 E8460E0000          <1> 	call	iget
  2173                              <1> 		; jsr r0,iget / get the i-node into core
  2174 00003AA7 8F05[F4650000]      <1> 	pop	dword [u.namep] ; ecx
  2175                              <1> 		; mov (sp)+,u.namep / u.namep points to 2nd name
  2176                              <1> 	; 24/12/2021
  2177 00003AAD 50                  <1> 	push	eax ; *
  2178                              <1> 	;push	ax
  2179                              <1> 		; mov r1,-(sp) / put i-number of name1 on the stack
  2180                              <1> 			    ; / (a link to this file is to be created)
  2181                              <1> 	; 24/12/2021
  2182 00003AAE 8A0D[C3650000]      <1> 	mov	cl, [cdev]
  2183 00003AB4 51                  <1> 	push	ecx ; **
  2184                              <1> 	;push	word [cdev]
  2185                              <1> 		; mov cdev,-(sp) / put i-nodes device on the stack
  2186 00003AB5 E852000000          <1> 	call	isdir
  2187                              <1> 		; jsr r0,isdir / is it a directory
  2188 00003ABA E81E060000          <1> 	call	namei
  2189                              <1> 		; jsr r0,namei / no, get i-number of name2
  2190                              <1> 	;jnc	error
  2191                              <1> 		; br .+4   / not found 
  2192                              <1> 			 ; / so r1 = i-number of current directory
  2193                              <1> 			 ; / ii = i-number of current directory
  2194                              <1> 		; br error9 / file already exists., error
  2195 00003ABF 720F                <1> 	jc	short syslink1
  2196                              <1> 	; pop eax ; 24/12/2021
  2197                              <1> 	; pop eax
  2198                              <1> 	; 'file exists !' error
  2199 00003AC1 C705[31660000]0E00- <1> 	mov	dword [u.error], ERR_FILE_EXISTS ; 14
  2199 00003AC9 0000                <1>
  2200 00003ACB E901F7FFFF          <1> 	jmp	error
  2201                              <1> syslink1:
  2202                              <1> 	;pop	cx
  2203                              <1> 	; 24/12/2021
  2204 00003AD0 59                  <1> 	pop	ecx ; **
  2205                              <1> 	;cmp	cx, [cdev]
  2206 00003AD1 3A0D[C3650000]      <1> 	cmp	cl, [cdev]
  2207                              <1> 	;jne	error
  2208                              <1> 		; cmp (sp)+,cdev / u.dirp now points to 
  2209                              <1> 			       ; / end of current directory
  2210                              <1> 	        ; bne error9
  2211 00003AD7 740F                <1> 	je	short syslink2
  2212                              <1> 	; 'not same drive !' error
  2213 00003AD9 C705[31660000]1500- <1> 	mov	dword [u.error],  ERR_DRV_NOT_SAME ; 21
  2213 00003AE1 0000                <1>
  2214 00003AE3 E9E9F6FFFF          <1> 	jmp	error
  2215                              <1> syslink2:
  2216                              <1> 	;pop	eax ; 24/12/2021
  2217                              <1> 	;push	eax
  2218                              <1> 	; 24/12/2021
  2219 00003AE8 8B0424              <1> 	mov	eax, [esp] ; *
  2220 00003AEB 66A3[0E660000]      <1> 	mov	[u.dirbuf], ax
  2221                              <1> 		; mov (sp),u.dirbuf / i-number of name1 into u.dirbuf
  2222 00003AF1 E89E000000          <1> 	call	mkdir
  2223                              <1> 		; jsr r0,mkdir / make directory entry for name2 
  2224                              <1> 		 	     ; / in current directory
  2225                              <1> 	; 24/12/2021
  2226 00003AF6 58                  <1> 	pop	eax ; *
  2227                              <1> 	;pop	ax
  2228                              <1> 		; mov (sp)+,r1 / r1 has i-number of name1
  2229 00003AF7 E8F10D0000          <1> 	call	iget
  2230                              <1> 		; jsr r0,iget / get i-node into core
  2231 00003AFC FE05[D6620000]      <1> 	inc	byte [i.nlks]
  2232                              <1> 		; incb i.nlks / add 1 to its number of links
  2233 00003B02 E8F00E0000          <1> 	call	setimod
  2234                              <1> 		; jsr r0,setimod / set the i-node modified flag
  2235 00003B07 E9E5F6FFFF          <1> 	jmp	sysret
  2236                              <1> 
  2237                              <1> isdir:
  2238                              <1> 	; 03/02/2022
  2239                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  2240                              <1> 	; 04/05/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  2241                              <1> 	;
  2242                              <1> 	; 'isdir' check to see if the i-node whose i-number is in r1
  2243                              <1> 	;  is a directory. If it is, an error occurs, because 'isdir'
  2244                              <1> 	;  called by syslink and sysunlink to make sure directories
  2245                              <1> 	;  are not linked. If the user is the super user (u.uid=0),
  2246                              <1> 	; 'isdir' does not bother checking. The current i-node
  2247                              <1> 	;  is not disturbed.			
  2248                              <1> 	;		
  2249                              <1> 	; INPUTS ->
  2250                              <1> 	;    r1 - contains the i-number whose i-node is being checked.
  2251                              <1> 	;    u.uid - user id
  2252                              <1> 	; OUTPUTS ->
  2253                              <1> 	;    r1 - contains current i-number upon exit
  2254                              <1> 	;    	 (current i-node back in core) 
  2255                              <1> 	;	
  2256                              <1> 	; ((AX = R1))
  2257                              <1> 	;
  2258                              <1>         ; ((Modified registers: eAX, eDX, eBX, eCX, eSI, eDI, eBP))  
  2259                              <1> 	;
  2260                              <1> 
  2261                              <1> 	; / if the i-node whose i-number is in r1 is a directory 
  2262                              <1> 	; / there is an error unless super user made the call
  2263                              <1> 	
  2264 00003B0C 803D[28660000]00    <1> 	cmp	byte [u.uid], 0 
  2265                              <1> 		; tstb u.uid / super user
  2266 00003B13 762B                <1> 	jna	short isdir1
  2267                              <1> 		; beq 1f / yes, don't care
  2268 00003B15 66FF35[C0650000]    <1> 	push	word [ii]
  2269                              <1> 		; mov ii,-(sp) / put current i-number on stack
  2270 00003B1C E8CC0D0000          <1> 	call	iget
  2271                              <1> 		; jsr r0,iget / get i-node into core (i-number in r1)
  2272                              <1> 	; 03/02/2022
  2273 00003B21 F605[D5620000]40    <1> 	test	byte [i.flgs+1], 40h
  2274                              <1> 	;test 	word [i.flgs], 4000h ; Bit 14 : Directory flag
  2275                              <1> 		; bit $40000,i.flgs / is it a directory
  2276                              <1> 	;jnz	error
  2277                              <1> 		; bne error9 / yes, error
  2278 00003B28 740F                <1> 	jz	short isdir0
  2279 00003B2A C705[31660000]0B00- <1> 	mov 	dword [u.error], ERR_NOT_FILE  ; 11 ; ERR_DIR_ACCESS 
  2279 00003B32 0000                <1>
  2280                              <1> 				; 'permission denied !' error
  2281                              <1> 	; pop	ax
  2282 00003B34 E998F6FFFF          <1> 	jmp	error	
  2283                              <1> isdir0:	
  2284 00003B39 6658                <1> 	pop	ax
  2285                              <1> 		; mov (sp)+,r1 / no, put current i-number in r1 (ii)
  2286 00003B3B E8AD0D0000          <1> 	call	iget
  2287                              <1> 		; jsr r0,iget / get it back in
  2288                              <1> isdir1: ; 1:
  2289 00003B40 C3                  <1> 	retn
  2290                              <1> 		; rts r0
  2291                              <1> 
  2292                              <1> sysunlink:
  2293                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2294                              <1> 	; 04/12/2015 (14 byte file names)
  2295                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  2296                              <1> 	; 19/06/2013 (Retro UNIX 8086 v1)
  2297                              <1> 	;
  2298                              <1> 	; 'sysunlink' removes the entry for the file pointed to by
  2299                              <1> 	; name from its directory. If this entry was the last link
  2300                              <1> 	; to the file, the contents of the file are freed and the
  2301                              <1> 	; file is destroyed. If, however, the file was open in any
  2302                              <1> 	; process, the actual destruction is delayed until it is 
  2303                              <1> 	; closed, even though the directory entry has disappeared.
  2304                              <1> 	; 
  2305                              <1> 	; The error bit (e-bit) is set to indicate that the file	
  2306                              <1> 	; does not exist or that its directory can not be written.
  2307                              <1> 	; Write permission is not required on the file itself.
  2308                              <1> 	; It is also illegal to unlink a directory (except for
  2309                              <1> 	; the superuser).
  2310                              <1> 	;
  2311                              <1> 	; Calling sequence:
  2312                              <1> 	;	sysunlink; name
  2313                              <1> 	; Arguments:
  2314                              <1> 	;	name - name of directory entry to be removed 
  2315                              <1> 	; Inputs: -
  2316                              <1> 	; Outputs: -
  2317                              <1> 	; ...............................................................
  2318                              <1> 	;				
  2319                              <1> 	; Retro UNIX 8086 v1 modification:
  2320                              <1> 	;	 The user/application program puts address of the name
  2321                              <1> 	;        in BX register as 'sysunlink' system call argument.
  2322                              <1> 
  2323                              <1> 	; / name - remove link name
  2324 00003B41 891D[F4650000]      <1> 	mov	[u.namep], ebx
  2325                              <1> 		;jsr r0,arg; u.namep / u.namep points to name
  2326 00003B47 E891050000          <1> 	call	namei
  2327                              <1> 		; jsr r0,namei / find the i-number associated 
  2328                              <1> 			     ; / with the path name
  2329                              <1> 	;jc	error
  2330                              <1> 		; br error9 / not found
  2331 00003B4C 730F                <1> 	jnc	short sysunlink1
  2332                              <1> 	; 'file not found !' error
  2333 00003B4E C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND ; 12
  2333 00003B56 0000                <1>
  2334 00003B58 E974F6FFFF          <1> 	jmp	error
  2335                              <1> sysunlink1:
  2336 00003B5D 50                  <1> 	push	eax ; 24/12/2021
  2337                              <1> 	;push	ax
  2338                              <1> 		; mov r1,-(sp) / put its i-number on the stack
  2339 00003B5E E8A9FFFFFF          <1> 	call	isdir
  2340                              <1> 		; jsr r0,isdir / is it a directory
  2341                              <1> 	;xor 	ax, ax
  2342                              <1> 	; 24/12/2021
  2343 00003B63 31C0                <1> 	xor	eax, eax
  2344 00003B65 66A3[0E660000]      <1> 	mov	[u.dirbuf], ax ; 0
  2345                              <1> 		; clr u.dirbuf / no, clear the location that will
  2346                              <1> 			   ; / get written into the i-number portion
  2347                              <1> 			 ; / of the entry
  2348 00003B6B 832D[F8650000]10    <1> 	sub	dword [u.off], 16 ; 04/12/2015 (10 -> 16) 
  2349                              <1> 		; sub $10.,u.off / move u.off back 1 directory entry
  2350 00003B72 E868000000          <1> 	call	wdir
  2351                              <1> 		; jsr r0,wdir / free the directory entry
  2352 00003B77 58                  <1> 	pop	eax ; 24/12/2021
  2353                              <1> 	;pop	ax
  2354                              <1> 		; mov (sp)+,r1 / get i-number back
  2355 00003B78 E8700D0000          <1> 	call	iget
  2356                              <1> 		; jsr r0,iget / get i-node
  2357 00003B7D E8750E0000          <1> 	call	setimod
  2358                              <1> 		; jsr r0,setimod / set modified flag
  2359 00003B82 FE0D[D6620000]      <1> 	dec	byte [i.nlks]
  2360                              <1> 		; decb i.nlks / decrement the number of links
  2361                              <1> 	; 24/12/2021
  2362 00003B88 7505                <1> 	jnz	short sysunlink_2
  2363                              <1> 	;jnz	sysret
  2364                              <1> 		; bgt sysret9 / if this was not the last link
  2365                              <1> 			    ; / to file return
  2366                              <1> 	; AX = r1 = i-number
  2367 00003B8A E8B3090000          <1> 	call	anyi
  2368                              <1> 		; jsr r0,anyi / if it was, see if anyone has it open.
  2369                              <1> 			 ; / Then free contents of file and destroy it.
  2370                              <1> sysunlink_2:
  2371 00003B8F E95DF6FFFF          <1> 	jmp	sysret
  2372                              <1> 		; br sysret9
  2373                              <1> 
  2374                              <1> mkdir:
  2375                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2376                              <1> 	; 04/12/2015 (14 byte directory names)
  2377                              <1> 	; 12/10/2015
  2378                              <1> 	; 17/06/2015 (Retro UNIX 386 v1 - Beginning)
  2379                              <1> 	; 29/04/2013 - 01/08/2013 (Retro UNIX 8086 v1)
  2380                              <1> 	;
  2381                              <1> 	; 'mkdir' makes a directory entry from the name pointed to
  2382                              <1> 	; by u.namep into the current directory.
  2383                              <1> 	;
  2384                              <1> 	; INPUTS ->
  2385                              <1> 	;    u.namep - points to a file name 
  2386                              <1> 	;	           that is about to be a directory entry.
  2387                              <1> 	;    ii - current directory's i-number.	
  2388                              <1> 	; OUTPUTS ->
  2389                              <1> 	;    u.dirbuf+2 - u.dirbuf+10 - contains file name. 
  2390                              <1> 	;    u.off - points to entry to be filled 
  2391                              <1> 	;	     in the current directory		
  2392                              <1> 	;    u.base - points to start of u.dirbuf.
  2393                              <1> 	;    r1 - contains i-number of current directory 
  2394                              <1> 	;	
  2395                              <1> 	; ((AX = R1)) output
  2396                              <1> 	;
  2397                              <1> 	;    (Retro UNIX Prototype : 11/11/2012, UNIXCOPY.ASM)
  2398                              <1>         ;    ((Modified registers: eAX, eDX, eBX, eCX, eSI, eDI, eBP))  
  2399                              <1> 	;
  2400                              <1> 
  2401                              <1> 	; 17/06/2015 - 32 bit modifications (Retro UNIX 386 v1)
  2402 00003B94 31C0                <1> 	xor 	eax, eax
  2403 00003B96 BF[10660000]        <1> 	mov     edi, u.dirbuf+2
  2404 00003B9B 89FE                <1> 	mov	esi, edi
  2405 00003B9D AB                  <1> 	stosd
  2406 00003B9E AB                  <1> 	stosd
  2407                              <1> 	; 04/12/2015 (14 byte directory names)
  2408 00003B9F AB                  <1> 	stosd
  2409 00003BA0 66AB                <1> 	stosw
  2410                              <1> 		; jsr r0,copyz; u.dirbuf+2; u.dirbuf+10. / clear this
  2411 00003BA2 89F7                <1> 	mov	edi, esi ; offset to u.dirbuf
  2412                              <1> 	; 12/10/2015 ([u.namep] -> ebp)
  2413                              <1> 	;mov 	ebp, [u.namep]
  2414 00003BA4 E8B3060000          <1> 	call	trans_addr_nmbp ; convert virtual address to physical
  2415                              <1> 		; esi = physical address (page start + offset)
  2416                              <1> 		; ecx = byte count in the page (1 - 4096)
  2417                              <1> 	; edi = offset to u.dirbuf (edi is not modified in trans_addr_nm)
  2418                              <1> 		; mov u.namep,r2 / r2 points to name of directory entry
  2419                              <1> 		; mov $u.dirbuf+2,r3 / r3 points to u.dirbuf+2
  2420                              <1> mkdir_1: ; 1: 
  2421 00003BA9 45                  <1> 	inc	ebp ; 12/10/2015
  2422                              <1> 	;
  2423                              <1> 	; / put characters in the directory name in u.dirbuf+2 - u.dirbuf+10
  2424                              <1> 	 ; 01/08/2013
  2425 00003BAA AC                  <1> 	lodsb
  2426                              <1> 		; movb (r2)+,r1 / move character in name to r1
  2427 00003BAB 20C0                <1> 	and 	al, al
  2428 00003BAD 7426                <1> 	jz 	short mkdir_3 	  
  2429                              <1> 		; beq 1f / if null, done
  2430 00003BAF 3C2F                <1> 	cmp	al, '/'
  2431                              <1> 		; cmp r1,$'/ / is it a "/"?
  2432 00003BB1 7413                <1> 	je	short mkdir_err
  2433                              <1> 	;je	error
  2434                              <1> 		; beq error9 / yes, error
  2435                              <1> 	; 12/10/2015
  2436                              <1> 	;dec	cx
  2437 00003BB3 49                  <1> 	dec	ecx ; 24/12/2021
  2438 00003BB4 7505                <1> 	jnz	short mkdir_2
  2439                              <1> 	; 12/10/2015 ([u.namep] -> ebp)
  2440 00003BB6 E8A7060000          <1> 	call	trans_addr_nm ; convert virtual address to physical
  2441                              <1> 		; esi = physical address (page start + offset)
  2442                              <1> 		; ecx = byte count in the page
  2443                              <1> 	; edi = offset to u.dirbuf (edi is not modified in trans_addr_nm)
  2444                              <1> mkdir_2:
  2445 00003BBB 81FF[1E660000]      <1> 	cmp     edi, u.dirbuf+16 ; ; 04/12/2015 (10 -> 16) 
  2446                              <1> 		; cmp r3,$u.dirbuf+10. / have we reached the last slot for
  2447                              <1> 				     ; / a char?
  2448 00003BC1 74E6                <1> 	je	short mkdir_1
  2449                              <1> 		; beq 1b / yes, go back
  2450 00003BC3 AA                  <1> 	stosb
  2451                              <1> 		; movb r1,(r3)+ / no, put the char in the u.dirbuf
  2452 00003BC4 EBE3                <1> 	jmp 	short mkdir_1
  2453                              <1> 		; br 1b / get next char
  2454                              <1> mkdir_err:
  2455                              <1> 	; 17/06/2015
  2456 00003BC6 C705[31660000]1300- <1> 	mov	dword [u.error], ERR_NOT_DIR ; 'not a valid directory !'
  2456 00003BCE 0000                <1>
  2457 00003BD0 E9FCF5FFFF          <1> 	jmp	error
  2458                              <1> 
  2459                              <1> mkdir_3: ; 1:
  2460 00003BD5 A1[F0650000]        <1> 	mov	eax, [u.dirp]
  2461 00003BDA A3[F8650000]        <1> 	mov	[u.off], eax
  2462                              <1> 		; mov u.dirp,u.off / pointer to empty current directory
  2463                              <1> 				 ; / slot to u.off
  2464                              <1> wdir: 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2465                              <1> 	; 29/04/2013
  2466 00003BDF C705[FC650000]-     <1>         mov     dword [u.base], u.dirbuf
  2466 00003BE5 [0E660000]          <1>
  2467                              <1> 		; mov $u.dirbuf,u.base / u.base points to created file name
  2468 00003BE9 C705[00660000]1000- <1>         mov     dword [u.count], 16 ; 04/12/2015 (10 -> 16) 
  2468 00003BF1 0000                <1>
  2469                              <1> 		; mov $10.,u.count / u.count = 10
  2470 00003BF3 66A1[C0650000]      <1> 	mov	ax, [ii] 
  2471                              <1> 		; mov ii,r1 / r1 has i-number of current directory
  2472 00003BF9 B201                <1> 	mov	dl, 1 ; owner flag mask ; RETRO UNIX 8086 v1 modification !
  2473 00003BFB E8C10D0000          <1> 	call 	access
  2474                              <1> 		; jsr r0,access; 1 / get i-node and set its file up 
  2475                              <1> 				 ; / for writing
  2476                              <1> 	; AX = i-number of current directory
  2477                              <1> 	; 01/08/2013
  2478 00003C00 FE05[43660000]      <1> 	inc     byte [u.kcall] ; the caller is 'mkdir' sign	
  2479                              <1> 	;call	writei
  2480                              <1> 	;	; jsr r0,writei / write into directory
  2481                              <1> 	;retn	
  2482                              <1> 	;	; rts r0
  2483                              <1> 	; 24/12/2021
  2484 00003C06 E9A4100000          <1> 	jmp	writei
  2485                              <1> 
  2486                              <1> sysexec:
  2487                              <1> 	; 09/05/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.3)
  2488                              <1> 	; 03/02/2022
  2489                              <1> 	; 12/01/2022
  2490                              <1> 	; 08/01/2022
  2491                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2492                              <1> 	; 23/10/2015
  2493                              <1> 	; 19/10/2015
  2494                              <1> 	; 10/10/2015, 18/10/2015
  2495                              <1> 	; 29/07/2015, 05/08/2015, 26/08/2015
  2496                              <1> 	; 21/07/2015, 24/07/2015, 25/07/2015
  2497                              <1> 	; 01/07/2015, 02/07/2015, 20/07/2015
  2498                              <1> 	; 24/06/2015, 25/06/2015
  2499                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  2500                              <1> 	; 03/06/2013 - 06/12/2013 (Retro UNIX 8086 v1)
  2501                              <1> 	;
  2502                              <1> 	; 'sysexec' initiates execution of a file whose path name if
  2503                              <1> 	; pointed to by 'name' in the sysexec call. 
  2504                              <1> 	; 'sysexec' performs the following operations:
  2505                              <1> 	;    1. obtains i-number of file to be executed via 'namei'.
  2506                              <1> 	;    2. obtains i-node of file to be exceuted via 'iget'.
  2507                              <1> 	;    3. sets trap vectors to system routines.
  2508                              <1> 	;    4. loads arguments to be passed to executing file into
  2509                              <1> 	;	highest locations of user's core
  2510                              <1> 	;    5. puts pointers to arguments in locations immediately
  2511                              <1> 	;	following arguments.
  2512                              <1> 	;    6.	saves number of arguments in next location.
  2513                              <1> 	;    7. initializes user's stack area so that all registers
  2514                              <1> 	;	will be zeroed and the PS is cleared and the PC set
  2515                              <1> 	;	to core when 'sysret' restores registers 
  2516                              <1> 	;	and does an rti.
  2517                              <1> 	;    8. inializes u.r0 and u.sp
  2518                              <1> 	;    9. zeros user's core down to u.r0
  2519                              <1> 	;   10.	reads executable file from storage device into core
  2520                              <1> 	;	starting at location 'core'.
  2521                              <1> 	;   11.	sets u.break to point to end of user's code with
  2522                              <1> 	;	data area appended.
  2523                              <1> 	;   12.	calls 'sysret' which returns control at location
  2524                              <1> 	;	'core' via 'rti' instruction. 		  		
  2525                              <1> 	;
  2526                              <1> 	; Calling sequence:
  2527                              <1> 	;	sysexec; namep; argp
  2528                              <1> 	; Arguments:
  2529                              <1> 	;	namep - points to pathname of file to be executed
  2530                              <1> 	;	argp  - address of table of argument pointers
  2531                              <1> 	;	argp1... argpn - table of argument pointers
  2532                              <1> 	;	argp1:<...0> ... argpn:<...0> - argument strings
  2533                              <1> 	; Inputs: (arguments)
  2534                              <1> 	; Outputs: -	
  2535                              <1> 	; ...............................................................
  2536                              <1> 	;
  2537                              <1> 	; Retro UNIX 386 v1 modification: 
  2538                              <1> 	;	User application runs in it's own virtual space 
  2539                              <1> 	;	which is izolated from kernel memory (and other
  2540                              <1> 	;	memory pages) via 80386	paging in ring 3 
  2541                              <1> 	;	privilige mode. Virtual start address is always 0.
  2542                              <1> 	;	User's core memory starts at linear address 400000h
  2543                              <1> 	;	(the end of the 1st 4MB).
  2544                              <1> 	;
  2545                              <1> 	; Retro UNIX 8086 v1 modification: 
  2546                              <1> 	;	user/application segment and system/kernel segment
  2547                              <1> 	;	are different and sysenter/sysret/sysrele routines
  2548                              <1> 	;	are different (user's registers are saved to 
  2549                              <1> 	;	and then restored from system's stack.)
  2550                              <1> 	;
  2551                              <1> 	;	NOTE: Retro UNIX 8086 v1 'arg2' routine gets these
  2552                              <1> 	;	      arguments which were in these registers;
  2553                              <1> 	;	      but, it returns by putting the 1st argument
  2554                              <1> 	;	      in 'u.namep' and the 2nd argument
  2555                              <1> 	;	      on top of stack. (1st argument is offset of the
  2556                              <1> 	;	      file/path name in the user's program segment.)		 	
  2557                              <1> 	
  2558                              <1> 	;call	arg2
  2559                              <1> 	; * name - 'u.namep' points to address of file/path name
  2560                              <1> 	;          in the user's program segment ('u.segmnt')
  2561                              <1> 	;          with offset in BX register (as sysopen argument 1).
  2562                              <1> 	; * argp - sysexec argument 2 is in CX register 
  2563                              <1> 	;          which is on top of stack.
  2564                              <1> 	;
  2565                              <1> 		; jsr r0,arg2 / arg0 in u.namep,arg1 on top of stack
  2566                              <1> 
  2567                              <1> 	; 23/06/2015 (32 bit modifications)
  2568                              <1> 
  2569 00003C0B 891D[F4650000]      <1> 	mov	[u.namep], ebx ; argument 1
  2570                              <1>         ; 18/10/2015
  2571 00003C11 890D[5C660000]      <1> 	mov     [argv], ecx  ; * ; argument 2
  2572 00003C17 E8C1040000          <1> 	call	namei
  2573                              <1> 		; jsr r0,namei / namei returns i-number of file 
  2574                              <1> 			     ; / named in sysexec call in r1
  2575                              <1> 	;jc	error
  2576                              <1> 		; br error9
  2577 00003C1C 731E                <1> 	jnc	short sysexec_0
  2578                              <1> 	;
  2579                              <1> 	; 'file not found !' error
  2580 00003C1E C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND
  2580 00003C26 0000                <1>
  2581 00003C28 E9A4F5FFFF          <1> 	jmp	error 
  2582                              <1> sysexec_not_exf:
  2583                              <1> 	; 'not executable file !' error
  2584 00003C2D C705[31660000]1600- <1> 	mov	dword [u.error], ERR_NOT_EXECUTABLE
  2584 00003C35 0000                <1>
  2585 00003C37 E995F5FFFF          <1> 	jmp	error 
  2586                              <1> sysexec_0:
  2587 00003C3C E8AC0C0000          <1> 	call	iget
  2588                              <1> 		; jsr r0,iget / get i-node for file to be executed
  2589                              <1> 	; 24/12/2021
  2590 00003C41 F605[D4620000]10    <1> 	test	byte [i.flgs], 10h
  2591                              <1> 	;test	word [i.flgs], 10h
  2592                              <1> 	;	; bit $20,i.flgs / is file executable
  2593 00003C48 74E3                <1> 	jz	short sysexec_not_exf
  2594                              <1> 	;jz	error
  2595                              <1> 		; beq error9
  2596                              <1> 	;;
  2597 00003C4A E8F8140000          <1> 	call	iopen
  2598                              <1> 		; jsr r0,iopen / gets i-node for file with i-number
  2599                              <1> 			     ; / given in r1 (opens file)
  2600                              <1> 	; AX = i-number of the file
  2601                              <1> 	; 24/12/2021
  2602 00003C4F F605[D4620000]20    <1> 	test	byte [i.flgs], 20h
  2603                              <1> 	;test	word [i.flgs], 20h
  2604                              <1> 		; bit $40,i.flgs / test user id on execution bit
  2605 00003C56 7415                <1> 	jz	short sysexec_1
  2606                              <1> 		; beq 1f
  2607 00003C58 803D[28660000]00    <1> 	cmp 	byte [u.uid], 0 ; 02/08/2013
  2608                              <1> 		; tstb u.uid / test user id
  2609 00003C5F 760C                <1> 	jna	short sysexec_1
  2610                              <1> 		; beq 1f / super user
  2611 00003C61 8A0D[D7620000]      <1> 	mov	cl, [i.uid]
  2612 00003C67 880D[28660000]      <1> 	mov	[u.uid], cl ; 02/08/2013
  2613                              <1> 		; movb i.uid,u.uid / put user id of owner of file
  2614                              <1> 				 ; / as process user id
  2615                              <1> sysexec_1:
  2616                              <1> 	; 03/02/2022
  2617                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2618                              <1> 	; 18/10/2215
  2619                              <1> 	; 10/10/2015
  2620                              <1> 	; 21/07/2015, 24/07/2015
  2621                              <1> 	; 24/06/2015, 25/06/2015
  2622                              <1>         ; Moving arguments to the end of [u.upage]
  2623                              <1> 	; (by regarding page borders in user's memory space)
  2624                              <1> 	;
  2625                              <1> 	; 10/10/2015
  2626                              <1> 	; 21/07/2015
  2627 00003C6D 89E5                <1> 	mov	ebp, esp ; (**)
  2628                              <1> 	; 18/10/2015
  2629 00003C6F 89EF                <1> 	mov 	edi, ebp
  2630 00003C71 B900010000          <1> 	mov 	ecx, MAX_ARG_LEN ; 256
  2631                              <1> 	;sub	edi, MAX_ARG_LEN ; 256
  2632 00003C76 29CF                <1> 	sub	edi, ecx
  2633 00003C78 89FC                <1> 	mov	esp, edi
  2634 00003C7A 31C0                <1> 	xor	eax, eax
  2635 00003C7C A3[04660000]        <1> 	mov 	[u.nread], eax ; 0
  2636                              <1> 	; 12/01/2022
  2637                              <1> 	; ([argc] must be cleared because previous 'sysexec'
  2638                              <1> 	; may leave it with any value after an error))
  2639                              <1> 	;mov	[argc], ax
  2640 00003C81 A2[5A660000]        <1> 	mov	[argc], al ; 0
  2641                              <1> 	;
  2642 00003C86 49                  <1> 	dec	ecx ; 256 - 1
  2643 00003C87 890D[00660000]      <1> 	mov 	[u.count], ecx ; MAX_ARG_LEN - 1 ; 255
  2644                              <1> 	;mov 	dword [u.count], MAX_ARG_LEN - 1 ; 255
  2645                              <1> sysexec_2:
  2646 00003C8D 8B35[5C660000]      <1> 	mov	esi, [argv] ; 18/10/2015 
  2647 00003C93 E863020000          <1> 	call	get_argp
  2648                              <1> 	;mov	ecx, 4 
  2649                              <1> 	; 03/02/2022
  2650 00003C98 31C9                <1> 	xor	ecx, ecx
  2651 00003C9A B104                <1> 	mov	cl, 4
  2652                              <1> sysexec_3:
  2653 00003C9C 21C0                <1> 	and	eax, eax
  2654 00003C9E 7455                <1> 	jz	short sysexec_6
  2655                              <1> 	; 18/10/2015
  2656 00003CA0 010D[5C660000]      <1> 	add	[argv], ecx ; 4
  2657                              <1> 	;inc	word [argc]
  2658                              <1> 	; 12/01/2022 ; ([argc] < 32)
  2659 00003CA6 FE05[5A660000]      <1> 	inc	byte [argc]
  2660                              <1> 	;
  2661 00003CAC A3[FC650000]        <1> 	mov	[u.base], eax
  2662                              <1>  	; 23/10/2015
  2663 00003CB1 66C705[41660000]00- <1> 	mov	word [u.pcount], 0
  2663 00003CB9 00                  <1>
  2664                              <1> sysexec_4:
  2665 00003CBA E81A120000          <1> 	call	cpass ; get a character from user's core memory
  2666 00003CBF 750B                <1>         jnz	short sysexec_5
  2667                              <1> 		; (max. 255 chars + null)
  2668                              <1> 	; 18/10/2015
  2669 00003CC1 28C0                <1> 	sub 	al, al
  2670 00003CC3 AA                  <1> 	stosb
  2671 00003CC4 FF05[04660000]      <1> 	inc	dword [u.nread]
  2672 00003CCA EB29                <1> 	jmp	short sysexec_6
  2673                              <1> sysexec_5:
  2674 00003CCC AA                  <1> 	stosb
  2675 00003CCD 20C0                <1> 	and 	al, al
  2676 00003CCF 75E9                <1> 	jnz	short sysexec_4
  2677                              <1> 	;mov	ecx, 4
  2678                              <1> 	; 24/12/2021
  2679 00003CD1 29C9                <1> 	sub	ecx, ecx
  2680 00003CD3 B104                <1> 	mov	cl, 4
  2681                              <1> 	;cmp	[ncount], ecx ; 4
  2682                              <1> 	; 24/12/2021
  2683 00003CD5 66390D[58660000]    <1> 	cmp	[ncount], cx ; 4
  2684 00003CDC 72AF                <1> 	jb	short sysexec_2
  2685 00003CDE 8B35[54660000]      <1> 	mov	esi, [nbase]
  2686 00003CE4 010D[54660000]      <1> 	add	[nbase], ecx ; 4	
  2687 00003CEA 66290D[58660000]    <1> 	sub	[ncount], cx 
  2688 00003CF1 8B06                <1> 	mov	eax, [esi]
  2689 00003CF3 EBA7                <1> 	jmp	short sysexec_3
  2690                              <1> sysexec_6:
  2691                              <1> 	; 18/10/2015
  2692                              <1> 	; argument list transfer from user's core memory to
  2693                              <1> 	; kernel stack frame is OK here.
  2694                              <1> 	; [u.nread] = ; argument list length
  2695                              <1> 	;mov	[argv], esp ; start address of argument list 	
  2696                              <1> 	;
  2697                              <1> 	; 18/10/2015
  2698                              <1> 	; 24/07/2015
  2699                              <1>         ; 21/07/2015
  2700                              <1> 	; 02/07/2015
  2701                              <1> 	; 25/06/2015
  2702                              <1> 	; 24/06/2015
  2703                              <1> 	; 23/06/2015
  2704                              <1> 	;
  2705 00003CF5 8B1D[39660000]      <1> 	mov	ebx, [u.ppgdir] ; parent's page directory
  2706 00003CFB 21DB                <1> 	and 	ebx, ebx  ; /etc/init ? (u.ppgdir = 0)	
  2707 00003CFD 740A                <1> 	jz	short sysexec_7
  2708 00003CFF A1[35660000]        <1> 	mov	eax, [u.pgdir] ; physical address of page directory
  2709 00003D04 E8EEE8FFFF          <1> 	call	deallocate_page_dir
  2710                              <1> sysexec_7:
  2711 00003D09 E81EE8FFFF          <1> 	call	make_page_dir
  2712                              <1> 	;jc	short sysexec_14
  2713                              <1> 	;jc	panic  ; allocation error 
  2714                              <1> 		       ; after a deallocation would be nonsence !?
  2715                              <1> 	; 08/01/2022
  2716 00003D0E 7243                <1> 	jc	short sysexec_panic
  2717                              <1> 
  2718                              <1> 	; 24/07/2015
  2719                              <1> 	; map kernel pages (1st 4MB) to PDE 0
  2720                              <1> 	;     of the user's page directory
  2721                              <1> 	;     (It is needed for interrupts!)
  2722                              <1> 	; 18/10/2015
  2723 00003D10 8B15[18620000]      <1> 	mov	edx, [k_page_dir] ; Kernel's page directory
  2724 00003D16 8B02                <1> 	mov	eax, [edx] ; physical address of
  2725                              <1> 			   ; kernel's first page table (1st 4 MB)
  2726                              <1> 			   ; (PDE 0 of kernel's page directory)
  2727 00003D18 8B15[35660000]      <1> 	mov 	edx, [u.pgdir]
  2728 00003D1E 8902                <1> 	mov	[edx], eax ; PDE 0 (1st 4MB)
  2729                              <1> 	;
  2730                              <1> 	; 20/07/2015
  2731 00003D20 BB00004000          <1> 	mov	ebx, CORE ; start address = 0 (virtual) + CORE
  2732                              <1> 	; 18/10/2015
  2733 00003D25 BE[4C660000]        <1> 	mov	esi, pcore ; physical start address
  2734                              <1> sysexec_8:	
  2735 00003D2A B907000000          <1> 	mov	ecx, PDE_A_USER + PDE_A_WRITE + PDE_A_PRESENT
  2736 00003D2F E816E8FFFF          <1> 	call	make_page_table
  2737                              <1> 	;jc	panic
  2738                              <1> 	; 24/12/2021
  2739 00003D34 721D                <1> 	jc	short sysexec_panic
  2740                              <1> 	;mov	ecx, PTE_A_USER + PTE_A_WRITE + PTE_A_PRESENT
  2741 00003D36 E81DE8FFFF          <1> 	call	make_page ; make new page, clear and set the pte 
  2742                              <1> 	;jc	panic
  2743                              <1> 	; 24/12/2021
  2744 00003D3B 7216                <1> 	jc	short sysexec_panic
  2745                              <1> 	;
  2746 00003D3D 8906                <1> 	mov	[esi], eax ; 24/06/2015
  2747                              <1> 	; ebx = virtual address (24/07/2015)
  2748                              <1> 	; 24/12/2021
  2749                              <1> 	;call 	add_to_swap_queue
  2750                              <1> 	; 18/10/2015
  2751 00003D3F 81FE[50660000]      <1> 	cmp	esi, ecore ; user's stack (last) page ?
  2752 00003D45 7411                <1> 	je	short sysexec_9 ; yes
  2753 00003D47 BE[50660000]        <1> 	mov	esi, ecore  ; physical address of the last page 
  2754                              <1> 	; 20/07/2015
  2755 00003D4C BB00F0FFFF          <1> 	mov	ebx, (ECORE - PAGE_SIZE) + CORE
  2756                              <1> 	; ebx = virtual end address + segment base address - 4K
  2757 00003D51 EBD7                <1>         jmp     short sysexec_8
  2758                              <1> 
  2759                              <1> sysexec_panic:
  2760                              <1> 	; 26/03/2021
  2761 00003D53 E93BEDFFFF          <1> 	jmp	panic
  2762                              <1> 
  2763                              <1> sysexec_9:
  2764                              <1> 	; 18/10/2015
  2765                              <1> 	; 26/08/2015
  2766                              <1> 	; 25/06/2015
  2767                              <1> 	; move arguments from kernel stack to [ecore]
  2768                              <1> 	; (argument list/line will be copied from kernel stack
  2769                              <1> 	; frame to the last (stack) page of user's core memory)
  2770                              <1> 	; 18/10/2015
  2771 00003D58 8B3D[50660000]      <1> 	mov	edi, [ecore]
  2772 00003D5E 81C700100000        <1> 	add	edi, PAGE_SIZE
  2773                              <1> 	;movzx	eax, word [argc]
  2774                              <1> 	; 12/01/2022
  2775 00003D64 31C0                <1> 	xor	eax, eax
  2776 00003D66 A0[5A660000]        <1> 	mov	al, [argc]
  2777 00003D6B 08C0                <1> 	or	al, al
  2778                              <1> 	;or	eax, eax
  2779 00003D6D 7509                <1> 	jnz	short sysexec_10
  2780 00003D6F 89FB                <1> 	mov 	ebx, edi
  2781 00003D71 83EB04              <1> 	sub	ebx, 4 
  2782 00003D74 8903                <1> 	mov	[ebx], eax ; 0
  2783 00003D76 EB43                <1> 	jmp 	short sysexec_13
  2784                              <1> sysexec_10:
  2785 00003D78 8B0D[04660000]      <1> 	mov	ecx, [u.nread]
  2786                              <1> 	;mov 	esi, [argv]
  2787 00003D7E 89E6                <1> 	mov	esi, esp ; start address of argument list
  2788 00003D80 29CF                <1> 	sub	edi, ecx ; page end address - argument list length
  2789                              <1> 
  2790                              <1> 	;;;;
  2791                              <1> 	; 09/05/2022
  2792                              <1> 	; (move edi -backward- to dword boundary)
  2793                              <1> 	; ((this will prevent 'general protection fault' error
  2794                              <1> 	;  as result of a lodsd or dword move instruction
  2795                              <1> 	;  at the end of argument list))
  2796 00003D82 83EF03              <1> 	sub	edi, 3
  2797 00003D85 83E7FC              <1> 	and	edi, ~3 ; (*)
  2798                              <1> 	;;;
  2799                              <1> 
  2800 00003D88 89C2                <1> 	mov	edx, eax
  2801                              <1> 	; 03/02/2022 ; ([argc] < 32)
  2802 00003D8A FEC2                <1> 	inc	dl ; argument count + 1 for argc value
  2803 00003D8C C0E202              <1> 	shl 	dl, 2  ; 4 * (argument count + 1)
  2804                              <1> 	; edx <= 128
  2805 00003D8F 89FB                <1> 	mov	ebx, edi
  2806                              <1> 	; 09/05/2022 (*) - edi is already dword aligned -
  2807                              <1> 	;and	bl, 0FCh ; 32 bit (dword) alignment
  2808 00003D91 29D3                <1> 	sub 	ebx, edx
  2809 00003D93 89FA                <1> 	mov	edx, edi
  2810 00003D95 F3A4                <1> 	rep	movsb
  2811 00003D97 89D6                <1> 	mov 	esi, edx
  2812 00003D99 89DF                <1> 	mov 	edi, ebx
  2813 00003D9B BA00F0BFFF          <1> 	mov	edx, ECORE - PAGE_SIZE ; virtual addr. of the last page
  2814 00003DA0 2B15[50660000]      <1> 	sub 	edx, [ecore] ; difference (virtual - physical) 
  2815 00003DA6 AB                  <1> 	stosd	; eax = argument count	
  2816                              <1> sysexec_11:
  2817 00003DA7 89F0                <1> 	mov	eax, esi
  2818 00003DA9 01D0                <1> 	add	eax, edx
  2819 00003DAB AB                  <1> 	stosd  ; eax = virtual address
  2820 00003DAC FE0D[5A660000]      <1> 	dec	byte [argc]
  2821 00003DB2 7407                <1> 	jz	short sysexec_13
  2822                              <1> sysexec_12:
  2823 00003DB4 AC                  <1> 	lodsb
  2824 00003DB5 20C0                <1> 	and	al, al
  2825 00003DB7 75FB                <1> 	jnz	short sysexec_12
  2826 00003DB9 EBEC                <1> 	jmp	short sysexec_11
  2827                              <1> 	;
  2828                              <1> 	; 1:
  2829                              <1> 		; mov (sp)+,r5 / r5 now contains address of list of 
  2830                              <1> 			     ; / pointers to arguments to be passed
  2831                              <1> 		; mov $1,u.quit / u.quit determines handling of quits;
  2832                              <1> 			      ; / u.quit = 1 take quit
  2833                              <1> 		; mov $1,u.intr / u.intr determines handling of 
  2834                              <1> 			     ; / interrupts; u.intr = 1 take interrupt
  2835                              <1> 		; mov $rtssym,30 / emt trap vector set to take 
  2836                              <1> 			       ; / system routine
  2837                              <1> 		; mov $fpsym,*10 / reserved instruction trap vector 
  2838                              <1> 			       ; / set to take system routine
  2839                              <1> 		; mov $sstack,sp / stack space used during swapping
  2840                              <1> 		; mov r5,-(sp) / save arguments pointer on stack
  2841                              <1> 		; mov $ecore,r5 / r5 has end of core
  2842                              <1> 		; mov $core,r4 / r4 has start of users core
  2843                              <1> 		; mov r4,u.base / u.base has start of users core
  2844                              <1> 		; mov (sp),r2 / move arguments list pointer into r2
  2845                              <1> 	; 1:
  2846                              <1> 		; tst (r2)+ / argument char = "nul"
  2847                              <1> 		; bne 1b
  2848                              <1> 		; tst -(r2) / decrement r2 by 2; r2 has addr of 
  2849                              <1> 			  ; / end of argument pointer list
  2850                              <1> 	; 1:
  2851                              <1> 	     ; / move arguments to bottom of users core
  2852                              <1> 		; mov -(r2),r3 / (r3) last non zero argument ptr
  2853                              <1> 		; cmp r2,(sp) / is r2 = beginning of argument
  2854                              <1> 			    ; / ptr list
  2855                              <1> 		; blo 1f / branch to 1f when all arguments
  2856                              <1> 		       ; / are moved
  2857                              <1> 		; mov -(r2),r3 / (r3) last non zero argument ptr
  2858                              <1> 	; 2:
  2859                              <1> 		; tstb (r3)+
  2860                              <1> 		; bne 2b / scan argument for \0 (nul)
  2861                              <1> 
  2862                              <1> 	; 2:
  2863                              <1> 		; movb -(r3),-(r5) / move argument char 
  2864                              <1> 				 ; / by char starting at "ecore"
  2865                              <1> 		; cmp r3,(r2) / moved all characters in 
  2866                              <1> 			    ; / this argument
  2867                              <1> 		; bhi 2b / branch 2b if not
  2868                              <1> 		; mov r5,(r4)+ / move r5 into top of users core;
  2869                              <1> 			     ; / r5 has pointer to nth arg
  2870                              <1> 		; br 1b / string
  2871                              <1> 	; 1:
  2872                              <1> 		; clrb -(r5)
  2873                              <1> 		; bic $1,r5 / make r5 even, r5 points to 
  2874                              <1> 			; / last word of argument strings
  2875                              <1> 		; mov $core,r2
  2876                              <1> 	
  2877                              <1> 	; 1: / move argument pointers into core following 
  2878                              <1> 	      ; / argument strings
  2879                              <1> 		; cmp r2,r4
  2880                              <1> 		; bhis 1f / branch to 1f when all pointers
  2881                              <1> 			; / are moved
  2882                              <1> 		; mov (r2)+,-(r5)
  2883                              <1> 		; br 1b
  2884                              <1> 	; 1:
  2885                              <1> 		; sub $core,r4 / gives number of arguments *2
  2886                              <1> 		; asr r4 / divide r4 by 2 to calculate 
  2887                              <1> 		       ; / the number of args stored
  2888                              <1> 		; mov r4,-(r5) / save number of arguments ahead
  2889                              <1> 			     ; / of the argument pointers
  2890                              <1> sysexec_13:
  2891                              <1> 	; 19/10/2015
  2892                              <1> 	; 18/10/2015
  2893                              <1> 	; 29/07/2015
  2894                              <1> 	; 25/07/2015
  2895                              <1> 	; 24/07/2015
  2896                              <1> 	; 20/07/2015
  2897                              <1> 	; 25/06/2015
  2898                              <1> 	; 24/06/2015
  2899                              <1> 	; 23/06/2015
  2900                              <1> 	;
  2901                              <1> 	; moving arguments to [ecore] is OK here..
  2902                              <1> 	; 18/10/2015
  2903 00003DBB 89EC                <1> 	mov 	esp, ebp ; (**) restore kernel stack pointer
  2904                              <1> 	; ebx = beginning addres of argument list pointers
  2905                              <1> 	;	in user's stack
  2906                              <1> 	; 19/10/2015
  2907 00003DBD 2B1D[50660000]      <1> 	sub 	ebx, [ecore]
  2908 00003DC3 81C300F0BFFF        <1> 	add     ebx, (ECORE - PAGE_SIZE)
  2909                              <1> 			; end of core - 4096 (last page)
  2910                              <1> 			; (virtual address)
  2911 00003DC9 891D[5C660000]      <1> 	mov	[argv], ebx
  2912 00003DCF 891D[08660000]      <1> 	mov	[u.break], ebx ; available user memory
  2913                              <1> 	;
  2914 00003DD5 29C0                <1> 	sub	eax, eax
  2915 00003DD7 C705[00660000]2000- <1> 	mov	dword [u.count], 32 ; Executable file header size
  2915 00003DDF 0000                <1>
  2916                              <1> 		; mov $14,u.count
  2917 00003DE1 C705[EC650000]-     <1> 	mov	dword [u.fofp], u.off
  2917 00003DE7 [F8650000]          <1>
  2918                              <1> 		; mov $u.off,u.fofp
  2919 00003DEB A3[F8650000]        <1> 	mov	[u.off], eax ; 0
  2920                              <1> 		; clr u.off / set offset in file to be read to zero
  2921                              <1> 	; 25/07/2015
  2922 00003DF0 A3[FC650000]        <1> 	mov	[u.base], eax ; 0, start of user's core (virtual)
  2923                              <1> 	; 25/06/2015 
  2924 00003DF5 66A1[C0650000]      <1> 	mov	ax, [ii]
  2925                              <1> 	; AX = i-number of the executable file
  2926 00003DFB E8C10C0000          <1> 	call	readi
  2927                              <1> 		; jsr r0,readi / read in first six words of 
  2928                              <1> 			; / user's file, starting at $core
  2929                              <1> 		; mov sp,r5 / put users stack address in r5
  2930                              <1> 		; sub $core+40.,r5 / subtract $core +40, 
  2931                              <1> 				; / from r5 (leaves number of words
  2932                              <1> 				; / less 26 available for
  2933                              <1> 			     	; / program in user core
  2934                              <1> 		; mov r5,u.count /
  2935                              <1> 	; 25/06/2015
  2936 00003E00 8B0D[08660000]      <1> 	mov	ecx, [u.break] ; top of user's stack (physical addr.)
  2937 00003E06 890D[00660000]      <1> 	mov	[u.count], ecx ; save for overrun check
  2938                              <1> 	;
  2939 00003E0C 8B0D[04660000]      <1> 	mov	ecx, [u.nread]
  2940 00003E12 890D[08660000]      <1> 	mov	[u.break], ecx ; virtual address (offset from start)
  2941 00003E18 80F920              <1> 	cmp	cl, 32
  2942 00003E1B 7540                <1>         jne     short sysexec_15
  2943                              <1> 	;:
  2944                              <1> 	; 25/06/2015
  2945                              <1> 	; Retro UNIX 386 v1 (32 bit) executable file header format
  2946                              <1> 	; 18/10/2015
  2947 00003E1D 8B35[4C660000]      <1> 	mov	esi, [pcore] ; start address of user's core memory 
  2948                              <1> 		             ; (phys. start addr. of the exec. file)
  2949 00003E23 AD                  <1> 	lodsd
  2950 00003E24 663DEB1E            <1> 	cmp	ax, 1EEBh ; EBH, 1Eh -> jump to +32
  2951 00003E28 7533                <1> 	jne	short sysexec_15
  2952                              <1> 		; cmp core,$405 / br .+14 is first instruction 
  2953                              <1> 			      ; / if file is standard a.out format
  2954                              <1> 		; bne 1f / branch, if not standard format
  2955 00003E2A AD                  <1> 	lodsd
  2956 00003E2B 89C1                <1> 	mov	ecx, eax ; text (code) section size
  2957 00003E2D AD                  <1> 	lodsd
  2958 00003E2E 01C1                <1> 	add	ecx, eax ; + data section size (initialized data)
  2959                              <1> 		; mov core+2,r5 / put 2nd word of users program in r5;
  2960                              <1> 		              ; / number of bytes in program text	
  2961                              <1> 		; sub $14,r5 / subtract 12
  2962 00003E30 89CB                <1> 	mov	ebx, ecx
  2963                              <1> 	;
  2964                              <1> 	; 25/06/2015
  2965                              <1> 	; NOTE: These are for next versions of Retro UNIX 386
  2966                              <1> 	;	and SINGLIX operating systems (as code template).
  2967                              <1> 	;	Current Retro UNIX 386 v1 files can be max. 64KB
  2968                              <1> 	;	due to RUFS (floppy disk file system) restriction...
  2969                              <1> 	;	Overrun is not possible for current version. 	
  2970                              <1> 	;
  2971 00003E32 AD                  <1> 	lodsd	
  2972 00003E33 01C3                <1> 	add	ebx, eax ; + bss section size (for overrun checking)
  2973 00003E35 3B1D[00660000]      <1> 	cmp	ebx, [u.count]
  2974 00003E3B 7711                <1> 	ja	short sysexec_14  ; program overruns stack !
  2975                              <1> 	;
  2976                              <1> 	; 24/07/2015
  2977                              <1> 	; add bss section size to [u.break]
  2978 00003E3D 0105[08660000]      <1> 	add 	[u.break], eax
  2979                              <1> 	;
  2980 00003E43 83E920              <1> 	sub	ecx, 32  ; header size (already loaded)
  2981                              <1> 	;cmp	ecx, [u.count]
  2982                              <1> 	;jnb	short sysexec_16
  2983                              <1> 		; cmp r5,u.count /
  2984                              <1> 		; bgt 1f / branch if r5 greater than u.count
  2985 00003E46 890D[00660000]      <1> 	mov	[u.count], ecx ; required read count
  2986                              <1> 		; mov r5,u.count
  2987                              <1> 	;
  2988 00003E4C EB2A                <1> 	jmp	short sysexec_16
  2989                              <1> 	;
  2990                              <1> sysexec_14:
  2991                              <1> 	; 23/06/2015
  2992                              <1> 	; insufficient (out of) memory
  2993 00003E4E C705[31660000]0400- <1> 	mov	dword [u.error], ERR_MINOR_IM ; 1
  2993 00003E56 0000                <1>
  2994 00003E58 E974F3FFFF          <1> 	jmp	error
  2995                              <1> 	;
  2996                              <1> sysexec_15:
  2997                              <1> 	; 25/06/2015
  2998 00003E5D 0FB715[D8620000]    <1>         movzx   edx, word [i.size] ; file size
  2999 00003E64 29CA                <1> 	sub	edx, ecx ; file size - loaded bytes
  3000 00003E66 7627                <1> 	jna	short sysexec_17 ; no need to next read
  3001 00003E68 01D1                <1> 	add	ecx, edx ; [i.size]
  3002 00003E6A 3B0D[00660000]      <1> 	cmp	ecx, [u.count] ; overrun check (!)
  3003 00003E70 77DC                <1> 	ja	short sysexec_14
  3004 00003E72 8915[00660000]      <1> 	mov	[u.count], edx
  3005                              <1> sysexec_16:
  3006 00003E78 66A1[C0650000]      <1> 	mov	ax, [ii] ; i-number
  3007 00003E7E E83E0C0000          <1> 	call	readi
  3008                              <1> 		; add core+10,u.nread / add size of user data area 
  3009                              <1> 		                    ; / to u.nread
  3010                              <1> 		; br 2f
  3011                              <1> 	; 1:
  3012                              <1> 		; jsr r0,readi / read in rest of file
  3013                              <1> 	; 2:
  3014 00003E83 8B0D[04660000]      <1> 	mov	ecx, [u.nread]
  3015 00003E89 010D[08660000]      <1> 	add	[u.break], ecx
  3016                              <1> 		; mov u.nread,u.break / set users program break to end of 
  3017                              <1> 				    ; / user code
  3018                              <1> 		; add $core+14,u.break / plus data area
  3019                              <1> sysexec_17: ; 20/07/2015
  3020                              <1> 	; 08/01/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.2)
  3021                              <1> 	; ('iclose' is not needed for regular files, from now on)
  3022                              <1> 	;;mov	ax, [ii] ; i-number
  3023                              <1> 	;call	iclose
  3024                              <1> 	;	; jsr r0,iclose / does nothing
  3025 00003E8F 31C0                <1>         xor     eax, eax
  3026 00003E91 FEC0                <1> 	inc	al
  3027 00003E93 66A3[20660000]      <1> 	mov	[u.intr], ax ; 1 (interrupt/time-out is enabled)
  3028 00003E99 66A3[22660000]      <1> 	mov	[u.quit], ax ; 1 ('crtl+brk' signal is enabled) 
  3029                              <1> 	; 02/07/2015
  3030 00003E9F 833D[39660000]00    <1>         cmp	dword [u.ppgdir], 0  ; is the caller sys_init (kernel) ?
  3031 00003EA6 770C                <1> 	ja	short sysexec_18 ; no, the caller is user process
  3032                              <1> 	; If the caller is kernel (sys_init), 'sysexec' will come here
  3033 00003EA8 8B15[18620000]      <1> 	mov	edx, [k_page_dir] ; kernel's page directory
  3034 00003EAE 8915[39660000]      <1> 	mov	[u.ppgdir], edx ; next time 'sysexec' must not come here 
  3035                              <1> sysexec_18:
  3036                              <1> 	; 18/10/2015
  3037                              <1> 	; 05/08/2015
  3038                              <1> 	; 29/07/2015
  3039 00003EB4 8B2D[5C660000]      <1> 	mov	ebp, [argv] ; user's stack pointer must point to argument
  3040                              <1> 			    ; list pointers (argument count)
  3041 00003EBA FA                  <1> 	cli
  3042 00003EBB 8B25[B4610000]      <1>         mov     esp, [tss.esp0]  ; ring 0 (kernel) stack pointer
  3043                              <1> 	;mov   	esp, [u.sp] ; Restore Kernel stack
  3044                              <1> 			    ; for this process	 
  3045                              <1> 	;add	esp, 20 ; --> EIP, CS, EFLAGS, ESP, SS
  3046                              <1> 	;xor	eax, eax ; 0
  3047 00003EC1 FEC8                <1> 	dec	al ; eax = 0
  3048 00003EC3 66BA2300            <1> 	mov	dx, UDATA
  3049 00003EC7 6652                <1> 	push	dx  ; user's stack segment
  3050 00003EC9 55                  <1> 	push	ebp ; user's stack pointer
  3051                              <1> 		    ; (points to number of arguments)
  3052 00003ECA FB                  <1> 	sti
  3053 00003ECB 9C                  <1> 	pushfd	; EFLAGS
  3054                              <1> 		; Set IF for enabling interrupts in user mode	
  3055                              <1> 	;or	dword [esp], 200h 
  3056                              <1> 	;
  3057                              <1> 	;mov	bx, UCODE
  3058                              <1> 	;push	bx ; user's code segment
  3059 00003ECC 6A1B                <1> 	push	UCODE
  3060                              <1> 	;push	0
  3061 00003ECE 50                  <1> 	push	eax ; EIP (=0) - start address -	
  3062                              <1> 		; clr -(r5) / popped into ps when rti in 
  3063                              <1> 			  ; / sysrele is executed
  3064                              <1> 		; mov $core,-(r5) / popped into pc when rti 
  3065                              <1> 		                ; / in sysrele is executed
  3066                              <1> 		;mov r5,0f / load second copyz argument
  3067                              <1> 		;tst -(r5) / decrement r5
  3068 00003ECF 8925[D4650000]      <1> 	mov	[u.sp], esp ; 29/07/2015
  3069                              <1> 	; 05/08/2015
  3070                              <1> 	; Remedy of a General Protection Fault during 'iretd' is here !
  3071                              <1> 	; ('push dx' would cause to general protection fault, 
  3072                              <1> 	; after 'pop ds' etc.)
  3073                              <1> 	;
  3074                              <1> 	;; push dx ; ds (UDATA)
  3075                              <1> 	;; push dx ; es (UDATA)
  3076                              <1> 	;; push dx ; fs (UDATA)
  3077                              <1> 	;; push dx ; gs (UDATA)
  3078                              <1> 	;
  3079                              <1> 	; This is a trick to prevent general protection fault
  3080                              <1> 	; during 'iretd' intruction at the end of 'sysrele' (in u1.s):
  3081 00003ED5 8EC2                <1> 	mov 	es, dx ; UDATA
  3082 00003ED7 06                  <1> 	push 	es ; ds (UDATA)
  3083 00003ED8 06                  <1> 	push 	es ; es (UDATA)
  3084 00003ED9 06                  <1> 	push 	es ; fs (UDATA)
  3085 00003EDA 06                  <1> 	push	es ; gs (UDATA)
  3086 00003EDB 66BA1000            <1> 	mov	dx, KDATA
  3087 00003EDF 8EC2                <1> 	mov	es, dx
  3088                              <1> 	;
  3089                              <1> 	;; pushad simulation
  3090 00003EE1 89E5                <1> 	mov	ebp, esp ; esp before pushad
  3091 00003EE3 50                  <1> 	push	eax ; eax (0)
  3092 00003EE4 50                  <1> 	push	eax ; ecx (0)
  3093 00003EE5 50                  <1> 	push	eax ; edx (0)
  3094 00003EE6 50                  <1> 	push	eax ; ebx (0)
  3095 00003EE7 55                  <1> 	push	ebp ; esp before pushad
  3096 00003EE8 50                  <1> 	push	eax ; ebp (0)
  3097 00003EE9 50                  <1> 	push	eax ; esi (0)		
  3098 00003EEA 50                  <1> 	push	eax ; edi (0)	
  3099                              <1> 	;
  3100 00003EEB A3[DC650000]        <1> 	mov	[u.r0], eax ; eax = 0
  3101 00003EF0 8925[D8650000]      <1> 	mov	[u.usp], esp
  3102                              <1> 		; mov r5,u.r0 /
  3103                              <1> 		; sub $16.,r5 / skip 8 words
  3104                              <1> 		; mov r5,u.sp / assign user stack pointer value, 
  3105                              <1> 		;             / effectively zeroes all regs
  3106                              <1> 			    ; / when sysrele is executed
  3107                              <1> 		; jsr r0,copyz; core; 0:0 / zero user's core
  3108                              <1> 		; clr u.break
  3109                              <1> 		; mov r5,sp / point sp to user's stack
  3110                              <1> 	;
  3111 00003EF6 E9F8F2FFFF          <1> 	jmp	sysret0
  3112                              <1> 	;jmp	sysret
  3113                              <1> 		; br sysret3 / return to core image at $core
  3114                              <1> 
  3115                              <1> get_argp:
  3116                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3117                              <1> 	; 18/10/2015 (nbase, ncount)
  3118                              <1> 	; 21/07/2015
  3119                              <1> 	; 24/06/2015 (Retro UNIX 386 v1)
  3120                              <1> 	; Get (virtual) address of argument from user's core memory
  3121                              <1> 	;
  3122                              <1> 	; INPUT:
  3123                              <1> 	;	esi = virtual address of argument pointer
  3124                              <1> 	; OUTPUT:
  3125                              <1> 	;	eax = virtual address of argument
  3126                              <1> 	;
  3127                              <1> 	; Modified registers: EAX, EBX, ECX, EDX, ESI 
  3128                              <1> 	;
  3129 00003EFB 833D[39660000]00    <1>  	cmp     dword [u.ppgdir], 0 ; /etc/init ?
  3130                              <1> 				    ; (the caller is kernel)
  3131                              <1> 	;jna	short get_argpk 
  3132                              <1> 	; 24/12/2021
  3133 00003F02 7719                <1> 	ja	short get_argp5
  3134                              <1> get_argpk:
  3135                              <1> 	; Argument is in kernel's memory space
  3136 00003F04 66C705[58660000]00- <1> 	mov	word [ncount], PAGE_SIZE ; 4096
  3136 00003F0C 10                  <1>
  3137 00003F0D 8935[54660000]      <1> 	mov	[nbase], esi
  3138 00003F13 8305[54660000]04    <1> 	add	dword [nbase], 4
  3139 00003F1A 8B06                <1> 	mov	eax, [esi] ; virtual addr. = physcal addr.
  3140 00003F1C C3                  <1> 	retn
  3141                              <1> get_argp5:
  3142 00003F1D 89F3                <1>      	mov	ebx, esi
  3143 00003F1F E88BE9FFFF          <1> 	call	get_physical_addr ; get physical address
  3144 00003F24 7257                <1>         jc      short get_argp_err ; 24/12/2021 (short jump)
  3145 00003F26 A3[54660000]        <1> 	mov 	[nbase], eax ; physical address	
  3146 00003F2B 66890D[58660000]    <1> 	mov	[ncount], cx ; remain byte count in page (1-4096)
  3147 00003F32 B804000000          <1> 	mov	eax, 4 ; 21/07/2015
  3148                              <1> 	;cmp	cx, ax ; 4
  3149 00003F37 39C1                <1> 	cmp	ecx, eax ; 24/12/2021
  3150 00003F39 734C                <1> 	jnb	short get_argp2
  3151 00003F3B 89F3                <1> 	mov	ebx, esi
  3152 00003F3D 01CB                <1> 	add	ebx, ecx
  3153 00003F3F E86BE9FFFF          <1> 	call	get_physical_addr ; get physical address
  3154 00003F44 7237                <1> 	jc	short get_argp_err
  3155                              <1> 	;push	esi
  3156 00003F46 89C6                <1> 	mov	esi, eax
  3157 00003F48 66870D[58660000]    <1> 	xchg	cx, [ncount]
  3158 00003F4F 8735[54660000]      <1> 	xchg	esi, [nbase]
  3159 00003F55 B504                <1> 	mov	ch, 4
  3160 00003F57 28CD                <1> 	sub	ch, cl
  3161                              <1> get_argp0:
  3162 00003F59 AC                  <1> 	lodsb
  3163                              <1> 	;push	ax
  3164                              <1> 	; 24/12/2021
  3165 00003F5A 50                  <1> 	push	eax
  3166 00003F5B FEC9                <1> 	dec	cl
  3167 00003F5D 75FA                <1>         jnz     short get_argp0
  3168 00003F5F 8B35[54660000]      <1> 	mov	esi, [nbase]
  3169                              <1> 	; 21/07/2015
  3170 00003F65 0FB6C5              <1> 	movzx	eax, ch
  3171 00003F68 0105[54660000]      <1> 	add	[nbase], eax
  3172 00003F6E 662905[58660000]    <1> 	sub	[ncount], ax
  3173                              <1> get_argp1:
  3174 00003F75 AC                  <1> 	lodsb
  3175 00003F76 FECD                <1> 	dec	ch
  3176 00003F78 7423                <1>         jz      short get_argp3
  3177                              <1> 	;push	ax
  3178                              <1> 	; 24/12/2021
  3179 00003F7A 50                  <1> 	push	eax
  3180 00003F7B EBF8                <1> 	jmp     short get_argp1
  3181                              <1> 	; 24/12/2021
  3182                              <1> get_argp_err:
  3183 00003F7D A3[31660000]        <1> 	mov	[u.error], eax
  3184 00003F82 E94AF2FFFF          <1> 	jmp	error
  3185                              <1> get_argp2:
  3186                              <1> 	; 21/07/2015
  3187                              <1> 	;mov	eax, 4
  3188 00003F87 8B15[54660000]      <1> 	mov 	edx, [nbase] ; 18/10/2015
  3189 00003F8D 0105[54660000]      <1> 	add	[nbase], eax
  3190 00003F93 662905[58660000]    <1> 	sub	[ncount], ax
  3191                              <1> 	;
  3192 00003F9A 8B02                <1> 	mov	eax, [edx]
  3193 00003F9C C3                  <1> 	retn
  3194                              <1> get_argp3:
  3195 00003F9D B103                <1> 	mov	cl, 3
  3196                              <1> get_argp4:
  3197 00003F9F C1E008              <1> 	shl	eax, 8
  3198                              <1> 	;pop	dx
  3199                              <1> 	; 24/12/2021
  3200 00003FA2 5A                  <1> 	pop	edx
  3201 00003FA3 88D0                <1> 	mov 	al, dl
  3202 00003FA5 E2F8                <1>         loop    get_argp4
  3203                              <1> 	;pop	esi
  3204 00003FA7 C3                  <1> 	retn	
  3205                              <1> 
  3206                              <1> sysfstat:
  3207                              <1> 	; 09/05/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.3)
  3208                              <1> 	;	([idev] return in eax)
  3209                              <1> 	;	0 = root device
  3210                              <1> 	;	1 = mounted device (>0)
  3211                              <1> 	; 03/02/2022
  3212                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  3213                              <1> 	; 19/06/2013 (Retro UNIX 8086 v1)
  3214                              <1> 	;
  3215                              <1> 	; 'sysfstat' is identical to 'sysstat' except that it operates
  3216                              <1> 	; on open files instead of files given by name. It puts the
  3217                              <1> 	; buffer address on the stack, gets the i-number and
  3218                              <1> 	; checks to see if the file is open for reading or writing.
  3219                              <1> 	; If the file is open for writing (i-number is negative)
  3220                              <1> 	; the i-number is set positive and a branch into 'sysstat'
  3221                              <1> 	; is made.	
  3222                              <1> 	;
  3223                              <1> 	; Calling sequence:
  3224                              <1> 	;	sysfstat; buf
  3225                              <1> 	; Arguments:
  3226                              <1> 	;	buf - buffer address
  3227                              <1> 	;
  3228                              <1> 	; Inputs: *u.r0 - file descriptor
  3229                              <1> 	; Outputs: buffer is loaded with file information
  3230                              <1> 	; ...............................................................
  3231                              <1> 	;				
  3232                              <1> 	; Retro UNIX 8086 v1 modification:
  3233                              <1> 	;       'sysfstat' system call has two arguments; so,
  3234                              <1> 	;	* 1st argument, file descriptor is in BX register
  3235                              <1> 	;	* 2nd argument, buf is pointed to by CX register
  3236                              <1> 
  3237                              <1> 	; / set status of open file
  3238                              <1> 		; jsr r0,arg; u.off / put buffer address in u.off
  3239 00003FA8 51                  <1> 	push	ecx
  3240                              <1> 		; mov u.off,-(sp) / put buffer address on the stack
  3241                              <1> 		; mov *u.r0,r1 / put file descriptor in r1
  3242                              <1> 		; jsr r0,getf / get the files i-number
  3243                              <1> 	; BX = file descriptor (file number)
  3244 00003FA9 E8FE000000          <1> 	call	getf1
  3245                              <1> 	; 03/02/2022
  3246 00003FAE 21C0                <1> 	and	eax, eax
  3247                              <1> 	;and	ax, ax ; i-number of the file
  3248                              <1> 		; tst	r1 / is it 0?
  3249                              <1> 	;jz	error
  3250                              <1> 		; beq error3 / yes, error
  3251 00003FB0 750F                <1> 	jnz	short sysfstat1
  3252 00003FB2 C705[31660000]0A00- <1> 	mov	dword [u.error], ERR_FILE_NOT_OPEN  ; 'file not open !'
  3252 00003FBA 0000                <1>
  3253 00003FBC E910F2FFFF          <1> 	jmp	error
  3254                              <1> sysfstat1:
  3255 00003FC1 80FC80              <1> 	cmp	ah, 80h
  3256 00003FC4 7222                <1>         jb      short sysstat1
  3257                              <1> 		; bgt 1f / if i-number is negative (open for writing)
  3258 00003FC6 66F7D8              <1> 	neg	ax
  3259                              <1> 		; neg r1 / make it positive, then branch
  3260 00003FC9 EB1D                <1> 	jmp	short sysstat1
  3261                              <1> 		; br 1f / to 1f
  3262                              <1> sysstat:
  3263                              <1> 	; 09/05/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.3)
  3264                              <1> 	;	([idev] return in eax)
  3265                              <1> 	;	0 = root device
  3266                              <1> 	;	1 = mounted device (>0)
  3267                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3268                              <1> 	; 18/10/2015
  3269                              <1> 	; 07/10/2015
  3270                              <1> 	; 02/09/2015
  3271                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  3272                              <1> 	; 19/06/2013 (Retro UNIX 8086 v1)
  3273                              <1> 	;
  3274                              <1> 	; 'sysstat' gets the status of a file. Its arguments are the
  3275                              <1> 	; name of the file and buffer address. The buffer is 34 bytes
  3276                              <1> 	; long and information about the file placed in it.	
  3277                              <1> 	; sysstat calls 'namei' to get the i-number of the file.
  3278                              <1> 	; Then 'iget' is called to get i-node in core. The buffer
  3279                              <1> 	; is then loaded and the results are given in the UNIX
  3280                              <1> 	; Programmers Manual sysstat (II).	
  3281                              <1> 	;
  3282                              <1> 	; Calling sequence:
  3283                              <1> 	;	sysstat; name; buf
  3284                              <1> 	; Arguments:
  3285                              <1> 	;	name - points to the name of the file
  3286                              <1> 	;	buf - address of a 34 bytes buffer
  3287                              <1> 	; Inputs: -
  3288                              <1> 	; Outputs: buffer is loaded with file information
  3289                              <1> 	; ...............................................................
  3290                              <1> 	;				
  3291                              <1> 	; Retro UNIX 8086 v1 modification: 
  3292                              <1> 	;       'sysstat' system call has two arguments; so,
  3293                              <1> 	;	Retro UNIX 8086 v1 argument transfer method 2 is used
  3294                              <1> 	;	to get sysstat system call arguments from the user;
  3295                              <1> 	;	* 1st argument, name is pointed to by BX register
  3296                              <1> 	;	* 2nd argument, buf is pointed to by CX register
  3297                              <1> 	;
  3298                              <1> 	;	NOTE: Retro UNIX 8086 v1 'arg2' routine gets these
  3299                              <1> 	;	      arguments which were in these registers;
  3300                              <1> 	;	      but, it returns by putting the 1st argument
  3301                              <1> 	;	      in 'u.namep' and the 2nd argument
  3302                              <1> 	;	      on top of stack. (1st argument is offset of the
  3303                              <1> 	;	      file/path name in the user's program segment.)		 	
  3304                              <1> 	
  3305                              <1> 	; / ; name of file; buffer - get files status
  3306                              <1> 		; jsr r0,arg2 / get the 2 arguments
  3307 00003FCB 891D[F4650000]      <1> 	mov	[u.namep], ebx
  3308 00003FD1 51                  <1> 	push	ecx
  3309 00003FD2 E806010000          <1> 	call	namei
  3310                              <1> 		; jsr r0,namei / get the i-number for the file
  3311                              <1> 	;jc	error
  3312                              <1> 		; br error3 / no such file, error
  3313 00003FD7 730F                <1> 	jnc	short sysstat1
  3314                              <1> 	; pop 	ecx
  3315                              <1> sysstat_err0:
  3316                              <1> 	; 'file not found !' error
  3317 00003FD9 C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND ; 12
  3317 00003FE1 0000                <1>
  3318 00003FE3 E9E9F1FFFF          <1> 	jmp	error
  3319                              <1> 
  3320                              <1> ;statx: db 0
  3321                              <1> 
  3322                              <1> sysstat1: ; 1:
  3323 00003FE8 E800090000          <1> 	call	iget
  3324                              <1> 		; jsr r0,iget / get the i-node into core
  3325                              <1> 	; 07/10/2015 (ax = [ii], inode number)
  3326                              <1> 	; 02/09/2015
  3327 00003FED 8F05[FC650000]      <1> 	pop	dword [u.base]
  3328                              <1> 		; mov (sp)+,r3 / move u.off to r3 (points to buffer)
  3329 00003FF3 E861000000          <1> 	call	sysstat_gpa ; get physical address
  3330 00003FF8 730A                <1> 	jnc 	short sysstat2
  3331                              <1> sysstat_err1:
  3332 00003FFA A3[31660000]        <1> 	mov	dword [u.error], eax ; error code
  3333 00003FFF E9CDF1FFFF          <1> 	jmp	error
  3334                              <1> sysstat2:
  3335 00004004 A0[C0650000]        <1> 	mov 	al, [ii] ; 07/10/2015 (result of 'iget' call, above)
  3336 00004009 AA                  <1> 	stosb
  3337 0000400A FF05[FC650000]      <1> 	inc 	dword [u.base]
  3338                              <1> 	;dec 	cx
  3339                              <1> 	; 24/12/2021
  3340 00004010 49                  <1> 	dec	ecx
  3341 00004011 7505                <1> 	jnz	short sysstat3
  3342 00004013 E841000000          <1> 	call	sysstat_gpa
  3343                              <1> 	;jc	short sysstat_err1
  3344                              <1> sysstat3:
  3345 00004018 A0[C1650000]        <1> 	mov 	al, [ii+1] ; 07/10/2015 (result of 'iget' call, above)
  3346 0000401D AA                  <1> 	stosb
  3347                              <1> 		; mov r1,(r3)+ / put i-number in 1st word of buffer
  3348 0000401E FF05[FC650000]      <1> 	inc 	dword [u.base]
  3349                              <1> 	;;dec 	word [u.pcount]
  3350                              <1> 	;dec	cx
  3351 00004024 49                  <1> 	dec	ecx ; 24/12/2021
  3352 00004025 7505                <1> 	jnz	short sysstat4
  3353 00004027 E82D000000          <1> 	call	sysstat_gpa
  3354                              <1> 	;jc	short sysstat_err1	
  3355                              <1> sysstat4:
  3356 0000402C BE[D4620000]        <1> 	mov	esi, inode
  3357                              <1> 		; mov $inode,r2 / r2 points to i-node
  3358                              <1> sysstat5: ; 1:
  3359 00004031 A4                  <1> 	movsb
  3360                              <1> 		; mov (r2)+,(r3)+ / move rest of i-node to buffer
  3361 00004032 FF05[FC650000]      <1> 	inc 	dword [u.base]
  3362                              <1> 	;;dec 	word [u.pcount]
  3363                              <1> 	;dec 	cx
  3364                              <1> 	; 24/12/2021
  3365 00004038 49                  <1> 	dec	ecx
  3366 00004039 7505                <1> 	jnz	short sysstat6
  3367 0000403B E819000000          <1> 	call	sysstat_gpa
  3368                              <1> 	;jc	short sysstat_err1
  3369                              <1> sysstat6:		
  3370 00004040 81FE[F4620000]      <1> 	cmp	esi, inode + 32
  3371                              <1> 		; cmp r2,$inode+32 / done?
  3372 00004046 75E9                <1> 	jne	short sysstat5
  3373                              <1> 		; bne 1b / no, go back
  3374                              <1> 
  3375                              <1> 	;;;
  3376                              <1> 	; 09/05/2022
  3377                              <1> 	;*** additional feature *** -retro unix only- 
  3378                              <1> 	;
  3379                              <1> 	; !! return device number -of current inode- in eax !!
  3380                              <1> 	;
  3381                              <1> 	; (modification reason/purpose:
  3382                              <1> 	; to improve 'pwd' command's pathname output/result
  3383                              <1> 	; and to correct 'cp' command's 'can not copy file itself'
  3384                              <1> 	; error due to same inode numbers in root file system
  3385                              <1> 	; and mounted file system.)
  3386                              <1> 	;
  3387 00004048 29C0                <1> 	sub	eax, eax
  3388 0000404A A0[C2650000]        <1> 	mov	al, [idev] ; [cdev]
  3389 0000404F A3[DC650000]        <1> 	mov	[u.r0], eax
  3390                              <1> 	;;;  
  3391                              <1> 
  3392 00004054 E998F1FFFF          <1> 	jmp	sysret
  3393                              <1> 		; br sysret3 / return through sysret
  3394                              <1> 	;
  3395                              <1> sysstat_gpa: ; get physical address of file status buffer
  3396                              <1> 	; 02/09/2015
  3397 00004059 8B1D[FC650000]      <1> 	mov 	ebx, [u.base]
  3398                              <1> 	; 07/10/2015
  3399 0000405F E84BE8FFFF          <1> 	call	get_physical_addr ; get physical address
  3400                              <1> 	;jc	short sysstat_gpa1
  3401 00004064 7294                <1> 	jc	short sysstat_err1
  3402                              <1> 	; 18/10/2015
  3403 00004066 89C7                <1> 	mov	edi, eax ; physical address
  3404                              <1> 	;mov	[u.pcount], cx ; remain bytes in page
  3405                              <1> ;sysstat_gpa1:
  3406 00004068 C3                  <1> 	retn
  3407                              <1> 
  3408                              <1> fclose:
  3409                              <1> 	; 08/01/2022
  3410                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3411                              <1> 	; 18/06/2015 (Retro UNIX 386 v1 - Beginning)
  3412                              <1> 	;            (32 bit offset pointer modification)
  3413                              <1> 	; 19/04/2013 - 12/01/2014 (Retro UNIX 8086 v1)
  3414                              <1> 	;
  3415                              <1> 	; Given the file descriptor (index to the u.fp list)
  3416                              <1> 	; 'fclose' first gets the i-number of the file via 'getf'.
  3417                              <1> 	; If i-node is active (i-number > 0) the entry in 
  3418                              <1> 	; u.fp list is cleared. If all the processes that opened
  3419                              <1> 	; that file close it, then fsp etry is freed and the file
  3420                              <1> 	; is closed. If not a return is taken. 
  3421                              <1> 	; If the file has been deleted while open, 'anyi' is called
  3422                              <1> 	; to see anyone else has it open, i.e., see if it is appears
  3423                              <1> 	; in another entry in the fsp table. Upon return from 'anyi'
  3424                              <1> 	; a check is made to see if the file is special.	
  3425                              <1> 	;
  3426                              <1> 	; INPUTS ->
  3427                              <1> 	;    r1 - contains the file descriptor (value=0,1,2...)
  3428                              <1> 	;    u.fp - list of entries in the fsp table
  3429                              <1> 	;    fsp - table of entries (4 words/entry) of open files.	 
  3430                              <1> 	; OUTPUTS ->
  3431                              <1> 	;    r1 - contains the same file descriptor
  3432                              <1> 	;    r2 - contains i-number
  3433                              <1> 	;
  3434                              <1> 	; ((AX = R1))
  3435                              <1> 	; ((Modified registers: eDX, eBX, eCX, eSI, eDI, eBP))
  3436                              <1> 	;
  3437                              <1> 	; Retro UNIX 8086 v1 modification : CF = 1
  3438                              <1> 	;              if i-number of the file is 0. (error)  	
  3439                              <1> 
  3440                              <1> 	;movzx	edx, ax ; **
  3441                              <1> 	; 24/12/2021
  3442                              <1> 	;movzx	edx, al
  3443 00004069 89C2                <1> 	mov	edx, eax ; eax <= 10 ; 24/12/2021
  3444 0000406B 50                  <1> 	push	eax ; ***
  3445                              <1> 	;push	ax ; ***
  3446                              <1> 		; mov r1,-(sp) / put r1 on the stack (it contains 
  3447                              <1> 			     ; / the index to u.fp list)
  3448 0000406C E839000000          <1> 	call	getf
  3449                              <1> 		; jsr r0,getf / r1 contains i-number, 
  3450                              <1> 			    ; / cdev has device =, u.fofp 
  3451                              <1> 			    ; / points to 3rd word of fsp entry
  3452 00004071 6683F801            <1> 	cmp	ax, 1 ; r1
  3453                              <1> 		; tst r1 / is i-number 0?
  3454 00004075 7231                <1> 	jb	short fclose_2
  3455                              <1> 		; beq 1f / yes, i-node not active so return
  3456                              <1> 		; tst (r0)+ / no, jump over error return
  3457 00004077 89D3                <1> 	mov	ebx, edx ; **
  3458                              <1> 	; 24/12/2021
  3459 00004079 89C2                <1> 	mov	edx, eax ; *
  3460                              <1> 	;mov 	dx, ax ; *
  3461                              <1> 		; mov r1,r2 / move i-number to r2 ;*
  3462                              <1> 		; mov (sp),r1 / restore value of r1 from the stack
  3463                              <1> 			    ; / which is index to u.fp ; **
  3464 0000407B C683[E2650000]00    <1> 	mov	byte [ebx+u.fp], 0
  3465                              <1> 		; clrb u.fp(r1) / clear that entry in the u.fp list
  3466 00004082 8B1D[EC650000]      <1> 	mov	ebx, [u.fofp]
  3467                              <1> 		; mov u.fofp,r1 / r1 points to 3rd word in fsp entry
  3468                              <1> fclose_0:
  3469 00004088 FE4B04              <1> 	dec	byte [ebx+4] ; 18/06/2015
  3470                              <1> 		; decb 2(r1) / decrement the number of processes 
  3471                              <1> 			   ; / that have opened the file
  3472 0000408B 791B                <1> 	jns	short fclose_2 ; jump if not negative (jump if bit 7 is 0)	 
  3473                              <1> 		; bge 1f / if all processes haven't closed the file, return
  3474                              <1> 	;
  3475                              <1> 	; 24/12/2021
  3476 0000408D 52                  <1> 	push	edx ; *
  3477                              <1> 	;push	dx ; *
  3478                              <1> 		; mov r2,-(sp) / put r2 on the stack (i-number)
  3479                              <1> 	;xor	ax, ax ; 0
  3480                              <1> 	; 24/12/2021
  3481 0000408E 31C0                <1> 	xor	eax, eax
  3482 00004090 668943FC            <1> 	mov	[ebx-4], ax ; 0
  3483                              <1> 		; clr -4(r1) / clear 1st word of fsp entry
  3484 00004094 8A4305              <1> 	mov	al, [ebx+5] ; 18/06/2015
  3485                              <1> 		; tstb	3(r1) / has this file been deleted
  3486 00004097 20C0                <1> 	and	al, al
  3487 00004099 7407                <1> 	jz	short fclose_1
  3488                              <1> 		; beq 2f / no, branch
  3489                              <1> 	; 08/01/2022
  3490 0000409B 89D0                <1> 	mov	eax, edx
  3491                              <1> 	;mov	ax, dx ; *
  3492                              <1> 		; mov r2,r1 / yes, put i-number back into r1
  3493                              <1> 	; AX = inode number
  3494 0000409D E8A0040000          <1> 	call	anyi
  3495                              <1> 		; jsr r0,anyi / free all blocks related to i-number
  3496                              <1> 			    ; / check if file appears in fsp again
  3497                              <1> fclose_1: ; 2:
  3498                              <1> 	; 24/12/2021
  3499 000040A2 58                  <1> 	pop	eax ; * 
  3500                              <1> 	;pop	ax ; *
  3501                              <1> 		; mov (sp)+,r1 / put i-number back into r1
  3502 000040A3 E8DE110000          <1> 	call	iclose ; close if it is special file 
  3503                              <1> 		; jsr r0,iclose / check to see if its a special file
  3504                              <1> fclose_2: ; 1:
  3505                              <1> 	; 24/12/2021
  3506 000040A8 58                  <1> 	pop	eax ; ***
  3507                              <1> 	;pop	ax ; ***
  3508                              <1> 		; mov (sp)+,r1 / put index to u.fp back into r1
  3509 000040A9 C3                  <1> 	retn
  3510                              <1> 		; rts r0
  3511                              <1> 
  3512                              <1> 	; 09/01/2022
  3513                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1. - Kernel v0.2.1.2)
  3514                              <1> getf:	; / get the device number and the i-number of an open file
  3515                              <1> 	; 13/05/2015
  3516                              <1> 	; 11/05/2015 (Retro UNIX 386 v1 - Beginning)
  3517                              <1> 	; 19/04/2013 - 18/11/2013 (Retro UNIX 8086 v1)
  3518                              <1> 	;
  3519 000040AA 89C3                <1> 	mov	ebx, eax
  3520                              <1> getf1: ;; Calling point from 'rw1' (23/05/2013)
  3521                              <1> 	; 08/01/2022
  3522 000040AC 29C0                <1> 	sub	eax, eax
  3523                              <1> 	;
  3524 000040AE 83FB0A              <1> 	cmp	ebx, 10
  3525                              <1> 		; cmp r1,$10. / user limited to 10 open files
  3526 000040B1 7329                <1>         jnb	short getf2 ; 13/05/2015
  3527                              <1> 	;jnb	error
  3528                              <1> 		; bhis error3 / u.fp is table of users open files, 
  3529                              <1> 			    ; / index in fsp table
  3530                              <1> 	; 08/01/2022
  3531 000040B3 8A83[E2650000]      <1> 	mov	al, [ebx+u.fp]
  3532                              <1> 	;mov	bl, [ebx+u.fp]
  3533                              <1> 		; movb	u.fp(r1),r1 / r1 contains number of entry 
  3534                              <1> 		                  ; / in fsp table
  3535                              <1> 	; 08/01/2022
  3536 000040B9 08C0                <1> 	or	al, al
  3537 000040BB 741F                <1> 	jz	short getf2	
  3538                              <1> 	;or	bl, bl
  3539                              <1> 	;jnz	short getf3
  3540                              <1> 	;;jz	short getf4
  3541                              <1> 		; beq 1f / if its zero return
  3542                              <1> ;getf2:
  3543                              <1> ;	; 08/01/2022
  3544                              <1> ;	; 'File not open !' error (ax=0)
  3545                              <1> ;	;sub	eax, eax
  3546                              <1> ;	retn
  3547                              <1> 
  3548                              <1> getf3:	
  3549                              <1> 	; Retro UNIX 386 v1 modification ! (11/05/2015)
  3550                              <1> 	;
  3551                              <1> 	; 'fsp' table (10 bytes/entry)
  3552                              <1> 	; bit 15				   bit 0
  3553                              <1> 	; ---|-------------------------------------------
  3554                              <1> 	; r/w|		i-number of open file
  3555                              <1> 	; ---|-------------------------------------------
  3556                              <1> 	;		   device number
  3557                              <1> 	; -----------------------------------------------
  3558                              <1> 	; offset pointer, r/w pointer to file (bit 0-15)
  3559                              <1> 	; -----------------------------------------------
  3560                              <1> 	; offset pointer, r/w pointer to file (bit 16-31)
  3561                              <1> 	; ----------------------|------------------------
  3562                              <1> 	;  flag that says file 	| number of processes
  3563                              <1> 	;   has been deleted	| that have file open 
  3564                              <1> 	; ----------------------|------------------------
  3565                              <1> 	;
  3566                              <1> 	;mov	eax, 10
  3567                              <1> 	; 08/01/2022
  3568 000040BD B30A                <1> 	mov	bl, 10
  3569 000040BF F6E3                <1> 	mul	bl
  3570 000040C1 BB[9E630000]        <1> 	mov	ebx, fsp-6 ; the 3rd word in the fsp entry
  3571 000040C6 01C3                <1> 	add	ebx, eax
  3572                              <1> 		; asl r1
  3573                              <1> 		; asl r1 / multiply by 8 to get index into 
  3574                              <1> 		       ; / fsp table entry
  3575                              <1> 		; asl r1
  3576                              <1> 		; add $fsp-4,r1 / r1 is pointing at the 3rd word 
  3577                              <1> 			      ; / in the fsp entry
  3578 000040C8 891D[EC650000]      <1> 	mov	[u.fofp], ebx
  3579                              <1> 		; mov r1,u.fofp / save address of 3rd word 
  3580                              <1> 			      ; / in fsp entry in u.fofp
  3581 000040CE 4B                  <1> 	dec	ebx
  3582 000040CF 4B                  <1> 	dec	ebx
  3583                              <1> 	;mov	ax, [ebx]
  3584                              <1> 	; 09/01/2022
  3585 000040D0 8A03                <1> 	mov	al, [ebx]
  3586 000040D2 A2[C3650000]        <1> 	mov	[cdev], al ; ;;Retro UNIX 8086 v1 ! 
  3587                              <1> 	;mov	[cdev], ax ; ;;in fact (!) 
  3588                              <1> 			     ;;dev number is in 1 byte
  3589                              <1> 		; mov -(r1),cdev / remove the device number cdev
  3590 000040D7 4B                  <1> 	dec	ebx
  3591 000040D8 4B                  <1> 	dec	ebx
  3592 000040D9 668B03              <1> 	mov	ax, [ebx]
  3593                              <1> 		; mov -(r1),r1 / and the i-number  r1
  3594                              <1> getf2:	; 08/01/2022
  3595                              <1> getf4:	; 1:
  3596 000040DC C3                  <1> 	retn
  3597                              <1> 		; rts r0
  3598                              <1> 
  3599                              <1> namei:
  3600                              <1> 	; 15/05/2022 (mounted directory path, '..' method)
  3601                              <1> 	; 03/02/2022
  3602                              <1> 	; 09/01/2022
  3603                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3604                              <1> 	; 04/12/2015 (Retro UNIX 386 v1.1, 14 byte file names)
  3605                              <1> 	; 18/10/2015 (nbase, ncount)
  3606                              <1> 	; 12/10/2015
  3607                              <1> 	; 21/08/2015
  3608                              <1> 	; 18/07/2015
  3609                              <1> 	; 02/07/2015
  3610                              <1> 	; 17/06/2015
  3611                              <1> 	; 16/06/2015 (Retro UNIX 386 v1 - Beginning)
  3612                              <1> 	; 24/04/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  3613                              <1> 	;
  3614                              <1> 	; 'namei' takes a file path name and returns i-number of
  3615                              <1> 	; the file in the current directory or the root directory
  3616                              <1> 	; (if the first character of the pathname is '/').	
  3617                              <1> 	;
  3618                              <1> 	; INPUTS ->
  3619                              <1> 	;    u.namep - points to a file path name
  3620                              <1> 	;    u.cdir - i-number of users directory
  3621                              <1> 	;    u.cdev - device number on which user directory resides	
  3622                              <1> 	; OUTPUTS ->
  3623                              <1> 	;    r1 - i-number of file
  3624                              <1> 	;    cdev
  3625                              <1> 	;    u.dirbuf - points to directory entry where a match 
  3626                              <1> 	;               occurs in the search for file path name.
  3627                              <1> 	;	        If no match u.dirb points to the end of 
  3628                              <1> 	;               the directory and r1 = i-number of the current
  3629                              <1> 	;	        directory.	
  3630                              <1> 	; ((AX = R1))
  3631                              <1> 	;
  3632                              <1> 	; (Retro UNIX Prototype : 07/10/2012 - 05/01/2013, UNIXCOPY.ASM)
  3633                              <1>         ; ((Modified registers: eDX, eBX, eCX, eSI, eDI, eBP))  
  3634                              <1> 	;
  3635                              <1> 
  3636 000040DD 66A1[E0650000]      <1> 	mov	ax, [u.cdir]
  3637                              <1> 		; mov u.cdir,r1 / put the i-number of current directory
  3638                              <1> 			      ; / in r1
  3639                              <1> 	; 09/01/2022
  3640 000040E3 8A15[26660000]      <1> 	mov	dl, [u.cdrv]
  3641 000040E9 8815[C3650000]      <1> 	mov	[cdev], dl
  3642                              <1> 	;mov	dx, [u.cdrv]
  3643                              <1> 	;mov	[cdev], dx 	    ; NOTE: Retro UNIX 8086 v1 
  3644                              <1> 				    ; device/drive number is in 1 byte, 
  3645                              <1> 				    ; not in 1 word!
  3646                              <1> 		; mov u.cdev,cdev / device number for users directory 
  3647                              <1> 				; / into cdev
  3648                              <1> 	; 12/10/2015
  3649                              <1> 	; 16/06/2015 - 32 bit modifications (Retro UNIX 386 v1)
  3650                              <1>       	 ; convert virtual (pathname) addr to physical address
  3651 000040EF E868010000          <1> 	call    trans_addr_nmbp ; 12/10/2015
  3652                              <1> 		; esi = physical address of [u.namep]
  3653                              <1> 		; ecx = byte count in the page
  3654 000040F4 803E2F              <1> 	cmp	byte [esi], '/'
  3655                              <1> 		; cmpb *u.namep,$'/ / is first char in file name a /
  3656 000040F7 751D                <1> 	jne	short namei_1
  3657                              <1> 		; bne 1f
  3658 000040F9 FF05[F4650000]      <1> 	inc	dword [u.namep]
  3659                              <1> 		; inc u.namep / go to next char
  3660                              <1> 	;dec	cx ; remain byte count in the page
  3661                              <1> 	; 24/12/2021
  3662 000040FF 49                  <1> 	dec	ecx
  3663 00004100 7506                <1> 	jnz	short namei_0
  3664                              <1> 	; 12/10/2015
  3665 00004102 E855010000          <1> 	call	trans_addr_nmbp ; convert virtual address to physical
  3666                              <1> 		; esi = physical address (page start + offset)
  3667                              <1> 		; ecx = byte count in the page
  3668 00004107 4E                  <1> 	dec	esi
  3669                              <1> namei_0:
  3670 00004108 46                  <1> 	inc 	esi  ; go to next char
  3671 00004109 66A1[CC650000]      <1> 	mov	ax, [rootdir] ; 09/07/2013
  3672                              <1> 		; mov rootdir,r1 / put i-number of rootdirectory in r1
  3673 0000410F C605[C3650000]00    <1> 	mov	byte [cdev], 0
  3674                              <1> 		; clr cdev / clear device number
  3675                              <1> namei_1: ; 1:
  3676 00004116 F606FF              <1> 	test	byte [esi], 0FFh
  3677                              <1> namei_10: ; 24/12/2021 (jump from namei_8)
  3678 00004119 74C1                <1> 	jz	short getf4
  3679                              <1> 	;jz	nig
  3680                              <1> 		; tstb *u.namep / is the character in file name a nul
  3681                              <1> 		; beq nig / yes, end of file name reached; 
  3682                              <1> 			; / branch to "nig"
  3683                              <1> namei_2: ; 1:
  3684                              <1> 	; 18/10/2015
  3685 0000411B 8935[54660000]      <1> 	mov 	[nbase], esi
  3686 00004121 66890D[58660000]    <1> 	mov 	[ncount], cx
  3687                              <1> 	;
  3688                              <1> 	;mov	dx, 2
  3689 00004128 B202                <1> 	mov	dl, 2 ; user flag (read, non-owner)
  3690 0000412A E892080000          <1> 	call	access
  3691                              <1> 		; jsr r0,access; 2 / get i-node with i-number r1
  3692                              <1> 	; 'access' will not return here if user has not "r" permission !
  3693                              <1> 	; 03/02/2022
  3694 0000412F F605[D5620000]40    <1> 	test	byte [i.flgs+1], 40h
  3695                              <1> 	;test 	word [i.flgs], 4000h
  3696                              <1> 		; bit $40000,i.flgs / directory i-node?
  3697 00004136 746A                <1>         jz      short namei_err
  3698                              <1> 		; beq error3 / no, got an error
  3699                              <1> 	; 16/06/2015 - 32 bit modifications (Retro UNIX 386 v1)
  3700 00004138 31C0                <1> 	xor	eax, eax
  3701 0000413A A3[F8650000]        <1> 	mov	[u.off], eax ; 0
  3702 0000413F 66A1[D8620000]      <1> 	mov	ax, [i.size]
  3703 00004145 A3[F0650000]        <1> 	mov	[u.dirp], eax
  3704                              <1> 		; mov i.size,u.dirp / put size of directory in u.dirp
  3705                              <1> 		; clr u.off / u.off is file offset used by user
  3706 0000414A C705[EC650000]-     <1> 	mov	dword [u.fofp], u.off
  3706 00004150 [F8650000]          <1>
  3707                              <1> 		; mov $u.off,u.fofp / u.fofp is a pointer to 
  3708                              <1> 				  ; / the offset portion of fsp entry
  3709                              <1> namei_3: ; 2:
  3710 00004154 C705[FC650000]-     <1> 	mov	dword [u.base], u.dirbuf
  3710 0000415A [0E660000]          <1>
  3711                              <1> 		; mov $u.dirbuf,u.base / u.dirbuf holds a file name 
  3712                              <1> 				    ; / copied from a directory
  3713 0000415E C705[00660000]1000- <1> 	mov 	dword [u.count], 16 ; 04/12/2015 (10 -> 16) 	
  3713 00004166 0000                <1>
  3714                              <1>  		; mov $10.,u.count / u.count is byte count 
  3715                              <1> 				 ; / for reads and writes
  3716 00004168 66A1[C0650000]      <1> 	mov 	ax, [ii]
  3717                              <1> 	; 31/07/2013 ('namei_r') - 16/06/2015 ('u.kcall')
  3718 0000416E FE05[43660000]      <1>  	inc     byte [u.kcall] ; the caller is 'namei' sign	
  3719 00004174 E848090000          <1>     	call	readi
  3720                              <1> 		; jsr r0,readi / read 10. bytes of file 
  3721                              <1> 		      ; with i-number (r1); i.e. read a directory entry
  3722 00004179 8B0D[04660000]      <1> 	mov 	ecx, [u.nread]
  3723 0000417F 09C9                <1> 	or 	ecx, ecx
  3724                              <1> 		; tst u.nread
  3725 00004181 741B                <1> 	jz	short nib
  3726                              <1> 		; ble nib / gives error return
  3727                              <1> 	;
  3728 00004183 668B1D[0E660000]    <1> 	mov 	bx, [u.dirbuf]
  3729 0000418A 6621DB              <1> 	and 	bx, bx       
  3730                              <1> 		; tst u.dirbuf /
  3731 0000418D 7522                <1> 	jnz	short namei_4
  3732                              <1> 		; bne 3f / branch when active directory entry 
  3733                              <1> 		       ; / (i-node word in entry non zero)
  3734 0000418F A1[F8650000]        <1> 	mov	eax, [u.off]
  3735 00004194 83E810              <1> 	sub	eax, 16 ; 04/12/2015 (10 -> 16) 
  3736 00004197 A3[F0650000]        <1> 	mov	[u.dirp], eax
  3737                              <1> 		; mov u.off,u.dirp
  3738                              <1> 		; sub $10.,u.dirp
  3739 0000419C EBB6                <1> 	jmp	short namei_3
  3740                              <1> 		; br 2b
  3741                              <1> 
  3742                              <1> 	; 18/07/2013
  3743                              <1> nib: 
  3744 0000419E 31C0                <1> 	xor	eax, eax  ; xor ax, ax ; ax = 0 -> file not found 
  3745 000041A0 F9                  <1> 	stc
  3746                              <1> nig:
  3747 000041A1 C3                  <1> 	retn
  3748                              <1> 
  3749                              <1> namei_err:
  3750                              <1> 	; 16/06/2015
  3751 000041A2 C705[31660000]1300- <1> 	mov	dword [u.error], ERR_NOT_DIR ; 'not a directory !' error
  3751 000041AA 0000                <1>
  3752 000041AC E920F0FFFF          <1> 	jmp	error
  3753                              <1> 
  3754                              <1> namei_4: ; 3:
  3755                              <1> 	; 18/10/2015
  3756                              <1> 	; 12/10/2015
  3757                              <1> 	; 21/08/2015
  3758                              <1> 	; 18/07/2015
  3759 000041B1 8B2D[F4650000]      <1> 	mov	ebp, [u.namep]
  3760                              <1> 		; mov u.namep,r2 / u.namep points into a file name string
  3761 000041B7 BF[10660000]        <1> 	mov 	edi, u.dirbuf + 2
  3762                              <1> 		; mov $u.dirbuf+2,r3 / points to file name of directory entry
  3763                              <1> 	; 18/10/2015
  3764 000041BC 8B35[54660000]      <1> 	mov	esi, [nbase]	
  3765 000041C2 668B0D[58660000]    <1> 	mov	cx, [ncount]
  3766                              <1> 	;
  3767 000041C9 6621C9              <1> 	and	cx, cx
  3768 000041CC 7505                <1> 	jnz	short namei_5	
  3769                              <1> 	;
  3770 000041CE E88F000000          <1> 	call	trans_addr_nm ; convert virtual address to physical
  3771                              <1> 		; esi = physical address (page start + offset)
  3772                              <1> 		; ecx = byte count in the page
  3773                              <1> namei_5: ; 3:
  3774 000041D3 45                  <1> 	inc	ebp ; 18/07/2015
  3775 000041D4 AC                  <1> 	lodsb   ; mov al, [esi] ; inc esi (al = r4)
  3776                              <1> 		; movb (r2)+,r4 / move a character from u.namep string into r4
  3777 000041D5 08C0                <1> 	or 	al, al
  3778 000041D7 741C                <1> 	jz 	short namei_7
  3779                              <1> 		; beq 3f / if char is nul, then the last char in string
  3780                              <1> 			; / has been moved
  3781 000041D9 3C2F                <1> 	cmp	al, '/'
  3782                              <1> 		; cmp r4,$'/ / is char a </>
  3783 000041DB 7418                <1> 	je 	short namei_7
  3784                              <1> 		; beq 3f	
  3785                              <1> 	; 24/12/2021
  3786 000041DD 49                  <1> 	dec	ecx
  3787                              <1> 	; 12/10/2015
  3788                              <1> 	;dec	cx ; remain byte count in the page
  3789 000041DE 7505                <1> 	jnz	short namei_6
  3790 000041E0 E87D000000          <1> 	call	trans_addr_nm ; convert virtual address to physical
  3791                              <1> 		; esi = physical address (page start + offset)
  3792                              <1> 		; ecx = byte count in the page
  3793                              <1> namei_6:
  3794 000041E5 81FF[1E660000]      <1>         cmp     edi, u.dirbuf + 16 ; 04/12/2015 (10 -> 16) 
  3795                              <1> 		; cmp r3,$u.dirbuf+10. / have I checked
  3796                              <1> 				     ; / all 8 bytes of file name
  3797 000041EB 74E6                <1> 	je	short namei_5
  3798                              <1> 		; beq 3b
  3799 000041ED AE                  <1> 	scasb	
  3800                              <1> 		; cmpb (r3)+,r4 / compare char in u.namep string to file name 
  3801                              <1> 			      ; / char read from directory
  3802 000041EE 74E3                <1> 	je 	short namei_5
  3803                              <1> 		; beq 3b / branch if chars match
  3804                              <1> namei_9:
  3805 000041F0 E95FFFFFFF          <1>         jmp	namei_3 ; 2b
  3806                              <1> 		; br 2b / file names do not match go to next directory entry
  3807                              <1> namei_7: ; 3:
  3808 000041F5 81FF[1E660000]      <1> 	cmp	edi, u.dirbuf + 16 ; 04/12/2015 (10 -> 16) 
  3809                              <1> 		; cmp r3,$u.dirbuf+10. / if equal all 8 bytes were matched
  3810 000041FB 7406                <1> 	je	short namei_8
  3811                              <1> 		; beq 3f
  3812 000041FD 8A27                <1> 	mov 	ah, [edi]
  3813                              <1> 	;inc 	edi 
  3814 000041FF 20E4                <1> 	and 	ah, ah
  3815                              <1> 		; tstb (r3)+ /
  3816                              <1>         ;jnz	namei_3
  3817                              <1> 		; bne 2b
  3818                              <1> 	; 24/12/2021
  3819 00004201 75ED                <1> 	jnz	short namei_9	
  3820                              <1> namei_8: ; 3
  3821 00004203 892D[F4650000]      <1> 	mov	[u.namep], ebp ; 18/07/2015
  3822                              <1> 		; mov r2,u.namep / u.namep points to char 
  3823                              <1> 			       ; / following a / or nul
  3824                              <1> 	;mov	bx, [u.dirbuf]
  3825                              <1> 		; mov u.dirbuf,r1 / move i-node number in directory 
  3826                              <1> 				; / entry to r1
  3827                              <1> 	;;;;
  3828                              <1> 	; 15/05/2022 - Retro UNIX (8086/386) feature only !
  3829                              <1> 	; ! 'pwd' utility modification !
  3830                              <1> 	; ((if directory entry name is a dotdot)))
  3831                              <1> 	;; check if it is mounted device's root directory inode
  3832                              <1> 	; and if so, replace it with parent dir inode number
  3833                              <1> 	;  of mounting directory in [mntp].
  3834                              <1> 
  3835 00004209 668B1D[0E660000]    <1> 	mov	bx, [u.dirbuf]
  3836                              <1> 
  3837 00004210 6683FB29            <1> 	cmp	bx, 41 ; root directory inode number
  3838 00004214 753C                <1> 	jne	short namei_11
  3839                              <1> 
  3840 00004216 663B1D[C0650000]    <1> 	cmp	bx, [ii] ; for root dir, '.' & '..' is 41
  3841 0000421D 7533                <1> 	jne	short namei_11 ; not root dir (of mounted dev)
  3842                              <1> 
  3843                              <1> 	;cmp	[idev], bh ; 0
  3844 0000421F 383D[C3650000]      <1> 	cmp	[cdev], bh ; 0
  3845                              <1> 			; 0 = root fs, dev num in [rdev]
  3846                              <1> 			; 1 = mounted, dev num in [mdev]
  3847 00004225 762B                <1> 	jna	short namei_11
  3848                              <1> 
  3849                              <1> 	; dotdot (parent directory link) check
  3850 00004227 66813D[10660000]2E- <1> 	cmp	word [u.dirbuf+2], '..'
  3850 0000422F 2E                  <1>
  3851 00004230 7520                <1> 	jne	short namei_11
  3852 00004232 803D[12660000]00    <1> 	cmp	byte [u.dirbuf+4], 0
  3853 00004239 7517                <1> 	jne	short namei_11
  3854                              <1> 	
  3855                              <1> 	; (This may not be necessary because [idev] = 1
  3856                              <1> 	; and [mnti] is expected as a sub dir inode number)
  3857 0000423B 66391D[C6650000]    <1> 	cmp	[mnti], bx ; 41
  3858 00004242 760E                <1> 	jna	short namei_11
  3859                              <1> 	
  3860                              <1> 	; change inumber to parent dir inum of mount directory
  3861 00004244 668B1D[C8650000]    <1> 	mov	bx, [mntp]
  3862 0000424B C605[C3650000]00    <1> 	mov	byte [cdev], 0 ; root fs
  3863                              <1> namei_11:
  3864                              <1> 	;;;;
  3865                              <1> 
  3866 00004252 20C0                <1> 	and 	al, al
  3867                              <1> 		; tst r4 / if r4 = 0 the end of file name reached,
  3868                              <1> 		      ;  / if r4 = </> then go to next directory
  3869                              <1> 	; 15/05/2022
  3870 00004254 6689D8              <1> 	mov	ax, bx
  3871                              <1> 	;mov 	ax, [u.dirbuf] ; 17/06/2015
  3872                              <1>   	; 24/12/2021
  3873 00004257 E9BDFEFFFF          <1> 	jmp	namei_10 ; (jnz short namei_2, retn)
  3874                              <1> 	;jnz	namei_2 
  3875                              <1> 		; bne 1b
  3876                              <1> 	; AX = i-number of the file
  3877                              <1> ;;nig:
  3878                              <1> 	;retn	; 24/12/2021
  3879                              <1> 		; tst (r0)+ / gives non-error return
  3880                              <1> ;;nib:
  3881                              <1> ;;	xor	ax, ax ; Retro UNIX 8086 v1 modification !
  3882                              <1> 		       ; ax = 0 -> file not found 
  3883                              <1> ;;	stc	; 27/05/2013
  3884                              <1> ;;	retn
  3885                              <1> 		; rts r0
  3886                              <1> 
  3887                              <1> trans_addr_nmbp:
  3888                              <1> 	; 08/01/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.2)
  3889                              <1> 	; 18/10/2015
  3890                              <1> 	; 12/10/2015
  3891 0000425C 8B2D[F4650000]      <1> 	mov 	ebp, [u.namep]
  3892                              <1> trans_addr_nm:
  3893                              <1> 	; 08/01/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.2) 
  3894                              <1> 	; Convert virtual (pathname) address to physical address
  3895                              <1> 	; (Retro UNIX 386 v1 feature only !)
  3896                              <1> 	; 18/10/2015
  3897                              <1> 	; 12/10/2015 (u.pnbase & u.pncount has been removed from code)
  3898                              <1> 	; 02/07/2015
  3899                              <1> 	; 17/06/2015
  3900                              <1> 	; 16/06/2015
  3901                              <1> 	;
  3902                              <1> 	; INPUTS: 
  3903                              <1> 	;	ebp = pathname address (virtual) ; [u.namep]
  3904                              <1> 	;	[u.pgdir] = user's page directory
  3905                              <1> 	; OUTPUT:
  3906                              <1> 	;       esi = physical address of the pathname
  3907                              <1> 	;	ecx = remain byte count in the page
  3908                              <1> 	;
  3909                              <1> 	; (Modified registers: EAX, EBX, ECX, EDX, ESI)
  3910                              <1> 	;
  3911                              <1> 
  3912                              <1> 	; 08/01/2022
  3913 00004262 29C9                <1> 	sub	ecx, ecx
  3914                              <1> 	;
  3915 00004264 833D[39660000]00    <1>         cmp     dword [u.ppgdir], 0  ; /etc/init ? (sysexec)
  3916 0000426B 7618                <1> 	jna	short trans_addr_nmk ; the caller is os kernel;
  3917                              <1> 				     ; it is already physical address
  3918 0000426D 50                  <1>    	push	eax	
  3919 0000426E 89EB                <1> 	mov	ebx, ebp ; [u.namep] ; pathname address (virtual)
  3920 00004270 E83AE6FFFF          <1>        	call	get_physical_addr ; get physical address
  3921 00004275 7204                <1> 	jc	short tr_addr_nm_err
  3922                              <1> 	; 18/10/2015
  3923                              <1> 	; eax = physical address 
  3924                              <1> 	; cx = remain byte count in page (1-4096) 
  3925                              <1> 		; 12/10/2015 (cx = [u.pncount])
  3926 00004277 89C6                <1> 	mov	esi, eax ; 12/10/2015 (esi=[u.pnbase])
  3927 00004279 58                  <1> 	pop	eax 
  3928 0000427A C3                  <1> 	retn
  3929                              <1> 
  3930                              <1> tr_addr_nm_err:
  3931 0000427B A3[31660000]        <1> 	mov	[u.error], eax
  3932                              <1> 	;pop 	eax
  3933 00004280 E94CEFFFFF          <1> 	jmp	error
  3934                              <1> 
  3935                              <1> trans_addr_nmk:
  3936                              <1> 	; 12/10/2015
  3937                              <1> 	; 02/07/2015
  3938 00004285 8B35[F4650000]      <1> 	mov	esi, [u.namep]  ; [u.pnbase]
  3939                              <1> 	;mov	cx, PAGE_SIZE ; 4096 ; [u.pncount]
  3940                              <1> 	; 08/01/2022
  3941 0000428B B510                <1> 	mov	ch, PAGE_SIZE/256
  3942 0000428D C3                  <1> 	retn
  3943                              <1> 
  3944                              <1> syschdir:
  3945                              <1> 	; / makes the directory specified in the argument
  3946                              <1> 	; / the current directory
  3947                              <1> 	;
  3948                              <1> 	; 09/01/2022
  3949                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  3950                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  3951                              <1> 	; 19/06/2013 (Retro UNIX 8086 v1)
  3952                              <1> 	;
  3953                              <1> 	; 'syschdir' makes the directory specified in its argument
  3954                              <1> 	; the current working directory.
  3955                              <1> 	;
  3956                              <1> 	; Calling sequence:
  3957                              <1> 	;	syschdir; name
  3958                              <1> 	; Arguments:
  3959                              <1> 	;	name - address of the path name of a directory
  3960                              <1> 	;	       terminated by nul byte.	
  3961                              <1> 	; Inputs: -
  3962                              <1> 	; Outputs: -
  3963                              <1> 	; ...............................................................
  3964                              <1> 	;				
  3965                              <1> 	; Retro UNIX 8086 v1 modification:
  3966                              <1> 	;	 The user/application program puts address of 
  3967                              <1> 	;	 the path name in BX register as 'syschdir' 
  3968                              <1> 	; 	 system call argument.
  3969                              <1> 
  3970 0000428E 891D[F4650000]      <1> 	mov	[u.namep], ebx
  3971                              <1> 		; jsr r0,arg; u.namep / u.namep points to path name
  3972 00004294 E844FEFFFF          <1> 	call	namei
  3973                              <1> 		; jsr r0,namei / find its i-number
  3974                              <1> 	;jc	error
  3975                              <1> 		; br error3
  3976 00004299 730F                <1> 	jnc	short syschdir0
  3977                              <1> 	; 'directory not found !' error
  3978 0000429B C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_DIR_NOT_FOUND ; 12
  3978 000042A3 0000                <1>
  3979 000042A5 E927EFFFFF          <1> 	jmp	error
  3980                              <1> syschdir0:
  3981                              <1> 	; 08/01/2022
  3982 000042AA B202                <1> 	mov	dl, 2  ; read access ; 08/01/2022 (BugFix)
  3983 000042AC E810070000          <1> 	call	access
  3984                              <1> 		; jsr r0,access; 2 / get i-node into core
  3985                              <1> 	; 08/01/2022
  3986 000042B1 F605[D5620000]40    <1> 	test	byte [i.flgs+1], 40h
  3987                              <1> 	;test	word [i.flgs], 4000h
  3988                              <1> 		; bit $40000,i.flgs / is it a directory?
  3989                              <1> 	;jz	error 
  3990                              <1> 		; beq error3 / no error
  3991 000042B8 750F                <1> 	jnz	short syschdir1
  3992 000042BA C705[31660000]1300- <1> 	mov	dword [u.error], ERR_NOT_DIR ; 'not a valid directory !'
  3992 000042C2 0000                <1>
  3993 000042C4 E908EFFFFF          <1> 	jmp	error
  3994                              <1> syschdir1:
  3995 000042C9 66A3[E0650000]      <1> 	mov	[u.cdir], ax
  3996                              <1> 		; mov r1,u.cdir / move i-number to users 
  3997                              <1> 			      ; / current directory
  3998                              <1> 	; 09/01/2022
  3999 000042CF A0[C3650000]        <1> 	mov	al, [cdev]
  4000 000042D4 A2[26660000]        <1> 	mov	[u.cdrv], al
  4001                              <1> 	;mov	ax, [cdev]
  4002                              <1> 	;mov	[u.cdrv], ax
  4003                              <1> 		; mov cdev,u.cdev / move its device to users 
  4004                              <1> 			        ; / current device
  4005 000042D9 E913EFFFFF          <1> 	jmp	sysret
  4006                              <1> 		; br sysret3
  4007                              <1> 
  4008                              <1> syschmod: ; < change mode of file >
  4009                              <1> 	; 29/04/2022 (bugfix)
  4010                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  4011                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  4012                              <1> 	; 20/06/2013 - 07/07/2013 (Retro UNIX 8086 v1)
  4013                              <1> 	;
  4014                              <1> 	; 'syschmod' changes mode of the file whose name is given as
  4015                              <1> 	; null terminated string pointed to by 'name' has it's mode 
  4016                              <1> 	; changed to 'mode'.
  4017                              <1> 	;
  4018                              <1> 	; Calling sequence:
  4019                              <1> 	;	syschmod; name; mode
  4020                              <1> 	; Arguments:
  4021                              <1> 	;	name - address of the file name
  4022                              <1> 	;	       terminated by null byte.
  4023                              <1> 	;	mode - (new) mode/flags < attributes >
  4024                              <1> 	;	
  4025                              <1> 	; Inputs: -
  4026                              <1> 	; Outputs: -
  4027                              <1> 	; ...............................................................
  4028                              <1> 	;				
  4029                              <1> 	; Retro UNIX 8086 v1 modification: 
  4030                              <1> 	;       'syschmod' system call has two arguments; so,
  4031                              <1> 	;	* 1st argument, name is pointed to by BX register
  4032                              <1> 	;	* 2nd argument, mode is in CX register
  4033                              <1> 	;
  4034                              <1> 	; Mode bits (Flags):
  4035                              <1> 	;	bit 15 - 'i-node is allocated' flag (8000h)
  4036                              <1> 	;	bit 14 - directory flag (4000h)
  4037                              <1> 	;	bit 13 - file has modified flag (always on) (2000h)
  4038                              <1> 	;	bit 12 - large file flag (1000h)
  4039                              <1> 	;	bit 6,7,8,9,10,11 are not used (undefined)
  4040                              <1> 	;	bit 5 - set user ID on execution flag (20h) 
  4041                              <1> 	;	bit 4 - executable flag (10h)
  4042                              <1> 	;	bit 3 - read permission for owner (08h)
  4043                              <1> 	;	bit 2 - write permission for owner (04h)
  4044                              <1> 	;	bit 1 - read permission for non-owner (02h)
  4045                              <1> 	;	bit 0 - write permission for non-owner (01h)
  4046                              <1> 
  4047                              <1> 	; / name; mode
  4048 000042DE E815000000          <1> 	call	isown
  4049                              <1> 		;jsr r0,isown / get the i-node and check user status
  4050                              <1> 	; 09/01/2022
  4051 000042E3 F605[D5620000]40    <1> 	test	byte [i.flgs+1], 40h
  4052                              <1> 	;test	word [i.flgs], 4000h
  4053                              <1> 		; bit $40000,i.flgs / directory?
  4054 000042EA 7402                <1> 	jz	short syschmod1
  4055                              <1> 		; beq 2f / no
  4056                              <1> 	; AL = (new) mode
  4057 000042EC 24CF                <1> 	and	al, 0CFh ; 11001111b (clears bit 4 & 5)
  4058                              <1> 		; bic $60,r2 / su & ex / yes, clear set user id and 
  4059                              <1> 			   ; / executable modes
  4060                              <1> syschmod1: ; 2:
  4061 000042EE A2[D4620000]        <1> 	mov	[i.flgs], al	
  4062                              <1> 		; movb r2,i.flgs / move remaining mode to i.flgs
  4063                              <1> 	;jmp	short isown1
  4064                              <1> 	;	; br 1f ; (jmp sysret4)
  4065                              <1> 	; 29/04/2022
  4066 000042F3 E9F9EEFFFF          <1> 	jmp	sysret
  4067                              <1> 
  4068                              <1> isown:
  4069                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4070                              <1> 	; 04/05/2013 - 07/07/2013 (Retro UNIX 8086 v1)
  4071                              <1> 	;
  4072                              <1> 	; 'isown' is given a file name (the 1st argument).
  4073                              <1> 	;  It find the i-number of that file via 'namei' 
  4074                              <1> 	;  then gets the i-node into core via 'iget'.
  4075                              <1> 	;  It then tests to see if the user is super user. 
  4076                              <1> 	;  If not, it cheks to see if the user is owner of 
  4077                              <1> 	;  the file. If he is not an error occurs.
  4078                              <1> 	;  If user is the owner 'setimod' is called to indicate
  4079                              <1> 	;  the inode has been modified and the 2nd argument of
  4080                              <1> 	;  the call is put in r2.
  4081                              <1> 	;
  4082                              <1> 	; INPUTS ->
  4083                              <1> 	;    arguments of syschmod and syschown calls
  4084                              <1> 	; OUTPUTS ->
  4085                              <1> 	;    u.uid - id of user
  4086                              <1> 	;    imod - set to a 1
  4087                              <1> 	;    r2 - contains second argument of the system call				 	
  4088                              <1> 	;
  4089                              <1> 	;   ((AX=R2) output as 2nd argument)
  4090                              <1> 	;
  4091                              <1>         ; ((Modified registers: eAX, eDX, eBX, eCX, eSI, eDI, eBP))  
  4092                              <1> 	;
  4093                              <1> 		; jsr r0,arg2 / u.namep points to file name
  4094                              <1> 	;; ! 2nd argument on top of stack !
  4095                              <1> 	;; 22/06/2015 - 32 bit modifications
  4096                              <1> 	;; 07/07/2013
  4097 000042F8 891D[F4650000]      <1> 	mov	[u.namep], ebx ;; 1st argument
  4098 000042FE 51                  <1> 	push 	ecx ;; 2nd argument
  4099                              <1> 	;;
  4100 000042FF E8D9FDFFFF          <1> 	call	namei
  4101                              <1> 		; jsr r0,namei / get its i-number
  4102                              <1>        ; Retro UNIX 8086 v1 modification !
  4103                              <1>        ; ax = 0 -> file not found 
  4104                              <1> 	;and	ax, ax
  4105                              <1> 	;jz	error
  4106                              <1> 	;jc	error ; 27/05/2013
  4107                              <1> 		; br error3
  4108 00004304 730F                <1> 	jnc	short isown0
  4109                              <1> 	; 'file not found !' error
  4110 00004306 C705[31660000]0C00- <1> 	mov	dword [u.error], ERR_FILE_NOT_FOUND ; 12
  4110 0000430E 0000                <1>
  4111 00004310 E9BCEEFFFF          <1> 	jmp	error
  4112                              <1> isown0:
  4113 00004315 E8D3050000          <1> 	call	iget
  4114                              <1> 		; jsr r0,iget / get i-node into core
  4115 0000431A A0[28660000]        <1> 	mov	al, [u.uid] ; 02/08/2013
  4116 0000431F 08C0                <1> 	or	al, al
  4117                              <1> 		; tstb u.uid / super user?
  4118 00004321 7417                <1> 	jz	short isown1
  4119                              <1> 		; beq 1f / yes, branch
  4120 00004323 3A05[D7620000]      <1> 	cmp	al, [i.uid]
  4121                              <1> 		; cmpb i.uid,u.uid / no, is this the owner of
  4122                              <1> 				 ; / the file
  4123                              <1> 	;jne	error
  4124                              <1> 		; beq 1f / yes
  4125                              <1> 		; jmp error3 / no, error
  4126 00004329 740F                <1> 	je	short isown1
  4127                              <1> 
  4128 0000432B C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_NOT_OWNER  ; 11
  4128 00004333 0000                <1>
  4129                              <1> 			;  'permission denied !' error
  4130 00004335 E997EEFFFF          <1> 	jmp	error
  4131                              <1> isown1: ; 1:
  4132 0000433A E8B8060000          <1> 	call	setimod
  4133                              <1> 		; jsr r0,setimod / indicates 
  4134                              <1> 		;	       ; / i-node has been modified
  4135 0000433F 58                  <1> 	pop	eax ; 2nd argument
  4136                              <1> 		; mov (sp)+,r2 / mode is put in r2 
  4137                              <1> 		       ; / (u.off put on stack with 2nd arg)
  4138 00004340 C3                  <1> 	retn
  4139                              <1> 		; rts r0
  4140                              <1> 
  4141                              <1> ;;arg:  ; < get system call arguments >
  4142                              <1> 	; 'arg' extracts an argument for a routine whose call is 
  4143                              <1> 	; of form:
  4144                              <1> 	;	sys 'routine' ; arg1
  4145                              <1> 	;		or
  4146                              <1> 	;	sys 'routine' ; arg1 ; arg2
  4147                              <1> 	;		or
  4148                              <1> 	;	sys 'routine' ; arg1;...;arg10 (sys exec) 
  4149                              <1> 	;	
  4150                              <1> 	; INPUTS ->
  4151                              <1> 	;    u.sp+18 - contains a pointer to one of arg1..argn
  4152                              <1> 	;	This pointers's value is actually the value of
  4153                              <1> 	;	update pc at the the trap to sysent (unkni) is
  4154                              <1> 	;	made to process the sys instruction
  4155                              <1> 	;    r0 - contains the return address for the routine
  4156                              <1> 	;	that called arg. The data in the word pointer 
  4157                              <1> 	;	to by the return address is used as address
  4158                              <1> 	;	in which the extracted argument is stored   		
  4159                              <1> 	;    	
  4160                              <1> 	; OUTPUTS ->
  4161                              <1> 	;    'address' - contains the extracted argument 
  4162                              <1> 	;    u.sp+18 - is incremented by 2 
  4163                              <1> 	;    r1 - contains the extracted argument
  4164                              <1> 	;    r0 - points to the next instruction to be
  4165                              <1> 	;	 executed in the calling routine.
  4166                              <1> 	;
  4167                              <1>   
  4168                              <1> 	; mov u.sp,r1
  4169                              <1> 	; mov *18.(r1),*(r0)+ / put argument of system call
  4170                              <1> 			; / into argument of arg2
  4171                              <1> 	; add $2,18.(r1) / point pc on stack 
  4172                              <1> 			      ; / to next system argument
  4173                              <1> 	; rts r0
  4174                              <1> 
  4175                              <1> ;;arg2: ; < get system calls arguments - with file name pointer>
  4176                              <1> 	; 'arg2' takes first argument in system call
  4177                              <1> 	;  (pointer to name of the file) and puts it in location
  4178                              <1> 	;  u.namep; takes second argument and puts it in u.off
  4179                              <1> 	;  and on top of the stack
  4180                              <1> 	;	
  4181                              <1> 	; INPUTS ->
  4182                              <1> 	;    u.sp, r0
  4183                              <1> 	;    	
  4184                              <1> 	; OUTPUTS ->
  4185                              <1> 	;    u.namep
  4186                              <1> 	;    u.off 
  4187                              <1> 	;    u.off pushed on stack
  4188                              <1> 	;    r1
  4189                              <1> 	;
  4190                              <1> 
  4191                              <1> 	; jsr	r0,arg; u.namep / u.namep contains value of
  4192                              <1> 				; / first arg in sys call
  4193                              <1> 	; jsr r0,arg; u.off / u.off contains value of 
  4194                              <1> 				; / second arg in sys call
  4195                              <1> 	; mov r0,r1 / r0 points to calling routine
  4196                              <1> 	; mov (sp),r0 / put operation code back in r0
  4197                              <1> 	; mov u.off,(sp) / put pointer to second argument 
  4198                              <1> 			; / on stack
  4199                              <1> 	; jmp (r1) / return to calling routine
  4200                              <1> 
  4201                              <1> syschown: ; < change owner of file >
  4202                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  4203                              <1> 	; 20/06/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  4204                              <1> 	;
  4205                              <1> 	; 'syschown' changes the owner of the file whose name is given
  4206                              <1> 	; as null terminated string pointed to by 'name' has it's owner
  4207                              <1> 	; changed to 'owner'
  4208                              <1> 	;
  4209                              <1> 	; Calling sequence:
  4210                              <1> 	;	syschown; name; owner
  4211                              <1> 	; Arguments:
  4212                              <1> 	;	name - address of the file name
  4213                              <1> 	;	       terminated by null byte.
  4214                              <1> 	;	owner - (new) owner (number/ID)
  4215                              <1> 	;	
  4216                              <1> 	; Inputs: -
  4217                              <1> 	; Outputs: -
  4218                              <1> 	; ...............................................................
  4219                              <1> 	;				
  4220                              <1> 	; Retro UNIX 8086 v1 modification: 
  4221                              <1> 	;       'syschown' system call has two arguments; so,
  4222                              <1> 	;	* 1st argument, name is pointed to by BX register
  4223                              <1> 	;	* 2nd argument, owner number is in CX register
  4224                              <1> 	;
  4225                              <1> 	; / name; owner
  4226 00004341 E8B2FFFFFF          <1> 	call	isown
  4227                              <1> 		; jsr r0,isown / get the i-node and check user status
  4228 00004346 803D[28660000]00    <1> 	cmp 	byte [u.uid], 0 ; 02/08/2013 
  4229                              <1> 		; tstb u.uid / super user
  4230 0000434D 7418                <1> 	jz	short syschown1
  4231                              <1> 		; beq 2f / yes, 2f
  4232 0000434F F605[D4620000]20    <1>         test    byte [i.flgs], 20h ; 32
  4233                              <1> 		; bit $40,i.flgs / no, set userid on execution?
  4234                              <1> 	;jnz	error
  4235                              <1> 		; bne 3f / yes error, could create Trojan Horses
  4236 00004356 740F                <1> 	jz	short syschown1
  4237                              <1> 	; 'permission denied !'
  4238 00004358 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS  ; 11
  4238 00004360 0000                <1>
  4239 00004362 E96AEEFFFF          <1> 	jmp	error
  4240                              <1> syschown1: ; 2:
  4241                              <1> 	; AL = owner (number/ID)
  4242 00004367 A2[D7620000]        <1> 	mov	[i.uid], al ; 23/06/2015
  4243                              <1> 		;  movb	r2,i.uid / no, put the new owners id 
  4244                              <1> 			       ; / in the i-node
  4245 0000436C E980EEFFFF          <1> 	jmp	sysret
  4246                              <1> 	; 1: 
  4247                              <1> 		; jmp sysret4
  4248                              <1> 	; 3:
  4249                              <1> 		; jmp	error
  4250                              <1> 
  4251                              <1> systime: ; / get time of year
  4252                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  4253                              <1> 	; 20/06/2013 (Retro UNIX 8086 v1)
  4254                              <1> 	;
  4255                              <1> 	; 20/06/2013
  4256                              <1> 	; 'systime' gets the time of the year.
  4257                              <1> 	; The present time is put on the stack.
  4258                              <1> 	;
  4259                              <1> 	; Calling sequence:
  4260                              <1> 	;	systime
  4261                              <1> 	; Arguments: -
  4262                              <1> 	;	
  4263                              <1> 	; Inputs: -
  4264                              <1> 	; Outputs: sp+2, sp+4 - present time
  4265                              <1> 	; ...............................................................
  4266                              <1> 	;	
  4267                              <1> 	; Retro UNIX 8086 v1 modification: 
  4268                              <1> 	;       'systime' system call will return to the user
  4269                              <1> 	;	with unix time (epoch) in DX:AX register pair
  4270                              <1> 	;
  4271                              <1> 	; 	!! Major modification on original Unix v1 'systime' 
  4272                              <1> 	;	system call for PC compatibility !!		 	
  4273                              <1> 
  4274 00004371 E8ACE9FFFF          <1> 	call 	epoch
  4275 00004376 A3[DC650000]        <1> 	mov 	[u.r0], eax
  4276                              <1> 		; mov s.time,4(sp)
  4277                              <1> 		; mov s.time+2,2(sp) / put the present time 
  4278                              <1> 				   ; / on the stack
  4279                              <1> 		; br sysret4
  4280 0000437B E971EEFFFF          <1> 	jmp	sysret 
  4281                              <1> 
  4282                              <1> sysstime: ; / set time
  4283                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  4284                              <1> 	; 20/06/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  4285                              <1> 	;
  4286                              <1> 	; 'sysstime' sets the time. Only super user can use this call.
  4287                              <1> 	;
  4288                              <1> 	; Calling sequence:
  4289                              <1> 	;	sysstime
  4290                              <1> 	; Arguments: -
  4291                              <1> 	;	
  4292                              <1> 	; Inputs: sp+2, sp+4 - time system is to be set to.
  4293                              <1> 	; Outputs: -
  4294                              <1> 	; ...............................................................
  4295                              <1> 	;	
  4296                              <1> 	; Retro UNIX 8086 v1 modification: 
  4297                              <1> 	;	the user calls 'sysstime' with unix (epoch) time
  4298                              <1> 	;	(to be set) is in CX:BX register pair as two arguments.
  4299                              <1> 	; 
  4300                              <1> 	;	Retro UNIX 8086 v1 argument transfer method 2 is used
  4301                              <1> 	;	to get sysstime system call arguments from the user;
  4302                              <1> 	;	* 1st argument, lowword of unix time is in BX register
  4303                              <1> 	;	* 2nd argument, highword of unix time is in CX register		 	
  4304                              <1> 	;
  4305                              <1> 	; 	!! Major modification on original Unix v1 'sysstime' 
  4306                              <1> 	;	system call for PC compatibility !!	
  4307                              <1> 
  4308 00004380 803D[28660000]00    <1> 	cmp	byte [u.uid], 0
  4309                              <1> 		; tstb u.uid / is user the super user
  4310                              <1> 	;ja	error
  4311                              <1> 		; bne error4 / no, error
  4312 00004387 760F                <1> 	jna	short systime1
  4313                              <1> 	; 'permission denied !'
  4314 00004389 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_NOT_SUPERUSER  ; 11 
  4314 00004391 0000                <1>
  4315 00004393 E939EEFFFF          <1> 	jmp	error
  4316                              <1> systime1:
  4317                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - 32 bit version)
  4318                              <1> 	; EBX = unix (epoch) time (from user)
  4319 00004398 89D8                <1> 	mov	eax, ebx
  4320 0000439A E800EBFFFF          <1> 	call 	set_date_time
  4321                              <1> 		; mov 4(sp),s.time
  4322                              <1> 		; mov 2(sp),s.time+2 / set the system time
  4323 0000439F E94DEEFFFF          <1> 	jmp	sysret
  4324                              <1> 		; br sysret4
  4325                              <1> 
  4326                              <1> sysbreak:
  4327                              <1> 	; 18/10/2015
  4328                              <1> 	; 07/10/2015
  4329                              <1> 	; 23/06/2015 (Retro UNIX 386 v1 - Beginning)
  4330                              <1> 	; 20/06/2013 - 24/03/2014 (Retro UNIX 8086 v1)
  4331                              <1> 	;
  4332                              <1> 	; 'sysbreak' sets the programs break points. 
  4333                              <1> 	; It checks the current break point (u.break) to see if it is
  4334                              <1> 	; between "core" and the stack (sp). If it is, it is made an
  4335                              <1> 	; even address (if it was odd) and the area between u.break
  4336                              <1> 	; and the stack is cleared. The new breakpoint is then put
  4337                              <1> 	; in u.break and control is passed to 'sysret'.
  4338                              <1> 	;
  4339                              <1> 	; Calling sequence:
  4340                              <1> 	;	sysbreak; addr
  4341                              <1> 	; Arguments: -
  4342                              <1> 	;	
  4343                              <1> 	; Inputs: u.break - current breakpoint
  4344                              <1> 	; Outputs: u.break - new breakpoint 
  4345                              <1> 	;	area between old u.break and the stack (sp) is cleared.
  4346                              <1> 	; ...............................................................
  4347                              <1> 	;	
  4348                              <1> 	; Retro UNIX 8086 v1 modification:
  4349                              <1> 	;	The user/application program puts breakpoint address
  4350                              <1> 	;       in BX register as 'sysbreak' system call argument.
  4351                              <1> 	; 	(argument transfer method 1)
  4352                              <1> 	;
  4353                              <1> 	;  NOTE: Beginning of core is 0 in Retro UNIX 8086 v1 !
  4354                              <1> 	; 	((!'sysbreak' is not needed in Retro UNIX 8086 v1!))
  4355                              <1> 	;  NOTE:
  4356                              <1> 	; 	'sysbreak' clears extended part (beyond of previous
  4357                              <1> 	;	'u.break' address) of user's memory for original unix's
  4358                              <1> 	;	'bss' compatibility with Retro UNIX 8086 v1 (19/11/2013)
  4359                              <1> 
  4360                              <1> 		; mov u.break,r1 / move users break point to r1
  4361                              <1> 		; cmp r1,$core / is it the same or lower than core?
  4362                              <1> 		; blos 1f / yes, 1f
  4363                              <1> 	; 23/06/2015
  4364 000043A4 8B2D[08660000]      <1> 	mov	ebp, [u.break] ; virtual address (offset)
  4365                              <1> 	;and	ebp, ebp
  4366                              <1> 	;jz	short sysbreak_3 
  4367                              <1> 	; Retro UNIX 386 v1 NOTE: u.break points to virtual address !!!
  4368                              <1> 	; (Even break point address is not needed for Retro UNIX 386 v1)
  4369 000043AA 8B15[D4650000]      <1> 	mov	edx, [u.sp] ; kernel stack at the beginning of sys call
  4370 000043B0 83C20C              <1> 	add	edx, 12 ; EIP -4-> CS -4-> EFLAGS -4-> ESP (user) 
  4371                              <1> 	; 07/10/2015
  4372 000043B3 891D[08660000]      <1> 	mov	[u.break], ebx ; virtual address !!!
  4373                              <1> 	;
  4374 000043B9 3B1A                <1> 	cmp	ebx, [edx] ; compare new break point with 
  4375                              <1> 			   ; with top of user's stack (virtual!)
  4376 000043BB 7327                <1> 	jnb	short sysbreak_3
  4377                              <1> 		; cmp r1,sp / is it the same or higher 
  4378                              <1> 			  ; / than the stack?
  4379                              <1> 		; bhis 1f / yes, 1f
  4380 000043BD 89DE                <1> 	mov	esi, ebx
  4381 000043BF 29EE                <1> 	sub	esi, ebp ; new break point - old break point
  4382 000043C1 7621                <1> 	jna	short sysbreak_3 
  4383                              <1> 	;push	ebx
  4384                              <1> sysbreak_1:
  4385 000043C3 89EB                <1> 	mov	ebx, ebp  
  4386 000043C5 E8E5E4FFFF          <1> 	call	get_physical_addr ; get physical address
  4387 000043CA 0F82ABFEFFFF        <1> 	jc	tr_addr_nm_err
  4388                              <1> 	; 18/10/2015
  4389 000043D0 89C7                <1> 	mov	edi, eax 
  4390 000043D2 29C0                <1> 	sub	eax, eax ; 0
  4391                              <1> 		 ; ECX = remain byte count in page (1-4096)
  4392 000043D4 39CE                <1> 	cmp	esi, ecx
  4393 000043D6 7302                <1> 	jnb	short sysbreak_2
  4394 000043D8 89F1                <1> 	mov	ecx, esi
  4395                              <1> sysbreak_2:
  4396 000043DA 29CE                <1> 	sub	esi, ecx
  4397 000043DC 01CD                <1> 	add	ebp, ecx
  4398 000043DE F3AA                <1> 	rep 	stosb
  4399 000043E0 09F6                <1> 	or	esi, esi
  4400 000043E2 75DF                <1> 	jnz	short sysbreak_1
  4401                              <1> 	;
  4402                              <1> 		; bit $1,r1 / is it an odd address
  4403                              <1> 		; beq 2f / no, its even
  4404                              <1> 		; clrb (r1)+ / yes, make it even
  4405                              <1> 	; 2: / clear area between the break point and the stack
  4406                              <1> 		; cmp r1,sp / is it higher or same than the stack
  4407                              <1> 		; bhis 1f / yes, quit
  4408                              <1> 		; clr (r1)+ / clear word
  4409                              <1> 		; br 2b / go back
  4410                              <1> 	;pop	ebx
  4411                              <1> sysbreak_3: ; 1:
  4412                              <1> 	;mov	[u.break], ebx ; virtual address !!!
  4413                              <1> 		; jsr r0,arg; u.break / put the "address" 
  4414                              <1> 			; / in u.break (set new break point)
  4415                              <1> 		; br sysret4 / br sysret
  4416 000043E4 E908EEFFFF          <1> 	jmp	sysret
  4417                              <1> 
  4418                              <1> maknod: 
  4419                              <1> 	; 11/02/2022
  4420                              <1> 	; 09/01/2022
  4421                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4422                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4423                              <1> 	; 02/05/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  4424                              <1> 	;
  4425                              <1> 	; 'maknod' creates an i-node and makes a directory entry
  4426                              <1> 	; for this i-node in the current directory.
  4427                              <1> 	;
  4428                              <1> 	; INPUTS ->
  4429                              <1> 	;    r1 - contains mode
  4430                              <1> 	;    ii - current directory's i-number	
  4431                              <1> 	;    	
  4432                              <1> 	; OUTPUTS ->
  4433                              <1> 	;    u.dirbuf - contains i-number of free i-node 
  4434                              <1> 	;    i.flgs - flags in new i-node 
  4435                              <1> 	;    i.uid - filled with u.uid
  4436                              <1> 	;    i.nlks - 1 is put in the number of links
  4437                              <1> 	;    i.ctim - creation time				
  4438                              <1> 	;    i.ctim+2 - modification time
  4439                              <1> 	;    imod - set via call to setimod
  4440                              <1> 	;	
  4441                              <1> 	; ((AX = R1)) input
  4442                              <1> 	;
  4443                              <1> 	; (Retro UNIX Prototype : 
  4444                              <1> 	;	30/10/2012 - 01/03/2013, UNIXCOPY.ASM)
  4445                              <1>         ; ((Modified registers: eAX, eDX, eBX, eCX, eSI, eDI, eBP))  
  4446                              <1> 
  4447                              <1> 	; / r1 contains the mode
  4448 000043E9 80CC80              <1> 	or 	ah, 80h	; 10000000b
  4449                              <1> 		; bis $100000,r1 / allocate flag set
  4450 000043EC 6650                <1> 	push	ax ; * ; 24/12/2021
  4451                              <1> 		; mov r1,-(sp) / put mode on stack
  4452                              <1> 	; 31/07/2013
  4453 000043EE 66A1[C0650000]      <1> 	mov	ax, [ii] ; move current i-number to AX/r1
  4454                              <1> 		; mov ii,r1 / move current i-number to r1
  4455 000043F4 B201                <1> 	mov	dl, 1 ; owner flag mask
  4456 000043F6 E8C6050000          <1> 	call	access	
  4457                              <1> 		; jsr r0,access; 1 / get its i-node into core
  4458 000043FB 50                  <1> 	push	eax ; ** ; 24/12/2021
  4459                              <1> 		; mov r1,-(sp) / put i-number on stack
  4460 000043FC 66B82800            <1> 	mov	ax, 40
  4461                              <1> 		; mov $40.,r1 / r1 = 40
  4462                              <1> maknod1: ; 1: / scan for a free i-node (next 4 instructions)
  4463 00004400 6640                <1> 	inc	ax
  4464                              <1> 		; inc r1 / r1 = r1 + 1
  4465 00004402 E87F060000          <1> 	call	imap
  4466                              <1> 		; jsr r0,imap / get byte address and bit position in 
  4467                              <1> 			    ; /	inode map in r2 & m
  4468                              <1>   
  4469                              <1>         ; DX (MQ) has a 1 in the calculated bit position
  4470                              <1>         ; eBX (R2) has byte address of the byte with allocation bit
  4471                              <1> 
  4472                              <1> 	; 22/06/2015 - NOTE for next Retro UNIX version: 
  4473                              <1> 	;	       Inode count must be checked here
  4474                              <1> 	; (Original UNIX v1 did not check inode count here !?) 	
  4475                              <1> 
  4476                              <1> 	; 11/02/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.2)
  4477                              <1> 	; (inode count check)
  4478                              <1> 	; ((if cf=1 --> requested inode number > inode count))
  4479                              <1> 
  4480 00004407 730F                <1> 	jnc	short maknod2
  4481                              <1> 
  4482                              <1> 	; no free inode in inode table !
  4483 00004409 C705[31660000]1B00- <1> 	mov	 dword [u.error], ERR_MISC ; 27
  4483 00004411 0000                <1>
  4484                              <1> 			; miscellaneous/other errors
  4485 00004413 E9B9EDFFFF          <1> 	jmp	error	
  4486                              <1> maknod2: 
  4487 00004418 8413                <1> 	test	[ebx], dl
  4488                              <1> 		; bitb mq,(r2) / is the i-node active
  4489 0000441A 75E4                <1> 	jnz	short maknod1
  4490                              <1> 		; bne 1b / yes, try the next one
  4491 0000441C 0813                <1> 	or	[ebx], dl
  4492                              <1> 		; bisb mq,(r2) / no, make it active 
  4493                              <1> 			     ; / (put a 1 in the bit map)
  4494 0000441E E8CA040000          <1> 	call	iget
  4495                              <1> 		; jsr r0,iget / get i-node into core
  4496                              <1> 	; 09/01/2022
  4497 00004423 F605[D5620000]80    <1> 	test	byte [i.flgs+1], 80h
  4498                              <1> 	;test	word [i.flgs], 8000h 
  4499                              <1> 		; tst i.flgs / is i-node already allocated
  4500 0000442A 75D4                <1> 	jnz	short maknod1	
  4501                              <1> 		; blt 1b / yes, look for another one
  4502 0000442C 66A3[0E660000]      <1> 	mov	[u.dirbuf], ax
  4503                              <1> 		; mov r1,u.dirbuf / no, put i-number in u.dirbuf
  4504 00004432 58                  <1> 	pop	eax ; ** ; 24/12/2021
  4505                              <1> 		; mov (sp)+,r1 / get current i-number back
  4506 00004433 E8B5040000          <1> 	call	iget
  4507                              <1> 		; jsr r0,iget / get i-node in core
  4508 00004438 E857F7FFFF          <1> 	call	mkdir
  4509                              <1> 		; jsr r0,mkdir / make a directory entry 
  4510                              <1> 			     ; / in current directory
  4511 0000443D 66A1[0E660000]      <1> 	mov	ax, [u.dirbuf]
  4512                              <1> 		; mov u.dirbuf,r1 / r1 = new inode number
  4513 00004443 E8A5040000          <1> 	call	iget
  4514                              <1> 		; jsr r0,iget / get it into core
  4515                              <1> 		; jsr r0,copyz; inode; inode+32. / 0 it out
  4516                              <1> 	;mov	ecx, 8
  4517                              <1> 	; 09/01/2022 
  4518 00004448 29C9                <1> 	sub	ecx, ecx
  4519 0000444A B108                <1> 	mov	cl, 8
  4520 0000444C 31C0                <1> 	xor	eax, eax ; 0
  4521 0000444E BF[D4620000]        <1> 	mov	edi, inode 
  4522 00004453 F3AB                <1> 	rep	stosd
  4523                              <1> 	;
  4524 00004455 668F05[D4620000]    <1> 	pop	word [i.flgs] ; * ; 24/12/2021
  4525                              <1> 		; mov (sp)+,i.flgs / fill flags
  4526 0000445C 8A0D[28660000]      <1> 	mov 	cl, [u.uid] ; 02/08/2013
  4527 00004462 880D[D7620000]      <1> 	mov 	[i.uid], cl
  4528                              <1> 		; movb u.uid,i.uid / user id	
  4529 00004468 C605[D6620000]01    <1> 	mov     byte [i.nlks], 1
  4530                              <1> 		; movb $1,i.nlks / 1 link
  4531                              <1> 	;call	epoch ; Retro UNIX 8086 v1 modification !
  4532                              <1> 	;mov	eax, [s.time]
  4533                              <1> 	;mov 	[i.ctim], eax
  4534                              <1> 	 	; mov s.time,i.ctim / time created
  4535                              <1> 	 	; mov s.time+2,i.ctim+2 / time modified
  4536                              <1> 	; Retro UNIX 8086 v1 modification !
  4537                              <1> 	; i.ctime=0, i.ctime+2=0 and
  4538                              <1>         ; 'setimod' will set ctime of file via 'epoch'
  4539                              <1> 	;call	setimod
  4540                              <1> 	;	; jsr r0,setimod / set modified flag
  4541                              <1> 	;retn
  4542                              <1> 	;	; rts r0 / return
  4543                              <1> 	; 24/12/2021
  4544 0000446F E983050000          <1> 	jmp	setimod
  4545                              <1> 
  4546                              <1> sysseek: ; / moves read write pointer in an fsp entry
  4547                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4548                              <1> 	; 07/07/2013 - 05/08/2013 (Retro UNIX 8086 v1)
  4549                              <1> 	;
  4550                              <1> 	; 'sysseek' changes the r/w pointer of (3rd word of in an
  4551                              <1> 	; fsp entry) of an open file whose file descriptor is in u.r0.
  4552                              <1> 	; The file descriptor refers to a file open for reading or
  4553                              <1> 	; writing. The read (or write) pointer is set as follows:
  4554                              <1> 	;	* if 'ptrname' is 0, the pointer is set to offset.
  4555                              <1> 	;	* if 'ptrname' is 1, the pointer is set to its
  4556                              <1> 	;	  current location plus offset.
  4557                              <1> 	;	* if 'ptrname' is 2, the pointer is set to the
  4558                              <1> 	;	  size of file plus offset.
  4559                              <1> 	; The error bit (e-bit) is set for an undefined descriptor.
  4560                              <1> 	;
  4561                              <1> 	; Calling sequence:
  4562                              <1> 	;	sysseek; offset; ptrname
  4563                              <1> 	; Arguments:
  4564                              <1> 	;	offset - number of bytes desired to move 
  4565                              <1> 	;		 the r/w pointer
  4566                              <1> 	;	ptrname - a switch indicated above
  4567                              <1> 	;
  4568                              <1> 	; Inputs: r0 - file descriptor 
  4569                              <1> 	; Outputs: -
  4570                              <1> 	; ...............................................................
  4571                              <1> 	;	
  4572                              <1> 	; Retro UNIX 8086 v1 modification: 
  4573                              <1> 	;       'sysseek' system call has three arguments; so,
  4574                              <1> 	;	* 1st argument, file descriptor is in BX (BL) register
  4575                              <1> 	;	* 2nd argument, offset is in CX register
  4576                              <1> 	;	* 3rd argument, ptrname/switch is in DX (DL) register	
  4577                              <1> 	;	
  4578                              <1> 
  4579 00004474 E822000000          <1> 	call	seektell
  4580                              <1> 	; AX = u.count
  4581                              <1> 	; BX = *u.fofp
  4582                              <1> 		; jsr r0,seektell / get proper value in u.count
  4583                              <1> 		; add u.base,u.count / add u.base to it
  4584 00004479 0305[FC650000]      <1> 	add	eax, [u.base] ; add offset (u.base) to base
  4585 0000447F 8903                <1> 	mov	[ebx], eax
  4586                              <1> 		; mov u.count,*u.fofp / put result into r/w pointer
  4587 00004481 E96BEDFFFF          <1> 	jmp	sysret
  4588                              <1> 		; br sysret4
  4589                              <1> 
  4590                              <1> systell: ; / get the r/w pointer
  4591                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  4592                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4593                              <1> 	; 07/07/2013 - 05/08/2013 (Retro UNIX 8086 v1)
  4594                              <1> 	;
  4595                              <1> 	; Retro UNIX 8086 v1 modification:
  4596                              <1> 	; ! 'systell' does not work in original UNIX v1,
  4597                              <1> 	; 	    it returns with error !
  4598                              <1> 	; Inputs: r0 - file descriptor 
  4599                              <1> 	; Outputs: r0 - file r/w pointer
  4600                              <1> 
  4601                              <1> 	;xor	ecx, ecx ; 0
  4602                              <1> 	;mov	edx, 1 ; 05/08/2013
  4603                              <1> 	; 24/12/2021
  4604 00004486 29D2                <1> 	sub	edx, edx
  4605 00004488 FEC2                <1> 	inc	dl
  4606                              <1> 	; edx = 1
  4607                              <1> 	;call 	seektell
  4608 0000448A E812000000          <1> 	call 	seektell0 ; 05/08/2013
  4609                              <1> 	;mov	ebx, [u.fofp]
  4610 0000448F 8B03                <1> 	mov	eax, [ebx]
  4611 00004491 A3[DC650000]        <1> 	mov	[u.r0], eax
  4612 00004496 E956EDFFFF          <1> 	jmp	sysret
  4613                              <1> 
  4614                              <1> ; Original unix v1 'systell' system call:
  4615                              <1> 		; jsr r0,seektell
  4616                              <1> 		; br error4
  4617                              <1> 
  4618                              <1> seektell:
  4619                              <1> 	; 03/02/2022
  4620                              <1> 	; 03/01/2016
  4621                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4622                              <1> 	; 07/07/2013 - 05/08/2013 (Retro UNIX 8086 v1)
  4623                              <1> 	;
  4624                              <1> 	; 'seektell' puts the arguments from sysseek and systell
  4625                              <1> 	; call in u.base and u.count. It then gets the i-number of
  4626                              <1> 	; the file from the file descriptor in u.r0 and by calling
  4627                              <1> 	; getf. The i-node is brought into core and then u.count
  4628                              <1> 	; is checked to see it is a 0, 1, or 2.
  4629                              <1> 	; If it is 0 - u.count stays the same
  4630                              <1> 	;          1 - u.count = offset (u.fofp)
  4631                              <1> 	;	   2 - u.count = i.size (size of file)
  4632                              <1> 	; 	 		
  4633                              <1> 	; !! Retro UNIX 8086 v1 modification:
  4634                              <1> 	;	Argument 1, file descriptor is in BX;
  4635                              <1> 	;	Argument 2, offset is in CX;
  4636                              <1> 	;	Argument 3, ptrname/switch is in DX register.	
  4637                              <1> 	;
  4638                              <1> 	; mov 	ax, 3 ; Argument transfer method 3 (three arguments)	
  4639                              <1> 	; call 	arg
  4640                              <1> 	;
  4641                              <1> 	; ((Return -> ax = base for offset (position= base+offset))
  4642                              <1> 	;
  4643 0000449B 890D[FC650000]      <1> 	mov 	[u.base], ecx ; offset
  4644                              <1> 		; jsr r0,arg; u.base / puts offset in u.base
  4645                              <1> seektell0:
  4646 000044A1 8915[00660000]      <1> 	mov 	[u.count], edx
  4647                              <1> 		; jsr r0,arg; u.count / put ptr name in u.count
  4648                              <1> 	; mov	ax, bx
  4649                              <1> 		; mov *u.r0,r1 / file descriptor in r1 
  4650                              <1> 			     ; / (index in u.fp list)
  4651                              <1> 	; call	getf
  4652                              <1> 		; jsr r0,getf / u.fofp points to 3rd word in fsp entry
  4653                              <1> 	; BX = file descriptor (file number)
  4654 000044A7 E800FCFFFF          <1> 	call	getf1
  4655                              <1> 	; 03/02/2022
  4656 000044AC 09C0                <1> 	or	eax, eax
  4657                              <1> 	;or	ax, ax ; i-number of the file
  4658                              <1> 		; mov r1,-(sp) / r1 has i-number of file, 
  4659                              <1> 		             ; / put it on the stack
  4660                              <1> 	;jz	error
  4661                              <1> 		; beq error4 / if i-number is 0, not active so error
  4662 000044AE 750F                <1> 	jnz	short seektell1
  4663 000044B0 C705[31660000]0A00- <1> 	mov	dword [u.error], ERR_FILE_NOT_OPEN  ; 'file not open !'
  4663 000044B8 0000                <1>
  4664 000044BA E912EDFFFF          <1> 	jmp	error
  4665                              <1> seektell1:
  4666                              <1> 	;push	eax
  4667 000044BF 80FC80              <1> 	cmp	ah, 80h
  4668 000044C2 7203                <1> 	jb	short seektell2
  4669                              <1> 		; bgt .+4 / if its positive jump
  4670 000044C4 66F7D8              <1> 	neg	ax
  4671                              <1> 		; neg r1 / if not make it positive
  4672                              <1> seektell2:
  4673 000044C7 E821040000          <1> 	call	iget
  4674                              <1> 		; jsr r0,iget / get its i-node into core
  4675 000044CC 8B1D[EC650000]      <1>         mov     ebx, [u.fofp] ; 05/08/2013
  4676 000044D2 803D[00660000]01    <1> 	cmp	byte [u.count], 1
  4677                              <1> 		; cmp u.count,$1 / is ptr name =1
  4678 000044D9 7705                <1> 	ja	short seektell3
  4679                              <1> 		; blt 2f / no its zero
  4680 000044DB 740A                <1> 	je	short seektell_4
  4681                              <1> 		; beq 1f / yes its 1
  4682 000044DD 31C0                <1> 	xor	eax, eax
  4683                              <1> 	;jmp	short seektell_5
  4684 000044DF C3                  <1> 	retn
  4685                              <1> seektell3:
  4686                              <1> 	; 03/01/2016
  4687                              <1> 	;movzx	eax, word [i.size]
  4688 000044E0 66A1[D8620000]      <1>         mov   	ax, [i.size]
  4689                              <1>                 ; mov i.size,u.count /  put number of bytes 
  4690                              <1>                                    ; / in file in u.count
  4691                              <1> 	;jmp	short seektell_5
  4692                              <1> 		; br 2f
  4693 000044E6 C3                  <1> 	retn
  4694                              <1> seektell_4: ; 1: / ptrname =1
  4695                              <1> 	;mov	ebx, [u.fofp]
  4696 000044E7 8B03                <1> 	mov	eax, [ebx]
  4697                              <1> 		; mov *u.fofp,u.count / put offset in u.count
  4698                              <1> ;seektell_5: ; 2: / ptrname =0
  4699                              <1> 	;mov	[u.count], eax
  4700                              <1> 	;pop	eax 
  4701                              <1> 		; mov (sp)+,r1 / i-number on stack  r1
  4702 000044E9 C3                  <1> 	retn
  4703                              <1> 		; rts r0
  4704                              <1> 
  4705                              <1> sysintr: ; / set interrupt handling
  4706                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4707                              <1> 	; 07/07/2013 (Retro UNIX 8086 v1)
  4708                              <1> 	;
  4709                              <1> 	; 'sysintr' sets the interrupt handling value. It puts
  4710                              <1> 	; argument of its call in u.intr then branches into 'sysquit'
  4711                              <1> 	; routine. u.tty is checked if to see if a control tty exists.
  4712                              <1> 	; If one does the interrupt character in the tty buffer is
  4713                              <1> 	; cleared and 'sysret'is called. If one does not exits
  4714                              <1> 	; 'sysret' is just called.	
  4715                              <1> 	;
  4716                              <1> 	; Calling sequence:
  4717                              <1> 	;	sysintr; arg
  4718                              <1> 	; Argument:
  4719                              <1> 	;	arg - if 0, interrupts (ASCII DELETE) are ignored.
  4720                              <1> 	;	    - if 1, intterupts cause their normal result
  4721                              <1> 	;		 i.e force an exit.
  4722                              <1> 	;	    - if arg is a location within the program,
  4723                              <1> 	;		control is passed to that location when
  4724                              <1> 	;		an interrupt occurs.	
  4725                              <1> 	; Inputs: -
  4726                              <1> 	; Outputs: -
  4727                              <1> 	; ...............................................................
  4728                              <1> 	;	
  4729                              <1> 	; Retro UNIX 8086 v1 modification: 
  4730                              <1> 	;       'sysintr' system call sets u.intr to value of BX
  4731                              <1> 	;	then branches into sysquit.
  4732                              <1> 	;
  4733 000044EA 66891D[20660000]    <1> 	mov	[u.intr], bx
  4734                              <1> 		; jsr r0,arg; u.intr / put the argument in u.intr
  4735                              <1> 		; br 1f / go into quit routine
  4736 000044F1 E9FBECFFFF          <1> 	jmp	sysret
  4737                              <1> 
  4738                              <1> sysquit:
  4739                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4740                              <1> 	; 07/07/2013 (Retro UNIX 8086 v1)
  4741                              <1> 	;
  4742                              <1> 	; 'sysquit' turns off the quit signal. it puts the argument of
  4743                              <1> 	; the call in u.quit. u.tty is checked if to see if a control 
  4744                              <1> 	; tty exists. If one does the interrupt character in the tty
  4745                              <1> 	; buffer is cleared and 'sysret'is called. If one does not exits
  4746                              <1> 	; 'sysret' is just called.	
  4747                              <1> 	;
  4748                              <1> 	; Calling sequence:
  4749                              <1> 	;	sysquit; arg
  4750                              <1> 	; Argument:
  4751                              <1> 	;	arg - if 0, this call diables quit signals from the
  4752                              <1> 	;		typewriter (ASCII FS)
  4753                              <1> 	;	    - if 1, quits are re-enabled and cause execution to
  4754                              <1> 	;		cease and a core image to be produced.
  4755                              <1> 	;		 i.e force an exit.
  4756                              <1> 	;	    - if arg is an addres in the program,
  4757                              <1> 	;		a quit causes control to sent to that
  4758                              <1> 	;		location.	
  4759                              <1> 	; Inputs: -
  4760                              <1> 	; Outputs: -
  4761                              <1> 	; ...............................................................
  4762                              <1> 	;	
  4763                              <1> 	; Retro UNIX 8086 v1 modification: 
  4764                              <1> 	;       'sysquit' system call sets u.quit to value of BX
  4765                              <1> 	;	then branches into 'sysret'.
  4766                              <1> 	;
  4767 000044F6 66891D[22660000]    <1> 	mov	[u.quit], bx
  4768 000044FD E9EFECFFFF          <1> 	jmp	sysret
  4769                              <1> 		; jsr r0,arg; u.quit / put argument in u.quit
  4770                              <1> 	;1:
  4771                              <1> 		; mov u.ttyp,r1 / move pointer to control tty buffer
  4772                              <1> 			      ; / to r1
  4773                              <1> 		; beq sysret4 / return to user
  4774                              <1> 		; clrb 6(r1) / clear the interrupt character 
  4775                              <1> 			   ; / in the tty buffer
  4776                              <1> 		; br sysret4 / return to user
  4777                              <1> 
  4778                              <1> syssetuid: ; / set process id
  4779                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4780                              <1> 	; 07/07/2013 - 02/08/2013 (Retro UNIX 8086 v1)
  4781                              <1> 	;
  4782                              <1> 	; 'syssetuid' sets the user id (u.uid) of the current process
  4783                              <1> 	; to the process id in (u.r0). Both the effective user and 
  4784                              <1> 	; u.uid and the real user u.ruid are set to this. 
  4785                              <1> 	; Only the super user can make this call.	
  4786                              <1> 	;
  4787                              <1> 	; Calling sequence:
  4788                              <1> 	;	syssetuid
  4789                              <1> 	; Arguments: -
  4790                              <1> 	;
  4791                              <1> 	; Inputs: (u.r0) - contains the process id.
  4792                              <1> 	; Outputs: -
  4793                              <1> 	; ...............................................................
  4794                              <1> 	;	
  4795                              <1> 	; Retro UNIX 8086 v1 modification: 
  4796                              <1> 	;       BL contains the (new) user ID of the current process
  4797                              <1> 
  4798                              <1> 		; movb *u.r0,r1 / move process id (number) to r1
  4799 00004502 3A1D[29660000]      <1> 	cmp	bl, [u.ruid] 
  4800                              <1> 		; cmpb r1,u.ruid / is it equal to the real user 
  4801                              <1> 			       ; / id number
  4802 00004508 741E                <1> 	je	short setuid1
  4803                              <1> 		; beq 1f / yes
  4804 0000450A 803D[28660000]00    <1> 	cmp	byte [u.uid], 0 ; 02/08/2013
  4805                              <1> 		; tstb u.uid / no, is current user the super user?
  4806                              <1> 	;ja	error
  4807                              <1> 		; bne error4 / no, error
  4808 00004511 760F                <1> 	jna	short setuid0
  4809 00004513 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_NOT_SUPERUSER  ; 11
  4809 0000451B 0000                <1>
  4810                              <1> 				; 'permission denied !' error
  4811 0000451D E9AFECFFFF          <1> 	jmp	error
  4812                              <1> setuid0:
  4813 00004522 881D[29660000]      <1> 	mov	[u.ruid], bl
  4814                              <1> setuid1: ; 1:
  4815 00004528 881D[28660000]      <1> 	mov	[u.uid], bl ; 02/08/2013
  4816                              <1> 		; movb r1,u.uid / put process id in u.uid
  4817                              <1> 		; movb r1,u.ruid / put process id in u.ruid
  4818 0000452E E9BEECFFFF          <1> 	jmp	sysret
  4819                              <1> 		; br sysret4 / system return
  4820                              <1> 
  4821                              <1> sysgetuid: ; < get user id >
  4822                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  4823                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4824                              <1> 	; 07/07/2013 (Retro UNIX 8086 v1)
  4825                              <1> 	;
  4826                              <1> 	; 'sysgetuid' returns the real user ID of the current process.
  4827                              <1> 	; The real user ID identifies the person who is logged in,
  4828                              <1> 	; in contradistinction to the effective user ID, which
  4829                              <1> 	; determines his access permission at each moment. It is thus
  4830                              <1> 	; useful to programs which operate using the 'set user ID'
  4831                              <1> 	; mode, to find out who invoked them.	
  4832                              <1> 	;
  4833                              <1> 	; Calling sequence:
  4834                              <1> 	;	syssetuid
  4835                              <1> 	; Arguments: -
  4836                              <1> 	;
  4837                              <1> 	; Inputs: -
  4838                              <1> 	; Outputs: (u.r0) - contains the real user's id.
  4839                              <1> 	; ...............................................................
  4840                              <1> 	;	
  4841                              <1> 	; Retro UNIX 8086 v1 modification: 
  4842                              <1> 	;       AL contains the real user ID at return.
  4843                              <1> 	;
  4844                              <1> 	;movzx 	eax, byte [u.ruid]
  4845                              <1> 	; 09/01/2022
  4846 00004533 A0[29660000]        <1> 	mov	al, [u.ruid]
  4847 00004538 A3[DC650000]        <1> 	mov	[u.r0], eax
  4848                              <1> 		; movb	u.ruid,*u.r0 / move the real user id to (u.r0)
  4849 0000453D E9AFECFFFF          <1> 	jmp	sysret
  4850                              <1> 		; br sysret4 / systerm return, sysret
  4851                              <1> 
  4852                              <1> anyi: 
  4853                              <1> 	; 22/06/2015 (Retro UNIX 386 v1 - Beginning)
  4854                              <1> 	; 25/04/2013 (Retro UNIX 8086 v1)
  4855                              <1> 	;
  4856                              <1> 	; 'anyi' is called if a file deleted while open.
  4857                              <1> 	; "anyi" checks to see if someone else has opened this file.
  4858                              <1> 	;
  4859                              <1> 	; INPUTS ->
  4860                              <1> 	;    r1 - contains an i-number
  4861                              <1> 	;    fsp - start of table containing open files
  4862                              <1> 	;
  4863                              <1> 	; OUTPUTS ->
  4864                              <1> 	;    "deleted" flag set in fsp entry of another occurrence of
  4865                              <1> 	;	   this file and r2 points 1st word of this fsp entry.
  4866                              <1> 	;    if file not found - bit in i-node map is cleared
  4867                              <1> 	;    			 (i-node is freed)
  4868                              <1> 	;               all blocks related to i-node are freed
  4869                              <1> 	;	        all flags in i-node are cleared
  4870                              <1> 	; ((AX = R1)) input
  4871                              <1> 	;
  4872                              <1> 	;    (Retro UNIX Prototype : 02/12/2012, UNIXCOPY.ASM)
  4873                              <1>         ;    ((Modified registers: eDX, eCX, eBX, eSI, eDI, eBP))  
  4874                              <1> 	;
  4875                              <1> 		; / r1 contains an i-number
  4876 00004542 BB[A4630000]        <1> 	mov	ebx, fsp
  4877                              <1> 		; mov $fsp,r2 / move start of fsp table to r2
  4878                              <1> anyi_1: ; 1:
  4879 00004547 663B03              <1> 	cmp	ax, [ebx]
  4880                              <1> 		; cmp r1,(r2) / do i-numbers match?
  4881 0000454A 7433                <1> 	je	short anyi_3
  4882                              <1> 		; beq 1f / yes, 1f
  4883 0000454C 66F7D8              <1> 	neg	ax
  4884                              <1> 		; neg r1 / no complement r1
  4885 0000454F 663B03              <1> 	cmp	ax, [ebx]
  4886                              <1> 		; cmp r1,(r2) / do they match now?
  4887 00004552 742B                <1> 	je	short anyi_3
  4888                              <1> 		; beq 1f / yes, transfer
  4889                              <1> 		; / i-numbers do not match
  4890 00004554 83C30A              <1> 	add	ebx, 10 ; fsp table size is 10 bytes
  4891                              <1> 			; in Retro UNIX 386 v1 (22/06/2015)
  4892                              <1> 		; add $8,r2 / no, bump to next entry in fsp table
  4893 00004557 81FB[98650000]      <1> 	cmp	ebx, fsp + (nfiles*10) ; 22/06/2015 
  4894                              <1> 		; cmp r2,$fsp+[nfiles*8] 
  4895                              <1> 				; / are we at last entry in the table
  4896 0000455D 72E8                <1> 	jb	short anyi_1
  4897                              <1> 		; blt 1b / no, check next entries i-number
  4898                              <1> 	;cmp	ax, 32768
  4899 0000455F 80FC80              <1> 	cmp	ah, 80h ; negative number check
  4900                              <1> 		; tst r1 / yes, no match
  4901                              <1> 		; bge .+4
  4902 00004562 7203                <1> 	jb	short anyi_2
  4903 00004564 66F7D8              <1> 	neg	ax
  4904                              <1> 		; neg r1 / make i-number positive
  4905                              <1> anyi_2:	
  4906 00004567 E81A050000          <1> 	call	imap
  4907                              <1> 		; jsr r0,imap / get address of allocation bit 
  4908                              <1> 			    ; / in the i-map in r2
  4909                              <1> 	;; DL/DX (MQ) has a 1 in the calculated bit position
  4910                              <1>         ;; eBX (R2) has address of the byte with allocation bit
  4911                              <1>  	; not	dx
  4912 0000456C F6D2                <1> 	not 	dl ;; 0 at calculated bit position, other bits are 1
  4913                              <1>         ;and	[ebx], dx
  4914 0000456E 2013                <1> 	and 	[ebx], dl 
  4915                              <1> 		; bicb mq,(r2) / clear bit for i-node in the imap
  4916 00004570 E8A4040000          <1> 	call	itrunc
  4917                              <1> 		; jsr r0,itrunc / free all blocks related to i-node
  4918 00004575 66C705[D4620000]00- <1>  	mov 	word [i.flgs], 0
  4918 0000457D 00                  <1>
  4919                              <1> 		; clr i.flgs / clear all flags in the i-node
  4920 0000457E C3                  <1> 	retn
  4921                              <1> 		;rts	r0 / return
  4922                              <1> anyi_3: ; 1: / i-numbers match
  4923 0000457F FE4309              <1> 	inc 	byte [ebx+9] ; 22/06/2015
  4924                              <1> 		;incb 7(r2) / increment upper byte of the 4th word
  4925                              <1> 		   ; / in that fsp entry (deleted flag of fsp entry)
  4926 00004582 C3                  <1> 	retn
  4927                              <1> 		; rts r0
  2113                                  %include 'u3.s'        ; 10/05/2015
  2114                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.1) - SYS3.INC
  2115                              <1> ; Last Modification: 24/12/2021
  2116                              <1> ; ----------------------------------------------------------------------------
  2117                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2118                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2119                              <1> ;
  2120                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2121                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2122                              <1> ; <Bell Laboratories (17/3/1972)>
  2123                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2124                              <1> ;
  2125                              <1> ; Retro UNIX 8086 v1 - U3.ASM (08/03/2014) //// UNIX v1 -> u3.s
  2126                              <1> ;
  2127                              <1> ; ****************************************************************************
  2128                              <1> 
  2129                              <1> tswitch: ; Retro UNIX 386 v1
  2130                              <1> tswap:
  2131                              <1> 	; 01/09/2015
  2132                              <1> 	; 10/05/2015 (Retro UNIX 386 v1 - Beginning)
  2133                              <1> 	; 14/04/2013 - 14/02/2014 (Retro UNIX 8086 v1)
  2134                              <1> 	; time out swap, called when a user times out.
  2135                              <1> 	; the user is put on the low priority queue.
  2136                              <1> 	; This is done by making a link from the last user
  2137                              <1> 	; on the low priority queue to him via a call to 'putlu'.
  2138                              <1> 	; then he is swapped out.
  2139                              <1> 	;
  2140                              <1> 	; Retro UNIX 386 v1 modification ->
  2141                              <1> 	;       swap (software task switch) is performed by changing
  2142                              <1> 	;	user's page directory (u.pgdir) instead of segment change
  2143                              <1> 	;	as in Retro UNIX 8086 v1.
  2144                              <1> 	;
  2145                              <1> 	; RETRO UNIX 8086 v1 modification ->
  2146                              <1> 	;       'swap to disk' is replaced with 'change running segment'
  2147                              <1> 	;	according to 8086 cpu (x86 real mode) architecture.
  2148                              <1> 	;	pdp-11 was using 64KB uniform memory while IBM PC
  2149                              <1> 	;	compatibles was using 1MB segmented memory 
  2150                              <1> 	;	in 8086/8088 times.
  2151                              <1> 	;
  2152                              <1> 	; INPUTS ->
  2153                              <1> 	;    u.uno - users process number
  2154                              <1> 	;    runq+4 - lowest priority queue
  2155                              <1> 	; OUTPUTS ->
  2156                              <1> 	;    r0 - users process number
  2157                              <1> 	;    r2 - lowest priority queue address
  2158                              <1> 	;
  2159                              <1> 	; ((AX = R0, BX = R2)) output
  2160                              <1> 	; ((Modified registers: EDX, EBX, ECX, ESI, EDI))  	
  2161                              <1> 	;
  2162 00004583 A0[2B660000]        <1> 	mov 	al, [u.uno]
  2163                              <1> 	       	; movb u.uno,r1 / move users process number to r1
  2164                              <1> 		; mov  $runq+4,r2 
  2165                              <1> 			; / move lowest priority queue address to r2
  2166 00004588 E8CD000000          <1>         call 	putlu
  2167                              <1> 		; jsr r0,putlu / create link from last user on Q to 
  2168                              <1> 		             ; / u.uno's user
  2169                              <1> 
  2170                              <1> switch: ; Retro UNIX 386 v1
  2171                              <1> swap:
  2172                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.2)
  2173                              <1> 	; 02/09/2015
  2174                              <1> 	; 01/09/2015
  2175                              <1> 	; 31/08/2015
  2176                              <1> 	; 10/05/2015 (Retro UNIX 386 v1 - Beginning)
  2177                              <1> 	; 14/04/2013 - 08/03/2014 (Retro UNIX 8086 v1)
  2178                              <1> 	; 'swap' is routine that controls the swapping of processes
  2179                              <1> 	; in and out of core.
  2180                              <1> 	;
  2181                              <1> 	; Retro UNIX 386 v1 modification ->
  2182                              <1> 	;       swap (software task switch) is performed by changing
  2183                              <1> 	;	user's page directory (u.pgdir) instead of segment change
  2184                              <1> 	;	as in Retro UNIX 8086 v1.
  2185                              <1> 	;
  2186                              <1> 	; RETRO UNIX 8086 v1 modification ->
  2187                              <1> 	;       'swap to disk' is replaced with 'change running segment'
  2188                              <1> 	;	according to 8086 cpu (x86 real mode) architecture.
  2189                              <1> 	;	pdp-11 was using 64KB uniform memory while IBM PC
  2190                              <1> 	;	compatibles was using 1MB segmented memory 
  2191                              <1> 	;	in 8086/8088 times.
  2192                              <1> 	;
  2193                              <1> 	; INPUTS ->
  2194                              <1> 	;    runq table - contains processes to run.
  2195                              <1> 	;    p.link - contains next process in line to be run.
  2196                              <1> 	;    u.uno - process number of process in core	
  2197                              <1> 	;    s.stack - swap stack used as an internal stack for swapping.	
  2198                              <1> 	; OUTPUTS ->
  2199                              <1> 	;    (original unix v1 -> present process to its disk block)
  2200                              <1> 	;    (original unix v1 -> new process into core -> 
  2201                              <1> 	;	   Retro Unix 8086 v1 -> segment registers changed 
  2202                              <1> 	;	   for new process)
  2203                              <1> 	;    u.quant = 3 (Time quantum for a process)
  2204                              <1> 	; 	((INT 1Ch count down speed -> 18.2 times per second)	 	
  2205                              <1> 	;    RETRO UNIX 8086 v1 will use INT 1Ch (18.2 times per second)
  2206                              <1> 	;	 for now, it will swap the process if there is not
  2207                              <1> 	;	 a keyboard event (keystroke) (Int 15h, function 4Fh)
  2208                              <1> 	;	 or will count down from 3 to 0 even if there is a
  2209                              <1> 	;        keyboard event locking due to repetitive key strokes.
  2210                              <1> 	;	 u.quant will be reset to 3 for RETRO UNIX 8086 v1.
  2211                              <1> 	;
  2212                              <1> 	;    u.pri -points to highest priority run Q.
  2213                              <1> 	;    r2 - points to the run queue.
  2214                              <1> 	;    r1 - contains new process number
  2215                              <1> 	;    r0 - points to place in routine or process that called
  2216                              <1> 	;	  swap all user parameters
  2217                              <1> 	;				
  2218                              <1> 	; ((Modified registers: EAX, EDX, EBX, ECX, ESI, EDI))  	
  2219                              <1> 	;
  2220                              <1> swap_0:
  2221                              <1> 		;mov $300,*$ps / processor priority = 6
  2222 0000458D BE[CE650000]        <1> 	mov	esi, runq
  2223                              <1> 		; mov $runq,r2 / r2 points to runq table
  2224                              <1> swap_1: ; 1: / search runq table for highest priority process
  2225 00004592 668B06              <1> 	mov	ax, [esi]
  2226 00004595 6621C0              <1> 	and 	ax, ax
  2227                              <1>        		; tst (r2)+ / are there any processes to run 
  2228                              <1> 			  ; / in this Q entry
  2229 00004598 7507                <1> 	jnz	short swap_2
  2230                              <1>        		; bne 1f / yes, process 1f
  2231                              <1> 		; cmp r2,$runq+6 / if zero compare address 
  2232                              <1> 			       ; / to end of table
  2233                              <1> 		; bne 1b / if not at end, go back
  2234 0000459A E8E0000000          <1> 	call	idle
  2235                              <1> 		; jsr r0,idle; s.idlet+2 / wait for interrupt; 
  2236                              <1> 				       ; / all queues are empty
  2237 0000459F EBF1                <1> 	jmp	short swap_1
  2238                              <1> 		; br swap
  2239                              <1> swap_2: ; 1:
  2240 000045A1 0FB6D8              <1> 	movzx	ebx, al ; 02/09/2015
  2241                              <1> 		; tst -(r2) / restore pointer to right Q entry
  2242                              <1>  		; mov r2,u.pri / set present user to this run queue
  2243                              <1> 	        ; movb (r2)+,r1 / move 1st process in queue to r1
  2244 000045A4 38E0                <1> 	cmp	al, ah
  2245                              <1> 		; cmpb r1,(r2)+ / is there only 1 process 
  2246                              <1> 			      ; / in this Q to be run
  2247 000045A6 740A                <1> 	je	short swap_3
  2248                              <1>        		; beq 1f / yes
  2249                              <1> 		; tst -(r2) / no, pt r2 back to this Q entry
  2250                              <1> 	;movzx	ebx, al
  2251 000045A8 8AA3[43630000]      <1> 	mov	ah, [ebx+p.link-1] 
  2252 000045AE 8826                <1>        	mov	[esi], ah
  2253                              <1> 		; movb p.link-1(r1),(r2) / move next process 
  2254                              <1> 				       ; / in line into run queue
  2255 000045B0 EB05                <1> 	jmp	short swap_4
  2256                              <1>        		; br 2f
  2257                              <1> swap_3: ; 1:
  2258                              <1> 	;xor	dx, dx
  2259                              <1> 	; 24/12/2021
  2260 000045B2 31D2                <1> 	xor	edx, edx
  2261 000045B4 668916              <1> 	mov	[esi], dx
  2262                              <1> 		; clr -(r2) / zero the entry; no processes on the Q
  2263                              <1> swap_4: ; / write out core to appropriate disk area and read 
  2264                              <1>       ; / in new process if required
  2265                              <1>        		; clr *$ps / clear processor status
  2266 000045B7 8A25[2B660000]      <1> 	mov 	ah, [u.uno]
  2267 000045BD 38C4                <1> 	cmp	ah, al
  2268                              <1> 		; cmpb r1,u.uno / is this process the same as 
  2269                              <1> 			      ; / the process in core?
  2270 000045BF 743B                <1>        	je	short swap_8
  2271                              <1>        		; beq 2f / yes, don't have to swap
  2272                              <1>        		; mov r0,-(sp) / no, write out core; save r0 
  2273                              <1> 			   ; / (address in routine that called swap)
  2274                              <1> 		; mov r1,-(sp) / put r1 (new process #) on the stack
  2275                              <1> 	; 01/09/2015
  2276                              <1> 	;mov	[u.usp], esp
  2277                              <1>        		; mov sp,u.usp / save stack pointer
  2278                              <1> 		; mov $sstack,sp / move swap stack pointer 
  2279                              <1> 			       ; / to the stack pointer
  2280 000045C1 08E4                <1> 	or	ah, ah
  2281                              <1>        		; tstb u.uno / is the process # = 0
  2282 000045C3 740D                <1>        	jz	short swap_6 ; 'sysexit'
  2283                              <1> 		; beq 1f / yes, kill process by overwriting
  2284                              <1> 	; 02/09/2015
  2285 000045C5 8925[D8650000]      <1> 	mov	[u.usp], esp ; return address for 'syswait' & 'sleep'
  2286                              <1> 	;
  2287 000045CB E834000000          <1> 	call	wswap
  2288                              <1> 		; jsr r0,wswap / write out core to disk
  2289                              <1> 	 ; 31/08/2015
  2290                              <1> 	;movzx	ebx, al ; New (running) process number
  2291 000045D0 EB1C                <1> 	jmp 	short swap_7
  2292                              <1> swap_6:
  2293                              <1> 	; 31/08/2015
  2294                              <1> 	; Deallocate memory pages belong to the process
  2295                              <1> 	; which is being terminated
  2296                              <1> 	; 14/05/2015 ('sysexit')
  2297                              <1>  	; Deallocate memory pages of the process
  2298                              <1> 	; (Retro UNIX 386 v1 modification !)
  2299                              <1> 	;
  2300                              <1> 	; movzx ebx, al
  2301 000045D2 53                  <1> 	push	ebx
  2302 000045D3 A1[35660000]        <1> 	mov 	eax, [u.pgdir]  ; page directory of the process
  2303 000045D8 8B1D[39660000]      <1> 	mov	ebx, [u.ppgdir] ; page directory of the parent process
  2304 000045DE E814E0FFFF          <1> 	call	deallocate_page_dir
  2305 000045E3 A1[2C660000]        <1> 	mov	eax, [u.upage] ; 'user' structure page of the process
  2306 000045E8 E8A0E0FFFF          <1> 	call	deallocate_page
  2307 000045ED 5B                  <1> 	pop	ebx
  2308                              <1> swap_7: ;1: 
  2309                              <1> 	; 02/09/2015
  2310                              <1> 	; 31/08/2015
  2311                              <1> 	; 14/05/2015
  2312 000045EE C0E302              <1> 	shl	bl, 2 ; * 4 
  2313 000045F1 8B83[60630000]      <1> 	mov	eax, [ebx+p.upage-4] ; the 'u' page of the new process
  2314                              <1> 	;cli
  2315 000045F7 E831000000          <1> 	call	rswap
  2316                              <1>  		; mov (sp)+,r1 / restore r1 to new process number
  2317                              <1> 		; jsr r0,rswap / read new process into core
  2318                              <1>        		; jsr r0,unpack / unpack the users stack from next
  2319                              <1> 			      ; / to his program to its normal
  2320                              <1> 	; 01/09/2015
  2321                              <1> 	;mov	esp, [u.usp]	
  2322                              <1> 		; mov u.usp,sp / location; restore stack pointer to
  2323                              <1> 			     ; / new process stack
  2324                              <1> 		; mov (sp)+,r0 / put address of where the process 
  2325                              <1> 			     ; / that just got swapped in, left off.,
  2326                              <1> 			     ; / i.e., transfer control to new process
  2327                              <1> 	;sti
  2328                              <1> swap_8: ;2:
  2329                              <1> 	; RETRO UNIX 8086 v1 modification !
  2330 000045FC C605[1E660000]04    <1> 	mov	byte [u.quant], time_count 
  2331                              <1> 		; movb $30.,uquant / initialize process time quantum
  2332 00004603 C3                  <1> 	retn
  2333                              <1> 		; rts r0 / return
  2334                              <1> 
  2335                              <1> wswap:  ; < swap out, swap to disk >
  2336                              <1> 	; 09/05/2015 (Retro UNIX 386 v1 - Beginning)
  2337                              <1> 	; 26/05/2013 - 08/03/2014 (Retro UNIX 8086 v1)
  2338                              <1> 	; 'wswap' writes out the process that is in core onto its 
  2339                              <1> 	; appropriate disk area.
  2340                              <1> 	;
  2341                              <1> 	; Retro UNIX 386 v1 modification ->
  2342                              <1> 	;       User (u) structure content and the user's register content
  2343                              <1> 	;	will be copied to the process's/user's UPAGE (a page for
  2344                              <1> 	;	saving 'u' structure and user registers for task switching).
  2345                              <1> 	;	u.usp - points to kernel stack address which contains
  2346                              <1> 	;		user's registers while entering system call.  
  2347                              <1> 	;	u.sp  - points to kernel stack address 
  2348                              <1> 	;		to return from system call -for IRET-.
  2349                              <1> 	;	[u.usp]+32+16 = [u.sp] 
  2350                              <1> 	;	[u.usp] -> edi, esi, ebp, esp (= [u.usp]+32), ebx, 
  2351                              <1> 	;		edx, ecx, eax, gs, fs, es, ds, -> [u.sp].
  2352                              <1> 	;
  2353                              <1> 	; Retro UNIX 8086 v1 modification ->
  2354                              <1> 	;       'swap to disk' is replaced with 'change running segment'
  2355                              <1> 	;	according to 8086 cpu (x86 real mode) architecture.
  2356                              <1> 	;	pdp-11 was using 64KB uniform memory while IBM PC
  2357                              <1> 	;	compatibles was using 1MB segmented memory 
  2358                              <1> 	;	in 8086/8088 times.
  2359                              <1> 	;
  2360                              <1> 	; INPUTS ->
  2361                              <1> 	;    u.break - points to end of program
  2362                              <1> 	;    u.usp - stack pointer at the moment of swap
  2363                              <1> 	;    core - beginning of process program		
  2364                              <1> 	;    ecore - end of core 	
  2365                              <1> 	;    user - start of user parameter area		
  2366                              <1> 	;    u.uno - user process number	
  2367                              <1> 	;    p.dska - holds block number of process	
  2368                              <1> 	; OUTPUTS ->
  2369                              <1> 	;    swp I/O queue
  2370                              <1> 	;    p.break - negative word count of process 
  2371                              <1> 	;    r1 - process disk address	
  2372                              <1> 	;    r2 - negative word count
  2373                              <1> 	;
  2374                              <1> 	; RETRO UNIX 8086 v1 input/output:
  2375                              <1> 	;
  2376                              <1> 	; INPUTS ->
  2377                              <1> 	;    u.uno - process number (to be swapped out)
  2378                              <1> 	; OUTPUTS ->
  2379                              <1> 	;    none
  2380                              <1> 	;
  2381                              <1> 	;   ((Modified registers: ECX, ESI, EDI))  
  2382                              <1> 	;
  2383 00004604 8B3D[2C660000]      <1> 	mov	edi, [u.upage] ; process's user (u) structure page addr
  2384 0000460A B91E000000          <1> 	mov	ecx, (U_SIZE + 3) / 4
  2385 0000460F BE[D4650000]        <1> 	mov	esi, user ; active user (u) structure	
  2386 00004614 F3A5                <1> 	rep	movsd
  2387                              <1> 	;
  2388 00004616 8B35[D8650000]      <1> 	mov	esi, [u.usp] ; esp (system stack pointer, 
  2389                              <1> 			     ;      points to user registers)
  2390 0000461C 8B0D[D4650000]      <1> 	mov	ecx, [u.sp]  ; return address from the system call
  2391                              <1> 			     ; (for IRET)
  2392                              <1> 			     ; [u.sp] -> EIP (user)
  2393                              <1> 			     ; [u.sp+4]-> CS (user)
  2394                              <1> 			     ; [u.sp+8] -> EFLAGS (user)
  2395                              <1> 			     ; [u.sp+12] -> ESP (user)
  2396                              <1> 			     ; [u.sp+16] -> SS (user)	
  2397 00004622 29F1                <1> 	sub	ecx, esi     ; required space for user registers
  2398 00004624 83C114              <1> 	add	ecx, 20	     ; +5 dwords to return from system call
  2399                              <1> 			     ; (for IRET) 	
  2400 00004627 C1E902              <1> 	shr	ecx, 2	     		
  2401 0000462A F3A5                <1> 	rep	movsd
  2402 0000462C C3                  <1> 	retn
  2403                              <1> 
  2404                              <1> 	; Original UNIX v1 'wswap' routine:
  2405                              <1> 	; wswap:
  2406                              <1> 		; mov *$30,u.emt / determines handling of emts
  2407                              <1>         	; mov *$10,u.ilgins / determines handling of 
  2408                              <1> 				; / illegal instructions
  2409                              <1> 		; mov u.break,r2 / put process program break address in r2
  2410                              <1> 		; inc r2 / add 1 to it 
  2411                              <1> 		; bic $1,r2 / make it even
  2412                              <1> 		; mov r2,u.break / set break to an even location
  2413                              <1> 		; mov u.usp,r3 / put users stack pointer 
  2414                              <1> 			     ; / at moment of swap in r3
  2415                              <1> 		; cmp r2,$core / is u.break less than $core
  2416                              <1> 		; blos 2f / yes
  2417                              <1> 		; cmp r2,r3 / no, is (u.break) greater than stack ptr.
  2418                              <1>        		; bhis 2f / yes
  2419                              <1> 	; 1:
  2420                              <1>        		; mov (r3)+,(r2)+ / no, pack stack next to users program
  2421                              <1> 		; cmp r3,$ecore / has stack reached end of core
  2422                              <1> 		; bne 1b / no, keep packing
  2423                              <1> 	 	; br 1f / yes
  2424                              <1> 	; 2:
  2425                              <1>        		; mov $ecore,r2 / put end of core in r2 
  2426                              <1> 	; 1:
  2427                              <1>        		; sub  $user,r2 / get number of bytes to write out 
  2428                              <1> 			   ; / (user up to end of stack gets written out)
  2429                              <1> 		; neg r2 / make it negative
  2430                              <1> 		; asr r2 / change bytes to words (divide by 2)
  2431                              <1> 		; mov r2,swp+4 / word count
  2432                              <1> 		; movb u.uno,r1 / move user process number to r1
  2433                              <1> 		; asl r1 / x2 for index
  2434                              <1>       		; mov r2,p.break-2(r1) / put negative of word count 
  2435                              <1> 				     ; / into the p.break table
  2436                              <1>        		; mov p.dska-2(r1),r1 / move disk address of swap area 
  2437                              <1> 				    ; /	for process to r1
  2438                              <1>        		; mov r1,swp+2 / put processes dska address in swp+2 
  2439                              <1> 			     ; / (block number)
  2440                              <1> 		; bis $1000,swp / set it up to write (set bit 9)
  2441                              <1>        		; jsr r0,ppoke / write process out on swap area of disk
  2442                              <1> 	; 1:
  2443                              <1>        		; tstb swp+1 / is lt done writing?
  2444                              <1>        		; bne 1b / no, wait
  2445                              <1> 		; rts r0 / yes, return to swap
  2446                              <1> 
  2447                              <1> rswap:  ; < swap in, swap from disk >
  2448                              <1> 	; 15/09/2015
  2449                              <1> 	; 28/08/2015
  2450                              <1> 	; 14/05/2015
  2451                              <1> 	; 09/05/2015 (Retro UNIX 386 v1 - Beginning)
  2452                              <1> 	; 26/05/2013 - 08/03/2014 (Retro UNIX 8086 v1)
  2453                              <1> 	; 'rswap' reads a process whose number is in r1, 
  2454                              <1> 	; from disk into core.
  2455                              <1> 	;
  2456                              <1> 	; Retro UNIX 386 v1 modification ->
  2457                              <1> 	;       User (u) structure content and the user's register content
  2458                              <1> 	;	will be restored from process's/user's UPAGE (a page for
  2459                              <1> 	;	saving 'u' structure and user registers for task switching).
  2460                              <1> 	;	u.usp - points to kernel stack address which contains
  2461                              <1> 	;		user's registers while entering system call.  
  2462                              <1> 	;	u.sp  - points to kernel stack address 
  2463                              <1> 	;		to return from system call -for IRET-.
  2464                              <1> 	;	[u.usp]+32+16 = [u.sp] 
  2465                              <1> 	;	[u.usp] -> edi, esi, ebp, esp (= [u.usp]+32), ebx, 
  2466                              <1> 	;		edx, ecx, eax, gs, fs, es, ds, -> [u.sp].
  2467                              <1> 	;
  2468                              <1> 	; RETRO UNIX 8086 v1 modification ->
  2469                              <1> 	;       'swap to disk' is replaced with 'change running segment'
  2470                              <1> 	;	according to 8086 cpu (x86 real mode) architecture.
  2471                              <1> 	;	pdp-11 was using 64KB uniform memory while IBM PC
  2472                              <1> 	;	compatibles was using 1MB segmented memory 
  2473                              <1> 	;	in 8086/8088 times.
  2474                              <1> 	;
  2475                              <1> 	; INPUTS ->
  2476                              <1> 	;    r1 - process number of process to be read in
  2477                              <1> 	;    p.break - negative of word count of process 
  2478                              <1> 	;    p.dska - disk address of the process		
  2479                              <1> 	;    u.emt - determines handling of emt's 	
  2480                              <1> 	;    u.ilgins - determines handling of illegal instructions		
  2481                              <1> 	; OUTPUTS ->
  2482                              <1> 	;    8 = (u.ilgins)
  2483                              <1> 	;    24 = (u.emt)
  2484                              <1> 	;    swp - bit 10 is set to indicate read 
  2485                              <1> 	;		(bit 15=0 when reading is done)	
  2486                              <1> 	;    swp+2 - disk block address
  2487                              <1> 	;    swp+4 - negative word count 	
  2488                              <1> 	;      ((swp+6 - address of user structure)) 
  2489                              <1> 	;
  2490                              <1> 	; RETRO UNIX 8086 v1 input/output:
  2491                              <1> 	;
  2492                              <1> 	; INPUTS ->
  2493                              <1> 	;    AL	- new process number (to be swapped in)	 
  2494                              <1> 	; OUTPUTS ->
  2495                              <1> 	;    none
  2496                              <1> 	;
  2497                              <1> 	;   ((Modified registers: EAX, ECX, ESI, EDI, ESP)) 
  2498                              <1> 	;
  2499                              <1> 	; Retro UNIX 386 v1 - modification ! 14/05/2015
  2500 0000462D 89C6                <1> 	mov	esi, eax  ; process's user (u) structure page addr
  2501 0000462F B91E000000          <1> 	mov	ecx, (U_SIZE + 3) / 4
  2502 00004634 BF[D4650000]        <1> 	mov	edi, user ; active user (u) structure	
  2503 00004639 F3A5                <1> 	rep	movsd
  2504 0000463B 58                  <1> 	pop	eax ; 15/09/2015, 'rswap' return address 
  2505 0000463C 8B3D[D8650000]      <1> 	mov	edi, [u.usp] ; esp (system stack pointer, 
  2506                              <1> 			     ;      points to user registers)
  2507 00004642 8B0D[D4650000]      <1> 	mov	ecx, [u.sp]  ; return address from the system call
  2508                              <1> 			     ; (for IRET)
  2509                              <1> 			     ; [u.sp] -> EIP (user)
  2510                              <1> 			     ; [u.sp+4]-> CS (user)
  2511                              <1> 			     ; [u.sp+8] -> EFLAGS (user)
  2512                              <1> 			     ; [u.sp+12] -> ESP (user)
  2513                              <1> 			     ; [u.sp+16] -> SS (user)		
  2514                              <1> 	; 28/08/2015
  2515 00004648 29F9                <1> 	sub	ecx, edi     ; required space for user registers
  2516 0000464A 83C114              <1> 	add	ecx, 20	     ; +5 dwords to return from system call
  2517                              <1> 			     ; (for IRET) 	
  2518 0000464D C1E902              <1> 	shr	ecx, 2	       		
  2519 00004650 F3A5                <1> 	rep	movsd
  2520 00004652 8B25[D8650000]      <1> 	mov	esp, [u.usp] ; 15/09/2015
  2521 00004658 50                  <1> 	push	eax ; 15/09/2015 'rswap' return address
  2522 00004659 C3                  <1> 	retn
  2523                              <1> 
  2524                              <1> 	; Original UNIX v1 'rswap'  and 'unpack' routines:
  2525                              <1> 	;rswap:
  2526                              <1>        		; asl r1 / process number x2 for index
  2527                              <1>        		; mov p.break-2(r1), swp+4 / word count
  2528                              <1>        		; mov p.dska-2(r1),swp+2 / disk address
  2529                              <1>        		; bis $2000,swp / read
  2530                              <1>        		; jsr r0,ppoke / read it in 
  2531                              <1> 	; 1:
  2532                              <1>        		; tstb swp+1 / done
  2533                              <1>        		; bne 1b / no, wait for bit 15 to clear (inhibit bit)
  2534                              <1>        		; mov u.emt,*$30 / yes move these
  2535                              <1>        		; mov u.ilgins,*$10 / back
  2536                              <1>        		; rts r0 / return
  2537                              <1> 
  2538                              <1> 	;unpack: ; / move stack back to its normal place
  2539                              <1> 		; mov u.break,r2 / r2 points to end of user program
  2540                              <1>        		; cmp r2,$core / at beginning of user program yet?
  2541                              <1> 		; blos 2f / yes, return
  2542                              <1> 		; cmp r2,u.usp / is break_above the stack pointer 
  2543                              <1> 			     ; / before swapping
  2544                              <1> 		; bhis 2f / yes, return
  2545                              <1> 		; mov $ecore,r3 / r3 points to end of core
  2546                              <1> 		; add r3,r2
  2547                              <1> 		; sub u.usp,r2 / end of users stack is in r2
  2548                              <1> 	; 1:
  2549                              <1> 		; mov -(r2),-(r3) / move stack back to its normal place
  2550                              <1> 		; cmp r2,u.break / in core
  2551                              <1> 		; bne 1b
  2552                              <1> 	; 2:
  2553                              <1>        		; rts r0
  2554                              <1> 
  2555                              <1> putlu: 
  2556                              <1> 	; 12/09/2015
  2557                              <1> 	; 02/09/2015
  2558                              <1> 	; 10/05/2015 (Retro UNIX 386 v1 - Beginning)
  2559                              <1> 	; 15/04/2013 - 23/02/2014 (Retro UNIX 8086 v1)
  2560                              <1> 	; 'putlu' is called with a process number in r1 and a pointer
  2561                              <1> 	; to lowest priority Q (runq+4) in r2. A link is created from
  2562                              <1> 	; the last process on the queue to process in r1 by putting
  2563                              <1> 	; the process number in r1 into the last process's link.
  2564                              <1> 	;
  2565                              <1> 	; INPUTS ->
  2566                              <1> 	;    r1 - user process number
  2567                              <1> 	;    r2 - points to lowest priority queue 
  2568                              <1> 	;    p.dska - disk address of the process		
  2569                              <1> 	;    u.emt - determines handling of emt's 	
  2570                              <1> 	;    u.ilgins - determines handling of illegal instructions		
  2571                              <1> 	; OUTPUTS ->
  2572                              <1> 	;    r3 - process number of last process on the queue upon
  2573                              <1> 	;	  entering putlu
  2574                              <1> 	;    p.link-1 + r3 - process number in r1
  2575                              <1> 	;    r2 - points to lowest priority queue
  2576                              <1> 	;
  2577                              <1> 	; ((Modified registers: EDX, EBX)) 
  2578                              <1> 	;
  2579                              <1> 	; / r1 = user process no.; r2 points to lowest priority queue
  2580                              <1> 
  2581                              <1> 	; eBX = r2
  2582                              <1> 	; eAX = r1 (AL=r1b)
  2583                              <1> 
  2584 0000465A BB[CE650000]        <1> 	mov	ebx, runq
  2585 0000465F 0FB613              <1> 	movzx  	edx, byte [ebx]
  2586 00004662 43                  <1> 	inc	ebx
  2587 00004663 20D2                <1> 	and	dl, dl
  2588                              <1> 		; tstb (r2)+ / is queue empty?
  2589 00004665 740A                <1>        	jz	short putlu_1
  2590                              <1> 		; beq 1f / yes, branch
  2591 00004667 8A13                <1> 	mov 	dl, [ebx] ; 12/09/2015
  2592                              <1> 		; movb (r2),r3 / no, save the "last user" process number
  2593                              <1> 			     ; / in r3
  2594 00004669 8882[43630000]      <1>        	mov	[edx+p.link-1], al
  2595                              <1> 		; movb r1,p.link-1(r3) / put pointer to user on 
  2596                              <1> 			     ; / "last users" link
  2597 0000466F EB03                <1> 	jmp	short putlu_2
  2598                              <1> 		; br 2f /
  2599                              <1> putlu_1: ; 1:
  2600 00004671 8843FF              <1> 	mov	[ebx-1], al
  2601                              <1>        		; movb r1,-1(r2) / user is only user; 
  2602                              <1> 			    ; / put process no. at beginning and at end
  2603                              <1> putlu_2: ; 2: 
  2604 00004674 8803                <1> 	mov	[ebx], al
  2605                              <1>        		; movb r1,(r2) / user process in r1 is now the last entry
  2606                              <1> 			     ; / on the queue
  2607 00004676 88C2                <1> 	mov	dl, al
  2608 00004678 88B2[43630000]      <1>         mov     [edx+p.link-1], dh ; 0
  2609                              <1> 		; dec r2 / restore r2
  2610 0000467E C3                  <1>         retn
  2611                              <1> 		; rts r0
  2612                              <1> 
  2613                              <1> ;copyz:
  2614                              <1> ;       mov     r1,-(sp) / put r1 on stack
  2615                              <1> ;       mov     r2,-(sp) / put r2 on stack
  2616                              <1> ;       mov     (r0)+,r1
  2617                              <1> ;       mov     (r0)+,r2
  2618                              <1> ;1:
  2619                              <1> ;       clr     (r1)+ / clear all locations between r1 and r2
  2620                              <1> ;       cmp     r1,r2 
  2621                              <1> ;       blo     1b
  2622                              <1> ;       mov     (sp)+,r2 / restore r2
  2623                              <1> ;       mov     (sp)+,r1 / restore r1
  2624                              <1> ;       rts     r0 
  2625                              <1> 
  2626                              <1> idle:
  2627                              <1> 	; 01/09/2015
  2628                              <1> 	; 10/05/2015 (Retro UNIX 386 v1 - Beginning)
  2629                              <1> 	; 10/04/2013 - 23/10/2013 (Retro UNIX 8086 v1)
  2630                              <1> 	; (idle & wait loop)
  2631                              <1> 	; Retro Unix 8086 v1 modification on original UNIX v1
  2632                              <1> 	; idle procedure!
  2633                              <1>       	;
  2634                              <1>   	; 01/09/2015
  2635 0000467F FB                  <1> 	sti
  2636                              <1>       	; 29/07/2013
  2637 00004680 F4                  <1>       	hlt
  2638 00004681 90                  <1>       	nop ; 10/10/2013
  2639 00004682 90                  <1>       	nop
  2640 00004683 90                  <1>       	nop
  2641                              <1>       	; 23/10/2013
  2642 00004684 90                  <1>       	nop
  2643 00004685 90                  <1>       	nop
  2644 00004686 90                  <1>       	nop
  2645 00004687 90                  <1>       	nop
  2646 00004688 C3                  <1>       	retn      
  2647                              <1> 
  2648                              <1> 	;mov *$ps,-(sp) / save ps on stack
  2649                              <1> 	;clr *$ps / clear ps
  2650                              <1> 	;mov clockp,-(sp) / save clockp on stack
  2651                              <1> 	;mov (r0)+,clockp / arg to idle in clockp
  2652                              <1> 	;1 / wait for interrupt
  2653                              <1> 	;mov (sp)+,clockp / restore clockp, ps
  2654                              <1> 	;mov (sp)+,*$ps
  2655                              <1> 	;rts r0
  2656                              <1> 
  2657                              <1> clear:
  2658                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2659                              <1> 	; 10/05/2015 (Retro UNIX 386 v1 - Beginning)
  2660                              <1> 	; 09/04/2013 - 03/08/2013 (Retro UNIX 8086 v1)
  2661                              <1> 	; 'clear' zero's out of a block (whose block number is in r1)
  2662                              <1> 	; on the current device (cdev)
  2663                              <1> 	;	
  2664                              <1> 	; INPUTS ->
  2665                              <1> 	;    r1 - block number of block to be zeroed
  2666                              <1> 	;    cdev - current device number 
  2667                              <1> 	; OUTPUTS ->
  2668                              <1> 	;    a zeroed I/O buffer onto the current device
  2669                              <1> 	;    r1 - points to last entry in the I/O buffer
  2670                              <1> 	;
  2671                              <1> 	; ((AX = R1)) input/output
  2672                              <1> 	;    (Retro UNIX Prototype : 18/11/2012 - 14/11/2012, UNIXCOPY.ASM)
  2673                              <1>         ;    ((Modified registers: EDX, ECX, EBX, ESI, EDI, EBP))  
  2674                              <1> 
  2675 00004689 E87C0E0000          <1> 	call 	wslot
  2676                              <1> 		; jsr r0,wslot / get an I/O buffer set bits 9 and 15 in first
  2677                              <1>                    ; / word of I/O queue r5 points to first data word in buffer
  2678 0000468E 89DF                <1> 	mov	edi, ebx ; r5
  2679 00004690 89C2                <1> 	mov	edx, eax
  2680 00004692 B980000000          <1> 	mov	ecx, 128
  2681                              <1> 		; mov $256.,r3
  2682 00004697 31C0                <1> 	xor	eax, eax
  2683 00004699 F3AB                <1> 	rep	stosd
  2684 0000469B 89D0                <1> 	mov	eax, edx
  2685                              <1> ; 1: 
  2686                              <1>        		; clr (r5)+ / zero data word in buffer
  2687                              <1>        		; dec r3
  2688                              <1>        		; bgt 1b / branch until all data words in buffer are zero
  2689                              <1> 	;call	dskwr
  2690                              <1> 		; jsr r0,dskwr / write zeroed buffer area out onto physical
  2691                              <1>                              ; / block specified in r1
  2692                              <1> 	; eAX (r1) = block number
  2693                              <1> 	;retn
  2694                              <1> 		; rts r0
  2695                              <1> 	; 24/12/2021
  2696 0000469D E9750E0000          <1> 	jmp	dskwr
  2114                                  %include 'u4.s'        ; 15/04/2015
  2115                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.2) - SYS4.INC
  2116                              <1> ; Last Modification: 26/02/2022
  2117                              <1> ; ----------------------------------------------------------------------------
  2118                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2119                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2120                              <1> ;
  2121                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2122                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2123                              <1> ; <Bell Laboratories (17/3/1972)>
  2124                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2125                              <1> ;
  2126                              <1> ; Retro UNIX 8086 v1 - U4.ASM (04/07/2014) //// UNIX v1 -> u4.s
  2127                              <1> ;
  2128                              <1> ; ****************************************************************************
  2129                              <1> 
  2130                              <1> ;setisp:
  2131                              <1>        ;mov     r1,-(sp)
  2132                              <1>        ;mov     r2,-(sp)
  2133                              <1>        ;mov     r3,-(sp)
  2134                              <1>        ;mov     clockp,-(sp)
  2135                              <1>        ;mov     $s.syst+2,clockp
  2136                              <1>        ;jmp     (r0)
  2137                              <1> 
  2138                              <1> clock: ; / interrupt from 60 cycle clock
  2139                              <1> 	
  2140                              <1> 	; 14/10/2015
  2141                              <1> 	; 14/05/2015 (Retro UNIX 386 v1 - Beginning)
  2142                              <1> 	; 07/12/2013 - 10/04/2014 (Retro UNIX 8086 v1)
  2143                              <1> 
  2144                              <1>        ;mov     r0,-(sp) / save r0
  2145                              <1>        ;tst     *$lks / restart clock?
  2146                              <1>        ;mov     $s.time+2,r0 / increment the time of day
  2147                              <1>        ;inc     (r0)
  2148                              <1>        ;bne     1f
  2149                              <1>        ;inc     -(r0)
  2150                              <1> ;1:
  2151                              <1>        ;mov     clockp,r0 / increment appropriate time category
  2152                              <1>        ;inc     (r0)
  2153                              <1>        ;bne     1f
  2154                              <1>        ;inc     -(r0)
  2155                              <1> ;1:
  2156                              <1> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  2157                              <1> 
  2158 000046A2 803D[1E660000]00    <1> 	cmp	byte [u.quant], 0
  2159 000046A9 772C                <1> 	ja	short clk_1
  2160                              <1> 	;
  2161 000046AB 803D[D3650000]FF    <1>         cmp     byte [sysflg], 0FFh ; user or system space ?
  2162 000046B2 7529                <1> 	jne	short clk_2 ; system space (sysflg <> 0FFh)
  2163 000046B4 803D[2B660000]01    <1> 	cmp     byte [u.uno], 1 ; /etc/init ?
  2164 000046BB 761A                <1> 	jna	short clk_1 ; yes, do not swap out
  2165 000046BD 66833D[20660000]00  <1> 	cmp	word [u.intr], 0
  2166 000046C5 7616                <1> 	jna	short clk_2
  2167                              <1> clk_0:
  2168                              <1> 	; 14/10/2015
  2169 000046C7 FE05[D3650000]      <1> 	inc	byte [sysflg] 	; Now, we are in system space
  2170 000046CD 58                  <1> 	pop	eax ; return address to the timer interrupt
  2171                              <1> 	;
  2172 000046CE B020                <1> 	MOV	AL,EOI			; GET END OF INTERRUPT MASK
  2173                              <1> 	;CLI				; DISABLE INTERRUPTS TILL STACK CLEARED
  2174 000046D0 E620                <1> 	OUT	INTA00,AL		; END OF INTERRUPT TO 8259 - 1	
  2175                              <1> 	;
  2176 000046D2 E97FEBFFFF          <1> 	jmp     sysrelease ; 'sys release' by clock/timer
  2177                              <1> clk_1:
  2178 000046D7 FE0D[1E660000]      <1> 	dec	byte [u.quant]
  2179                              <1> clk_2:
  2180 000046DD C3                  <1> 	retn   ; return to (hardware) timer interrupt routine
  2181                              <1> 
  2182                              <1> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
  2183                              <1> 
  2184                              <1>        ;mov     $uquant,r0 / decrement user time quantum
  2185                              <1>        ;decb    (r0)
  2186                              <1>        ;bge     1f / if less than 0
  2187                              <1>        ;clrb    (r0) / make it 0
  2188                              <1> ;1: / decrement time out counts return now if priority was not 0
  2189                              <1>        ;cmp     4(sp),$200 / ps greater than or equal to 200
  2190                              <1>        ;bge     2f / yes, check time outs
  2191                              <1>        ;tstb    (r0) / no, user timed out?
  2192                              <1>        ;bne     1f / no
  2193                              <1>        ;cmpb    sysflg,$-1 / yes, are we outside the system?
  2194                              <1>        ;bne     1f / no, 1f
  2195                              <1>        ;mov     (sp)+,r0 / yes, put users r0 in r0
  2196                              <1>        ;sys     0 / sysrele
  2197                              <1>        ;rti
  2198                              <1> ;2: / priority is high so just decrement time out counts
  2199                              <1>        ;mov     $toutt,r0 / r0 points to beginning of time out table
  2200                              <1> ;2:
  2201                              <1>        ;tstb    (r0) / is the time out?
  2202                              <1>        ;beq     3f / yes, 3f (get next entry)
  2203                              <1>        ;decb    (r0) / no, decrement the time
  2204                              <1>        ;bne     3f / isit zero now?
  2205                              <1>        ;incb    (r0) / yes, increment the time
  2206                              <1> ;3:
  2207                              <1>        ;inc     r0 / next entry
  2208                              <1>        ;cmp     r0,$touts / end of toutt table?
  2209                              <1>        ;blo     2b / no, check this entry
  2210                              <1>        ;mov     (sp)+,r0 / yes, restore r0
  2211                              <1>        ;rti / return from interrupt
  2212                              <1> ;1: / decrement time out counts; if 0 call subroutine
  2213                              <1>        ;mov     (sp)+,r0 / restore r0
  2214                              <1>        ;mov     $240,*$ps / set processor priority to 5
  2215                              <1>        ;jsr     r0,setisp / save registers
  2216                              <1>        ;mov     $touts-toutt-1,r0 / set up r0 as index to decrement thru
  2217                              <1>                                ;  / the table
  2218                              <1> ;1:
  2219                              <1>        ;tstb    toutt(r0) / is the time out for this entry
  2220                              <1>        ;beq     2f / yes
  2221                              <1>        ;decb    toutt(r0) / no, decrement the time
  2222                              <1>        ;bne     2f / is the time 0, now
  2223                              <1>        ;asl     r0 / yes, 2 x r0 to get word index for tout entry
  2224                              <1>        ;jsr     r0,*touts(r0) / go to appropriate routine specified in this
  2225                              <1>        ;asr     r0 / touts entry; set r0 back to toutt index
  2226                              <1> ;2:
  2227                              <1>        ;dec     r0 / set up r0 for next entry
  2228                              <1>        ;bge     1b / finished? , no, go back
  2229                              <1>        ;br      retisp / yes, restore registers and do a rti
  2230                              <1> 
  2231                              <1> ;retisp:
  2232                              <1>        ;mov     (sp)+,clockp / pop values before interrupt off the stack
  2233                              <1>        ;mov     (sp)+,r3
  2234                              <1>        ;mov     (sp)+,r2
  2235                              <1>        ;mov     (sp)+,r1
  2236                              <1>        ;mov     (sp)+,r0
  2237                              <1>        ;rti     / return from interrupt
  2238                              <1> 
  2239                              <1> 
  2240                              <1> wakeup: ; / wakeup processes waiting for an event 
  2241                              <1> 	; / by linking them to the queue
  2242                              <1> 	;
  2243                              <1> 	; 26/02/2022
  2244                              <1> 	; 15/09/2015
  2245                              <1> 	; 29/06/2015
  2246                              <1> 	; 15/04/2015 (Retro UNIX 386 v1 - Beginning)
  2247                              <1> 	;
  2248                              <1> 	; 15/05/2013 - 02/06/2014
  2249                              <1> 	; Retro UNIX 8086 v1 modification !
  2250                              <1> 	; (Process/task switching routine by using
  2251                              <1> 	; Retro UNIX 8086 v1 keyboard interrupt output.)
  2252                              <1> 	;
  2253                              <1> 	; In original UNIX v1, 'wakeup' is called to wake the process
  2254                              <1> 	; sleeping in the specified wait channel by creating a link 
  2255                              <1> 	; to it from the last user process on the run queue.
  2256                              <1> 	; If there is no process to wake up, nothing happens.
  2257                              <1> 	;
  2258                              <1> 	; In Retro UNIX 8086 v1, Int 09h keyboard interrupt will set
  2259                              <1> 	; 'switching' status of the current process (owns current tty)
  2260                              <1> 	; (via alt + function keys) to a process which has highest
  2261                              <1> 	; priority (on run queue) on the requested tty (0 to 7, except
  2262                              <1> 	; 8 and 9 which are tty identifiers of COM1, COM2 serial ports)
  2263                              <1> 	; as it's console tty. (NOTE: 'p.ttyc' is used to set console
  2264                              <1> 	; tty for tty switching by keyboard.)	 
  2265                              <1> 	; 
  2266                              <1> 	; INPUT -> 
  2267                              <1> 	;	   AL = wait channel (r3) ('tty number' for now)
  2268                              <1> 	;	   ;;EBX = Run queue (r2) offset
  2269                              <1> 	;
  2270                              <1> 	; ((modified registers: EAX, EBX))
  2271                              <1> 	;
  2272 000046DE 0FB6D8              <1> 	movzx	ebx, al ; 29/06/2015
  2273 000046E1 81C3[78620000]      <1> 	add	ebx, wlist
  2274 000046E7 8A03                <1> 	mov	al, [ebx] ; waiting list (waiting process number)
  2275 000046E9 20C0                <1> 	and	al, al
  2276 000046EB 741E                <1> 	jz	short wa0 ; nothing to wakeup
  2277                              <1> 	;
  2278 000046ED 30E4                <1> 	xor	ah, ah
  2279 000046EF 8825[1E660000]      <1> 	mov 	[u.quant], ah ; 0 ; time quantum = 0	
  2280 000046F5 8823                <1> 	mov	[ebx], ah ; 0 ; zero wait channel entry
  2281                              <1> 	; 15/09/2015
  2282 000046F7 0FB6D8              <1> 	movzx	ebx, al
  2283                              <1> 	; 26/02/2022 (p.waitc is not used)
  2284                              <1> 	;mov	[ebx+p.waitc-1], ah ; 0
  2285 000046FA FEC4                <1> 	inc	ah
  2286 000046FC 88A3[53630000]      <1> 	mov	byte [ebx+p.stat-1], ah ; 1 ; SRUN
  2287                              <1> 	;
  2288 00004702 57                  <1> 	push	edi
  2289 00004703 52                  <1> 	push	edx
  2290 00004704 E851FFFFFF          <1> 	call	putlu
  2291 00004709 5A                  <1> 	pop	edx
  2292 0000470A 5F                  <1> 	pop	edi
  2293                              <1> wa0:
  2294 0000470B C3                  <1> 	retn
  2295                              <1> 
  2296                              <1> sleep: 
  2297                              <1> 	; 26/02/2022
  2298                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2299                              <1> 	; 15/09/2015
  2300                              <1> 	; 30/06/2015 (Retro UNIX 386 v1 - Beginning)
  2301                              <1> 	;
  2302                              <1> 	; 09/05/2013 - 20/03/2014
  2303                              <1> 	;
  2304                              <1> 	; Retro UNIX 8086 v1 modification !
  2305                              <1> 	; (Process/task switching and quit routine by using
  2306                              <1> 	; Retro UNIX 8086 v1 keyboard interrupt output.))
  2307                              <1> 	;
  2308                              <1> 	; In original UNIX v1, 'sleep' is called to wait for
  2309                              <1> 	; tty and tape output or input becomes available
  2310                              <1> 	; and process is put on waiting channel and swapped out,
  2311                              <1> 	; then -when the tty or tape is ready to write or read-
  2312                              <1> 	; 'wakeup' gets process back to active swapped-in status.)
  2313                              <1> 	;
  2314                              <1> 	; In Retro UNIX 8086 v1, Int 1Bh ctrl+brk interrupt and
  2315                              <1> 	; Int 09h keyboard interrupt will set 'quit' or 'switching'		
  2316                              <1> 	; status of the current process also INT 1Ch will count down
  2317                              <1> 	; 'uquant' value and INT 09h will redirect scancode of keystroke
  2318                              <1> 	; to tty buffer of the current process and kernel will get
  2319                              <1> 	; user input by using tty buffer of the current process
  2320                              <1> 	; (instead of standard INT 16h interrupt).
  2321                              <1> 	; TTY output will be redirected to related video page of text mode
  2322                              <1> 	; (INT 10h will be called with different video page depending
  2323                              <1> 	; on tty assignment of the active process: 0 to 7 for
  2324                              <1> 	; pseudo screens.)
  2325                              <1> 	;
  2326                              <1> 	; In Retro UNIX 8086 v1, 'sleep' will be called to wait for
  2327                              <1> 	; a keystroke from keyboard or wait for reading or writing
  2328                              <1> 	; characters/data on serial port(s).
  2329                              <1> 	;
  2330                              <1> 	; Character/Terminal input/output through COM1 and COM2 will be
  2331                              <1> 	; performed by related routines in addition to pseudo TTY routines.
  2332                              <1> 	; 
  2333                              <1> 	; R1 = AH = wait channel (0-9 for TTYs) ; 05/10/2013 (22/09/2013)
  2334                              <1> 	;
  2335                              <1> 	;; 05/10/2013
  2336                              <1>         ;10/12/2013
  2337                              <1> 	;cmp   byte [u.uno], 1
  2338                              <1>         ;ja    short sleep0
  2339                              <1> 	;retn
  2340                              <1> 
  2341                              <1> 	; 20/03/2014
  2342                              <1> 	;mov	bx, [runq]
  2343                              <1> 	;cmp	bl, bh
  2344                              <1> 	;jne	short sleep0	
  2345                              <1> 	; 25/02/2014
  2346                              <1> 	;cmp word ptr [runq], 0
  2347                              <1> 	;ja short sleep0	
  2348                              <1> 	;retn
  2349                              <1> sleep0:
  2350                              <1> 	;
  2351 0000470C E849000000          <1> 	call	isintr
  2352                              <1> 	;jnz	sysret
  2353                              <1> 		; / wait for event
  2354                              <1>        		; jsr r0,isintr / check to see if interrupt 
  2355                              <1> 			      ; / or quit from user
  2356                              <1>                		; br 2f / something happened
  2357                              <1> 			      ; / yes, his interrupt so return
  2358                              <1>                      	      ;	/ to user
  2359                              <1> 	; 24/12/2021
  2360 00004711 7405                <1> 	jz	short sleep_2
  2361                              <1> sleep_3:
  2362 00004713 E9D9EAFFFF          <1> 	jmp	sysret
  2363                              <1> sleep_2:
  2364                              <1> 	; 30/06/2015
  2365 00004718 0FB6DC              <1>     	movzx	ebx, ah ; 30/06/2015
  2366 0000471B 81C3[78620000]      <1> 	add	ebx, wlist
  2367 00004721 8A03                <1> 	mov	al, [ebx]
  2368 00004723 20C0                <1> 	and	al, al
  2369 00004725 7407                <1> 	jz	short sleep1
  2370 00004727 53                  <1> 	push	ebx
  2371 00004728 E82DFFFFFF          <1> 	call	putlu
  2372 0000472D 5B                  <1> 	pop	ebx
  2373                              <1> sleep1:
  2374 0000472E A0[2B660000]        <1> 	mov	al, [u.uno]    
  2375 00004733 8803                <1>   	mov	[ebx], al 	; put the process number
  2376                              <1> 				; in the wait channel
  2377                              <1> 		; mov (r0)+,r1 / put number of wait channel in r1
  2378                              <1> 		; movb wlist(r1),-(sp) / put old process number in there,
  2379                              <1> 				     ; / on the stack
  2380                              <1>        		; movb u.uno,wlist(r1) / put process number of process
  2381                              <1> 				     ; / to put to sleep in there
  2382                              <1>         ; 15/09/2015
  2383 00004735 0FB6D8              <1> 	movzx	ebx, al
  2384 00004738 C683[53630000]04    <1>         mov     byte [ebx+p.stat-1], 4 ; SSLEEP
  2385                              <1> 	; 26/02/2022 (p.waitc is not used)
  2386                              <1> 	;inc	ah
  2387                              <1> 	;mov	[ebx+p.waitc-1], ah ; wait channel + 1
  2388                              <1> 	;
  2389 0000473F 66FF35[C3650000]    <1> 	push    word [cdev]
  2390                              <1> 		; mov cdev,-(sp) / nothing happened in isintr so
  2391 00004746 E842FEFFFF          <1> 	call	swap
  2392                              <1>        		; jsr r0,swap / swap out process that needs to sleep
  2393 0000474B 668F05[C3650000]    <1>         pop     word [cdev]
  2394                              <1> 		; mov (sp)+,cdev / restore device
  2395 00004752 E803000000          <1> 	call	isintr
  2396                              <1> 	; 22/09/2013
  2397                              <1> 	;jnz	sysret         
  2398                              <1> 		; jsr r0,isintr / check for interrupt of new process
  2399                              <1>                		; br 2f / yes, return to new user
  2400                              <1> 		; movb (sp)+,r1 / no, r1 = old process number that was 
  2401                              <1> 				; / originally on the wait channel
  2402                              <1>        		; beq 1f / if 0 branch
  2403                              <1>   		; mov $runq+4,r2 / r2 points to lowest priority queue
  2404                              <1>        		; mov $300,*$ps / processor priority = 6
  2405                              <1> 		; jsr r0,putlu / create link to old process number
  2406                              <1>        		; clr *$ps / clear the status; process priority = 0
  2407                              <1> 	; 24/12/2021
  2408 00004757 75BA                <1> 	jnz	short sleep_3 ; jump to sysret
  2409                              <1>      ;1:
  2410 00004759 C3                  <1> 	retn
  2411                              <1> 		; rts r0 / return
  2412                              <1>      ;2:
  2413                              <1>         ;;jmp	sysret
  2414                              <1> 		; jmp sysret / return to user
  2415                              <1> 
  2416                              <1> isintr:
  2417                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2418                              <1> 	; 30/06/2015 (Retro UNIX 386 v1 - Beginning)
  2419                              <1> 	;
  2420                              <1> 	; 09/05/2013 - 30/05/2014
  2421                              <1> 	;
  2422                              <1> 	; Retro UNIX 8086 v1 modification !
  2423                              <1> 	; (Process/task switching and quit routine by using
  2424                              <1> 	; Retro UNIX 8086 v1 keyboard interrupt output.))
  2425                              <1> 	;
  2426                              <1> 	; Retro UNIX 8086 v1 modification:
  2427                              <1> 	; 'isintr' checks if user interrupt request is enabled
  2428                              <1> 	;  and there is a 'quit' request by user;
  2429                              <1> 	;  otherwise, 'isintr' will return with zf=1 that means
  2430                              <1> 	;  "nothing to do". (20/10/2013)
  2431                              <1> 	;
  2432                              <1> 	; 20/10/2013
  2433 0000475A 66833D[0C660000]00  <1> 	cmp 	word [u.ttyp], 0 ; has process got a tty ?
  2434 00004762 761F                <1> 	jna	short isintr2 ; retn
  2435                              <1> 	; 03/09/2013
  2436                              <1> 	; (nothing to do)
  2437                              <1> 	;retn
  2438                              <1> 	; 22/09/2013
  2439 00004764 66833D[20660000]00  <1> 	cmp	word [u.intr], 0
  2440 0000476C 7615                <1> 	jna	short isintr2 ; retn
  2441                              <1> 	; 30/05/2014
  2442                              <1> 	;push	ax
  2443                              <1> 	; 24/12/2021
  2444 0000476E 50                  <1> 	push	eax
  2445 0000476F 66A1[22660000]      <1> 	mov	ax, [u.quit]
  2446 00004775 6609C0              <1> 	or	ax, ax ; 0 ?
  2447 00004778 7408                <1> 	jz	short isintr1 ; zf = 1
  2448 0000477A 6683F8FE            <1> 	cmp	ax, 0FFFEh  ; 'ctrl + brk' check
  2449 0000477E 7702                <1> 	ja	short isintr1 ; 0FFFFh, zf = 0
  2450                              <1> 	;xor	ax, ax ; zf = 1
  2451                              <1> 	; 24/12/2021
  2452 00004780 31C0                <1> 	xor	eax, eax ; zf = 1
  2453                              <1> isintr1:
  2454                              <1> 	;pop	ax
  2455                              <1> 	; 24/12/2021
  2456 00004782 58                  <1> 	pop	eax
  2457                              <1> isintr2: ; 22/09/2013
  2458                              <1> 	; zf=1 -> nothing to do
  2459 00004783 C3                  <1> 	retn
  2460                              <1> 
  2461                              <1> 	; UNIX v1 original 'isintr' routine... 
  2462                              <1>        	;mov     r1,-(sp) / put number of wait channel on the stack
  2463                              <1>        	;mov     r2,-(sp) / save r2
  2464                              <1>        	;mov     u.ttyp,r1 / r1 = pointer to buffer of process control
  2465                              <1>         ;                 / typewriter
  2466                              <1>        	;beq     1f / if 0, do nothing except skip return
  2467                              <1>        	;movb    6(r1),r1 / put interrupt char in the tty buffer in r1
  2468                              <1>        	;beq     1f / if its 0 do nothing except skip return
  2469                              <1>        	;cmp     r1,$177 / is interrupt char = delete?
  2470                              <1>        	;bne     3f / no, so it must be a quit (fs)
  2471                              <1>        	;tst     u.intr / yes, value of u.intr determines handling
  2472                              <1>         ;              / of interrupts
  2473                              <1>        	;bne     2f / if not 0, 2f. If zero do nothing.
  2474                              <1>      ;1:
  2475                              <1>        	;tst     (r0)+ / bump r0 past system return (skip)
  2476                              <1>      ;4:
  2477                              <1>        	;mov     (sp)+,r2 / restore r1 and r2
  2478                              <1>        	;mov     (sp)+,r1
  2479                              <1>        	;rts     r0
  2480                              <1>      ;3: / interrupt char = quit (fs)
  2481                              <1>        	;tst     u.quit / value of u.quit determines handling of quits
  2482                              <1>        	;beq     1b / u.quit = 0 means do nothing
  2483                              <1>      ;2: / get here because either u.intr <> 0 or u.qult <> O
  2484                              <1>        	;mov     $tty+6,r1 / move pointer to tty block into r1
  2485                              <1>      ;1: / find process control tty entry in tty block
  2486                              <1>        	;cmp     (r1),u.ttyp / is this the process control tty buffer?
  2487                              <1>        	;beq     1f / block found go to 1f
  2488                              <1>        	;add     $8,r1 / look at next tty block
  2489                              <1>        	;cmp     r1,$tty+[ntty*8]+6 / are we at end of tty blocks
  2490                              <1>        	;blo     1b / no
  2491                              <1>        	;br      4b / no process control tty found so go to 4b
  2492                              <1>      ;1:
  2493                              <1>        	;mov     $240,*$ps / set processor priority to 5
  2494                              <1>        	;movb    -3(r1),0f / load getc call argument; character llst
  2495                              <1>         ;                  / identifier
  2496                              <1>        	;inc     0f / increment
  2497                              <1>      ;1:
  2498                              <1>        	;jsr     r0,getc; 0:.. / erase output char list for control
  2499                              <1>         ;        br 4b / process tty. This prevents a line of stuff
  2500                              <1>         ;             / being typed out after you hit the interrupt
  2501                              <1>         ;             / key
  2502                              <1>        	;br      1b
  2115                                  %include 'u5.s'        ; 03/06/2015
  2116                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.2) - SYS5.INC
  2117                              <1> ; Last Modification: 22/04/2022
  2118                              <1> ; ----------------------------------------------------------------------------
  2119                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2120                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2121                              <1> ;
  2122                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2123                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2124                              <1> ; <Bell Laboratories (17/3/1972)>
  2125                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2126                              <1> ;
  2127                              <1> ; Retro UNIX 8086 v1 - U5.ASM (07/08/2013) //// UNIX v1 -> u5.s
  2128                              <1> ;
  2129                              <1> ; ****************************************************************************
  2130                              <1> 
  2131                              <1> mget:
  2132                              <1> 	; 22/04/2022
  2133                              <1> 	; 09/01/2022
  2134                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2135                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2136                              <1> 	; 22/03/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  2137                              <1> 	;
  2138                              <1> 	; Get existing or (allocate) a new disk block for file
  2139                              <1> 	; 
  2140                              <1> 	; INPUTS ->
  2141                              <1> 	;    u.fofp (file offset pointer)
  2142                              <1> 	;    inode 
  2143                              <1> 	;    u.off (file offset)
  2144                              <1> 	; OUTPUTS ->
  2145                              <1> 	;    r1 (physical block number)
  2146                              <1> 	;    r2, r3, r5 (internal)
  2147                              <1> 	;
  2148                              <1> 	; ((AX = R1)) output
  2149                              <1> 	;    (Retro UNIX Prototype : 05/03/2013 - 14/11/2012, UNIXCOPY.ASM)
  2150                              <1>         ;    ((Modified registers: eDX, eBX, eCX, eSI, eDI, eBP))  
  2151                              <1> 
  2152                              <1> 		; mov *u.fofp,mq / file offset in mq
  2153                              <1> 		; clr ac / later to be high sig
  2154                              <1> 		; mov $-8,lsh   / divide ac/mq by 256.
  2155                              <1> 		; mov mq,r2
  2156                              <1> 		; bit $10000,i.flgs / lg/sm is this a large or small file
  2157                              <1> 		; bne 4f / branch for large file
  2158                              <1> mget_0:	
  2159                              <1> 	; 09/01/2022
  2160 00004784 29C0                <1> 	sub	eax, eax
  2161 00004786 29D2                <1> 	sub	edx, edx
  2162 00004788 29C9                <1> 	sub	ecx, ecx
  2163 0000478A 29DB                <1> 	sub	ebx, ebx
  2164                              <1> 
  2165 0000478C 8B35[EC650000]      <1>         mov     esi, [u.fofp]
  2166                              <1>         ;movzx	ebx, byte [esi+1]
  2167                              <1> 	; 09/01/2022
  2168 00004792 46                  <1> 	inc	esi
  2169 00004793 8A1E                <1> 	mov	bl, [esi]
  2170                              <1> 
  2171                              <1> 	; BX = r2
  2172                              <1>         ; 24/12/2021
  2173 00004795 F605[D5620000]10    <1> 	test	byte [i.flgs+1], 10h
  2174                              <1> 	;test 	word [i.flgs], 4096 ; 1000h
  2175                              <1> 				  ; is this a large or small file
  2176 0000479C 756C                <1> 	jnz 	short mget_5 ; 4f ; large file
  2177                              <1> 
  2178 0000479E F6C3F0              <1>         test    bl, 0F0h ; !0Fh                    
  2179                              <1> 		; bit $!17,r2
  2180 000047A1 7525                <1> 	jnz 	short mget_2
  2181                              <1> 		; bne 3f / branch if r2 greater than or equal to 16
  2182 000047A3 80E30E              <1>         and     bl, 0Eh  
  2183                              <1> 		; bic $!16,r2 / clear all bits but bits 1,2,3
  2184                              <1> 	; 09/01/2021
  2185 000047A6 668B83[DA620000]    <1> 	mov	ax, [ebx+i.dskp]
  2186                              <1> 	;movzx 	eax, word [ebx+i.dskp] ; AX = R1, physical block number
  2187                              <1> 		; mov i.dskp(r2),r1 / r1 has physical block number
  2188                              <1> 	; 24/12/2021
  2189 000047AD 09C0                <1> 	or	eax, eax
  2190                              <1> 	;or 	ax, ax
  2191 000047AF 7516                <1> 	jnz 	short mget_1 
  2192                              <1> 		; bne 2f / if physical block num is zero then need a new block
  2193                              <1> 		       ; / for file
  2194 000047B1 E8A6000000          <1> 	call 	alloc
  2195                              <1> 		; jsr r0,alloc / allocate a new block
  2196                              <1>          ; eAX (r1) = Physical block number
  2197 000047B6 668983[DA620000]    <1> 	mov 	[ebx+i.dskp], ax
  2198                              <1> 		; mov r1,i.dskp(r2) / physical block number stored in i-node
  2199 000047BD E835020000          <1> 	call 	setimod	
  2200                              <1> 		; jsr r0,setimod / set inode modified byte (imod)
  2201 000047C2 E8C2FEFFFF          <1> 	call	clear
  2202                              <1> 		; jsr r0,clear / zero out disk/drum block just allocated
  2203                              <1> mget_1: ; 2:
  2204                              <1>         ; eAX (r1) = Physical block number
  2205 000047C7 C3                  <1> 	retn 
  2206                              <1> 		; rts r0
  2207                              <1> mget_2: ; 3: / adding on block which changes small file to a large file
  2208 000047C8 E88F000000          <1> 	call 	alloc
  2209                              <1> 		; jsr r0,alloc / allocate a new block for this file;
  2210                              <1> 	                     ; / block number in r1
  2211                              <1>         ; eAX (r1) = Physical block number
  2212 000047CD E8380D0000          <1> 	call 	wslot
  2213                              <1> 		; jsr r0,wslot / set up I/O buffer for write, r5 points to 
  2214                              <1> 			     ; / first data word in buffer
  2215                              <1>         ; eAX (r1) = Physical block number
  2216                              <1> 	; 09/01/2022
  2217 000047D2 31C9                <1> 	xor	ecx, ecx
  2218 000047D4 B108                <1> 	mov	cl, 8
  2219                              <1> 	;mov 	ecx, 8  ; R3, transfer old physical block pointers
  2220                              <1> 		   ; into new indirect block area for the new
  2221                              <1> 		   ; large file		
  2222 000047D6 89DF                <1> 	mov 	edi, ebx ; r5
  2223 000047D8 BE[DA620000]        <1> 	mov 	esi, i.dskp 
  2224                              <1> 		; mov $8.,r3 / next 6 instructions transfer old physical 
  2225                              <1> 			   ; / block pointers
  2226                              <1> 		; mov $i.dskp,r2 / into new indirect block for the new 
  2227                              <1> 			  ; / large file
  2228                              <1> 	; 22/04/2022
  2229 000047DD 50                  <1> 	push	eax ; * ; bugfix
  2230                              <1> 
  2231                              <1> 	;xor 	ax, ax ; mov ax, 0
  2232                              <1> 	; 24/12/2021
  2233 000047DE 31C0                <1> 	xor	eax, eax
  2234                              <1> mget_3: ;1:
  2235 000047E0 66A5                <1> 	movsw
  2236                              <1> 		; mov (r2),(r5)+
  2237 000047E2 668946FE            <1> 	mov 	[esi-2], ax
  2238                              <1> 		; clr (r2)+
  2239 000047E6 E2F8                <1> 	loop	mget_3 ; 1b
  2240                              <1> 		; dec r3
  2241                              <1> 		; bgt 1b
  2242                              <1> 
  2243 000047E8 B1F8                <1> 	mov 	cl, 256-8
  2244                              <1> 		; mov $256.-8.,r3 / clear rest of data buffer
  2245                              <1> mget_4:	; 1
  2246 000047EA F366AB              <1> 	rep 	stosw
  2247                              <1> 		; clr (r5)+
  2248                              <1> 		; dec r3
  2249                              <1> 		; bgt 1b
  2250                              <1> 
  2251                              <1> 	; 22/04/2022
  2252                              <1> 	;pop	eax ; * ; bugfix
  2253                              <1> 
  2254                              <1> 	; 24/03/2013
  2255                              <1>         ; AX (r1) = Physical block number
  2256 000047ED E8250D0000          <1> 	call	dskwr
  2257                              <1> 		; jsr r0,dskwr / write new indirect block on disk
  2258                              <1> 
  2259                              <1> 	; 22/04/2022
  2260 000047F2 58                  <1> 	pop	eax ; * ; bugfix
  2261                              <1> 
  2262                              <1>         ; eAX (r1) = Physical block number
  2263 000047F3 66A3[DA620000]      <1> 	mov 	[i.dskp], ax
  2264                              <1> 		; mov r1,i.dskp / put pointer to indirect block in i-node
  2265                              <1> 	; 09/01/2022
  2266 000047F9 800D[D5620000]10    <1> 	or	byte [i.flgs+1], 10h
  2267                              <1> 	;or 	word [i.flgs], 4096 ; 1000h
  2268                              <1> 		; bis $10000,i.flgs / set large file bit 
  2269                              <1> 				  ; / in i.flgs word of i-node
  2270 00004800 E8F2010000          <1> 	call	setimod
  2271                              <1> 		; jsr r0,setimod / set i-node modified flag
  2272 00004805 E97AFFFFFF          <1>         jmp     mget_0 
  2273                              <1> 		; br mget
  2274                              <1> 
  2275                              <1> mget_5:  ; 4 ; large file
  2276                              <1> 		; mov $-8,lsh / divide byte number by 256.
  2277                              <1> 		; bic $!776,r2 / zero all bits but 1,2,3,4,5,6,7,8; gives offset
  2278                              <1> 			    ; / in indirect block
  2279                              <1> 		; mov r2,-(sp) / save on stack (*)
  2280                              <1> 		; mov mq,r2 / calculate offset in i-node for pointer to proper
  2281                              <1>        		          ; / indirect block
  2282                              <1> 		; bic $!16,r2
  2283 0000480A 80E3FE              <1>         and     bl, 0FEh ; bh = 0
  2284 0000480D 53                  <1>         push    ebx  ; i-node pointer offset in indirect block  (*) 
  2285                              <1>         ; 01/03/2013 Max. possible BX (offset) value is 127 (65535/512)
  2286                              <1> 	; 	     for this file system (offset 128 to 255 not in use)
  2287                              <1> 	; There is always 1 indirect block for this file system
  2288                              <1> 	; 09/01/2022
  2289 0000480E 66A1[DA620000]      <1> 	mov	ax, [i.dskp]
  2290                              <1> 	;movzx 	eax, word [i.dskp] ; i.dskp[0]
  2291                              <1> 		; mov i.dskp(r2),r1
  2292                              <1> 	; 09/01/2022
  2293 00004814 09C0                <1> 	or	eax, eax
  2294                              <1> 	;or 	ax, ax ; R1
  2295 00004816 7515                <1> 	jnz 	short mget_6 ; 2f
  2296                              <1> 		; bne 2f / if no indirect block exists
  2297 00004818 E83F000000          <1> 	call 	alloc
  2298                              <1> 		; jsr r0,alloc / allocate a new block
  2299 0000481D 66A3[DA620000]      <1> 	mov 	[i.dskp], ax  ; 03/03/2013
  2300                              <1> 		; mov r1,i.dskp(r2) / put block number of new block in i-node
  2301 00004823 E8CF010000          <1> 	call 	setimod
  2302                              <1> 		; jsr r0,setimod / set i-node modified byte
  2303                              <1> 	; eAX = new block number
  2304 00004828 E85CFEFFFF          <1> 	call 	clear
  2305                              <1> 		; jsr r0,clear / clear new block
  2306                              <1> mget_6: ;2
  2307                              <1> 	; 05/03/2013
  2308                              <1> 	; eAX = r1, physical block number (of indirect block)
  2309 0000482D E8740C0000          <1> 	call 	dskrd ; read indirect block
  2310                              <1> 		; jsr r0,dskrd / read in indirect block
  2311 00004832 5A                  <1> 	pop 	edx  ; R2, get offset (*)
  2312                              <1> 		; mov (sp)+,r2 / get offset
  2313                              <1> 	; eAX = r1, physical block number (of indirect block)
  2314 00004833 50                  <1> 	push 	eax ; ** ; 24/03/2013
  2315                              <1> 		; mov r1,-(sp) / save block number of indirect block on stack
  2316                              <1> 	; eBX (r5) = pointer to buffer (indirect block)
  2317 00004834 01D3                <1> 	add 	ebx, edx ; / r5 points to first word in indirect block, r2
  2318                              <1> 		; add r5,r2 / r5 points to first word in indirect block, r2
  2319                              <1> 	                  ; / points to location of inter
  2320                              <1> 	; 09/01/2022
  2321 00004836 668B03              <1> 	mov	ax, [ebx]
  2322                              <1> 	;movzx 	eax, word [ebx] ; put physical block no of block
  2323                              <1> 			      ; in file sought in R1 (AX)
  2324                              <1> 		; mov (r2),r1 / put physical block no of block in file
  2325                              <1> 	               	    ; / sought in r1
  2326                              <1> 	; 09/01/2022
  2327 00004839 09C0                <1> 	or	eax, eax
  2328                              <1> 	;or 	ax, ax
  2329 0000483B 751D                <1>         jnz 	short mget_7 ; 2f
  2330                              <1> 		; bne 2f / if no block exists 
  2331 0000483D E81A000000          <1> 	call 	alloc
  2332                              <1> 		; jsr r0,alloc / allocate a new block
  2333 00004842 668903              <1> 	mov 	[ebx], ax ; R1
  2334                              <1> 		; mov r1,(r2) / put new block number into proper location in
  2335                              <1> 	                    ; / indirect block
  2336 00004845 5A                  <1> 	pop	edx ; ** ; 24/03/2013
  2337                              <1> 		; mov (sp)+,r1 / get block number of indirect block
  2338 00004846 52                  <1> 	push 	edx ; ** ; 31/07/2013
  2339 00004847 50                  <1> 	push	eax ; * ; 24/03/2013, 31/07/2013 (new block number)
  2340 00004848 89D0                <1> 	mov	eax, edx ; 24/03/2013
  2341                              <1> 		; mov (r2),-(sp) / save block number of new block
  2342                              <1> 	; eAX (r1) = physical block number (of indirect block)
  2343 0000484A E8BB0C0000          <1> 	call 	wslot
  2344                              <1> 		; jsr r0,wslot
  2345                              <1>         ; eAX (r1) = physical block number
  2346                              <1> 	; eBX (r5) = pointer to buffer (indirect block)
  2347 0000484F E8C30C0000          <1> 	call 	dskwr
  2348                              <1> 	; eAX = r1 = physical block number (of indirect block)
  2349                              <1> 		; jsr r0,dskwr / write newly modified indirect block 
  2350                              <1> 			     ; / back out on disk
  2351 00004854 58                  <1> 	pop	eax ; *  ; 31/07/2013
  2352                              <1> 		; mov (sp),r1 / restore block number of new block	
  2353                              <1> 	; eAX (r1) = physical block number of new block
  2354 00004855 E82FFEFFFF          <1> 	call 	clear
  2355                              <1> 		; jsr r0,clear / clear new block	
  2356                              <1> mget_7: ; 2
  2357 0000485A 5A                  <1> 	pop 	edx ; **
  2358                              <1> 		; tst (sp)+ / bump stack pointer
  2359                              <1> 	; eAX (r1) = Block number of new block
  2360 0000485B C3                  <1> 	retn
  2361                              <1> 		; rts r0
  2362                              <1> 
  2363                              <1> alloc:
  2364                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2365                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2366                              <1> 	; 01/04/2013 - 01/08/2013 (Retro UNIX 8086 v1)
  2367                              <1> 	;
  2368                              <1> 	; get a free block and 
  2369                              <1> 	; set the corresponding bit in the free storage map
  2370                              <1> 	; 
  2371                              <1> 	; INPUTS ->
  2372                              <1> 	;    cdev (current device)
  2373                              <1> 	;    r2 
  2374                              <1> 	;    r3
  2375                              <1> 	; OUTPUTS ->
  2376                              <1> 	;    r1 (physical block number of block assigned)
  2377                              <1> 	;    smod, mmod, systm (super block), mount (mountable super block)	
  2378                              <1> 	;
  2379                              <1> 	; ((AX = R1)) output
  2380                              <1> 	;    (Retro UNIX Prototype : 14/11/2012 - 21/07/2012, UNIXCOPY.ASM)
  2381                              <1>         ;    ((Modified registers: DX, CX))  
  2382                              <1> 
  2383                              <1> 		;mov r2,-(sp) / save r2, r3 on stack
  2384                              <1> 		;mov r3,-(sp)
  2385                              <1> 	;push 	ecx
  2386 0000485C 53                  <1> 	push 	ebx ; R2
  2387                              <1> 	;push 	edx ; R3
  2388 0000485D BB[AC760000]        <1> 	mov 	ebx, systm ; SuperBlock 
  2389                              <1> 		; mov $systm,r2 / start of inode and free storage map for drum
  2390 00004862 803D[C3650000]00    <1> 	cmp 	byte [cdev], 0
  2391                              <1> 		; tst cdev
  2392 00004869 7605                <1> 	jna	short alloc_1
  2393                              <1> 		; beq 1f / drum is device
  2394 0000486B BB[B4780000]        <1> 	mov	ebx, mount
  2395                              <1> 		; mov $mount,r2 / disk or tape is device, start of inode and
  2396                              <1> 			      ; / free storage map
  2397                              <1> alloc_1: ; 1
  2398                              <1> 	; 09/01/2022
  2399                              <1> 	;sub	ecx, ecx
  2400                              <1> 	;sub	edx, edx
  2401                              <1> 	;sub	eax, eax
  2402                              <1> 
  2403 00004870 668B0B              <1>         mov	cx, [ebx]
  2404                              <1> 		; mov (r2)+,r1 / first word contains number of bytes in free
  2405                              <1> 			     ; / storage map
  2406                              <1> 	; 09/01/2022
  2407 00004873 C1E103              <1> 	shl	ecx, 3
  2408                              <1> 	;shl	cx, 3
  2409                              <1> 		; asl r1 / multiply r1 by eight gives 
  2410                              <1> 		; number of blocks in device
  2411                              <1> 		; asl r1
  2412                              <1> 		; asl r1
  2413                              <1> 	;;push	cx ;; 01/08/2013
  2414                              <1> 		; mov r1,-(sp) / save # of blocks in device on stack
  2415 00004876 31C0                <1> 	xor 	eax, eax ; 0
  2416                              <1> 		; clr r1 / r1 contains bit count of free storage map
  2417                              <1> alloc_2: ; 1
  2418 00004878 43                  <1> 	inc 	ebx ; 18/8/2012
  2419 00004879 43                  <1> 	inc 	ebx ; 
  2420 0000487A 668B13              <1> 	mov 	dx, [ebx]
  2421                              <1> 		; mov (r2)+,r3 / word of free storage map in r3 
  2422                              <1> 	; 09/01/2022
  2423 0000487D 09D2                <1> 	or	edx, edx
  2424                              <1> 	;or 	dx, dx
  2425 0000487F 750D                <1> 	jnz 	short alloc_3 ; 1f
  2426                              <1> 		; bne 1f / branch if any free blocks in this word	
  2427 00004881 6683C010            <1> 	add 	ax, 16
  2428                              <1> 		; add $16.,r1
  2429                              <1> 	; 09/01/2022
  2430 00004885 39C8                <1> 	cmp	eax, ecx
  2431                              <1> 	;cmp 	ax, cx    
  2432                              <1> 		; cmp r1 ,(sp) / have we examined all free storage bytes
  2433 00004887 72EF                <1> 	jb 	short alloc_2
  2434                              <1> 		; blo 1b
  2435                              <1> 	; 14/11/2015
  2436                              <1> 	; Note: If the super block buffer has wrong content (zero bytes)
  2437                              <1> 	;	because of a (DMA or another) r/w error, 
  2438                              <1> 	;	we will be here, at 'jmp panic' code address,
  2439                              <1> 	;	even if the (disk) file system space is not full !!!
  2440                              <1> 	;	(cx = 0)	
  2441                              <1> 	;
  2442 00004889 E905E2FFFF          <1> 	jmp     panic 
  2443                              <1> 		; jmp panic / found no free storage
  2444                              <1> alloc_3: ; 1
  2445                              <1> 	; 09/01/2022
  2446 0000488E D1EA                <1> 	shr	edx, 1
  2447                              <1> 	;shr	dx, 1
  2448                              <1> 		; asr r3 / find a free block
  2449 00004890 7203                <1> 	jc	short alloc_4 ; 1f
  2450                              <1> 		; bcs 1f / branch when free block found; bit for block k
  2451                              <1> 		       ; / is in byte k/8 / in bit k (mod 8)
  2452                              <1> 	; 09/01/2022
  2453 00004892 40                  <1> 	inc	eax
  2454                              <1> 	;inc	ax
  2455                              <1> 		; inc r1 / increment bit count in bit k (mod8)
  2456 00004893 EBF9                <1> 	jmp 	short alloc_3
  2457                              <1> 		; br 1b
  2458                              <1> alloc_4: ; 1:
  2459                              <1> 	;; pop cx ;; 01/08/2013
  2460                              <1> 		; tst (sp)+ / bump sp
  2461                              <1> 	; 02/04/2013 
  2462 00004895 E829000000          <1> 	call	free3
  2463                              <1> 		; jsr r0,3f / have found a free block
  2464                              <1> 	; 21/8/2012
  2465 0000489A 66F7D2              <1> 	not 	dx ; masking bit is '0' and others are '1'
  2466 0000489D 662113              <1> 	and	[ebx], dx   ;; 0 -> allocated 
  2467                              <1> 		; bic r3,(r2) / set bit for this block 
  2468                              <1> 		            ; / i.e. assign block
  2469                              <1> 		; br 2f
  2470 000048A0 EB09                <1> 	jmp 	short alloc_5
  2471                              <1> 
  2472                              <1> free:
  2473                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2474                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2475                              <1> 	; 07/04/2013 - 01/08/2013 (Retro UNIX 8086 v1)
  2476                              <1> 	;
  2477                              <1> 	; calculates byte address and bit position for given block number
  2478                              <1> 	; then sets the corresponding bit in the free storage map
  2479                              <1> 	; 
  2480                              <1> 	; INPUTS ->
  2481                              <1> 	;    r1 - block number for a block structured device
  2482                              <1> 	;    cdev - current device 
  2483                              <1> 	; OUTPUTS ->
  2484                              <1> 	;    free storage map is updated
  2485                              <1> 	;    smod is incremented if cdev is root device (fixed disk)
  2486                              <1> 	;    mmod is incremented if cdev is a removable disk 	
  2487                              <1> 	;
  2488                              <1> 	;  (Retro UNIX Prototype : 01/12/2012, UNIXCOPY.ASM)
  2489                              <1>         ;  ((Modified registers: DX, CX))  
  2490                              <1> 
  2491                              <1> 		;mov r2,-(sp) / save r2, r3
  2492                              <1> 		;mov r3,-(sp)
  2493                              <1> 	;push 	ecx
  2494 000048A2 53                  <1> 	push 	ebx ; R2
  2495                              <1> 	;push 	edx ; R3 
  2496                              <1> 
  2497 000048A3 E81B000000          <1>         call    free3
  2498                              <1> 	     	; jsr r0,3f  / set up bit mask and word no. 
  2499                              <1> 				 ; / in free storage map for block
  2500 000048A8 660913              <1> 	or 	[ebx], dx  
  2501                              <1> 	  	; bis r3, (r2) / set free storage block bit;
  2502                              <1> 			    ;  / indicates free block	
  2503                              <1> 	; 0 -> allocated, 1 -> free
  2504                              <1> 
  2505                              <1> alloc_5:
  2506                              <1> 	; 07/04/2013
  2507                              <1> free_1: ; 2:
  2508                              <1> 	;pop 	edx
  2509                              <1> 		; mov (sp)+,r3 / restore r2, r3
  2510 000048AB 5B                  <1> 	pop	ebx
  2511                              <1> 		; mov (sp)+,r2
  2512                              <1> 	; pop	ecx
  2513 000048AC 803D[C3650000]00    <1> 	cmp 	byte [cdev], 0
  2514                              <1> 		; tst cdev / cdev = 0, block structured, drum; 
  2515                              <1> 			 ; / cdev = 1, mountable device
  2516 000048B3 7707                <1> 	ja	short alloc_6 ; 1f
  2517                              <1> 		; bne 1f
  2518                              <1> 	;mov	byte [smod], 1
  2519 000048B5 FE05[D1650000]      <1> 	inc 	byte [smod]
  2520                              <1> 		; incb smod / set super block modified for drum
  2521                              <1> 	; eAX (r1) = block number
  2522 000048BB C3                  <1> 	retn
  2523                              <1> 		; rts r0
  2524                              <1> free_2:
  2525                              <1> alloc_6: ; 1:
  2526                              <1> 	;mov 	byte [mmod], 1
  2527 000048BC FE05[D2650000]      <1> 	inc 	byte [mmod]
  2528                              <1> 		; incb	mmod 
  2529                              <1> 		  ; / set super block modified for mountable device
  2530                              <1> 	; eAX (r1) = block number
  2531 000048C2 C3                  <1> 	retn	
  2532                              <1> 		; rts r0
  2533                              <1> free3:
  2534                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2535                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2536                              <1> 	; 02/04/2013 - 01/08/2013 (Retro UNIX 8086 v1)
  2537                              <1> 	;
  2538                              <1> 	; free3 is called from 'alloc' and 'free' procedures
  2539                              <1> 	; 
  2540                              <1> alloc_free_3: ; 3
  2541                              <1> 	;mov 	dx, 1
  2542                              <1> 	; 09/01/2022
  2543 000048C3 31D2                <1> 	xor	edx, edx
  2544 000048C5 42                  <1> 	inc	edx
  2545                              <1> 	; edx = 1
  2546 000048C6 88C1                <1> 	mov 	cl, al
  2547                              <1> 		; mov r1,r2 / block number, k, = 1		
  2548 000048C8 80E10F              <1> 	and 	cl, 0Fh  ; 0Fh <-- (k) mod 16
  2549                              <1> 		; bic $!7,r2 / clear all bits but 0,1,2; r2 = (k) mod (8)
  2550 000048CB 7402                <1> 	jz 	short free4
  2551                              <1> 		; bisb 2f(r2),r3 / use mask to set bit in r3 corresponding to
  2552                              <1> 			       ; / (k) mod 8
  2553                              <1> 	;shl 	dx, cl
  2554                              <1> 	; 09/01/2022
  2555 000048CD D3E2                <1> 	shl	edx, cl
  2556                              <1> free4:
  2557 000048CF 0FB7D8              <1> 	movzx 	ebx, ax
  2558                              <1> 		; mov r1,r2 / divide block number by 16
  2559                              <1> 	; 09/01/2022
  2560 000048D2 C1EB04              <1> 	shr	ebx, 4
  2561                              <1> 	;shr 	bx, 4
  2562                              <1> 		; asr r2
  2563                              <1> 		; asr r2
  2564                              <1> 		; asr r2
  2565                              <1> 		; asr r2
  2566                              <1> 		; bcc 1f / branch if bit 3 in r1 was 0 i.e., 
  2567                              <1> 		       ; / bit for block is in lower half of word
  2568                              <1> 		; swab r3 / swap bytes in r3; bit in upper half of word in free
  2569                              <1> 		        ; / storage map
  2570                              <1> alloc_free_4: ; 1
  2571                              <1> 	; 09/01/2022
  2572 000048D5 D1E3                <1> 	shl	ebx, 1
  2573                              <1> 	;shl 	bx, 1
  2574                              <1> 		; asl r2 / multiply block number by 2; r2 = k/8
  2575 000048D7 81C3[AE760000]      <1> 	add 	ebx, systm+2 ; SuperBlock+2
  2576                              <1> 		; add $systm+2,r2 / address of word of free storage map for drum
  2577                              <1> 	    		        ; / with block bit in it 	
  2578 000048DD 803D[C3650000]00    <1> 	cmp	byte [cdev], 0
  2579                              <1> 		; tst cdev
  2580 000048E4 7606                <1> 	jna	short alloc_free_5
  2581                              <1> 		; beq 1f / cdev = 0 indicates device is drum
  2582 000048E6 81C308020000        <1> 	add	ebx, mount - systm
  2583                              <1> 		; add $mount-systm,r2 / address of word of free storage map for
  2584                              <1> 				    ; / mountable device with bit of block to be
  2585                              <1> 				    ; / freed
  2586                              <1> alloc_free_5: ; 1 
  2587 000048EC C3                  <1> 	retn
  2588                              <1> 		; rts r0 / return to 'free'
  2589                              <1> 	      ; 2
  2590                              <1> 	        ; .byte	1,2,4,10,20,40,100,200 / masks for bits 0,...,7
  2591                              <1> 	
  2592                              <1> iget:
  2593                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2594                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2595                              <1> 	; 07/04/2013 - 07/08/2013 (Retro UNIX 8086 v1)
  2596                              <1> 	;
  2597                              <1> 	; get a new i-node whose i-number in r1 and whose device is in cdev
  2598                              <1> 	;
  2599                              <1> 	; ('iget' returns current i-number in r1, if input value of r1 is 0)
  2600                              <1> 	; 
  2601                              <1> 	; INPUTS ->
  2602                              <1> 	;    ii - current i-number, rootdir
  2603                              <1> 	;    cdev - new i-node device
  2604                              <1> 	;    idev - current i-node device
  2605                              <1> 	;    imod - current i-node modified flag
  2606                              <1> 	;    mnti - cross device file i-number
  2607                              <1> 	;    r1 - i-numbe rof new i-node
  2608                              <1> 	;    mntd - mountable device number		
  2609                              <1> 	; 	 
  2610                              <1> 	; OUTPUTS ->
  2611                              <1> 	;    cdev, idev, imod, ii, r1
  2612                              <1> 	;
  2613                              <1> 	; ((AX = R1)) input/output
  2614                              <1> 	;
  2615                              <1> 	;  (Retro UNIX Prototype : 14/07/2012 - 18/11/2012, UNIXCOPY.ASM)
  2616                              <1>         ;  ((Modified registers: eDX, eCX, eBX, eSI, eDI, eBP))  
  2617                              <1> 
  2618 000048ED 8A15[C3650000]      <1> 	mov	dl, [cdev] ; 18/07/2013
  2619 000048F3 8A35[C2650000]      <1> 	mov	dh, [idev] ; 07/08/2013
  2620                              <1> 	;
  2621 000048F9 663B05[C0650000]    <1> 	cmp 	ax, [ii]
  2622                              <1> 		; cmp r1,ii / r1 = i-number of current file
  2623 00004900 7504                <1> 	jne 	short iget_1
  2624                              <1> 		; bne 1f
  2625 00004902 38F2                <1> 	cmp	dl, dh
  2626                              <1> 		; cmp idev,cdev
  2627                              <1> 			  ; / is device number of i-node = current device
  2628 00004904 7472                <1>         je      short iget_5
  2629                              <1> 		; beq 2f
  2630                              <1> iget_1: ; 1:
  2631 00004906 30DB                <1> 	xor	bl, bl
  2632 00004908 381D[D0650000]      <1> 	cmp	[imod], bl ; 0	
  2633                              <1> 		; tstb imod / has i-node of current file
  2634                              <1> 			  ; / been modified i.e., imod set
  2635 0000490E 7629                <1> 	jna	short iget_2
  2636                              <1> 		; beq 1f
  2637 00004910 881D[D0650000]      <1> 	mov	[imod], bl ; 0
  2638                              <1> 		;  clrb	imod / if it has, 
  2639                              <1> 			   ; / we must write the new i-node out on disk
  2640                              <1> 	; 24/12/2021
  2641 00004916 50                  <1> 	push	eax ; *
  2642                              <1> 	;push	ax
  2643                              <1> 		; mov r1,-(sp)
  2644                              <1> 	;mov	dl, [cdev]
  2645 00004917 52                  <1> 	push	edx ; **
  2646                              <1> 	;push	dx
  2647                              <1> 		; mov cdev,-(sp)
  2648 00004918 66A1[C0650000]      <1> 	mov	ax, [ii]
  2649                              <1> 		; mov ii,r1
  2650                              <1> 	;mov	dh, [idev]
  2651 0000491E 8835[C3650000]      <1> 	mov	[cdev], dh
  2652                              <1> 		; mov idev,cdev
  2653 00004924 FEC3                <1> 	inc	bl ; 1
  2654                              <1> 	; 31/07/2013
  2655 00004926 881D[60660000]      <1> 	mov     [rw], bl ; 1 == write 
  2656                              <1> 	;;28/07/2013 rw -> u.rw
  2657                              <1>         ;;mov   [u.rw], bl ; 1 == write
  2658 0000492C E848000000          <1> 	call	icalc
  2659                              <1> 		; jsr r0,icalc; 1
  2660                              <1> 	;pop	dx
  2661                              <1> 	; 24/12/2021
  2662 00004931 5A                  <1> 	pop	edx ; **
  2663 00004932 8815[C3650000]      <1> 	mov	[cdev], dl
  2664                              <1> 		; mov (sp)+,cdev
  2665                              <1> 	; 24/12/2021
  2666 00004938 58                  <1> 	pop	eax ; *
  2667                              <1> 	;pop	ax
  2668                              <1> 		; mov (sp)+,r1
  2669                              <1> iget_2: ; 1:
  2670 00004939 6621C0              <1> 	and	ax, ax
  2671                              <1> 		; tst r1 / is new i-number non zero
  2672 0000493C 7434                <1> 	jz	short iget_4 ; 2f
  2673                              <1> 		; beq 2f / branch if r1=0
  2674                              <1> 
  2675                              <1> 	;mov 	dl, [cdev]
  2676 0000493E 08D2                <1> 	or	dl, dl
  2677                              <1> 		; tst cdev / is the current device number non zero
  2678                              <1> 			 ; / (i.e., device =/ drum)
  2679 00004940 7517                <1> 	jnz	short iget_3 ;  1f
  2680                              <1> 		; bne 1f / branch 1f cdev =/ 0  ;; (cdev != 0)
  2681 00004942 663B05[C6650000]    <1> 	cmp	ax, [mnti]			
  2682                              <1> 		; cmp r1,mnti / mnti is the i-number of the cross device
  2683                              <1> 			    ; / file (root directory of mounted device)
  2684 00004949 750E                <1> 	jne	short iget_3 ; 1f
  2685                              <1> 		; bne 1f
  2686                              <1>         ;mov    bl, [mntd]
  2687 0000494B FEC2                <1> 	inc	dl ; mov dl, 1 ; 17/07/2013
  2688 0000494D 8815[C3650000]      <1>         mov	[cdev], dl ; 17/07/2013 - 09/07/2013
  2689                              <1> 		; mov mntd,cdev / make mounted device the current device
  2690 00004953 66A1[CC650000]      <1> 	mov	ax, [rootdir]
  2691                              <1> 		; mov rootdir,r1
  2692                              <1> iget_3: ; 1:
  2693 00004959 66A3[C0650000]      <1> 	mov	[ii], ax
  2694                              <1> 		; mov r1,ii
  2695 0000495F 8815[C2650000]      <1> 	mov	[idev], dl ; cdev
  2696                              <1> 		; mov cdev,idev
  2697 00004965 30DB                <1> 	xor	bl, bl
  2698                              <1>         ; 31/07/2013
  2699 00004967 881D[60660000]      <1> 	mov     [rw], bl ; 0 == read 
  2700                              <1> 	;;28/07/2013 rw -> u.rw       
  2701                              <1>         ;;mov   [u.rw], bl ; 0 = read
  2702 0000496D E807000000          <1> 	call	icalc
  2703                              <1> 		; jsr r0,icalc; 0 / read in i-node ii
  2704                              <1> iget_4: ; 2:
  2705 00004972 66A1[C0650000]      <1> 	mov	ax, [ii]
  2706                              <1> 		; mov ii,r1
  2707                              <1> iget_5:
  2708 00004978 C3                  <1> 	retn
  2709                              <1> 		; rts r0
  2710                              <1> 
  2711                              <1> icalc:
  2712                              <1> 	; 04/04/2022 (47->31)
  2713                              <1> 	;	(Inode Table/List Address modification)
  2714                              <1> 	; 09/01/2022
  2715                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2716                              <1> 	; 02/07/2015
  2717                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2718                              <1> 	; 07/04/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  2719                              <1> 	;
  2720                              <1> 	; calculate physical block number from i-number then
  2721                              <1> 	; read or write that block
  2722                              <1> 	;
  2723                              <1> 	; 'icalc' is called from 'iget'
  2724                              <1> 	;
  2725                              <1> 	; for original unix v1:
  2726                              <1> 	; / i-node i is located in block (i+31.)/16. and begins 32.*
  2727                              <1>        	; / (i+31.) mod 16. bytes from its start
  2728                              <1> 	;
  2729                              <1> 	; for retro unix 8086 v1:
  2730                              <1> 	;  i-node is located in block (i+47)/16 and
  2731                              <1> 	;  begins 32*(i+47) mod 16 bytes from its start
  2732                              <1> 	;
  2733                              <1> 	; INPUTS ->
  2734                              <1> 	;    r1 - i-number of i-node
  2735                              <1> 	; 	 
  2736                              <1> 	; OUTPUTS ->
  2737                              <1> 	;    inode r/w
  2738                              <1> 	;
  2739                              <1> 	; ((AX = R1)) input
  2740                              <1> 	;
  2741                              <1> 	;  (Retro UNIX Prototype : 14/07/2012 - 18/11/2012, UNIXCOPY.ASM)
  2742                              <1>         ;  ((Modified registers: eAX, eDX, eCX, eBX, eSI, eDI, eBP))  
  2743                              <1> 	;
  2744 00004979 0FB7D0              <1> 	movzx	edx, ax	
  2745                              <1> 	;add	dx, 47
  2746                              <1> 	; 04/04/2022
  2747 0000497C 6683C21F            <1> 	add	dx, 31
  2748 00004980 89D0                <1> 	mov	eax, edx
  2749                              <1> 	;;add	ax, 47	; add 47 to inode number
  2750                              <1> 	;add	ax, 31
  2751                              <1> 		; add $31.,r1 / add 31. to i-number
  2752 00004982 50                  <1> 	push	eax
  2753                              <1> 		; mov r1,-(sp) / save i+31. on stack
  2754                              <1> 	; 09/01/2022
  2755 00004983 C1E804              <1> 	shr	eax, 4
  2756                              <1> 	;shr 	ax, 4
  2757                              <1> 		; asr r1 / divide by 16.
  2758                              <1> 		; asr r1
  2759                              <1> 		; asr r1
  2760                              <1> 		; asr r1 / r1 contains block number of block
  2761                              <1> 		       ; / in which i-node exists
  2762 00004986 E81B0B0000          <1> 	call	dskrd
  2763                              <1> 		; jsr r0,dskrd / read in block containing i-node i.
  2764                              <1> 	; 31/07/2013
  2765 0000498B 803D[60660000]00    <1>         cmp     byte [rw], 0 ; Retro Unix 8086 v1 feature !
  2766                              <1> 	;; 28/07/2013 rw -> u.rw
  2767                              <1>         ;;cmp	byte [u.rw], 0 ; Retro Unix 8086 v1 feature !
  2768                              <1> 		; tst (r0)
  2769 00004992 7605                <1> 	jna	short icalc_1
  2770                              <1> 		; beq 1f / branch to wslot when argument
  2771                              <1> 		       ; / in icalc call = 1
  2772                              <1> 	; eAX = r1 = block number
  2773 00004994 E8710B0000          <1> 	call	wslot
  2774                              <1> 		; jsr r0,wslot / set up data buffer for write
  2775                              <1> 			     ; / (will be same buffer as dskrd got)
  2776                              <1> 	; eBX = r5 points to first word in data area for this block
  2777                              <1> icalc_1: ; 1:
  2778 00004999 5A                  <1> 	pop	edx 
  2779 0000499A 83E20F              <1> 	and 	edx, 0Fh ; (i+31) mod 16 (2022) ; (i+47) mod 16
  2780                              <1> 		; bic $!17,(sp) / zero all but last 4 bits; 
  2781                              <1> 			      ; / gives (i+31.) mod 16
  2782 0000499D C1E205              <1> 	shl 	edx, 5
  2783                              <1> 	; eDX = 32 * ((i+31) mod 16) ; 32 * ((i+47) mod 16)
  2784 000049A0 89DE                <1> 	mov	esi, ebx  ; ebx points 1st word of the buffer
  2785 000049A2 01D6                <1> 	add	esi, edx  ; edx is inode offset in the buffer
  2786                              <1>           	; eSI (r5) points to first word in i-node i.	
  2787                              <1> 		; mov (sp)+,mq / calculate offset in data buffer; 
  2788                              <1> 			     ; / 32.*(i+31.)mod16
  2789                              <1> 		; mov $5,lsh / for i-node i.
  2790                              <1> 		; add mq,r5 / r5 points to first word in i-node i.
  2791 000049A4 BF[D4620000]        <1> 	mov	edi, inode
  2792                              <1> 		; mov $inode,r1 / inode is address of first word 
  2793                              <1> 			      ; / of current i-node
  2794                              <1> 	; 09/01/2022
  2795 000049A9 29C9                <1> 	sub	ecx, ecx
  2796 000049AB B108                <1> 	mov	cl, 8 
  2797                              <1> 	;mov 	ecx, 8 ; 02/07/2015(32 bit modification)
  2798                              <1> 		; mov $16.,r3
  2799                              <1>        ; 31/07/2013
  2800 000049AD 382D[60660000]      <1>   	cmp     [rw], ch ; 0  ;; Retro Unix 8086 v1 feature !
  2801                              <1>        ;;28/07/2013 rw -> u.rw                 
  2802                              <1>        ;;cmp    [u.rw], ch ; 0  ;; Retro Unix 8086 v1 feature !
  2803                              <1> 		; tst (r0)+ / branch to 2f when argument in icalc call = 0
  2804 000049B3 7609                <1> 	jna	short icalc_3
  2805                              <1> 		; beq 2f / r0 now contains proper return address 
  2806                              <1> 		       ; / for rts r0
  2807                              <1> icalc_2: ; 1:
  2808 000049B5 87F7                <1> 	xchg 	esi, edi
  2809                              <1> 	; overwrite old i-node (in buffer to be written)
  2810 000049B7 F3A5                <1> 	rep 	movsd
  2811                              <1> 		; mov (r1)+,(r5)+ / over write old i-node
  2812                              <1> 		; dec r3
  2813                              <1> 		; bgt 1b
  2814                              <1> 	;call	dskwr
  2815                              <1> 		; jsr r0,dskwr / write inode out on device
  2816                              <1> 	;retn
  2817                              <1> 		; rts r0
  2818                              <1> 	; 24/12/2021
  2819 000049B9 E9590B0000          <1> 	jmp	dskwr
  2820                              <1> 
  2821                              <1> icalc_3: ; 2:
  2822                              <1> 	; copy new i-node into inode area of (core) memory
  2823 000049BE F3A5                <1> 	rep 	movsd
  2824                              <1> 		; mov (r5)+,(r1)+ / read new i-node into 
  2825                              <1> 		                ; / "inode" area of core
  2826                              <1> 		; dec r3
  2827                              <1> 		; bgt 2b
  2828 000049C0 C3                  <1> 	retn
  2829                              <1> 		; rts r0
  2830                              <1> 
  2831                              <1> access:
  2832                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2833                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2834                              <1> 	; 24/04/2013 - 29/04/2013 (Retro UNIX 8086 v1)
  2835                              <1> 	;
  2836                              <1> 	; check whether user is owner of file or user has read or write
  2837                              <1> 	; permission (based on i.flgs).
  2838                              <1> 	;
  2839                              <1> 	; INPUTS ->
  2840                              <1> 	;    r1 - i-number of file
  2841                              <1> 	;    u.uid
  2842                              <1> 	; arg0 -> (owner flag mask)	 		
  2843                              <1> 	;     Retro UNIX 8086 v1 feature -> owner flag mask in DL (DX) 	 
  2844                              <1> 	; OUTPUTS ->
  2845                              <1> 	;    inode (or jump to error)
  2846                              <1> 	;
  2847                              <1> 	; ((AX = R1)) input/output
  2848                              <1> 	;
  2849                              <1>         ;  ((Modified registers: eCX, eBX, eDX, eSI, eDI, eBP))  
  2850                              <1> 	
  2851                              <1> 	;push	dx  ; save flags (DL)
  2852                              <1> 	; 24/12/2021
  2853 000049C1 52                  <1> 	push	edx ; save flags (DL)
  2854 000049C2 E826FFFFFF          <1> 	call	iget
  2855                              <1> 		; jsr r0,iget / read in i-node for current directory
  2856                              <1> 			    ; / (i-number passed in r1)
  2857 000049C7 8A0D[D4620000]      <1> 	mov	cl, [i.flgs]
  2858                              <1> 		; mov i.flgs,r2
  2859                              <1> 	; 24/12/2021
  2860 000049CD 5A                  <1> 	pop	edx ; restore flags (DL)
  2861                              <1> 	;pop	dx  ; restore flags (DL)
  2862 000049CE 8A35[28660000]      <1> 	mov	dh, [u.uid]
  2863 000049D4 3A35[D7620000]      <1> 	cmp	dh, [i.uid]
  2864                              <1> 		; cmpb i.uid,u.uid / is user same as owner of file
  2865 000049DA 7503                <1> 	jne	short access_1
  2866                              <1> 		; bne 1f / no, then branch
  2867 000049DC C0E902              <1> 	shr	cl, 2
  2868                              <1> 		; asrb r2 / shift owner read write bits into non owner
  2869                              <1> 		        ; / read/write bits
  2870                              <1> 		; asrb r2
  2871                              <1> access_1: ; 1:
  2872 000049DF 20D1                <1> 	and	cl, dl
  2873                              <1> 		; bit r2,(r0)+ / test read-write flags against argument
  2874                              <1> 			     ; / in access call
  2875 000049E1 7513                <1> 	jnz	short access_2
  2876                              <1> 		; bne 1f
  2877 000049E3 08F6                <1> 	or	dh, dh	; super user (root) ?
  2878                              <1> 		; tstb u.uid
  2879 000049E5 740F                <1> 	jz	short access_2 ; yes, super user
  2880                              <1> 	;jnz	error
  2881                              <1> 		; beq 1f
  2882                              <1> 		; jmp error
  2883 000049E7 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS 
  2883 000049EF 0000                <1>
  2884                              <1> 			; 'permission denied !' error
  2885 000049F1 E9DBE7FFFF          <1> 	jmp	error
  2886                              <1> 
  2887                              <1> access_2: ; 1:
  2888                              <1> 	; DL = flags
  2889 000049F6 C3                  <1> 	retn
  2890                              <1> 		; rts r0
  2891                              <1> 
  2892                              <1> setimod:
  2893                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2894                              <1> 	; 09/04/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  2895                              <1> 	;
  2896                              <1> 	; 'setimod' sets byte at location 'imod' to 1; thus indicating that 
  2897                              <1> 	; the inode has been modified. Also puts the time of modification
  2898                              <1> 	; into the inode.
  2899                              <1> 	;
  2900                              <1> 	; (Retro UNIX Prototype : 14/07/2012 - 23/02/2013, UNIXCOPY.ASM)
  2901                              <1>         ; ((Modified registers: eDX, eCX, eBX)) 
  2902                              <1> 	;
  2903                              <1> 	
  2904                              <1> 	;push 	edx
  2905 000049F7 50                  <1> 	push	eax
  2906                              <1> 
  2907 000049F8 C605[D0650000]01    <1> 	mov 	byte [imod], 1
  2908                              <1> 		; movb $1,imod / set current i-node modified bytes
  2909                              <1> 	; Erdogan Tan 14-7-2012
  2910 000049FF E81EE3FFFF          <1> 	call 	epoch
  2911                              <1> 		 ; mov s.time,i.mtim 
  2912                              <1> 			    ; / put present time into file modified time
  2913                              <1> 		 ; mov s.time+2,i.mtim+2
  2914                              <1> 
  2915 00004A04 A3[EE620000]        <1> 	mov 	[i.mtim], eax
  2916                              <1> 	
  2917                              <1> 	; Retro UNIX 386 v1 modification ! (cmp)
  2918                              <1> 	; Retro UNIX 8086 v1 modification ! (test)
  2919 00004A09 833D[EA620000]00    <1> 	cmp	dword [i.ctim], 0
  2920 00004A10 7505                <1> 	jnz	short setimod_ok
  2921                              <1> 
  2922 00004A12 A3[EA620000]        <1> 	mov 	[i.ctim], eax
  2923                              <1> 
  2924                              <1> setimod_ok: ; 31/07/2013
  2925 00004A17 58                  <1> 	pop	eax
  2926                              <1> 	;pop	edx
  2927                              <1> 	
  2928 00004A18 C3                  <1> 	retn
  2929                              <1> 		; rts r0
  2930                              <1> 
  2931                              <1> itrunc:
  2932                              <1> 	; 03/02/2022
  2933                              <1> 	; 09/01/2022
  2934                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1) 
  2935                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  2936                              <1> 	; 23/04/2013 - 01/08/2013 (Retro UNIX 8086 v1)
  2937                              <1> 	;
  2938                              <1> 	; 'itrunc' truncates a file whose i-number is given in r1
  2939                              <1> 	;  to zero length.
  2940                              <1> 	;
  2941                              <1> 	; INPUTS ->
  2942                              <1> 	;    r1 - i-number of i-node
  2943                              <1> 	;    i.dskp - pointer to contents or indirect block in an i-node
  2944                              <1> 	;    i.flgs - large file flag		
  2945                              <1> 	;    i.size - size of file	
  2946                              <1> 	; 	 
  2947                              <1> 	; OUTPUTS ->
  2948                              <1> 	;    i.flgs - large file flag is cleared
  2949                              <1> 	;    i.size - set to 0	
  2950                              <1> 	;    i.dskp .. i.dskp+16 - entire list is cleared
  2951                              <1> 	;    setimod - set to indicate i-node has been modified
  2952                              <1> 	;    r1 - i-number of i-node  					
  2953                              <1> 	;
  2954                              <1> 	; ((AX = R1)) input/output
  2955                              <1> 	;
  2956                              <1> 	;  (Retro UNIX Prototype : 01/12/2012 - 10/03/2013, UNIXCOPY.ASM)
  2957                              <1>         ;  ((Modified registers: eDX, eCX, eBX, eSI, eDI, eBP))  
  2958                              <1> 
  2959 00004A19 E8CFFEFFFF          <1> 	call	iget
  2960                              <1> 		; jsr r0,iget
  2961 00004A1E BE[DA620000]        <1> 	mov	esi, i.dskp
  2962                              <1> 		; mov $i.dskp,r2 / address of block pointers in r2
  2963 00004A23 31C0                <1> 	xor	eax, eax
  2964                              <1> itrunc_1: ; 1:
  2965 00004A25 66AD                <1> 	lodsw
  2966                              <1> 		; mov (r2)+,r1 / move physical block number into r1
  2967                              <1> 	; 09/01/2022
  2968 00004A27 09C0                <1> 	or	eax, eax
  2969                              <1> 	;or 	ax, ax
  2970 00004A29 7433                <1> 	jz	short itrunc_5
  2971                              <1> 		; beq 5f
  2972 00004A2B 56                  <1> 	push	esi
  2973                              <1> 		; mov r2,-(sp)
  2974                              <1> 	; 09/01/2022
  2975 00004A2C F605[D5620000]10    <1> 	test	byte [i.flgs+1], 10h
  2976                              <1> 	;test	word [i.flgs], 1000h
  2977                              <1> 		; bit $10000,i.flgs / test large file bit?
  2978 00004A33 7423                <1> 	jz	short itrunc_4
  2979                              <1> 		; beq 4f / if clear, branch
  2980 00004A35 50                  <1> 	push	eax
  2981                              <1> 		; mov r1,-(sp) / save block number of indirect block
  2982 00004A36 E86B0A0000          <1> 	call	dskrd
  2983                              <1> 		; jsr r0,dskrd / read in block, 1st data word 
  2984                              <1> 			     ; / pointed to by r5
  2985                              <1> 	; eBX = r5 = Buffer data address (the 1st word)
  2986                              <1> 	; 09/01/2022
  2987 00004A3B 31C9                <1> 	xor	ecx, ecx
  2988 00004A3D FEC5                <1> 	inc	ch ; mov ch, 1
  2989                              <1> 	; ecx = 256
  2990                              <1> 	;mov	ecx, 256
  2991                              <1> 		; mov $256.,r3 / move word count into r3
  2992 00004A3F 89DE                <1> 	mov	esi, ebx
  2993                              <1> itrunc_2: ; 2:
  2994 00004A41 66AD                <1> 	lodsw
  2995                              <1> 		; mov (r5)+,r1 / put 1st data word in r1; 
  2996                              <1> 			     ; / physical block number
  2997                              <1> 	; 09/01/2022
  2998 00004A43 21C0                <1> 	and	eax, eax
  2999                              <1> 	;and	ax, ax
  3000 00004A45 7407                <1> 	jz	short itrunc_3
  3001                              <1> 		; beq 3f / branch if zero
  3002                              <1> 	; 24/12/2021
  3003 00004A47 51                  <1> 	push	ecx
  3004                              <1> 	;push	cx
  3005                              <1> 		; mov r3,-(sp) / save r3, r5 on stack
  3006                              <1> 	;push	esi
  3007                              <1> 		; mov r5,-(sp)
  3008 00004A48 E855FEFFFF          <1> 	call	free
  3009                              <1> 		; jsr r0,free / free block in free storage map
  3010                              <1> 	;pop	esi
  3011                              <1> 		; mov(sp)+,r5
  3012                              <1> 	;pop	cx
  3013 00004A4D 59                  <1> 	pop	ecx
  3014                              <1> 		; mov (sp)+,r3
  3015                              <1> itrunc_3: ; 3:
  3016 00004A4E E2F1                <1> 	loop	itrunc_2
  3017                              <1> 		; dec r3 / decrement word count
  3018                              <1> 		; bgt 2b / branch if positive
  3019 00004A50 58                  <1> 	pop	eax
  3020                              <1> 		; mov (sp)+,r1 / put physical block number of 
  3021                              <1> 			     ; / indirect block
  3022                              <1> 	; 01/08/2013
  3023                              <1> 	;and	word [i.flgs], 0EFFFh ; 1110111111111111b
  3024                              <1> 	; 03/02/2022
  3025 00004A51 8025[D5620000]EF    <1> 	and	byte [i.flgs+1], 0EFh
  3026                              <1> itrunc_4: ; 4:
  3027 00004A58 E845FEFFFF          <1> 	call	free
  3028                              <1> 		; jsr r0,free / free indirect block
  3029 00004A5D 5E                  <1> 	pop	esi
  3030                              <1> 		; mov (sp)+,r2
  3031                              <1> itrunc_5: ; 5:
  3032 00004A5E 81FE[EA620000]      <1> 	cmp	esi, i.dskp+16
  3033                              <1> 		; cmp r2,$i.dskp+16.
  3034 00004A64 72BF                <1> 	jb	short itrunc_1	
  3035                              <1> 		; bne 1b / branch until all i.dskp entries check
  3036                              <1> 	; 03/02/2022
  3037                              <1> 	;and	byte [i.flgs+1], 0EFh
  3038                              <1> 	; 01/08/2013
  3039                              <1> 	;and	word [i.flgs], 0EFFFh ; 1110111111111111b
  3040                              <1> 		; bic $10000,i.flgs / clear large file bit
  3041 00004A66 BF[DA620000]        <1> 	mov	edi, i.dskp
  3042                              <1> 	;mov	cx, 8
  3043                              <1> 	;xor 	ax, ax
  3044                              <1> 	; 09/01/2022
  3045 00004A6B 29C9                <1> 	sub	ecx, ecx
  3046 00004A6D B108                <1> 	mov	cl, 8
  3047 00004A6F 29C0                <1> 	sub	eax, eax
  3048 00004A71 66A3[D8620000]      <1> 	mov	[i.size], ax ; 0
  3049                              <1> 		; clr i.size / zero file size
  3050 00004A77 F366AB              <1> 	rep	stosw
  3051                              <1> 		; jsr r0,copyz; i.dskp; i.dskp+16. 
  3052                              <1> 			   ; / zero block pointers
  3053 00004A7A E878FFFFFF          <1> 	call	setimod
  3054                              <1> 		; jsr r0,setimod / set i-node modified flag
  3055 00004A7F 66A1[C0650000]      <1> 	mov	ax, [ii]
  3056                              <1> 		; mov ii,r1
  3057 00004A85 C3                  <1> 	retn
  3058                              <1> 		; rts r0
  3059                              <1> 
  3060                              <1> imap:
  3061                              <1> 	; 11/02/2022
  3062                              <1> 	; 03/02/2022
  3063                              <1> 	; 03/06/2015 (Retro UNIX 386 v1 - Beginning)
  3064                              <1> 	; 26/04/2013 (Retro UNIX 8086 v1)
  3065                              <1> 	;
  3066                              <1> 	; 'imap' finds the byte in core (superblock) containing
  3067                              <1> 	; allocation bit for an i-node whose number in r1.
  3068                              <1> 	;
  3069                              <1> 	; INPUTS ->
  3070                              <1> 	;    r1 - contains an i-number
  3071                              <1> 	;    fsp - start of table containing open files
  3072                              <1> 	;
  3073                              <1> 	; OUTPUTS ->
  3074                              <1> 	;    r2 - byte address of byte with the allocation bit
  3075                              <1> 	;    mq - a mask to locate the bit position.	
  3076                              <1> 	;	  (a 1 is in calculated bit posisiton)
  3077                              <1> 	;
  3078                              <1> 	; ((AX = R1)) input/output
  3079                              <1> 	; ((DL/DX = MQ)) output
  3080                              <1> 	; ((BX = R2)) output
  3081                              <1> 	;
  3082                              <1> 	;    (Retro UNIX Prototype : 02/12/2012, UNIXCOPY.ASM)
  3083                              <1>         ;    ((Modified registers: eDX, eCX, eBX, eSI))  
  3084                              <1> 	;
  3085                              <1> 		; / get the byte that has the allocation bit for 
  3086                              <1> 		; / the i-number contained in r1
  3087                              <1> 	;mov	dx, 1
  3088 00004A86 B201                <1> 	mov	dl, 1
  3089                              <1> 		; mov $1,mq / put 1 in the mq
  3090 00004A88 0FB7D8              <1> 	movzx	ebx, ax
  3091                              <1> 		; mov r1,r2 / r2 now has i-number whose byte
  3092                              <1>  		          ; / in the map we must find
  3093 00004A8B 6683EB29            <1> 	sub	bx, 41
  3094                              <1> 		; sub $41.,r2 / r2 has i-41
  3095 00004A8F 88D9                <1> 	mov	cl, bl
  3096                              <1> 		; mov r2,r3 / r3 has i-41
  3097 00004A91 80E107              <1> 	and	cl, 7
  3098                              <1> 		; bic $!7,r3 / r3 has (i-41) mod 8 to get 
  3099                              <1> 			   ; / the bit position
  3100 00004A94 7402                <1> 	jz	short imap1
  3101                              <1> 	;shl	dx, cl
  3102 00004A96 D2E2                <1> 	shl	dl, cl
  3103                              <1> 		; mov r3,lsh / move the 1 over (i-41) mod 8 positions
  3104                              <1> imap1:			   ; / to the left to mask the correct bit
  3105                              <1> 	; 03/02/2022
  3106 00004A98 C1EB03              <1> 	shr	ebx, 3
  3107                              <1> 	;shr	bx, 3
  3108                              <1> 		; asr r2
  3109                              <1> 		; asr r2
  3110                              <1> 		; asr r2 / r2 has (i-41) base 8 of the byte number
  3111                              <1> 		       ; / from the start of the map
  3112                              <1> 		; mov r2,-(sp) / put (i-41) base 8 on the stack
  3113 00004A9B BE[AC760000]        <1> 	mov	esi, systm
  3114                              <1> 		; mov $systm,r2 / r2 points to the in-core image of
  3115                              <1> 				; / the super block for drum
  3116                              <1> 	;cmp	word [cdev], 0
  3117 00004AA0 803D[C3650000]00    <1> 	cmp	byte [cdev], 0
  3118                              <1> 		; tst cdev / is the device the disk
  3119 00004AA7 7606                <1> 	jna	short imap2
  3120                              <1> 		; beq 1f / yes
  3121 00004AA9 81C608020000        <1> 	add	esi, mount - systm
  3122                              <1> 		; add $mount-systm,r2 / for mounted device,
  3123                              <1> 			; / r2 points to 1st word of its super block
  3124                              <1> imap2: ; 1:
  3125 00004AAF 66031E              <1> 	add	bx, [esi] ;; add free map size to si
  3126                              <1> 		; add (r2)+,(sp) / get byte address of allocation bit
  3127 00004AB2 6683C304            <1> 	add	bx, 4
  3128 00004AB6 01F3                <1> 	add	ebx, esi
  3129                              <1>         	; add (sp)+,r2 / ?
  3130                              <1> 	;add	ebx, 4 ;; inode map offset in superblock
  3131                              <1> 		      ;; (2 + free map size + 2)
  3132                              <1> 		; add $2,r2 / ?
  3133                              <1> 
  3134                              <1> 	; 11/02/2022
  3135 00004AB8 81C68B010000        <1> 	add	esi, eofitab-1 ; last byte of the inode table in sb
  3136 00004ABE 39DE                <1> 	cmp	esi, ebx  ; cf will be 1
  3137                              <1> 			  ; if inode num overs inode count
  3138                              <1> 
  3139                              <1>  	; DL/DX (MQ) has a 1 in the calculated bit position
  3140                              <1>         ; BX (R2) has byte address of the byte with allocation bit
  3141                              <1> 
  3142                              <1> 	; 11/02/2022
  3143                              <1> 	; if ebx > last byte of the inode table --> cf = 1
  3144                              <1> 	;	(number of requested inode > inode count)
  3145                              <1> 
  3146 00004AC0 C3                  <1> 	retn
  3147                              <1> 		; rts r0
  2116                                  %include 'u6.s'        ; 31/05/2015
  2117                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.6) - SYS6.INC
  2118                              <1> ; Last Modification: 15/07/2022
  2119                              <1> ; ----------------------------------------------------------------------------
  2120                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2121                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2122                              <1> ;
  2123                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2124                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2125                              <1> ; <Bell Laboratories (17/3/1972)>
  2126                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2127                              <1> ;
  2128                              <1> ; Retro UNIX 8086 v1 - U6.ASM (23/07/2014) //// UNIX v1 -> u6.s
  2129                              <1> ;
  2130                              <1> ; ****************************************************************************
  2131                              <1> 
  2132                              <1> readi:
  2133                              <1> 	; 11/01/2022
  2134                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2135                              <1> 	; 20/05/2015
  2136                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2137                              <1> 	; 11/03/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  2138                              <1> 	;
  2139                              <1> 	; Reads from an inode whose number in R1
  2140                              <1> 	; 
  2141                              <1> 	; INPUTS ->
  2142                              <1> 	;    r1 - inode number
  2143                              <1> 	;    u.count - byte count user desires
  2144                              <1> 	;    u.base - points to user buffer
  2145                              <1> 	;    u.fofp - points to word with current file offset
  2146                              <1> 	; OUTPUTS ->
  2147                              <1> 	;    u.count - cleared
  2148                              <1> 	;    u.nread - accumulates total bytes passed back
  2149                              <1> 	;
  2150                              <1> 	; ((AX = R1)) input/output
  2151                              <1> 	;    (Retro UNIX Prototype : 01/03/2013 - 14/12/2012, UNIXCOPY.ASM)
  2152                              <1>         ;    ((Modified registers: EDX, EBX, ECX, ESI, EDI)) -15/07/2022- 
  2153                              <1> 
  2154 00004AC1 31D2                <1> 	xor	edx, edx ; 0
  2155 00004AC3 8915[04660000]      <1> 	mov 	[u.nread], edx ; 0
  2156                              <1> 		 ; clr u.nread / accumulates number of bytes transmitted
  2157 00004AC9 668915[41660000]    <1> 	mov	[u.pcount], dx ; 19/05/2015
  2158 00004AD0 3915[00660000]      <1> 	cmp 	[u.count], edx ; 0
  2159                              <1> 	         ; tst u.count / is number of bytes to be read greater than 0
  2160 00004AD6 7701                <1> 	ja 	short readi_1 ; 1f
  2161                              <1> 		 ; bgt 1f / yes, branch
  2162 00004AD8 C3                  <1> 	retn
  2163                              <1> 		 ; rts r0 / no, nothing to read; return to caller
  2164                              <1> readi_1: ; 1:
  2165                              <1> 	         ; mov r1,-(sp) / save i-number on stack
  2166 00004AD9 6683F828            <1> 	cmp	ax, 40
  2167                              <1> 		 ; cmp r1,$40. / want to read a special file 
  2168                              <1> 		 ;             / (i-nodes 1,...,40 are for special files)
  2169                              <1>         ;ja	dskr 
  2170                              <1> 		 ; ble 1f / yes, branch
  2171                              <1> 		 ; jmp dskr / no, jmp to dskr; 
  2172                              <1> 		 ;         / read file with i-node number (r1)
  2173                              <1> 		 ;    / starting at byte ((u.fofp)), read in u.count bytes
  2174                              <1> 	; 24/12/2021
  2175 00004ADD 7605                <1> 	jna	short readi_3
  2176 00004ADF E9CF000000          <1> 	jmp	dskr
  2177                              <1> readi_3:
  2178                              <1> 	; (20/05/2015)
  2179 00004AE4 50                  <1> 	push	eax ; because subroutines will jump to 'ret_'
  2180                              <1> 	; 1:
  2181 00004AE5 0FB6D8              <1> 	movzx	ebx, al
  2182                              <1> 	; 11/01/2022
  2183 00004AE8 C1E302              <1> 	shl	ebx, 2
  2184                              <1> 	;shl	bx, 2
  2185                              <1> 		 ; asl r1 / multiply inode number by 2
  2186 00004AEB 81C3[EF4A0000]      <1> 	add	ebx, readi_2 - 4
  2187 00004AF1 FF23                <1> 	jmp	dword [ebx]	
  2188                              <1> 		 ; jmp *1f-2(r1)
  2189                              <1> readi_2: ; 1:
  2190 00004AF3 [3F4B0000]          <1> 	dd	rtty ; tty, AX = 1 (runix)
  2191                              <1> 		 ;rtty / tty; r1=2
  2192                              <1> 		 ;rppt / ppt; r1=4
  2193 00004AF7 [8F4B0000]          <1> 	dd	rmem ; mem, AX = 2 (runix)
  2194                              <1> 		 ;rmem / mem; r1=6
  2195                              <1> 		 ;rrf0 / rf0
  2196                              <1> 		 ;rrk0 / rk0
  2197                              <1> 		 ;rtap / tap0
  2198                              <1> 		 ;rtap / tap1
  2199                              <1> 		 ;rtap / tap2
  2200                              <1> 		 ;rtap / tap3
  2201                              <1> 		 ;rtap / tap4
  2202                              <1> 		 ;rtap / tap5
  2203                              <1> 		 ;rtap / tap6
  2204                              <1> 		 ;rtap / tap7
  2205 00004AFB [6F530000]          <1> 	dd	rfd ; fd0, AX = 3 (runix only)
  2206 00004AFF [6F530000]          <1> 	dd	rfd ; fd1, AX = 4 (runix only)
  2207 00004B03 [6F530000]          <1> 	dd	rhd ; hd0, AX = 5 (runix only)
  2208 00004B07 [6F530000]          <1> 	dd	rhd ; hd1, AX = 6 (runix only)	
  2209 00004B0B [6F530000]          <1> 	dd	rhd ; hd2, AX = 7 (runix only)
  2210 00004B0F [6F530000]          <1> 	dd	rhd ; hd3, AX = 8 (runix only)	
  2211 00004B13 [A44B0000]          <1> 	dd	rlpr ; lpr, AX = 9 (invalid, write only device !?)
  2212 00004B17 [8B4B0000]          <1> 	dd	rcvt ; tty0, AX = 10 (runix)	  
  2213                              <1> 		 ;rcvt / tty0
  2214 00004B1B [8B4B0000]          <1> 	dd	rcvt ; tty1, AX = 11 (runix)	  
  2215                              <1> 		 ;rcvt / tty1
  2216 00004B1F [8B4B0000]          <1> 	dd	rcvt ; tty2, AX = 12 (runix)	  
  2217                              <1> 		 ;rcvt / tty2
  2218 00004B23 [8B4B0000]          <1> 	dd	rcvt ; tty3, AX = 13 (runix)	  
  2219                              <1> 		 ;rcvt / tty3
  2220 00004B27 [8B4B0000]          <1> 	dd	rcvt ; tty4, AX = 14 (runix)	  
  2221                              <1> 		 ;rcvt / tty4
  2222 00004B2B [8B4B0000]          <1> 	dd	rcvt ; tty5, AX = 15 (runix)	  
  2223                              <1> 		 ;rcvt / tty5
  2224 00004B2F [8B4B0000]          <1> 	dd	rcvt ; tty6, AX = 16 (runix)	  
  2225                              <1> 		 ;rcvt / tty6
  2226 00004B33 [8B4B0000]          <1> 	dd	rcvt ; tty7, AX = 17 (runix)	  
  2227                              <1> 		 ;rcvt / tty7
  2228 00004B37 [8B4B0000]          <1> 	dd	rcvt ; COM1, AX = 18 (runix only)	  
  2229                              <1> 		 ;rcrd / crd
  2230 00004B3B [8B4B0000]          <1> 	dd	rcvt ; COM2, AX = 19 (runix only)
  2231                              <1> 
  2232                              <1> rtty: ; / read from console tty
  2233                              <1> 	; 11/01/2022
  2234                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2235                              <1> 	; 17/10/2015 - 16/07/2015 (Retro UNIX 8086 v1)
  2236                              <1> 	; 	     (Only 1 byte is read, by ignoring byte count!)
  2237                              <1> 	;  	     WHAT FOR: Every character from Keyboard input 
  2238                              <1> 	;	     must be written immediate on video page (screen)
  2239                              <1> 	;	     when it is required.	
  2240                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2241                              <1> 	; 11/03/2013 - 19/06/2014 (Retro UNIX 8086 v1)
  2242                              <1> 	;
  2243                              <1> 	; Console tty buffer is PC keyboard buffer
  2244                              <1> 	; and keyboard-keystroke handling is different than original
  2245                              <1> 	; unix (PDP-11) here. TTY/Keyboard procedures here are changed
  2246                              <1> 	; according to IBM PC compatible ROM BIOS keyboard functions. 
  2247                              <1> 	;
  2248                              <1> 	; 06/12/2013
  2249 00004B3F 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  2250 00004B46 8A83[33630000]      <1> 	mov	al, [ebx+p.ttyc-1] ; current/console tty
  2251                              <1> rttys:
  2252                              <1> 		; mov tty+[8*ntty]-8+6,r5 / r5 is the address of the 4th word of
  2253                              <1> 	               ; / of the control and status block
  2254                              <1> 		; tst 2(r5) / for the console tty; this word points to the console
  2255                              <1> 		       ; / tty buffer
  2256                              <1> 	; 28/07/2013
  2257 00004B4C A2[30660000]        <1> 	mov 	[u.ttyn], al
  2258                              <1> 	; 13/01/2014
  2259 00004B51 FEC0                <1> 	inc	al
  2260 00004B53 A2[0C660000]        <1> 	mov	[u.ttyp], al ; tty number + 1
  2261                              <1> rtty_nc: ; 01/02/2014
  2262                              <1> 	; 29/09/2013
  2263                              <1> 	;mov	ecx, 10
  2264                              <1> 	; 11/01/2022
  2265 00004B58 29C9                <1> 	sub	ecx, ecx
  2266 00004B5A B10A                <1> 	mov	cl, 10
  2267                              <1> rtty_1: 	; 01/02/2014
  2268                              <1> 	;push 	cx ; 29/09/2013
  2269                              <1> 	; 24/12/2021
  2270 00004B5C 51                  <1> 	push	ecx
  2271                              <1> 	; byte [u.ttyn] = tty number (0 to 9) 
  2272 00004B5D B001                <1> 	mov 	al, 1
  2273 00004B5F E80E0B0000          <1> 	call 	getc
  2274                              <1> 	; 24/12/2021
  2275 00004B64 59                  <1> 	pop	ecx
  2276                              <1> 	;pop 	cx ; 29/09/2013	
  2277 00004B65 7516                <1> 	jnz	short rtty_2
  2278                              <1> 		; bne 1f / 2nd word of console tty buffer contains number
  2279                              <1> 	               ; / of chars. Is this number non-zero?
  2280 00004B67 E20D                <1> 	loop	rtty_idle ; 01/02/2014
  2281                              <1> 	; 05/10/2013
  2282 00004B69 8A25[30660000]      <1> 	mov	ah, [u.ttyn]
  2283                              <1> 	; 29/09/2013
  2284 00004B6F E898FBFFFF          <1> 	call	sleep
  2285                              <1> 		; jsr r0,canon; ttych / if 0, call 'canon' to get a line
  2286                              <1>                 ;           / (120 chars.)
  2287                              <1> 	;byte [u.ttyn] = tty number (0 to 9) 
  2288 00004B74 EBE2                <1> 	jmp	short rtty_nc ; 01/02/2014
  2289                              <1> 
  2290                              <1> rtty_idle:
  2291                              <1> 	; 29/07/2013
  2292 00004B76 E804FBFFFF          <1> 	call 	idle
  2293 00004B7B EBDF                <1> 	jmp	short rtty_1 ; 01/02/2014
  2294                              <1> 	;1:
  2295                              <1> 		; tst 2(r5) / is the number of characters zero
  2296                              <1> 		; beq ret1 / yes, return to caller via 'ret1'
  2297                              <1> 		; movb *4(r5),r1 / no, put character in r1
  2298                              <1> 		; inc 4(r5) / 3rd word of console tty buffer points to byte which
  2299                              <1> 		          ; / contains the next char.
  2300                              <1> 		; dec 2(r5) / decrement the character count
  2301                              <1> rtty_2:
  2302 00004B7D 30C0                <1> 	xor 	al, al
  2303 00004B7F E8EE0A0000          <1> 	call 	getc
  2304 00004B84 E892000000          <1> 	call	passc
  2305                              <1> 		; jsr r0,passc / move the character to core (user)
  2306                              <1> 	;; 17/10/2015 - 16/07/2015
  2307                              <1> 	; 19/06/2014
  2308                              <1> 	;;jnz	short rtty_nc
  2309 00004B89 58                  <1> 	pop	eax  ; (20/05/2015)
  2310 00004B8A C3                  <1> 	retn 
  2311                              <1> ;ret1:
  2312                              <1> 		; jmp ret / return to caller via 'ret'
  2313                              <1> 
  2314                              <1> rcvt:   ; < receive/read character from tty >
  2315                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2316                              <1> 	; 15/05/2013 - 06/12/2013 (Retro UNIX 8086 v1)
  2317                              <1> 	;
  2318                              <1> 	; Retro UNIX 8086 v1 modification !
  2319                              <1> 	; 
  2320                              <1> 	; In original UNIX v1, 'rcvt' routine 
  2321                              <1> 	;		(exactly different than this one)
  2322                              <1> 	;	was in 'u9.s' file.
  2323                              <1> 	;
  2324 00004B8B 2C0A                <1> 	sub 	al, 10
  2325                              <1> 	; AL = tty number (0 to 9), (COM1=8, COM2=9)
  2326                              <1> 	; 16/07/2013
  2327                              <1> 	; 21/05/2013
  2328 00004B8D EBBD                <1>         jmp     short rttys
  2329                              <1>       
  2330                              <1> ;rppt: / read paper tape
  2331                              <1> ;	jsr	r0,pptic / gets next character in clist for ppt input and
  2332                              <1> ;			 / places
  2333                              <1> ;		br ret / it in r1; if there 1s no problem with reader, it
  2334                              <1> ;		       / also enables read bit in prs
  2335                              <1> ;	jsr	r0,passc / place character in users buffer area
  2336                              <1> ;	br	rppt
  2337                              <1> 
  2338                              <1> rmem: ; / transfer characters from memory to a user area of core
  2339                              <1> 	; 17/10/2015
  2340                              <1> 	; 11/06/2015
  2341                              <1> 	; 24/05/2015
  2342                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2343                              <1> 	;
  2344 00004B8F 8B35[EC650000]      <1> 	mov     esi, [u.fofp]
  2345                              <1> rmem_1:
  2346 00004B95 8B1E                <1>         mov     ebx, [esi]        
  2347                              <1> 	        ; mov *u.fofp,r1 / save file offset which points to the char
  2348                              <1> 		               ; / to be transferred to user
  2349 00004B97 FF06                <1>         inc     dword [esi] ; 17/10/2015
  2350                              <1> 		; inc *u.fofp / increment file offset to point to 'next' 
  2351                              <1> 			    ; / char in memory file
  2352 00004B99 8A03                <1> 	mov	al, [ebx]
  2353                              <1> 		; movb (r1),r1 / get character from memory file, 
  2354                              <1> 		             ; / put it in r1
  2355 00004B9B E87B000000          <1> 	call	passc        ; jsr r0,passc / move this character to 
  2356                              <1> 			     ;  / the next byte of the users core area
  2357                              <1> 		; br rmem / continue
  2358 00004BA0 75F3                <1> 	jnz	short rmem_1
  2359                              <1> ret_:
  2360 00004BA2 58                  <1> 	pop	eax ; 09/06/2015
  2361 00004BA3 C3                  <1> 	retn
  2362                              <1> 
  2363                              <1> rlpr:
  2364                              <1> ;1:
  2365                              <1> ;rcrd:
  2366 00004BA4 C705[31660000]0F00- <1>         mov     dword [u.error], ERR_DEV_NOT_RDY ; 19/05/2015
  2366 00004BAC 0000                <1>
  2367 00004BAE E91EE6FFFF          <1> 	jmp	error
  2368                              <1> 		;jmp	error / see 'error' routine
  2369                              <1> 
  2370                              <1> dskr:
  2371                              <1> 	; 12/10/2015
  2372                              <1> 	; 21/08/2015
  2373                              <1> 	; 25/07/2015
  2374                              <1> 	; 10/07/2015
  2375                              <1> 	; 16/06/2015
  2376                              <1> 	; 31/05/2015
  2377                              <1> 	; 24/05/2015 (Retro UNIX 386 v1 - Beginning)
  2378                              <1> 	; 26/04/2013 - 03/08/2013 (Retro UNIX 8086 v1)
  2379                              <1> dskr_0:
  2380 00004BB3 50                  <1> 	push	eax
  2381                              <1> 		; mov (sp),r1 / i-number in r1
  2382                              <1> 	; AX = i-number
  2383 00004BB4 E834FDFFFF          <1> 	call	iget
  2384                              <1> 		; jsr r0,iget / get i-node (r1) into i-node section of core
  2385 00004BB9 0FB715[D8620000]    <1>         movzx   edx, word [i.size] ; 16/06/2015
  2386                              <1> 		; mov i.size,r2 / file size in bytes in r2
  2387 00004BC0 8B1D[EC650000]      <1> 	mov	ebx, [u.fofp]
  2388 00004BC6 2B13                <1> 	sub	edx, [ebx]
  2389                              <1> 		; sub *u.fofp,r2 / subtract file offset
  2390                              <1>         ; 12/10/2015
  2391                              <1> 	; jna     short ret_ 
  2392                              <1> 		; blos ret
  2393 00004BC8 7709                <1> 	ja	short dskr_1
  2394                              <1> 	;
  2395                              <1> dskr_retn: ; 12/10/2015
  2396 00004BCA 58                  <1> 	pop	eax
  2397 00004BCB C605[43660000]00    <1> 	mov	byte [u.kcall], 0
  2398 00004BD2 C3                  <1> 	retn	
  2399                              <1> dskr_1: 
  2400 00004BD3 3B15[00660000]      <1> 	cmp     edx, [u.count] 
  2401                              <1> 		; cmp r2,u.count / are enough bytes left in file 
  2402                              <1> 			       ; / to carry out read
  2403 00004BD9 7306                <1> 	jnb	short dskr_2
  2404                              <1> 		; bhis 1f
  2405 00004BDB 8915[00660000]      <1> 	mov	[u.count], edx
  2406                              <1> 		; mov r2,u.count / no, just read to end of file
  2407                              <1> dskr_2: ; 1:
  2408                              <1> 	; AX = i-number
  2409 00004BE1 E89EFBFFFF          <1> 	call	mget
  2410                              <1> 		; jsr r0,mget / returns physical block number of block 
  2411                              <1> 			    ; / in file where offset points
  2412                              <1> 	; EAX = physical block number
  2413 00004BE6 E8BB080000          <1> 	call	dskrd
  2414                              <1> 		; jsr r0,dskrd / read in block, r5 points to 
  2415                              <1> 			     ; / 1st word of data in buffer
  2416                              <1> 	; 09/06/2015
  2417 00004BEB 803D[43660000]00    <1> 	cmp	byte [u.kcall], 0 ; the caller is 'namei' sign (=1)
  2418 00004BF2 770F                <1> 	ja	short dskr_4	  ; zf=0 -> the caller is 'namei'
  2419 00004BF4 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0
  2420 00004BFC 7705                <1> 	ja	short dskr_4
  2421                              <1> dskr_3:
  2422                              <1> 	; [u.base] = virtual address to transfer (as destination address)
  2423 00004BFE E853000000          <1> 	call	trans_addr_w ; translate virtual address to physical (w)
  2424                              <1> dskr_4:
  2425                              <1> 	; EBX (r5) = system (I/O) buffer address -physical-
  2426 00004C03 E831030000          <1> 	call	sioreg
  2427                              <1> 		; jsr r0,sioreg
  2428 00004C08 87F7                <1> 	xchg	esi, edi
  2429                              <1> 	; EDI = file (user data) offset
  2430                              <1> 	; ESI = sector (I/O) buffer offset
  2431                              <1> 	; ECX = byte count
  2432 00004C0A F3A4                <1> 	rep	movsb
  2433                              <1> 		; movb (r2)+,(r1)+ / move data from buffer into working core
  2434                              <1> 		                 ; / starting at u.base
  2435                              <1> 		; dec r3
  2436                              <1> 		; bne 2b / branch until proper number of bytes are transferred
  2437                              <1> 	; 25/07/2015
  2438                              <1> 	; eax = remain bytes in buffer
  2439                              <1>         ;       (check if remain bytes in the buffer > [u.pcount])
  2440 00004C0C 09C0                <1> 	or	eax, eax
  2441 00004C0E 75EE                <1> 	jnz	short dskr_3 ; (page end before system buffer end!)		
  2442                              <1> 	; 03/08/2013
  2443                              <1> 	;pop	eax
  2444 00004C10 390D[00660000]      <1> 	cmp	[u.count], ecx ; 0
  2445                              <1> 		; tst u.count / all bytes read off disk
  2446                              <1> 		; bne dskr
  2447                              <1> 		; br ret
  2448                              <1>         ;ja	short dskr_0
  2449                              <1> 	;mov	[u.kcall], cl ; 0 ; 09/06/2015
  2450                              <1> 	;retn
  2451                              <1> 	; 12/10/2015
  2452 00004C16 76B2                <1> 	jna	short dskr_retn
  2453 00004C18 58                  <1> 	pop	eax  ; (i-node number)
  2454 00004C19 EB98                <1> 	jmp	short dskr_0
  2455                              <1> 	
  2456                              <1> passc:
  2457                              <1> 	; 18/10/2015
  2458                              <1> 	; 10/07/2015
  2459                              <1> 	; 01/07/2015
  2460                              <1> 	; 08/06/2015
  2461                              <1> 	; 04/06/2015
  2462                              <1> 	; 20/05/2015
  2463                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2464                              <1> 	;
  2465                              <1>    	;(Retro UNIX 386 v1 - translation from user's virtual address
  2466                              <1> 	;		      to physical address
  2467 00004C1B 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0 ; byte count in page = 0 (initial value)
  2468                              <1> 			     ; 1-4095 --> use previous physical base address
  2469                              <1> 			     ; in [u.pbase]
  2470 00004C23 7705                <1> 	ja	short passc_3
  2471                              <1> 	; 08/06/2015 - 10/07/2015
  2472 00004C25 E82C000000          <1> 	call	trans_addr_w
  2473                              <1> passc_3:
  2474                              <1> 	; 19/05/2015
  2475 00004C2A 66FF0D[41660000]    <1> 	dec	word [u.pcount]
  2476                              <1> 	;
  2477 00004C31 8B1D[3D660000]      <1> 	mov	ebx, [u.pbase]
  2478 00004C37 8803                <1> 	mov	[ebx], al
  2479                              <1> 		; movb r1,*u.base / move a character to the next byte of the
  2480                              <1> 		               ; / users buffer
  2481 00004C39 FF05[FC650000]      <1> 	inc	dword [u.base]
  2482                              <1> 		; inc u.base / increment the pointer to point to 
  2483                              <1> 			  ; / the next byte in users buffer
  2484 00004C3F FF05[3D660000]      <1> 	inc	dword [u.pbase] ; 04/06/2015
  2485 00004C45 FF05[04660000]      <1> 	inc	dword [u.nread]
  2486                              <1> 		; inc u.nread / increment the number of bytes read
  2487 00004C4B FF0D[00660000]      <1> 	dec	dword [u.count]
  2488                              <1> 		; dec u.count / decrement the number of bytes to be read
  2489                              <1> 		; bne 1f / any more bytes to read?; yes, branch
  2490 00004C51 C3                  <1> 	retn
  2491                              <1> 		; mov (sp)+,r0 / no, do a non-local return to the caller of
  2492                              <1> 		             ; / 'readi' by:
  2493                              <1> 		;/ (1) pop the return address off the stack into r0
  2494                              <1> 		; mov (sp)+,r1 / (2) pop the i-number off the stack into r1
  2495                              <1> 	;1:
  2496                              <1> 		; clr	*$ps / clear processor status
  2497                              <1> 		; rts r0 / return to address currently on top of stack
  2498                              <1> 
  2499                              <1> trans_addr_r:
  2500                              <1> 	; Translate virtual address to physical address 
  2501                              <1> 	; for reading from user's memory space
  2502                              <1> 	; (Retro UNIX 386 v1 feature only !)
  2503                              <1> 	; 18/10/2015
  2504                              <1> 	; 10/07/2015
  2505                              <1> 	; 09/06/2015
  2506                              <1> 	; 08/06/2015 
  2507                              <1> 	; 04/06/2015
  2508                              <1> 	;
  2509                              <1> 	; 18/10/2015
  2510 00004C52 31D2                <1> 	xor	edx, edx ; 0 (read access sign)
  2511 00004C54 EB04                <1> 	jmp 	short trans_addr_rw
  2512                              <1> 
  2513                              <1> 	;push	eax
  2514                              <1> 	;push	ebx
  2515                              <1> 	;mov	ebx, [u.base]
  2516                              <1> 	;call	get_physical_addr ; get physical address
  2517                              <1> 	;;jnc	short cpass_0
  2518                              <1> 	;jnc	short passc_1
  2519                              <1> 	;mov	[u.error], eax
  2520                              <1> 	;;pop	ebx
  2521                              <1> 	;;pop	eax
  2522                              <1> 	;jmp	error
  2523                              <1> ;cpass_0:
  2524                              <1> 	; 18/10/2015
  2525                              <1> 	; 20/05/2015
  2526                              <1> 	;mov 	[u.pbase], eax ; physical address	
  2527                              <1> 	;mov	[u.pcount], cx ; remain byte count in page (1-4096)
  2528                              <1> 	;pop	ebx
  2529                              <1> 	;pop	eax
  2530                              <1> 	;retn	; 08/06/2015
  2531                              <1> 
  2532                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2533                              <1> trans_addr_w:
  2534                              <1> 	; 31/12/2021
  2535                              <1> 	; Translate virtual address to physical address 
  2536                              <1> 	; for writing to user's memory space
  2537                              <1> 	; (Retro UNIX 386 v1 feature only !)
  2538                              <1> 	; 18/10/2015
  2539                              <1> 	; 29/07/2015
  2540                              <1> 	; 10/07/2015
  2541                              <1> 	; 09/06/2015
  2542                              <1> 	; 08/06/2015
  2543                              <1> 	; 04/06/2015 (passc)
  2544                              <1> 	;
  2545                              <1> 	; 18/10/2015
  2546 00004C56 29D2                <1> 	sub	edx, edx
  2547 00004C58 FEC2                <1> 	inc	dl ; 1 (write access sign)
  2548                              <1> trans_addr_rw:
  2549 00004C5A 50                  <1> 	push	eax
  2550 00004C5B 53                  <1> 	push	ebx
  2551                              <1> 	; 18/10/2015
  2552 00004C5C 52                  <1> 	push 	edx ; r/w sign (in DL)
  2553                              <1> 	;
  2554 00004C5D 8B1D[FC650000]      <1> 	mov	ebx, [u.base]
  2555 00004C63 E847DCFFFF          <1> 	call	get_physical_addr ; get physical address
  2556 00004C68 730A                <1> 	jnc	short passc_0
  2557 00004C6A A3[31660000]        <1> 	mov	[u.error], eax
  2558                              <1> 	;pop	edx
  2559                              <1> 	;pop 	ebx
  2560                              <1> 	;pop	eax
  2561 00004C6F E95DE5FFFF          <1> 	jmp	error
  2562                              <1> passc_0:
  2563 00004C74 F6C202              <1> 	test	dl, PTE_A_WRITE ; writable page ; 18/10/2015
  2564 00004C77 5A                  <1> 	pop	edx ; 18/10/2015
  2565 00004C78 7517                <1> 	jnz	short passc_1
  2566                              <1> 	; 18/10/2015
  2567 00004C7A 20D2                <1> 	and 	dl, dl
  2568 00004C7C 7413                <1> 	jz	short passc_1
  2569                              <1> 	; 20/05/2015
  2570                              <1> 	; read only (duplicated) page -must be copied to a new page-
  2571                              <1> 	; EBX = linear address
  2572 00004C7E 51                  <1> 	push 	ecx
  2573 00004C7F 53                  <1> 	push	ebx ; * ; 31/12/2021 (BugFix)
  2574 00004C80 E89BDBFFFF          <1> 	call 	copy_page
  2575 00004C85 5B                  <1> 	pop	ebx ; * ; 31/12/2021 (BugFix)
  2576 00004C86 59                  <1> 	pop	ecx
  2577 00004C87 7217                <1> 	jc	short passc_2
  2578                              <1> 	; 24/12/2021
  2579                              <1> 	;push	eax ; physical address of the new/allocated page
  2580                              <1> 	;call	add_to_swap_queue
  2581                              <1> 	;pop	eax
  2582                              <1> 	; 18/10/2015
  2583 00004C89 81E3FF0F0000        <1> 	and 	ebx, PAGE_OFF ; 0FFFh
  2584                              <1> 	;mov 	ecx, PAGE_SIZE
  2585                              <1> 	;sub	ecx, ebx 
  2586 00004C8F 01D8                <1> 	add	eax, ebx  
  2587                              <1> passc_1: 
  2588                              <1> 	; 18/10/2015
  2589                              <1> 	; 20/05/2015
  2590 00004C91 A3[3D660000]        <1> 	mov 	[u.pbase], eax ; physical address	
  2591 00004C96 66890D[41660000]    <1> 	mov	[u.pcount], cx ; remain byte count in page (1-4096)
  2592 00004C9D 5B                  <1> 	pop	ebx
  2593 00004C9E 58                  <1> 	pop	eax
  2594 00004C9F C3                  <1> 	retn	; 08/06/2015
  2595                              <1> passc_2:
  2596 00004CA0 C705[31660000]0400- <1> 	mov	dword [u.error], ERR_MINOR_IM ; "Insufficient memory !" error
  2596 00004CA8 0000                <1>
  2597                              <1> 	;pop 	ebx
  2598                              <1> 	;pop	eax
  2599 00004CAA E922E5FFFF          <1> 	jmp	error
  2600                              <1> 
  2601                              <1> writei:
  2602                              <1> 	; 13/06/2022
  2603                              <1> 	; 03/02/2022
  2604                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2605                              <1> 	; 20/05/2015
  2606                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2607                              <1> 	; 12/03/2013 - 31/07/2013 (Retro UNIX 8086 v1)
  2608                              <1> 	;
  2609                              <1> 	; Write data to file with inode number in R1
  2610                              <1> 	; 
  2611                              <1> 	; INPUTS ->
  2612                              <1> 	;    r1 - inode number
  2613                              <1> 	;    u.count - byte count to be written
  2614                              <1> 	;    u.base - points to user buffer
  2615                              <1> 	;    u.fofp - points to word with current file offset
  2616                              <1> 	; OUTPUTS ->
  2617                              <1> 	;    u.count - cleared
  2618                              <1> 	;    u.nread - accumulates total bytes passed back	
  2619                              <1> 	; ((AX = R1))
  2620                              <1> 	;    (Retro UNIX Prototype : 18/11/2012 - 11/11/2012, UNIXCOPY.ASM)
  2621                              <1> 	;    ((Modified registers: EDX, EBX, ECX, ESI, EDI)) -15/07/2022-
  2622                              <1> 
  2623 00004CAF 31C9                <1> 	xor	ecx, ecx
  2624 00004CB1 890D[04660000]      <1> 	mov 	[u.nread], ecx  ; 0
  2625                              <1> 		; clr u.nread / clear the number of bytes transmitted during
  2626                              <1> 		            ; / read or write calls
  2627 00004CB7 66890D[41660000]    <1> 	mov	[u.pcount], cx ; 19/05/2015
  2628 00004CBE 390D[00660000]      <1> 	cmp 	[u.count], ecx
  2629                              <1> 	;	; tst u.count / test the byte count specified by the user
  2630 00004CC4 770B                <1> 	ja 	short writei_1 ; 1f
  2631                              <1> 		; bgt 1f / any bytes to output; yes, branch
  2632                              <1> 
  2633                              <1> 	; 13/06/2022 - ('get/read LPT printer status' modification)
  2634 00004CC6 83F810              <1> 	cmp	eax, 16  ; LPR_INODE ; lpt (parallel port printer) ?
  2635 00004CC9 7505                <1> 	jne	short writei_0
  2636 00004CCB E924010000          <1> 	jmp	lpr_stat	; get/read line status
  2637                              <1> writei_0:
  2638 00004CD0 C3                  <1> 	retn
  2639                              <1> 	;	; rts r0 / no, return - no writing to do
  2640                              <1> writei_1: ;1:
  2641                              <1> 		; mov r1 ,-(sp) / save the i-node number on the stack
  2642 00004CD1 6683F828            <1> 	cmp 	ax, 40
  2643                              <1> 		; cmp r1,$40.
  2644                              <1> 		; / does the i-node number indicate a special file?
  2645                              <1> 	;ja	dskw 
  2646                              <1> 		; bgt dskw / no, branch to standard file output
  2647                              <1> 	; 24/12/2021
  2648 00004CD5 7605                <1> 	jna	short writei_3
  2649 00004CD7 E958010000          <1> 	jmp	dskw
  2650                              <1> writei_3:
  2651                              <1> 	; (20/05/2015)
  2652 00004CDC 50                  <1> 	push	eax ; because subroutines will jump to 'wret'
  2653 00004CDD 0FB6D8              <1> 	movzx	ebx, al
  2654                              <1> 	; 03/02/2022
  2655 00004CE0 C1E302              <1> 	shl	ebx, 2
  2656                              <1> 	;shl	bx, 2
  2657                              <1> 		; asl r1 / yes, calculate the index into the special file
  2658 00004CE3 81C3[E74C0000]      <1> 	add	ebx, writei_2 - 4
  2659 00004CE9 FF23                <1> 	jmp	dword [ebx]	
  2660                              <1> 		; jmp *1f-2(r1)
  2661                              <1> 		; / jump table and jump to the appropriate routine
  2662                              <1> writei_2: ;1:
  2663 00004CEB [374D0000]          <1> 	dd	wtty ; tty, AX = 1 (runix)
  2664                              <1> 		 ;wtty / tty; r1=2
  2665                              <1> 		 ;wppt / ppt; r1=4
  2666 00004CEF [8A4D0000]          <1> 	dd	wmem ; mem, AX = 2 (runix)
  2667                              <1> 		 ;wmem / mem; r1=6
  2668                              <1> 		 ;wrf0 / rf0
  2669                              <1> 		 ;wrk0 / rk0
  2670                              <1> 		 ;wtap / tap0
  2671                              <1> 		 ;wtap / tap1
  2672                              <1> 		 ;wtap / tap2
  2673                              <1> 		 ;wtap / tap3
  2674                              <1> 		 ;wtap / tap4
  2675                              <1> 		 ;wtap / tap5
  2676                              <1> 		 ;wtap / tap6
  2677                              <1> 		 ;wtap / tap7
  2678 00004CF3 [E0530000]          <1> 	dd	wfd ; fd0, AX = 3 (runix only)
  2679 00004CF7 [E0530000]          <1> 	dd	wfd ; fd1, AX = 4 (runix only)
  2680 00004CFB [E0530000]          <1> 	dd	whd ; hd0, AX = 5 (runix only)
  2681 00004CFF [E0530000]          <1> 	dd	whd ; hd1, AX = 6 (runix only)	
  2682 00004D03 [E0530000]          <1> 	dd	whd ; hd2, AX = 7 (runix only)
  2683 00004D07 [E0530000]          <1> 	dd	whd ; hd3, AX = 8 (runix only)	
  2684 00004D0B [BA4D0000]          <1> 	dd	wlpr ; lpr, AX = 9   (runix)
  2685 00004D0F [844D0000]          <1> 	dd	xmtt ; tty0, AX = 10 (runix)	  
  2686                              <1> 		 ;xmtt / tty0
  2687 00004D13 [844D0000]          <1> 	dd	xmtt ; tty1, AX = 11 (runix)	  
  2688                              <1> 		 ;xmtt / tty1
  2689 00004D17 [844D0000]          <1> 	dd	xmtt ; tty2, AX = 12 (runix)	  
  2690                              <1> 		 ;xmtt / tty2
  2691 00004D1B [844D0000]          <1> 	dd	xmtt ; tty3, AX = 13 (runix)	  
  2692                              <1> 		 ;xmtt / tty3
  2693 00004D1F [844D0000]          <1> 	dd	xmtt ; tty4, AX = 14 (runix)	  
  2694                              <1> 		 ;xmtt / tty4
  2695 00004D23 [844D0000]          <1> 	dd	xmtt ; tty5, AX = 15 (runix)	  
  2696                              <1> 		 ;xmtt / tty5
  2697 00004D27 [844D0000]          <1> 	dd	xmtt ; tty6, AX = 16 (runix)	  
  2698                              <1> 		 ;xmtt / tty6
  2699 00004D2B [844D0000]          <1> 	dd	xmtt ; tty7, AX = 17 (runix)	  
  2700                              <1> 		 ;xmtt / tty7
  2701 00004D2F [844D0000]          <1> 	dd	xmtt ; COM1, AX = 18 (runix only)	  
  2702                              <1> 		; / wlpr / lpr
  2703 00004D33 [844D0000]          <1> 	dd	xmtt ; COM2, AX = 19 (runix only)	
  2704                              <1> 
  2705                              <1> wtty: ; write to console tty (write to screen)
  2706                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2707                              <1> 	; 18/11/2015
  2708                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2709                              <1> 	; 12/03/2013 - 07/07/2014 (Retro UNIX 8086 v1)
  2710                              <1> 	;
  2711                              <1> 	; Console tty output is on current video page
  2712                              <1> 	; Console tty character output procedure is changed here
  2713                              <1> 	; acconding to IBM PC compatible ROM BIOS video (text mode) functions.
  2714                              <1> 	;
  2715 00004D37 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  2716 00004D3E 8AA3[33630000]      <1> 	mov	ah, [ebx+p.ttyc-1] ; current/console tty
  2717 00004D44 88E0                <1> 	mov	al, ah ; 07/07/2014
  2718                              <1> wttys:	
  2719                              <1> 	; 10/10/2013
  2720 00004D46 8825[30660000]      <1> 	mov 	[u.ttyn], ah
  2721                              <1> 	; 13/01/2014
  2722 00004D4C FEC0                <1> 	inc	al
  2723 00004D4E A2[0D660000]        <1> 	mov	[u.ttyp+1], al ; tty number + 1
  2724                              <1> wtty_nc: ; 15/05/2013
  2725                              <1> 	; AH = [u.ttyn] = tty number ; 28/07/2013
  2726 00004D53 E881010000          <1> 	call	cpass
  2727                              <1> 		; jsr r0,cpass / get next character from user buffer area; if
  2728                              <1> 		             ; / none go to return address in syswrite
  2729                              <1> 		; tst r1 / is character = null
  2730                              <1> 		; beq wtty / yes, get next character
  2731                              <1> 	; 10/10/2013
  2732 00004D58 7428                <1> 	jz	short wret
  2733                              <1> 	;1 : 
  2734                              <1> 		;mov 	$240,*$ps / no, set processor priority to five
  2735                              <1> 		;cmpb	cc+1,$20. / is character count for console tty greater
  2736                              <1> 		;	          / than 20
  2737                              <1> 		;bhis	2f / yes; branch to put process to sleep
  2738                              <1> 	; 27/06/2014
  2739                              <1> wtty_1:
  2740                              <1> 	; AH = tty number
  2741                              <1> 	; AL = ASCII code of the character
  2742                              <1> 	; 15/04/2014
  2743                              <1> 	;push	ax
  2744                              <1> 	; 24/12/2021
  2745 00004D5A 50                  <1> 	push	eax
  2746 00004D5B E880090000          <1> 	call	putc ; 14/05/2013
  2747 00004D60 731D                <1> 	jnc	short wtty_2
  2748                              <1> 	; 18/11/2015
  2749 00004D62 E818F9FFFF          <1> 	call	idle
  2750                              <1> 	;mov	ax, [esp]
  2751                              <1> 	; 24/12/2021
  2752 00004D67 8B0424              <1> 	mov	eax, [esp]
  2753 00004D6A E871090000          <1> 	call	putc
  2754 00004D6F 730E                <1> 	jnc	short wtty_2 
  2755                              <1> 	; 02/06/2014
  2756 00004D71 8A25[30660000]      <1> 	mov	ah, [u.ttyn]
  2757 00004D77 E890F9FFFF          <1> 	call	sleep
  2758                              <1> 	;pop	ax
  2759                              <1> 	; 24/12/2021
  2760 00004D7C 58                  <1> 	pop	eax
  2761 00004D7D EBDB                <1> 	jmp 	short wtty_1
  2762                              <1> 		; jc 	error ; 15/05/2013 (COM1 or COM2 serial port error)
  2763                              <1> 		; jsr 	r0,putc; 1 / find place in freelist to assign to 
  2764                              <1> 			      ; / console tty and
  2765                              <1> 		; br 	2f / place character in list; if none available
  2766                              <1> 		   	  ; / branch to put process to sleep
  2767                              <1> 		; jsr	r0,startty / attempt to output character on tty
  2768                              <1> wtty_2:
  2769                              <1> 	; 15/04/2014
  2770                              <1> 	;pop	ax
  2771                              <1> 	; 24/12/2021
  2772 00004D7F 58                  <1> 	pop	eax
  2773 00004D80 EBD1                <1> 	jmp	short wtty_nc
  2774                              <1> 		; br wtty
  2775                              <1> wret:	; 10/10/2013 (20/05/2015)
  2776 00004D82 58                  <1> 	pop	eax
  2777 00004D83 C3                  <1> 	retn
  2778                              <1> 	;2:
  2779                              <1> 		;mov	r1,-(sp) / place character on stack
  2780                              <1> 		;jsr	r0,sleep; 1 / put process to sleep
  2781                              <1> 		;mov	(sp)+,r1 / remove character from stack
  2782                              <1> 		;br	1b / try again to place character in clist and output
  2783                              <1> 
  2784                              <1> xmtt:   ; < send/write character to tty >
  2785                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2786                              <1> 	; 15/05/2013 - 06/12/2013 (Retro UNIX 8086 v1)
  2787                              <1> 	;
  2788                              <1> 	; Retro UNIX 8086 v1 modification !
  2789                              <1> 	; 
  2790                              <1> 	; In original UNIX v1, 'xmtt' routine 
  2791                              <1> 	;		(exactly different than this one)
  2792                              <1> 	;	was in 'u9.s' file.
  2793                              <1> 	;
  2794 00004D84 2C0A                <1> 	sub 	al, 10
  2795                              <1> 	; AL = tty number (0 to 9), (COM1=8, COM2=9)
  2796                              <1> 	; 10/10/2013
  2797 00004D86 88C4                <1> 	mov	ah, al
  2798                              <1> 	; 28/07/2013
  2799 00004D88 EBBC                <1> 	jmp	short wttys
  2800                              <1> 
  2801                              <1> ;wppt:
  2802                              <1> ;	jsr	r0,cpass / get next character from user buffer area,
  2803                              <1> ;		         / if none return to writei's calling routine
  2804                              <1> ;	jsr	r0,pptoc / output character on ppt
  2805                              <1> ;	br	wppt
  2806                              <1> 
  2807                              <1> wmem: ; / transfer characters from a user area of core to memory file
  2808                              <1> 	; 17/10/2015
  2809                              <1> 	; 11/06/2015
  2810                              <1> 	; 24/05/2015
  2811                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  2812                              <1> 	;
  2813 00004D8A 813D[F1060000]-     <1> 	cmp	dword [x_timer], clock ; multi tasking clock/timer
  2813 00004D90 [A2460000]          <1>
  2814 00004D94 7415                <1>         je      short wmem_acc_err
  2815                              <1> 	;
  2816 00004D96 8B35[EC650000]      <1>         mov     esi, [u.fofp] 
  2817                              <1> wmem_1:
  2818 00004D9C E838010000          <1> 	call	cpass
  2819                              <1> 		; jsr r0,cpass / get next character from users area of
  2820                              <1> 			     ; / core and put it in r1
  2821                              <1>         	; mov r1,-(sp) / put character on the stack
  2822                              <1> 	; 20/09/2013
  2823 00004DA1 74DF                <1> 	jz	short wret ; wmem_2  
  2824 00004DA3 8B1E                <1>         mov     ebx, [esi]
  2825                              <1> 		; mov *u.fofp,r1 / save file offset in r1
  2826 00004DA5 FF06                <1>         inc     dword [esi] ; 17/10/2015
  2827                              <1> 		; inc *u.fofp / increment file offset to point to next
  2828                              <1> 			    ; / available location in file
  2829 00004DA7 8803                <1> 	mov	[ebx], al	
  2830                              <1> 		; movb (sp)+,(r1) / pop char off stack, put in memory loc 
  2831                              <1> 			        ; / assigned to it
  2832 00004DA9 EBF1                <1> 	jmp	short wmem_1
  2833                              <1> 		; br wmem / continue
  2834                              <1> 	;1:
  2835                              <1> 	;jmp	error / ?
  2836                              <1> ;wmem_2:	
  2837                              <1> ;	; 20/09/2013
  2838                              <1> ;	pop	ax
  2839                              <1> ;	retn
  2840                              <1> 
  2841                              <1> wmem_acc_err:
  2842 00004DAB C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS ; permission denied !
  2842 00004DB3 0000                <1>
  2843 00004DB5 E917E4FFFF          <1> 	jmp	error
  2844                              <1> 
  2845                              <1> ;wlpr:
  2846                              <1> 	; 13/06/2022
  2847                              <1> 	;mov	dword [u.error], ERR_DEV_NOT_RDY ; 19/05/2015
  2848                              <1> 	;jmp	error   ; ... Printing procedure will be located here ...
  2849                              <1> 		;/	jsr	r0,cpass
  2850                              <1> 		;/	cmp	r0,$'a
  2851                              <1> 		;/	blo	1f
  2852                              <1> 		;/	cmp	r1,$'z
  2853                              <1> 		;/	bhi	1f
  2854                              <1> 		;/	sub	$40,r1
  2855                              <1> 		;/1:
  2856                              <1> 		;/	jsr	r0,lptoc
  2857                              <1> 		;/	br	wlpr
  2858                              <1> 		; br rmem / continue
  2859                              <1> 
  2860                              <1> ; 13/06/2022 - Retro UNIX 386 v1.1 - PRINTER BIOS (Functions)
  2861                              <1> 
  2862                              <1> ;; Ref: MSDOS 3.3 (Retro DOS 3.2) Printer driver code (MSLPT.ASM)
  2863                              <1> ;; MSLPT.ASM - MSDOS 3.3 - 24/07/1987
  2864                              <1> ;; 23/03/2018 - Retro DOS v2.0
  2865                              <1> ;; RETRODOS32.ASM - 03/08/2019 (Retro DOS v3.2)
  2866                              <1> 
  2867                              <1> ; IBM ROMBIOS (INT 17h) STATUS BITS
  2868                              <1> 
  2869                              <1> NOTBUSYSTATUS	equ 10000000b	; NOT BUSY
  2870                              <1> ACKSTATUS	equ 01000000b	; ACKNOWLEDGE (FOR WHAT?)
  2871                              <1> NOPAPERSTATUS	equ 00100000b	; NO MORE PAPER
  2872                              <1> SELECTEDSTATUS	equ 00010000b	; THE PRINTER SAID IT WAS SELECTED
  2873                              <1> IOERRSTATUS	equ 00001000b	; SOME KIND ERROR
  2874                              <1> RESERVED	equ 00000110b	; NOPS
  2875                              <1> TIMEOUTSTATUS	equ 00000001b	; TIME OUT.
  2876                              <1> 
  2877                              <1> ;----------------------------------------------------------------
  2878                              <1> ;								:
  2879                              <1> ;		WRITE TO PRINTER DEVICE 			:
  2880                              <1> ;								:
  2881                              <1> ;   CX has count of bytes to be printed 			:
  2882                              <1> ;   ES:DI point to source buffer contains characters		:
  2883                              <1> ;   AuxNum (in msbio.asm) has printer number			:
  2884                              <1> ;								:
  2885                              <1> ;----------------------------------------------------------------
  2886                              <1> 
  2887                              <1> wlpr:
  2888                              <1> 	; 15/07/2022
  2889                              <1> 	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2890                              <1> PRN$WRIT:
  2891                              <1> 	; INPUT:
  2892                              <1> 	;	[u.count] = count of characters to be printed
  2893                              <1> 	;	[u.base] = buffer address in user's memory space
  2894                              <1> 	;
  2895                              <1> 	;	(if ECX = 0, printer status will be returned)
  2896                              <1> 	
  2897                              <1> 	;xor	ebx, ebx
  2898                              <1> PRN$LOOP:
  2899 00004DBA E81A010000          <1> 	call	cpass		  ; Get a character into AL
  2900 00004DBF 7431                <1> 	jz	short pr_exit
  2901                              <1> 	;
  2902 00004DC1 B302                <1> 	mov	bl, 2  ; retry count
  2903                              <1> PRN$OUT:
  2904                              <1> 	; al = character which will be printed
  2905 00004DC3 30E4                <1> 	xor	ah, ah ; 0	  ; PRINT THE CHARACTER IN (AL)
  2906 00004DC5 E850000000          <1> 	call	PRNOP
  2907 00004DCA 74EE                <1> 	jz	short PRN$LOOP 	  ; if error, try to print again
  2908                              <1> PrRetry:
  2909                              <1> 	; al = character
  2910 00004DCC FECB                <1> 	dec	bl
  2911 00004DCE 75F3                <1> 	jnz	short PRN$OUT
  2912                              <1> pr_err_exit:
  2913 00004DD0 0FB6C0              <1> 	movzx	eax, al
  2914 00004DD3 A3[31660000]        <1> 	mov	[u.error], eax
  2915 00004DD8 A3[DC650000]        <1> 	mov	[u.r0], eax ; error code in AL
  2916                              <1> 	;mov 	ebp, [u.sp]
  2917 00004DDD 8B1D[D4650000]      <1> 	mov	ebx, [u.sp] ; 15/07/2022
  2918                              <1> 			; Kernel stack at the beginning of sys call
  2919 00004DE3 8B15[04660000]      <1> 	mov	edx, [u.nread]
  2920 00004DE9 4A                  <1> 	dec	edx ; last char failed
  2921                              <1> 	;mov	[ebp+20], edx ; count of printed characters in edx
  2922 00004DEA 895314              <1> 	mov	[ebx+20], edx ; 15/07/2022
  2923 00004DED E9DFE3FFFF          <1> 	jmp	error
  2924                              <1> pr_exit:
  2925 00004DF2 58                  <1> 	pop	eax ; inode number
  2926                              <1> 
  2927                              <1> 	;mov	eax, [u.nread]
  2928                              <1> 	;mov	[u.r0], eax ; count of printed chacters
  2929                              <1> 	;jmp	sysret
  2930 00004DF3 C3                  <1> 	retn	; return from writei to syswrite (rw0)
  2931                              <1> 
  2932                              <1> ; 13/06/2022
  2933                              <1> 
  2934                              <1> ;----------------------------------------------------------------
  2935                              <1> ;								:
  2936                              <1> ;		PRINTER STATUS ROUTINE				:
  2937                              <1> ;								:
  2938                              <1> ;----------------------------------------------------------------
  2939                              <1> ;
  2940                              <1> 
  2941                              <1> lpr_stat:
  2942                              <1> 	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2943                              <1> PRN$STAT:
  2944 00004DF4 E81F000000          <1> 	call	PRNSTAT		  ; get the status
  2945 00004DF9 750E                <1> 	jnz	short prn_stat_retn
  2946                              <1> 				  ; if error jump to error routine
  2947                              <1> 	;mov	al, 9		  ; AGAIN, ASSUME OUT OF PAPER...
  2948 00004DFB B01F                <1> 	mov	al, ERR_PRN_PAPER
  2949 00004DFD F6C420              <1> 	test	ah, NOPAPERSTATUS
  2950 00004E00 7507                <1> 	jnz	short prn_stat_retn
  2951 00004E02 F6C480              <1> 	test	ah, NOTBUSYSTATUS
  2952 00004E05 750D                <1> 	jnz	short prn_stat_ok ; if not busy return (with cf=0)
  2953 00004E07 B022                <1> 	mov	al, ERR_PRN_BUSY  ; else busy, return to busy exit
  2954                              <1> prn_stat_retn:
  2955                              <1> 	; al = error code
  2956                              <1> 	; ah = status flags
  2957 00004E09 A3[DC650000]        <1> 	mov	[u.r0], eax
  2958                              <1> 	;movzx	eax, al
  2959                              <1> 	;mov 	[u.error], eax
  2960 00004E0E 58                  <1> 	pop	eax ; discard return address to syswrite
  2961 00004E0F E9DDE3FFFF          <1> 	jmp	sysret
  2962                              <1> prn_stat_ok:
  2963 00004E14 30C0                <1> 	xor	al, al ; 0
  2964 00004E16 EBF1                <1> 	jmp	short prn_stat_retn
  2965                              <1> 
  2966                              <1> ;
  2967                              <1> ;   PRNSTAT	get printer status
  2968                              <1> ;   PRNOP	print a character
  2969                              <1> ;
  2970                              <1> ; PRNSTAT and PRNOP are two routines which call on the ROM-BIOS
  2971                              <1> ; printer routines.  The routines share code which calls on the bios and
  2972                              <1> ; then determines which, if any, error occured. PRNSTAT and PRNOP differ
  2973                              <1> ; only by the value put into AH before the ROM-BIOS call.
  2974                              <1> ;
  2975                              <1> ;   INPUT	if PRNOP then character in AL
  2976                              <1> ;
  2977                              <1> ;   OUTPUT	- AL holds error code
  2978                              <1> ;		- AH status byte from printer
  2979                              <1> ;		- flag NZ if error
  2980                              <1> 
  2981                              <1> PRNSTAT:
  2982 00004E18 B402                <1> 	mov	ah, 2		  ; set command for get status 
  2983                              <1> 
  2984                              <1> PRNOP:
  2985                              <1> 	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2986                              <1> 	;
  2987                              <1> 	; Print character (on paper)
  2988                              <1> 
  2989                              <1> 	; INPUT:
  2990                              <1> 	;	al = character to be printed
  2991                              <1> 	; OUTPUT:
  2992                              <1> 	;	zf = 1 -> ok
  2993                              <1> 	;	zf = 0 -> error code in AL
  2994                              <1> 
  2995 00004E1A E8FA0A0000          <1> 	call	int17h	 ; call lpt bios
  2996                              <1> 	
  2997 00004E1F F6C408              <1> 	test	ah, IOERRSTATUS	  ; I/O ERROR?
  2998 00004E22 740A                <1> 	jz	short short prnop_chk_nrdy ; NO, TRY NOT READY
  2999                              <1> 
  3000                              <1> 	; AT THIS POINT, WE KNOW WE HAVE AN ERROR.
  3001                              <1> 	; THE CONVERSE IS NOT TRUE.
  3002                              <1> 
  3003                              <1> 	;mov	al, 9		  ; FIRST, ASSUME OUT OF PAPER
  3004 00004E24 B01F                <1> 	mov	al, ERR_PRN_PAPER
  3005 00004E26 F6C420              <1> 	test	ah, NOPAPERSTATUS ; OUT OF PAPER SET?
  3006 00004E29 7502                <1> 	jnz	short PRNOP1	  ; YES, ERROR IS SET
  3007                              <1> 	;mov	al, ERR_PRN_IO
  3008 00004E2B FEC0                <1> 	inc	al		  ; INDICATE I/O ERROR
  3009                              <1> PRNOP1: 
  3010                              <1> 
  3011                              <1> ; WE HAVE TRIAGED NOW FOR OUT OF PAPER AND IO ERR (IGNORING TIME-OUT)
  3012                              <1> 
  3013 00004E2D C3                  <1> 	retn			  ; RETURN WITH ERROR
  3014                              <1>  
  3015                              <1> ; THE BITS SAID NO ERROR.
  3016                              <1> ; UNFORTUNATELY, THERE MAY BE OTHER THINGS AT WORK HERE.
  3017                              <1> 
  3018                              <1> prnop_chk_nrdy:
  3019                              <1> 	;mov	al, 2		  ; ASSUME NOT-READY
  3020 00004E2E B019                <1> 	mov	al, ERR_PRN_TIMEOUT ; ''time out !' error
  3021                              <1> 	
  3022 00004E30 F6C401              <1> 	test	ah, TIMEOUTSTATUS ; IS TIME-OUT SET?
  3023                              <1> 				  ; IF NZ THEN ERROR, ELSE OK???
  3024                              <1> PRNOP2: 
  3025 00004E33 C3                  <1> 	retn
  3026                              <1> 
  3027                              <1> 
  3028                              <1> dskw: ; / write routine for non-special files
  3029                              <1> 	;
  3030                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  3031                              <1> 	; 25/07/2015
  3032                              <1> 	; 16/06/2015
  3033                              <1> 	; 09/06/2015
  3034                              <1> 	; 31/05/2015 (Retro UNIX 386 v1 - Beginning)
  3035                              <1> 	; 26/04/2013 - 20/09/2013 (Retro UNIX 8086 v1)
  3036                              <1> 	;
  3037                              <1> 	; 01/08/2013 (mkdir_w check)
  3038                              <1> 
  3039                              <1> 	;push	ax ; 26/04/2013
  3040                              <1> 		; mov (sp),r1 / get an i-node number from the stack into r1
  3041                              <1> 	; 24/12/2021
  3042 00004E34 50                  <1> 	push	eax
  3043                              <1> 	; AX = inode number
  3044 00004E35 E8B3FAFFFF          <1> 	call	iget
  3045                              <1> 		; jsr r0,iget / write i-node out (if modified), 
  3046                              <1> 		            ; / read i-node 'r1' into i-node area of core
  3047 00004E3A 8B1D[EC650000]      <1>         mov     ebx, [u.fofp] 
  3048 00004E40 8B13                <1> 	mov 	edx, [ebx]
  3049                              <1> 		; mov *u.fofp,r2 / put the file offset [(u.off) or the offset
  3050                              <1> 			       ; / in the fsp entry for this file] in r2
  3051 00004E42 0315[00660000]      <1> 	add 	edx, [u.count]	
  3052                              <1> 		; add u.count,r2 / no. of bytes to be written
  3053                              <1> 			       ; / + file offset is put in r2
  3054                              <1> 	; 16/06/2015        
  3055 00004E48 81FAFFFF0000        <1> 	cmp	edx, 65535 ; file size limit (for UNIX v1 file system)
  3056 00004E4E 760F                <1> 	jna	short dskw_0
  3057 00004E50 C705[31660000]1400- <1> 	mov	dword [u.error], ERR_FILE_SIZE ; 'file size error !'
  3057 00004E58 0000                <1>
  3058 00004E5A E972E3FFFF          <1> 	jmp	error
  3059                              <1> dskw_0:	
  3060 00004E5F 663B15[D8620000]    <1> 	cmp     dx, [i.size]
  3061                              <1> 		; cmp r2,i.size / is this greater than the present size of
  3062                              <1> 		              ; / the file?
  3063 00004E66 760C                <1> 	jna	short dskw_1
  3064                              <1> 		; blos 1f / no, branch
  3065 00004E68 668915[D8620000]    <1>         mov     [i.size], dx
  3066                              <1> 	 	; mov r2,i.size / yes, increase the file size to 
  3067                              <1> 			      ; / file offset + no. of data bytes
  3068 00004E6F E883FBFFFF          <1> 	call	setimod
  3069                              <1> 	 	; jsr r0,setimod / set imod=1 (i.e., core inode has been
  3070                              <1> 		          ; / modified), stuff time of modification into
  3071                              <1> 	          	  ; / core image of i-node
  3072                              <1> dskw_1: ; 1:	
  3073 00004E74 E80BF9FFFF          <1> 	call	mget
  3074                              <1> 	; EAX = Block number
  3075                              <1> 		; jsr r0,mget / get the block no. in which to write 
  3076                              <1> 			    ; /	the next data byte
  3077                              <1> 	; eax = block number
  3078 00004E79 8B1D[EC650000]      <1> 	mov     ebx, [u.fofp]
  3079 00004E7F 8B13                <1> 	mov	edx, [ebx]
  3080 00004E81 81E2FF010000        <1> 	and	edx, 1FFh  
  3081                              <1> 		; bit *u.fofp,$777 / test the lower 9 bits of the file offset
  3082 00004E87 750C                <1> 	jnz	short dskw_2
  3083                              <1> 		; bne 2f / if its non-zero, branch; if zero, file offset = 0,
  3084                              <1> 		       ; / 512, 1024,...(i.e., start of new block)
  3085 00004E89 813D[00660000]0002- <1> 	cmp	dword [u.count], 512
  3085 00004E91 0000                <1>
  3086                              <1> 		; cmp u.count,$512. / if zero, is there enough data to fill
  3087                              <1> 				  ; / an entire block? (i.e., no. of
  3088 00004E93 7305                <1> 	jnb	short dskw_3
  3089                              <1> 		; bhis 3f / bytes to be written greater than 512.? 
  3090                              <1> 			; / Yes, branch. Don't have to read block
  3091                              <1> dskw_2: ; 2: / in as no past info. is to be saved (the entire block will be
  3092                              <1>    		; / overwritten).
  3093 00004E95 E80C060000          <1> 	call	dskrd
  3094                              <1> 		; jsr r0,dskrd / no, must retain old info.. 
  3095                              <1> 			     ; / Hence, read block 'r1' into an I/O buffer
  3096                              <1> dskw_3: ; 3:
  3097                              <1> 	; EAX (r1) = block/sector number
  3098 00004E9A E86B060000          <1> 	call	wslot
  3099                              <1> 		; jsr r0,wslot / set write and inhibit bits in I/O queue, 
  3100                              <1> 			   ; / proc. status=0, r5 points to 1st word of data
  3101 00004E9F 803D[43660000]00    <1> 	cmp	byte [u.kcall], 0
  3102 00004EA6 770F                <1> 	ja	short dskw_5 ; zf=0 -> the caller is 'mkdir'
  3103                              <1> 	;
  3104 00004EA8 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0
  3105 00004EB0 7705                <1> 	ja	short dskw_5
  3106                              <1> dskw_4:
  3107                              <1> 	; [u.base] = virtual address to transfer (as source address)
  3108 00004EB2 E89BFDFFFF          <1> 	call	trans_addr_r ; translate virtual address to physical (r)
  3109                              <1> dskw_5:
  3110                              <1> 	; EBX (r5) = system (I/O) buffer address
  3111 00004EB7 E87D000000          <1> 	call	sioreg
  3112                              <1> 		; jsr r0,sioreg / r3 = no. of bytes of data, 
  3113                              <1> 			     ; / r1 = address of data, r2 points to location
  3114                              <1> 			     ; / in buffer in which to start writing data
  3115                              <1> 	; ESI = file (user data) offset
  3116                              <1> 	; EDI = sector (I/O) buffer offset
  3117                              <1> 	; ECX = byte count
  3118                              <1> 	;
  3119 00004EBC F3A4                <1>   	rep	movsb
  3120                              <1> 		; movb (r1 )+,(r2)+ 
  3121                              <1> 		         ; / transfer a byte of data to the I/O buffer
  3122                              <1> 		; dec r3 / decrement no. of bytes to be written
  3123                              <1> 		; bne 2b / have all bytes been transferred? No, branch
  3124                              <1> 	; 25/07/2015
  3125                              <1> 	; eax = remain bytes in buffer
  3126                              <1>         ;       (check if remain bytes in the buffer > [u.pcount])
  3127 00004EBE 09C0                <1> 	or	eax, eax
  3128 00004EC0 75F0                <1> 	jnz	short dskw_4 ; (page end before system buffer end!)	
  3129                              <1> dskw_6:
  3130 00004EC2 E850060000          <1> 	call	dskwr
  3131                              <1> 		; jsr r0,dskwr / yes, write the block and the i-node
  3132 00004EC7 833D[00660000]00    <1>         cmp     dword [u.count], 0
  3133                              <1> 		; tst u.count / any more data to write?
  3134 00004ECE 77A4                <1> 	ja	short dskw_1
  3135                              <1> 		; bne 1b / yes, branch
  3136                              <1> 	; 03/08/2013
  3137 00004ED0 C605[43660000]00    <1> 	mov	byte [u.kcall], 0
  3138                              <1> 	; 20/09/2013 (;;)
  3139                              <1> 	;pop	ax
  3140                              <1> 	; 24/12/2021
  3141 00004ED7 58                  <1> 	pop	eax
  3142 00004ED8 C3                  <1> 	retn
  3143                              <1> 	;;jmp 	short dskw_ret 
  3144                              <1> 	        ; jmp ret / no, return to the caller via 'ret'
  3145                              <1> 
  3146                              <1> cpass: ; / get next character from user area of core and put it in r1
  3147                              <1> 	; 18/10/2015
  3148                              <1> 	; 10/10/2015
  3149                              <1> 	; 10/07/2015
  3150                              <1> 	; 02/07/2015
  3151                              <1> 	; 01/07/2015
  3152                              <1> 	; 24/06/2015
  3153                              <1> 	; 08/06/2015
  3154                              <1> 	; 04/06/2015
  3155                              <1> 	; 20/05/2015
  3156                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  3157                              <1> 	;
  3158                              <1> 	; INPUTS -> 
  3159                              <1> 	;     [u.base] = virtual address in user area
  3160                              <1> 	;     [u.count] = byte count (max.)
  3161                              <1> 	;     [u.pcount] = byte count in page (0 = reset)		
  3162                              <1> 	; OUTPUTS -> 
  3163                              <1> 	;     AL = the character which is pointed by [u.base]
  3164                              <1> 	;     zf = 1 -> transfer count has been completed	
  3165                              <1>         ;
  3166                              <1> 	; ((Modified registers:  EAX, EDX, ECX))
  3167                              <1> 	;
  3168                              <1> 	;
  3169 00004ED9 833D[00660000]00    <1> 	cmp 	dword [u.count], 0  ; 14/08/2013
  3170                              <1> 		; tst u.count / have all the characters been transferred
  3171                              <1> 			    ; / (i.e., u.count, # of chars. left
  3172 00004EE0 763F                <1> 	jna	short cpass_3
  3173                              <1> 		; beq 1f / to be transferred = 0?) yes, branch
  3174 00004EE2 FF0D[00660000]      <1> 	dec	dword [u.count]
  3175                              <1> 		; dec u.count / no, decrement u.count
  3176                              <1>         ; 19/05/2015 
  3177                              <1> 	;(Retro UNIX 386 v1 - translation from user's virtual address
  3178                              <1> 	;		      to physical address
  3179 00004EE8 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0 ; byte count in page = 0 (initial value)
  3180                              <1> 			     ; 1-4095 --> use previous physical base address
  3181                              <1> 			     ; in [u.pbase]
  3182 00004EF0 770E                <1> 	ja	short cpass_1
  3183                              <1> 	; 02/07/2015
  3184 00004EF2 833D[39660000]00    <1>         cmp     dword [u.ppgdir], 0  ; is the caller os kernel
  3185 00004EF9 7427                <1>         je      short cpass_k       ; (sysexec, '/etc/init') ? 
  3186                              <1> 	; 08/06/2015 - 10/07/2015
  3187 00004EFB E852FDFFFF          <1> 	call	trans_addr_r
  3188                              <1> cpass_1:
  3189                              <1> 	; 02/07/2015
  3190                              <1> 	; 24/06/2015
  3191 00004F00 66FF0D[41660000]    <1> 	dec	word [u.pcount]
  3192                              <1> cpass_2: 
  3193                              <1> 	; 10/10/2015
  3194                              <1> 	; 02/07/2015
  3195 00004F07 8B15[3D660000]      <1> 	mov	edx, [u.pbase]
  3196 00004F0D 8A02                <1> 	mov	al, [edx] ; 10/10/2015
  3197                              <1> 		; movb *u.base,r1 / take the character pointed to 
  3198                              <1> 				; / by u.base and put it in r1
  3199 00004F0F FF05[04660000]      <1> 	inc	dword [u.nread]
  3200                              <1> 		; inc u.nread / increment no. of bytes transferred
  3201 00004F15 FF05[FC650000]      <1> 	inc	dword [u.base]
  3202                              <1> 		; inc u.base / increment the buffer address to point to the
  3203                              <1> 			   ; / next byte
  3204 00004F1B FF05[3D660000]      <1> 	inc	dword [u.pbase] ; 04/06/2015
  3205                              <1> cpass_3:
  3206 00004F21 C3                  <1> 	retn
  3207                              <1> 		; rts	r0 / next byte
  3208                              <1> 	; 1: 
  3209                              <1> 		; mov (sp)+,r0 
  3210                              <1> 		         ; / put return address of calling routine into r0
  3211                              <1> 		; mov (sp)+,r1 / i-number in r1
  3212                              <1> 		; rts r0 / non-local return
  3213                              <1> cpass_k:
  3214                              <1> 	; 02/07/2015
  3215                              <1> 	; The caller is os kernel 
  3216                              <1> 	; (get sysexec arguments from kernel's memory space)
  3217                              <1> 	;
  3218 00004F22 8B1D[FC650000]      <1> 	mov	ebx, [u.base]
  3219 00004F28 66C705[41660000]00- <1>         mov     word [u.pcount], PAGE_SIZE ; 4096
  3219 00004F30 10                  <1>
  3220 00004F31 891D[3D660000]      <1> 	mov	[u.pbase], ebx
  3221 00004F37 EBCE                <1> 	jmp	short cpass_2
  3222                              <1> 	
  3223                              <1> sioreg: 
  3224                              <1> 	; 25/07/2015
  3225                              <1> 	; 18/07/2015
  3226                              <1> 	; 02/07/2015
  3227                              <1> 	; 17/06/2015
  3228                              <1> 	; 09/06/2015
  3229                              <1> 	; 19/05/2015 (Retro UNIX 386 v1 - Beginning)
  3230                              <1> 	; 12/03/2013 - 22/07/2013 (Retro UNIX 8086 v1)
  3231                              <1> 	;
  3232                              <1> 	; INPUTS -> 
  3233                              <1> 	;     EBX = system buffer (data) address (r5)
  3234                              <1> 	;     [u.fofp] = pointer to file offset pointer
  3235                              <1> 	;     [u.base] = virtual address of the user buffer
  3236                              <1> 	;     [u.pbase] = physical address of the user buffer
  3237                              <1> 	;     [u.count] = byte count
  3238                              <1> 	;     [u.pcount] = byte count within page frame 			
  3239                              <1> 	; OUTPUTS -> 
  3240                              <1> 	;     ESI = user data offset (r1)
  3241                              <1> 	;     EDI = system (I/O) buffer offset (r2)
  3242                              <1> 	;     ECX = byte count (r3)
  3243                              <1> 	;     EAX = remain bytes after byte count within page frame
  3244                              <1> 	;	(If EAX > 0, transfer will continue from the next page)
  3245                              <1>         ;
  3246                              <1> 	; ((Modified registers:  EDX))
  3247                              <1>  
  3248 00004F39 8B35[EC650000]      <1>         mov     esi, [u.fofp]
  3249 00004F3F 8B3E                <1>         mov     edi, [esi]
  3250                              <1> 		; mov *u.fofp,r2 / file offset (in bytes) is moved to r2
  3251 00004F41 89F9                <1> 	mov	ecx, edi
  3252                              <1> 		; mov r2,r3 / and also to r3
  3253 00004F43 81C900FEFFFF        <1> 	or	ecx, 0FFFFFE00h
  3254                              <1> 		; bis $177000,r3 / set bits 9,...,15 of file offset in r3
  3255 00004F49 81E7FF010000        <1> 	and	edi, 1FFh
  3256                              <1> 		; bic $!777,r2 / calculate file offset mod 512.
  3257 00004F4F 01DF                <1> 	add	edi, ebx ; EBX = system buffer (data) address
  3258                              <1> 		; add r5,r2 / r2 now points to 1st byte in system buffer
  3259                              <1> 			  ; / where data is to be placed
  3260                              <1>                 ; mov u.base,r1 / address of data is in r1
  3261 00004F51 F7D9                <1> 	neg	ecx
  3262                              <1> 		; neg r3 / 512 - file offset (mod512.) in r3 
  3263                              <1> 		       ; / (i.e., the no. of free bytes in the file block)
  3264 00004F53 3B0D[00660000]      <1> 	cmp	ecx, [u.count]
  3265                              <1> 		; cmp r3,u.count / compare this with the no. of data bytes
  3266                              <1> 			       ; / to be written to the file
  3267 00004F59 7606                <1> 	jna	short sioreg_0
  3268                              <1> 		; blos	2f / if less than branch. Use the no. of free bytes
  3269                              <1> 			 ; / in the file block as the number to be written
  3270 00004F5B 8B0D[00660000]      <1> 	mov	ecx, [u.count]
  3271                              <1> 		; mov u.count,r3 / if greater than, use the no. of data 
  3272                              <1> 			       ; / bytes as the number to be written
  3273                              <1> sioreg_0:
  3274                              <1> 	; 17/06/2015
  3275 00004F61 803D[43660000]00    <1> 	cmp	byte [u.kcall], 0 
  3276 00004F68 7613                <1> 	jna	short sioreg_1
  3277                              <1> 	; 25/07/2015
  3278                              <1> 	; the caller is 'mkdir' or 'namei'
  3279 00004F6A A1[FC650000]        <1> 	mov	eax, [u.base] ; 25/07/2015
  3280 00004F6F A3[3D660000]        <1> 	mov 	[u.pbase], eax ; physical address = virtual address
  3281 00004F74 66890D[41660000]    <1> 	mov	word [u.pcount], cx ; remain bytes in buffer (1 sector)
  3282 00004F7B EB0B                <1> 	jmp	short sioreg_2
  3283                              <1> sioreg_1:
  3284                              <1> 	; 25/07/2015
  3285                              <1> 	; 18/07/2015
  3286                              <1> 	; 09/06/2015 
  3287 00004F7D 0FB715[41660000]    <1> 	movzx	edx, word [u.pcount]
  3288                              <1> 		; ecx and [u.pcount] are always > 0, here
  3289 00004F84 39D1                <1> 	cmp	ecx, edx	
  3290 00004F86 772A                <1> 	ja	short sioreg_4 ; transfer count > [u.pcount]
  3291                              <1> sioreg_2: ; 2:
  3292 00004F88 31C0                <1> 	xor 	eax, eax ; 25/07/2015
  3293                              <1> sioreg_3:
  3294 00004F8A 010D[04660000]      <1> 	add 	[u.nread], ecx
  3295                              <1> 		; add r3,u.nread / r3 + number of bytes xmitted 
  3296                              <1> 			         ; / during write is put into u.nread
  3297 00004F90 290D[00660000]      <1> 	sub 	[u.count], ecx
  3298                              <1> 		; sub r3,u.count / u.count = no. of bytes that still 
  3299                              <1> 			       ; / must be written or read
  3300 00004F96 010D[FC650000]      <1> 	add 	[u.base], ecx
  3301                              <1> 		; add r3,u.base / u.base points to the 1st of the remaining
  3302                              <1> 			      ; / data bytes
  3303 00004F9C 010E                <1>         add 	[esi], ecx 
  3304                              <1> 		; add r3,*u.fofp / new file offset = number of bytes done
  3305                              <1> 			       ; / + old file offset
  3306                              <1> 	; 25/07/2015
  3307 00004F9E 8B35[3D660000]      <1> 	mov	esi, [u.pbase]
  3308 00004FA4 66290D[41660000]    <1> 	sub	[u.pcount], cx
  3309 00004FAB 010D[3D660000]      <1> 	add	[u.pbase], ecx
  3310 00004FB1 C3                  <1>         retn
  3311                              <1> 		; rts r0
  3312                              <1> 		; transfer count > [u.pcount]
  3313                              <1> sioreg_4:
  3314                              <1> 	; 25/07/2015
  3315                              <1> 	; transfer count > [u.pcount] 
  3316                              <1> 	; (ecx > edx)
  3317 00004FB2 89C8                <1> 	mov	eax, ecx
  3318 00004FB4 29D0                <1> 	sub	eax, edx ; remain bytes for 1 sector (block) transfer 
  3319 00004FB6 89D1                <1> 	mov	ecx, edx ; current transfer count = [u.pcount]
  3320 00004FB8 EBD0                <1> 	jmp	short sioreg_3
  2117                                  %include 'u7.s'        ; 18/04/2015
  2118                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.4) - SYS7.INC
  2119                              <1> ; Last Modification: 13/06/2022
  2120                              <1> ; ----------------------------------------------------------------------------
  2121                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2122                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2123                              <1> ;
  2124                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2125                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2126                              <1> ; <Bell Laboratories (17/3/1972)>
  2127                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2128                              <1> ;
  2129                              <1> ; Retro UNIX 8086 v1 - U7.ASM (13/07/2014) //// UNIX v1 -> u7.s
  2130                              <1> ;
  2131                              <1> ; ****************************************************************************
  2132                              <1> 
  2133                              <1> sysmount: ; / mount file system; args special; name
  2134                              <1> 	; 15/05/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.3)
  2135                              <1> 	; 09/02/2022
  2136                              <1> 	; 08/02/2022
  2137                              <1> 	; 07/02/2022
  2138                              <1> 	; 11/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2139                              <1> 	; 14/11/2015
  2140                              <1> 	; 24/10/2015
  2141                              <1> 	; 13/10/2015
  2142                              <1> 	; 10/07/2015
  2143                              <1> 	; 16/05/2015 (Retro UNIX 386 v1 - Beginning)
  2144                              <1> 	; 09/07/2013 - 04/11/2013 (Retro UNIX 8086 v1)
  2145                              <1> 	;
  2146                              <1> 	; 'sysmount' anounces to the system that a removable 
  2147                              <1> 	; file system has been mounted on a special file.
  2148                              <1> 	; The device number of the special file is obtained via
  2149                              <1> 	; a call to 'getspl'. It is put in the I/O queue entry for
  2150                              <1> 	; dismountable file system (sb1) and the I/O queue entry is
  2151                              <1> 	; set up to read (bit 10 is set). 'ppoke' is then called to
  2152                              <1> 	; to read file system into core, i.e. the first block on the
  2153                              <1> 	; mountable file system is read in. This block is super block
  2154                              <1> 	; for the file system. This call is super user restricted.	
  2155                              <1> 	;
  2156                              <1> 	; Calling sequence:
  2157                              <1> 	;	sysmount; special; name
  2158                              <1> 	; Arguments:
  2159                              <1> 	;	special - pointer to name of special file (device)
  2160                              <1> 	;	name -  pointer to name of the root directory of the
  2161                              <1> 	;		newly mounted file system. 'name' should 
  2162                              <1> 	;		always be a directory.
  2163                              <1> 	; Inputs: - 
  2164                              <1> 	; Outputs: -
  2165                              <1> 	; ...............................................................
  2166                              <1> 	;				
  2167                              <1> 	; Retro UNIX 8086 v1 modification: 
  2168                              <1> 	;       'sysmount' system call has two arguments; so,
  2169                              <1> 	;	* 1st argument, special is pointed to by BX register
  2170                              <1> 	;	* 2nd argument, name is in CX register
  2171                              <1> 	;
  2172                              <1> 	;	NOTE: Device numbers, names and related procedures are 
  2173                              <1> 	;	       already modified for IBM PC compatibility and 
  2174                              <1> 	;	       Retro UNIX 8086 v1 device configuration.	
  2175                              <1> 	
  2176                              <1> 	;call	arg2
  2177                              <1> 		; jsr r0,arg2 / get arguments special and name
  2178 00004FBA 891D[F4650000]      <1> 	mov	[u.namep], ebx
  2179                              <1> 	; 09/02/2022
  2180                              <1> 	;push	ecx ; directory name
  2181 00004FC0 66833D[C6650000]00  <1> 	cmp	word [mnti], 0
  2182                              <1> 		; tst mnti / is the i-number of the cross device file
  2183                              <1> 			 ; / zero?
  2184                              <1> 	;;ja	error
  2185                              <1>         	; bne errora / no, error
  2186                              <1> 	;ja	sysmnt_err0
  2187                              <1> 	; 11/01/2022
  2188 00004FC8 7605                <1> 	jna	short sysmnt_0
  2189 00004FCA E968010000          <1> 	jmp	sysmnt_err0
  2190                              <1> sysmnt_0:
  2191                              <1> 	; 09/02/2022
  2192 00004FCF 51                  <1> 	push	ecx ; directory name
  2193 00004FD0 E84A010000          <1> 	call	getspl
  2194                              <1> 		; jsr r0,getspl / get special files device number in r1
  2195                              <1> 	; 09/02/2022
  2196 00004FD5 8F05[F4650000]      <1> 	pop	dword [u.namep] ; directory name
  2197                              <1> 	; 13/10/2015
  2198                              <1> 	;movzx	ebx, ax ; Retro UNIX 8086 v1 device number (0 to 5)
  2199                              <1> 	; 11/01/2022
  2200 00004FDB 29DB                <1> 	sub	ebx, ebx
  2201 00004FDD 88C3                <1> 	mov	bl, al
  2202 00004FDF F683[5E5D0000]80    <1> 	test    byte [ebx+drv.status], 80h ; 24/10/2015 
  2203 00004FE6 750F                <1> 	jnz	short sysmnt_1
  2204                              <1> sysmnt_err1:
  2205 00004FE8 C705[31660000]0F00- <1>         mov     dword [u.error], ERR_DRV_NOT_RDY ; drive not ready !
  2205 00004FF0 0000                <1>
  2206 00004FF2 E9DAE1FFFF          <1> 	jmp	error
  2207                              <1> sysmnt_1:
  2208                              <1> 	; 09/02/2022
  2209                              <1> 	;pop	dword [u.namep]
  2210                              <1>         	; mov (sp)+,u.namep / put the name of file to be placed
  2211                              <1> 				  ; / on the device
  2212                              <1> 	; 14/11/2015
  2213 00004FF7 53                  <1> 	push	ebx ; 13/10/2015
  2214                              <1> 		; mov r1,-(sp) / save the device number
  2215                              <1>         ;
  2216 00004FF8 E8E0F0FFFF          <1> 	call	namei
  2217                              <1> 	;or	ax, ax ; Retro UNIX 8086 v1 modification !
  2218                              <1> 		       ; ax = 0 -> file not found 	
  2219                              <1> 	;jz	error
  2220                              <1> 	;jc	error
  2221                              <1> 		; jsr r0,namei / get the i-number of the file
  2222                              <1>                	; br errora
  2223 00004FFD 730F                <1> 	jnc	short sysmnt_2
  2224                              <1> sysmnt_err2:
  2225 00004FFF C705[31660000]0C00- <1>         mov     dword [u.error], ERR_FILE_NOT_FOUND ; drive not ready !
  2225 00005007 0000                <1>
  2226 00005009 E9C3E1FFFF          <1> 	jmp	error
  2227                              <1> sysmnt_2:	
  2228 0000500E 66A3[C6650000]      <1> 	mov	[mnti], ax
  2229                              <1>         	; mov r1,mnti / put it in mnti
  2230                              <1> 
  2231                              <1> 	; 15/05/2022
  2232                              <1> 	; -Retro UNIX 8086/386 v1 feaure only-
  2233 00005014 66A1[C0650000]      <1> 	mov	ax, [ii]
  2234 0000501A 66A3[C8650000]      <1> 	mov	[mntp], ax ; parent dir inumber of [mnti]
  2235                              <1> 
  2236                              <1> 	; 11/01/2022
  2237 00005020 BB[AC780000]        <1> 	mov	ebx, sb1 ; super block buffer header (of mounted disk)
  2238                              <1> sysmnt_3: ;1:
  2239                              <1>         ;cmp	byte [ebx+1], 0
  2240                              <1> 		; tstb sb1+1 / is 15th bit of I/O queue entry for
  2241                              <1> 			   ; / dismountable device set?
  2242                              <1>         ;jna	short sysmnt_4		
  2243                              <1> 		; bne 1b / (inhibit bit) yes, skip writing
  2244                              <1> 	;call	idle 	; (wait for hardware interrupt)
  2245                              <1> 	;jmp	short sysmnt_3
  2246                              <1> sysmnt_4:   
  2247 00005025 58                  <1> 	pop	eax ; Retro UNIX 8086 v1 device number/ID (0 to 5)     
  2248 00005026 A2[C5650000]        <1> 	mov	[mdev], al
  2249                              <1> 		; mov (sp),mntd / no, put the device number in mntd
  2250 0000502B 8803                <1> 	mov	[ebx], al
  2251                              <1>         	; movb (sp),sb1 / put the device number in the lower byte
  2252                              <1> 			      ; / of the I/O queue entry
  2253                              <1> 	;mov	byte [cdev], 1 ; mounted device/drive
  2254                              <1>         	; mov (sp)+,cdev / put device number in cdev
  2255 0000502D 66810B0004          <1>         or	word [ebx], 400h ; Bit 10, 'read' flag/bit
  2256                              <1> 		; bis $2000,sb1 / set the read bit
  2257                              <1> 	; Retro UNIX 386 v1 modification : 
  2258                              <1> 	;	32 bit block number at buffer header offset 4
  2259 00005032 C7430401000000      <1> 	mov	dword [ebx+4], 1 ; physical block number = 1
  2260 00005039 E8A3050000          <1> 	call 	diskio
  2261 0000503E 7345                <1> 	jnc	short sysmnt_5
  2262 00005040 31C0                <1> 	xor 	eax, eax
  2263 00005042 66A3[C6650000]      <1> 	mov	[mnti], ax ; 0
  2264 00005048 A2[C5650000]        <1> 	mov	[mdev], al ; 0
  2265                              <1> 	;mov	[cdev], al ; 0
  2266                              <1> 	; 08/02/2022
  2267 0000504D 803D[44660000]FF    <1> 	cmp	byte [u.brwdev], 0FFh ; is error code set in [u.error] ?
  2268 00005054 7508                <1> 	jne	short sysmnt_err3
  2269                              <1> 	; yes, clear [u.brwdev] for next check
  2270                              <1> 	; ([u.error] = DRV_NOT_RDY or OUT_OF_VOLUME error) 
  2271 00005056 FE05[44660000]      <1> 	inc	byte [u.brwdev] ; 0, reset
  2272 0000505C EB0A                <1> 	jmp	short sysmnt_err4
  2273                              <1> sysmnt_err3:	; 08/02/2022
  2274                              <1> 	; no, set [u.error] to disk read error
  2275 0000505E C705[31660000]1100- <1> 	mov	dword [u.error], ERR_DRV_READ ; 'disk read error !'
  2275 00005066 0000                <1>
  2276                              <1> sysmnt_err4:
  2277                              <1> 	; 08/02/2022
  2278                              <1> 	; 14/11/2015
  2279 00005068 FEC8                <1> 	dec 	al
  2280 0000506A 8903                <1> 	mov	[ebx], eax ; 000000FFh
  2281 0000506C FEC0                <1> 	inc	al
  2282 0000506E 48                  <1> 	dec	eax
  2283 0000506F 894304              <1> 	mov	[ebx+4], eax ; 0FFFFFFFFh
  2284 00005072 E95AE1FFFF          <1> 	jmp	error
  2285                              <1> sysmnt_invd:
  2286                              <1> 	; 08/02/2022
  2287 00005077 C705[31660000]1C00- <1> 	mov	 dword [u.error], ERR_INV_FS ; 28
  2287 0000507F 0000                <1>
  2288                              <1> 				 ;'invalid fs/superblock !' error
  2289 00005081 30C0                <1> 	xor	al, al
  2290 00005083 EBE3                <1> 	jmp	short sysmnt_err4	
  2291                              <1> 
  2292                              <1> sysmnt_5:
  2293                              <1> 	; 08/02/2022
  2294                              <1> 	; 11/01/2022 (BugFix)
  2295                              <1> 	; 14/11/2015 (Retro UNIX 386 v1 modification)
  2296                              <1> 	; (Following check is needed to prevent mounting an
  2297                              <1> 	; invalid file system (invalid super block).
  2298                              <1> 	; 
  2299 00005085 0FB603              <1> 	movzx	eax, byte [ebx] ; device number
  2300 00005088 C0E002              <1> 	shl	al, 2 ; 4*index
  2301 0000508B 8B88[425D0000]      <1> 	mov	ecx, [eax+drv.size] ; volume (fs) size
  2302 00005091 C1E903              <1> 	shr 	ecx, 3 ; 11/01/2021 (8 sectors per 1 fbm byte)
  2303                              <1> 	; ecx = number of free map bytes (required)
  2304                              <1> 	;movzx	edx, word [sb1+8] ; the 1st data word ('mount:')
  2305 00005094 0FB75308            <1> 	movzx	edx, word [ebx+8] ; the 1st data word (of the buffer)	
  2306                              <1> 	; edx = number of free blocks map bytes
  2307                              <1> 	;shl	edx, 3 ; convert free map bytes to free map bits
  2308                              <1> 	; 07/02/2022
  2309                              <1> 	;xor	al, al ; 08/02/2022
  2310 00005098 39D1                <1> 	cmp	ecx, edx ; compare free map bits and volume size
  2311                              <1> 			 ; (in sectors), if they are not equal
  2312                              <1> 			 ; the disk to be mounted is an...	
  2313 0000509A 75DB                <1> 	jne	short sysmnt_invd ; invalid disk !
  2314                              <1> 			 ; (which has not got a valid super block)
  2315                              <1> 	;
  2316 0000509C C6430100            <1> 	mov	byte [ebx+1], 0
  2317                              <1> 	       	; jsr r0,ppoke / read in entire file system
  2318                              <1> ;sysmnt_6: ;1:
  2319                              <1> 	;;cmp	byte [sb1+1], 0
  2320                              <1> 		; tstb sb1+1 / done reading?
  2321                              <1>    	;;jna	sysret
  2322                              <1> 	;;call	idle ; (wait for hardware interrupt)
  2323                              <1> 	;;jmp	short sysmnt_6
  2324                              <1> 		; bne 1b / no, wait
  2325                              <1>         	; br sysreta / yes
  2326 000050A0 E94CE1FFFF          <1> 	jmp	sysret
  2327                              <1> 
  2328                              <1> sysumount: ; / special dismount file system
  2329                              <1> 	; 15/05/2022
  2330                              <1> 	; 09/05/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.3)
  2331                              <1> 	; 11/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2332                              <1> 	; 16/05/2015 (Retro UNIX 386 v1 - Beginning)
  2333                              <1> 	; 09/07/2013 - 04/11/2013 (Retro UNIX 8086 v1)
  2334                              <1> 	;
  2335                              <1> 	; 04/11/2013
  2336                              <1> 	; 09/07/2013
  2337                              <1> 	; 'sysumount' anounces to the system that the special file, 
  2338                              <1> 	; indicated as an argument is no longer contain a removable
  2339                              <1> 	; file system. 'getspl' gets the device number of the special
  2340                              <1> 	; file. If no file system was mounted on that device an error
  2341                              <1> 	; occurs. 'mntd' and 'mnti' are cleared and control is passed
  2342                              <1> 	; to 'sysret'.
  2343                              <1> 	;
  2344                              <1> 	; Calling sequence:
  2345                              <1> 	;	sysmount; special
  2346                              <1> 	; Arguments:
  2347                              <1> 	;	special - special file to dismount (device)
  2348                              <1> 	;
  2349                              <1> 	; Inputs: - 
  2350                              <1> 	; Outputs: -
  2351                              <1> 	; ...............................................................
  2352                              <1> 	;				
  2353                              <1> 	; Retro UNIX 8086 v1 modification: 
  2354                              <1> 	;       'sysumount' system call has one argument; so,
  2355                              <1> 	;	* Single argument, special is pointed to by BX register
  2356                              <1> 	;
  2357                              <1> 	
  2358                              <1> 	;mov 	ax, 1 ; one/single argument, put argument in BX	
  2359                              <1> 	;call	arg
  2360                              <1> 		; jsr r0,arg; u.namep / point u.namep to special
  2361 000050A5 891D[F4650000]      <1>         mov	[u.namep], ebx
  2362 000050AB E86F000000          <1> 	call	getspl
  2363                              <1> 		; jsr r0,getspl / get the device number in r1
  2364                              <1> 
  2365                              <1> 	;;;
  2366                              <1> 	; 09/05/2022 - Erdogan Tan
  2367                              <1> 	; (I have added [mnti] check because
  2368                              <1> 	;  retro unix device number of /dev/fd0 is 0
  2369                              <1> 	;  .. so, 'cmp al, [mdev]' is not enough
  2370                              <1> 	;  for dismounting /dev/fd0. sysumount system call would give
  2371                              <1> 	;  wrong cf=0 result while /dev/fd0 is not mounted.)
  2372 000050B0 66833D[C6650000]00  <1> 	cmp	word [mnti], 0
  2373 000050B8 767D                <1> 	jna	short sysmnt_err0 ; there is not a mounted device !
  2374                              <1> 	;;;
  2375                              <1> 
  2376 000050BA 3A05[C5650000]      <1> 	cmp	al, [mdev]
  2377                              <1> 		; cmp r1,mntd / is it equal to the last device mounted?
  2378 000050C0 7575                <1> 	jne	short sysmnt_err0 ; 'permission denied !' error
  2379                              <1> 	;jne	error
  2380                              <1>         	; bne errora / no error
  2381 000050C2 30C0                <1> 	xor	al, al ; ah = 0
  2382                              <1> sysumnt_0: ;1:
  2383                              <1>      	; 11/01/2022
  2384                              <1> 	;cmp 	[sb1+1], al ; 0
  2385                              <1> 	;	; tstb sb1+1 / yes, is the device still doing I/O 
  2386                              <1> 	;		   ; / (inhibit bit set)?
  2387                              <1> 	;jna	short sysumnt_1		
  2388                              <1> 	;	; bne 1b / yes, wait
  2389                              <1> 	;call	idle ; (wait for hardware interrupt)
  2390                              <1> 	;jmp	short sysumnt_0
  2391                              <1> sysumnt_1:        
  2392                              <1> 	; 15/05/2022
  2393                              <1> 	; change user's current directory to mounting directory
  2394                              <1> 	; if it is on the mounted device (chdir back to root fs)
  2395 000050C4 3805[26660000]      <1> 	cmp	byte [u.cdrv], al ; 0
  2396 000050CA 7643                <1> 	jna	short sysumnt_4
  2397                              <1> 	;;;
  2398                              <1> 	; 15/05/2022
  2399                              <1> 	; It is needed to change the parent process's current
  2400                              <1> 	; directory because shell runs (/etc/umount) 
  2401                              <1> 	; as child process.
  2402 000050CC 31DB                <1> 	xor	ebx, ebx 
  2403 000050CE 8A1D[2B660000]      <1> 	mov	bl, [u.uno]
  2404 000050D4 D0E3                <1> 	shl	bl, 1 ; >= 2 .. <= 32
  2405 000050D6 81C3[12630000]      <1> 	add	ebx, p.ppid-2
  2406 000050DC 668B13              <1> 	mov	dx, [ebx] ; process id of the parent [p.ppid]	
  2407 000050DF BE[F4620000]        <1> 	mov	esi, p.pid
  2408 000050E4 29C9                <1> 	sub	ecx, ecx
  2409 000050E6 B110                <1> 	mov	cl, nproc ; 16  
  2410                              <1> sysumnt_2:	
  2411 000050E8 66AD                <1> 	lodsw
  2412 000050EA 6639D0              <1> 	cmp	ax, dx
  2413 000050ED 7402                <1> 	je	short sysumnt_3
  2414 000050EF E2F7                <1> 	loop	sysumnt_2
  2415                              <1> sysumnt_3:
  2416 000050F1 31C0                <1> 	xor	eax, eax
  2417 000050F3 81EE[F4620000]      <1> 	sub	esi, p.pid
  2418 000050F9 D1E6                <1> 	shl	esi, 1
  2419 000050FB 8B9E[60630000]      <1> 	mov	ebx, [esi+p.upage-4] ; the parent's upage
  2420                              <1> 	; ebx points to user (u) structure in upage
  2421 00005101 668B15[C6650000]    <1> 	mov	dx, [mnti]
  2422                              <1> 	;mov	[u.cdir], dx
  2423                              <1> 	;mov	[u.cdrv], al ; 0
  2424 00005108 6689530C            <1> 	mov	[ebx+u.cdir-user], dx
  2425 0000510C 884352              <1> 	mov	[ebx+u.cdrv-user], al ; 0
  2426                              <1> 	;;;
  2427                              <1> sysumnt_4: 
  2428 0000510F A2[C5650000]        <1> 	mov	[mdev], al ; 0
  2429                              <1> 	     	; clr mntd / no, clear these
  2430 00005114 66A3[C6650000]      <1>    	mov	[mnti], ax ; 0
  2431                              <1>         	; clr mnti
  2432                              <1> 
  2433                              <1> 	;; 15/05/2022
  2434                              <1> 	;mov	[cdev], al ; 0 ; [u.cdrv] = 0
  2435                              <1> 	;mov	ax, dx  ; [u.cdir]
  2436                              <1> 	;call	iget
  2437                              <1> 
  2438 0000511A E9D2E0FFFF          <1>         jmp	sysret
  2439                              <1> 		; br sysreta / return
  2440                              <1> 
  2441                              <1> getspl: ; / get device number from a special file name
  2442 0000511F E8B9EFFFFF          <1> 	call	namei
  2443                              <1> 	;or	ax, ax ; Retro UNIX 8086 v1 modification !
  2444                              <1> 		       ; ax = 0 -> file not found 	
  2445                              <1> 	;jc	sysmnt_err2 ; 'file not found !' error
  2446                              <1> 	; 11/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2447 00005124 7305                <1> 	jnc	short getspl_0
  2448 00005126 E9D4FEFFFF          <1> 	jmp	sysmnt_err2 ; 'file not found !' error
  2449                              <1> getspl_0:
  2450                              <1> 	;jz	error
  2451                              <1> 	;jc	error
  2452                              <1> 		; jsr r0,namei / get the i-number of the special file
  2453                              <1>                 ; br errora / no such file
  2454 0000512B 6683E803            <1>         sub	ax, 3 ; Retro UNIX 8086 v1 modification !
  2455                              <1> 		      ;	i-number-3, 0 = fd0, 5 = hd3 
  2456                              <1> 		; sub $4,r1 / i-number-4 rk=1,tap=2+n
  2457 0000512F 7206                <1>         jc	short sysmnt_err0 ; 'permission denied !' error
  2458                              <1> 	;jc	error
  2459                              <1> 		; ble errora / less than 0?  yes, error
  2460 00005131 6683F805            <1>         cmp	ax, 5 ;
  2461                              <1> 		; cmp r1,$9. / greater than 9  tap 7
  2462                              <1> 	;ja	short sysmnt_err0 ; 'permission denied !' error
  2463                              <1> 	;;ja	error
  2464                              <1> 		; bgt errora / yes, error
  2465                              <1> 	; 11/01/2022
  2466 00005135 760F                <1> 	jna	short getspl_retn
  2467                              <1> 	; AX = Retro UNIX 8086 v1 Device Number (0 to 5)
  2468                              <1> ;iopen_retn:
  2469                              <1> ;	retn
  2470                              <1> 		; rts r0 / return with device number in r1
  2471                              <1> sysmnt_err0:
  2472 00005137 C705[31660000]0B00- <1> 	mov	dword [u.error], ERR_FILE_ACCESS ; permission denied !
  2472 0000513F 0000                <1>
  2473 00005141 E98BE0FFFF          <1> 	jmp	error
  2474                              <1> 
  2475                              <1> getspl_retn:
  2476                              <1> 	; AX = Retro UNIX 8086 v1 Device Number (0 to 5)
  2477                              <1> 	; 11/01/2022
  2478                              <1> iopen_retn:
  2479 00005146 C3                  <1> 	retn
  2480                              <1> 
  2481                              <1> iopen:	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2482                              <1> 	;		(Printer initialization)
  2483                              <1> 	; 11/01/2022
  2484                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2485                              <1> 	; 19/05/2015
  2486                              <1> 	; 18/05/2015 (Retro UNIX 386 v1 - Beginning)
  2487                              <1> 	; 21/05/2013 - 27/08/2013 (Retro UNIX 8086 v1)
  2488                              <1> 	;
  2489                              <1> 	; open file whose i-number is in r1
  2490                              <1> 	; 
  2491                              <1> 	; INPUTS ->
  2492                              <1> 	;    r1 - inode number
  2493                              <1> 	; OUTPUTS ->
  2494                              <1> 	;    file's inode in core	
  2495                              <1> 	;    r1 - inode number (positive)
  2496                              <1> 	;
  2497                              <1> 	; ((AX = R1))
  2498                              <1>         ; ((Modified registers: edx, ebx, ecx, esi, edi, ebp)) 
  2499                              <1> 	;        
  2500                              <1> ; / open file whose i-number is in r1
  2501 00005147 F6C480              <1> 	test	ah, 80h ; Bit 15 of AX
  2502                              <1> 		; tst r1 / write or read access?
  2503 0000514A 7568                <1>         jnz	short iopen_2
  2504                              <1> 		; blt 2f / write, go to 2f
  2505 0000514C B202                <1> 	mov	dl, 2 ; read access
  2506 0000514E E86EF8FFFF          <1> 	call	access
  2507                              <1>         	; jsr r0,access; 2 
  2508                              <1> 	; / get inode into core with read access
  2509                              <1> 	; DL=2
  2510                              <1> iopen_0:
  2511 00005153 6683F828            <1>         cmp	ax, 40
  2512                              <1> 		; cmp r1,$40. / is it a special file
  2513 00005157 77ED                <1>         ja	short iopen_retn
  2514                              <1> 		; bgt  3f / no. 3f
  2515 00005159 50                  <1> 	push	eax ; 08/01/2022
  2516                              <1> 	;push	ax
  2517                              <1> 		; mov r1,-(sp) / yes, figure out
  2518 0000515A 0FB6D8              <1> 	movzx	ebx, al
  2519 0000515D C0E302              <1> 	shl	bl, 2 ; * 4 ; 08/01/2022
  2520                              <1> 	;shl	bx, 2
  2521                              <1> 		; asl r1
  2522 00005160 81C3[64510000]      <1>         add     ebx, iopen_1 - 4
  2523 00005166 FF23                <1> 	jmp	dword [ebx]
  2524                              <1>         	; jmp *1f-2(r1) / which one and transfer to it
  2525                              <1> iopen_1: ; 1:
  2526 00005168 [CC510000]          <1> 	dd	otty ; tty, AX = 1 (runix)
  2527                              <1>  		 ;otty / tty ; r1=2
  2528                              <1>         	 ;oppt / ppt ; r1=4
  2529 0000516C [84520000]          <1> 	dd	sret ; mem, AX = 2 (runix)
  2530                              <1> 		 ;sret / mem ; r1=6
  2531                              <1> 		 ;sret / rf0
  2532                              <1>         	 ;sret / rk0
  2533                              <1>         	 ;sret / tap0
  2534                              <1>         	 ;sret / tap1
  2535                              <1>         	 ;sret / tap2
  2536                              <1>         	 ;sret / tap3
  2537                              <1>         	 ;sret / tap4
  2538                              <1>         	 ;sret / tap5
  2539                              <1>         	 ;sret / tap6
  2540                              <1>         	 ;sret / tap7
  2541 00005170 [84520000]          <1>         dd	sret ; fd0, AX = 3 (runix only)
  2542 00005174 [84520000]          <1>         dd	sret ; fd1, AX = 4 (runix only)
  2543 00005178 [84520000]          <1>         dd	sret ; hd0, AX = 5 (runix only)
  2544 0000517C [84520000]          <1>         dd	sret ; hd1, AX = 6 (runix only) 
  2545 00005180 [84520000]          <1>         dd	sret ; hd2, AX = 7 (runix only)
  2546 00005184 [84520000]          <1>         dd	sret ; hd3, AX = 8 (runix only) 
  2547                              <1> 	;;dd	error ; lpr, AX = 9 (error !)
  2548                              <1>         ;dd	sret ; lpr, AX = 9 (runix)
  2549                              <1> 	; 13/06/2022 - (lpt_init)
  2550 00005188 [50530000]          <1>         dd	ejec ; lpr, AX = 9 (runix)
  2551 0000518C [DD510000]          <1> 	dd	ocvt ; tty0, AX = 10 (runix)	  
  2552                              <1> 		 ;ocvt / tty0
  2553 00005190 [DD510000]          <1> 	dd	ocvt ; tty1, AX = 11 (runix)	  
  2554                              <1> 		 ;ocvt / tty1
  2555 00005194 [DD510000]          <1> 	dd	ocvt ; tty2, AX = 12 (runix)	  
  2556                              <1> 		 ;ocvt / tty2
  2557 00005198 [DD510000]          <1> 	dd	ocvt ; tty3, AX = 13 (runix)	  
  2558                              <1> 		 ;ocvt / tty3
  2559 0000519C [DD510000]          <1> 	dd	ocvt ; tty4, AX = 14 (runix)	  
  2560                              <1> 		 ;ocvt / tty4
  2561 000051A0 [DD510000]          <1> 	dd	ocvt ; tty5, AX = 15 (runix)	  
  2562                              <1> 		 ;ocvt / tty5
  2563 000051A4 [DD510000]          <1> 	dd	ocvt ; tty6, AX = 16 (runix)	  
  2564                              <1> 		 ;ocvt / tty6
  2565 000051A8 [DD510000]          <1> 	dd	ocvt ; tty7, AX = 17 (runix)	  
  2566                              <1> 		 ;ocvt / tty7
  2567 000051AC [DD510000]          <1> 	dd	ocvt ; COM1, AX = 18 (runix only)	  
  2568                              <1> 		 ;error / crd
  2569 000051B0 [DD510000]          <1> 	dd	ocvt ; COM2, AX = 19 (runix only)
  2570                              <1> 
  2571                              <1> iopen_2: ; 2: / check open write access
  2572 000051B4 66F7D8              <1> 	neg	ax
  2573                              <1> 		;neg r1 / make inode number positive
  2574 000051B7 B201                <1> 	mov	dl, 1 ; write access
  2575 000051B9 E803F8FFFF          <1> 	call	access
  2576                              <1> 		;jsr r0,access; 1 / get inode in core
  2577                              <1> 	; DL=1
  2578                              <1> 	; 11/01/2022
  2579 000051BE F605[D5620000]40    <1> 	test	byte [i.flgs+1], 40h
  2580                              <1> 	;test	word [i.flgs], 4000h ; Bit 14 : Directory flag
  2581                              <1>  		; bit $40000,i.flgs / is it a directory?
  2582 000051C5 748C                <1> 	jz	short iopen_0
  2583                              <1> 	;mov	[u.error], ERR_DIR_ACCESS
  2584                              <1> 	;jmp	error ; permission denied !
  2585 000051C7 E96BFFFFFF          <1> 	jmp	sysmnt_err0
  2586                              <1> 	;;jnz	error		
  2587                              <1>        		; bne 2f / yes, transfer (error)
  2588                              <1>         ;;jmp	short iopen_0
  2589                              <1> 	;cmp	ax, 40
  2590                              <1> 		; cmp r1,$40. / no, is it a special file?
  2591                              <1>         ;ja	short iopen_2
  2592                              <1> 		; bgt 3f / no, return
  2593                              <1> 	;push	ax
  2594                              <1> 		; mov r1,-(sp) / yes
  2595                              <1> 	;movzx	ebx, al
  2596                              <1> 	;shl	bx, 1
  2597                              <1> 		; asl r1
  2598                              <1> 	;add	ebx, ipen_3 - 2
  2599                              <1> 	;jmp	dword [ebx]
  2600                              <1> 		; jmp *1f-2(r1) / figure out 
  2601                              <1> 			; / which special file it is and transfer
  2602                              <1> ;iopen_3: ; 1:
  2603                              <1> ;	dd 	otty ; tty, AX = 1 (runix)
  2604                              <1>  		 ;otty / tty ; r1=2
  2605                              <1>         	 ;leadr / ppt ; r1=4
  2606                              <1> ;	dd	sret ; mem, AX = 2 (runix)
  2607                              <1> 		 ;sret / mem ; r1=6
  2608                              <1> 		 ;sret / rf0
  2609                              <1>         	 ;sret / rk0
  2610                              <1>         	 ;sret / tap0
  2611                              <1>         	 ;sret / tap1
  2612                              <1>         	 ;sret / tap2
  2613                              <1>         	 ;sret / tap3
  2614                              <1>         	 ;sret / tap4
  2615                              <1>         	 ;sret / tap5
  2616                              <1>         	 ;sret / tap6
  2617                              <1>         	 ;sret / tap7
  2618                              <1> ;	dd 	sret ; fd0, AX = 3 (runix only)
  2619                              <1> ;	dd 	sret ; fd1, AX = 4 (runix only)
  2620                              <1> ;	dd 	sret ; hd0, AX = 5 (runix only)
  2621                              <1> ;	dd 	sret ; hd1, AX = 6 (runix only)	
  2622                              <1> ;	dd 	sret ; hd2, AX = 7 (runix only)
  2623                              <1> ;	dd 	sret ; hd3, AX = 8 (runix only)	
  2624                              <1> ;	dd	sret ; lpr, AX = 9  (runix)
  2625                              <1> 	;dd	ejec ; lpr, AX = 9  (runix)
  2626                              <1> ;	dd	sret ; tty0, AX = 10 (runix)	  
  2627                              <1> 		 ;ocvt / tty0
  2628                              <1> ;	dd	sret ; tty1, AX = 11 (runix)	  
  2629                              <1> 		 ;ocvt / tty1
  2630                              <1> ;	dd	sret ; tty2, AX = 12 (runix)	  
  2631                              <1> 		 ;ocvt / tty2
  2632                              <1> ;	dd	sret ; tty3, AX = 13 (runix)	  
  2633                              <1> 		 ;ocvt / tty3
  2634                              <1> ;	dd	sret ; tty4, AX = 14 (runix)	  
  2635                              <1> 		 ;ocvt / tty4
  2636                              <1> ;	dd	sret ; tty5, AX = 15 (runix)	  
  2637                              <1> 		 ;ocvt / tty5
  2638                              <1> ;	dd	sret ; tty6, AX = 16 (runix)	  
  2639                              <1> 		 ;ocvt / tty6
  2640                              <1> ;	dd	sret ; tty7, AX = 17 (runix)	  
  2641                              <1> 		 ;ocvt / tty7
  2642                              <1> ;	dd	ocvt ; COM1, AX = 18 (runix only)	  
  2643                              <1> 		 ;/ ejec / lpr
  2644                              <1> ;	dd	ocvt ; COM2, AX = 19 (runix only)
  2645                              <1> 
  2646                              <1> otty: ;/ open console tty for reading or writing
  2647                              <1> 	; 03/03/2022
  2648                              <1> 	; 02/03/2022
  2649                              <1> 	; 26/02/2022
  2650                              <1> 	; 09/02/2022
  2651                              <1> 	; 06/02/2022
  2652                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2653                              <1> 	; 16/11/2015
  2654                              <1> 	; 12/11/2015
  2655                              <1> 	; 18/05/2015 (Retro UNIX 386 v1 - Beginning)
  2656                              <1> 	; 21/05/2013 - 13/07/2014 (Retro UNIX 8086 v1)
  2657                              <1> 	; 16/07/2013
  2658                              <1> 	; Retro UNIX 8086 v1 modification:
  2659                              <1> 	;  If a tty is open for read or write by
  2660                              <1> 	;     a process (u.uno), only same process can open
  2661                              <1> 	;     same tty to write or read (R->R&W or W->W&R).	
  2662                              <1> 	;
  2663                              <1> 	; (INPUT: DL=2 for Read, DL=1 for Write, DL=0 for sysstty)
  2664                              <1> 	;
  2665 000051CC 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  2666 000051D3 8A83[33630000]      <1> 	mov	al, [ebx+p.ttyc-1] ; current/console tty
  2667                              <1> 	; 13/01/2014
  2668                              <1> 	;jmp	short ottyp
  2669                              <1> 	; 26/02/2022
  2670 000051D9 88C4                <1> 	mov	ah, al
  2671 000051DB EB06                <1> 	jmp	short ottypc ; ah = al = console tty number
  2672                              <1> ocvt:
  2673 000051DD 2C0A                <1> 	sub	al, 10
  2674                              <1> ;ottyp:	; (call from sysstty)
  2675                              <1> 	; 08/01/2022
  2676 000051DF 31DB                <1> 	xor	ebx, ebx
  2677                              <1> ottyp:	; (ebx < 256) ; 06/02/2022
  2678                              <1> 	; 26/02/2022
  2679 000051E1 B4FF                <1> 	mov	ah, 0FFh
  2680                              <1> ottypc:
  2681                              <1> 	; 03/03/2022
  2682                              <1> 	; 26/02/2022
  2683                              <1> 	; 09/02/2022
  2684                              <1> 	; 08/01/2022
  2685                              <1> 	; 16/11/2015
  2686                              <1> 	; 12/11/2015
  2687                              <1> 	; 18/05/2015 (32 bit modifications)
  2688                              <1> 	; 06/12/2013 - 13/07/2014
  2689 000051E3 88C6                <1> 	mov	dh, al ; tty number
  2690                              <1> 	;movzx 	ebx, al ; AL = tty number (0 to 9), AH = 0
  2691                              <1> 	; 08/01/2022
  2692 000051E5 88C3                <1> 	mov	bl, al
  2693 000051E7 D0E3                <1> 	shl 	bl, 1  ; aligned to word
  2694                              <1> 	; 26/01/2014	
  2695 000051E9 81C3[64620000]      <1> 	add 	ebx, ttyl
  2696 000051EF 668B0B              <1> 	mov 	cx, [ebx]
  2697                              <1> 		   ; CL = lock value (0 or process number)
  2698                              <1> 		   ; CH = open count 
  2699 000051F2 20C9                <1> 	and 	cl, cl
  2700                              <1> 	; 13/01/2014
  2701                              <1> 	;jz 	short otty_ret
  2702                              <1> 	; 08/01/2022
  2703 000051F4 7447                <1> 	jz 	short ottys_0
  2704                              <1> 	;
  2705                              <1> 	; 16/11/2015
  2706 000051F6 3A0D[2B660000]      <1> 	cmp 	cl, [u.uno]
  2707 000051FC 746E                <1> 	je	short ottys_3
  2708                              <1> 	;
  2709                              <1> 	;
  2710                              <1> 	; 26/02/2022
  2711                              <1> 	; (is it the console tty of the current process?)
  2712                              <1> 	; ((fast check/permit for console tty open function))
  2713 000051FE 38E0                <1> 	cmp	al, ah ; cmp dh, ah
  2714 00005200 746A                <1> 	je	short ottys_3 ; bypass parent process check
  2715                              <1> 	;
  2716                              <1> 	; 26/02/2022
  2717                              <1> 	;movzx 	ebx, cl ; the process which has locked the tty
  2718                              <1> 	;shl 	bl, 1
  2719                              <1> 	;mov 	ax, [ebx+p.pid-2]
  2720                              <1> 	;;movzx ebx, byte [u.uno]
  2721                              <1> 	;mov	bl, [u.uno]
  2722                              <1> 	;shl 	bl, 1
  2723                              <1> 	;cmp 	ax, [ebx+p.ppid-2]
  2724                              <1> 	;je 	short ottys_3  ; 16/11/2015
  2725                              <1> 	; 26/02/2022 (BugFix) ; *
  2726 00005202 0FB6F1              <1> 	movzx 	esi, cl ; the process which has locked the tty
  2727 00005205 D1E6                <1> 	shl 	esi, 1
  2728 00005207 668B86[F2620000]    <1> 	mov 	ax, [esi+p.pid-2]
  2729 0000520E 96                  <1> 	xchg	esi, eax
  2730 0000520F A0[2B660000]        <1> 	mov	al, [u.uno]
  2731 00005214 D0E0                <1> 	shl 	al, 1
  2732 00005216 663BB0[12630000]    <1> 	cmp 	si, [eax+p.ppid-2]
  2733 0000521D 744D                <1> 	je 	short ottys_3 ; *
  2734                              <1> 	; 26/02/2022
  2735                              <1> 	; check console tty of the process
  2736                              <1> 	; (open permission must be given if the -requested- tty is
  2737                              <1> 	;  console tty of current process)
  2738 0000521F D0E8                <1> 	shr	al, 1
  2739 00005221 38B0[33630000]      <1> 	cmp	[eax+p.ttyc-1], dh ; console tty ?
  2740 00005227 7443                <1> 	je 	short ottys_3
  2741                              <1> 	;
  2742                              <1> 	; the tty is locked by another process
  2743                              <1> 	; except the parent process (p.ppid)
  2744                              <1>         ;
  2745                              <1> 	; 09/02/2022
  2746                              <1> 	;mov	dword [u.error], ERR_DEV_ACCESS
  2747                              <1> 	;		; permission denied ! error
  2748                              <1> otty_err: ; 13/01/2014
  2749                              <1> 	;or 	dl, dl	; DL = 0 -> called by sysstty
  2750                              <1> 	;;jnz	error
  2751                              <1> 	; 05/12/2021
  2752                              <1> 	;jz	short otty_stc_retn
  2753                              <1> 	;jmp	error
  2754                              <1> 	; 09/02/2022
  2755 00005229 80FA01              <1> 	cmp	dl, 1 ; dl = 0 ?
  2756 0000522C 7257                <1> 	jb	short otty_retn ; yes, cf=1, called by sysstty
  2757                              <1> 	; iopen (dl=1 or dl=2)
  2758 0000522E C705[31660000]0B00- <1> 	mov     dword [u.error], ERR_DEV_ACCESS
  2758 00005236 0000                <1>
  2759                              <1> 			; permission denied ! error
  2760 00005238 E994DFFFFF          <1> 	jmp	error
  2761                              <1> ;otty_stc_retn:
  2762                              <1> 	;stc
  2763                              <1> 	;retn
  2764                              <1> ottys_0:
  2765                              <1> 	; 08/01/2022
  2766                              <1> otty_ret: 
  2767                              <1> 	; 13/01/2014
  2768 0000523D 80FE07              <1> 	cmp 	dh, 7
  2769 00005240 7624                <1> 	jna	short ottys_2
  2770                              <1> 	; 16/11/2015
  2771                              <1> com_port_check:
  2772 00005242 BE[82620000]        <1> 	mov	esi, com1p
  2773 00005247 80FE08              <1> 	cmp	dh, 8	; COM1 (tty8) ?
  2774 0000524A 7601                <1> 	jna	short ottys_1 ; yes, it is COM1
  2775 0000524C 46                  <1> 	inc	esi	; no, it is COM2 (tty9)
  2776                              <1> ottys_1:
  2777                              <1> 	; 12/11/2015
  2778 0000524D 803E00              <1> 	cmp	byte [esi], 0 ; E3h (or 23h)
  2779 00005250 7714                <1> 	ja	short com_port_ready
  2780                              <1> 	;
  2781                              <1> 	; 09/02/2022
  2782 00005252 80FA01              <1> 	cmp	dl, 1 ; dl = 0 ?
  2783 00005255 722E                <1> 	jb	short otty_retn ; yes, cf=1, called by sysstty
  2784 00005257 C705[31660000]0F00- <1>         mov     dword [u.error], ERR_DEV_NOT_RDY
  2784 0000525F 0000                <1>
  2785                              <1> 			   ; device not ready ! error
  2786                              <1> 	;jmp	short otty_err
  2787 00005261 E96BDFFFFF          <1> 	jmp	error
  2788                              <1> com_port_ready:
  2789                              <1> ottys_2:
  2790                              <1> 	; 02/03/2022
  2791                              <1> 	;or	cl, cl  ; cl = lock/owner, ch = open count
  2792                              <1> 	;jnz	short ottys_3
  2793 00005266 8A0D[2B660000]      <1> 	mov	cl, [u.uno]
  2794                              <1> ottys_3:
  2795 0000526C FEC5                <1> 	inc 	ch
  2796 0000526E 66890B              <1> 	mov 	[ebx], cx ; set tty lock again
  2797                              <1> 	; 06/12/2013
  2798 00005271 FEC6                <1> 	inc	dh ; tty number + 1
  2799 00005273 BB[0C660000]        <1> 	mov	ebx, u.ttyp
  2800                              <1> 	; 13/01/2014
  2801 00005278 F6C202              <1> 	test	dl, 2 ; open for read sign
  2802 0000527B 7501                <1> 	jnz	short ottys_4
  2803 0000527D 43                  <1> 	inc	ebx
  2804                              <1> ottys_4:
  2805                              <1> 	; Set 'u.ttyp' ('the recent TTY') value
  2806 0000527E 8833                <1> 	mov 	[ebx], dh ; tty number + 1
  2807                              <1> 	; 09/02/2022
  2808 00005280 08D2                <1> 	or	dl, dl ; sysstty system call check (DL=0)
  2809 00005282 7401                <1> 	jz	short otty_retn ; 03/03/2022
  2810                              <1> sret:
  2811                              <1> 	;pop 	ax
  2812 00005284 58                  <1> 	pop	eax ; 08/01/2022
  2813                              <1> otty_retn:	; 09/02/2022
  2814                              <1> iclose_retn:	
  2815 00005285 C3                  <1> 	retn
  2816                              <1> 
  2817                              <1> 	;
  2818                              <1> 	; Original UNIX v1 'otty' routine:
  2819                              <1> 	;	
  2820                              <1> 	;mov    $100,*$tks / set interrupt enable bit (zero others) in
  2821                              <1>         ;                 / reader status reg
  2822                              <1>         ;mov    $100,*$tps / set interrupt enable bit (zero others) in
  2823                              <1>         ;                 / punch status reg
  2824                              <1>         ;mov    tty+[ntty*8]-8+6,r5 / r5 points to the header of the
  2825                              <1>         ;                          / console tty buffer
  2826                              <1>         ;incb   (r5) / increment the count of processes that opened the
  2827                              <1>         ;            / console tty
  2828                              <1>         ;tst    u.ttyp / is there a process control tty (i.e., has a tty
  2829                              <1>         ;             / buffer header
  2830                              <1>         ;bne    sret / address been loaded into u.ttyp yet)?  yes, branch
  2831                              <1>         ;mov    r5,u.ttyp / no, make the console tty the process control
  2832                              <1>         ;                 / tty
  2833                              <1>         ;br     sret / ?
  2834                              <1> ;sret:
  2835                              <1> 		;clr *$ps / set processor priority to zero
  2836                              <1> ;	pop	ax
  2837                              <1>         	;mov (sp)+,r1 / pop stack to r1
  2838                              <1> ;3:
  2839                              <1> ;	retn
  2840                              <1>         	;rts r0
  2841                              <1> 	
  2842                              <1> ;ocvt:	; < open tty >
  2843                              <1> 	; 13/01/2014
  2844                              <1> 	; 06/12/2013 (major modification: p.ttyc, u.ttyp)
  2845                              <1> 	; 24/09/2013 consistency check -> ok
  2846                              <1> 	; 16/09/2013
  2847                              <1> 	; 03/09/2013
  2848                              <1> 	; 27/08/2013
  2849                              <1> 	; 16/08/2013
  2850                              <1> 	; 16/07/2013
  2851                              <1> 	; 27/05/2013
  2852                              <1> 	; 21/05/2013
  2853                              <1> 	;
  2854                              <1> 	; Retro UNIX 8086 v1 modification !
  2855                              <1> 	; 
  2856                              <1> 	; In original UNIX v1, 'ocvt' routine 
  2857                              <1> 	;	(exactly different than this one)
  2858                              <1> 	;	was in 'u9.s' file.
  2859                              <1> 	;
  2860                              <1> 	; 16/07/2013
  2861                              <1> 	; Retro UNIX 8086 v1 modification:
  2862                              <1> 	;  If a tty is open for read or write by
  2863                              <1> 	;     a process (u.uno), only same process can open
  2864                              <1> 	;     same tty to write or read (R->R&W or W->W&R).	
  2865                              <1> 	;
  2866                              <1> 	; INPUT: DL=2 for Read DL=1 for Write
  2867                              <1> 
  2868                              <1> 	; 16/09/2013
  2869                              <1> 	; sub 	al, 10
  2870                              <1> 	
  2871                              <1> 	; 06/12/2013
  2872                              <1> 	;cmp	al, 7
  2873                              <1>         ;jna     short ottyp
  2874                              <1> 	; 13/01/2014
  2875                              <1> 	;jmp	short ottyp
  2876                              <1> 
  2877                              <1> ;oppt: / open paper tape for reading or writing
  2878                              <1> ;        mov    $100,*$prs / set reader interrupt enable bit
  2879                              <1> ;        tstb   pptiflg / is file already open
  2880                              <1> ;        bne    2f / yes, branch
  2881                              <1> ;1:
  2882                              <1> ;        mov    $240,*$ps / no, set processor priority to 5
  2883                              <1> ;        jsr    r0,getc; 2 / remove all entries in clist
  2884                              <1> ;               br .+4 / for paper tape input and place in free list
  2885                              <1> ;        br     1b
  2886                              <1> ;        movb   $2,pptiflg / set pptiflg to indicate file just open
  2887                              <1> ;        movb   $10.,toutt+1 / place 10 in paper tape input tout entry
  2888                              <1> ;        br     sret
  2889                              <1> ;2:
  2890                              <1> ;        jmp    error / file already open
  2891                              <1> 
  2892                              <1> iclose:
  2893                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2894                              <1> 	; 19/05/2015
  2895                              <1> 	; 18/05/2015 (Retro UNIX 386 v1 - Beginning)
  2896                              <1> 	; 21/05/2013 - 13/01/2014 (Retro UNIX 8086 v1)
  2897                              <1> 	;
  2898                              <1> 	; close file whose i-number is in r1
  2899                              <1> 	; 
  2900                              <1> 	; INPUTS ->
  2901                              <1> 	;    r1 - inode number
  2902                              <1> 	; OUTPUTS ->
  2903                              <1> 	;    file's inode in core	
  2904                              <1> 	;    r1 - inode number (positive)
  2905                              <1> 	;
  2906                              <1> 	; ((AX = R1))
  2907                              <1>         ;    ((Modified registers: -ebx-, edx)) 
  2908                              <1> 	;        
  2909                              <1> ;/ close file whose i-number is in r1
  2910 00005286 B202                <1> 	mov	dl, 2 ; 12/01/2014
  2911 00005288 F6C480              <1> 	test	ah, 80h ; Bit 15 of AX
  2912                              <1> 		; tst r1 / test i-number
  2913                              <1>         ;jnz	short iclose_2
  2914                              <1> 		; blt 2f / if neg., branch
  2915 0000528B 7405                <1> 	jz	short iclose_0 ; 30/07/2013
  2916                              <1> 	; 16/07/2013 
  2917 0000528D 66F7D8              <1> 	neg	ax ; make it positive
  2918                              <1> 	; 12/01/2014
  2919 00005290 FECA                <1> 	dec	dl ; dl = 1 (open for write)
  2920                              <1> iclose_0:
  2921 00005292 6683F828            <1> 	cmp	ax, 40
  2922                              <1> 		; cmp r1,$40. / is it a special file
  2923 00005296 77ED                <1>         ja	short iclose_retn  ; 13/01/2014
  2924                              <1> 		; bgt 3b / no, return
  2925                              <1> 	; 12/01/2014
  2926                              <1> 	; DL=2 -> special file was opened for reading
  2927                              <1> 	; DL=1 -> special file was opened for writing
  2928 00005298 50                  <1> 	push	eax ; 08/01/2022
  2929                              <1> 	;push	ax
  2930                              <1> 		; mov r1,-(sp) / yes, save r1 on stack
  2931 00005299 0FB6D8              <1> 	movzx	ebx, al
  2932                              <1> 	; 08/01/2022
  2933 0000529C C0E302              <1> 	shl	bl, 2
  2934                              <1> 	;shl	bx, 2
  2935                              <1> 		; asl r1
  2936 0000529F 81C3[A3520000]      <1> 	add	ebx, iclose_1 - 4
  2937 000052A5 FF23                <1> 	jmp	dword [ebx]
  2938                              <1> 		; jmp *1f-2(r1) / compute jump address and transfer
  2939                              <1> iclose_1 :
  2940 000052A7 [F3520000]          <1> 	dd	ctty ; tty, AX = 1 (runix)
  2941 000052AB [4E530000]          <1> 	dd	cret ; mem, AX = 2 (runix)
  2942 000052AF [4E530000]          <1> 	dd	cret ; fd0, AX = 3 (runix only)
  2943 000052B3 [4E530000]          <1> 	dd	cret ; fd1, AX = 4 (runix only)
  2944 000052B7 [4E530000]          <1> 	dd	cret ; hd0, AX = 5 (runix only)
  2945 000052BB [4E530000]          <1> 	dd	cret ; hd1, AX = 6 (runix only)	
  2946 000052BF [4E530000]          <1> 	dd	cret ; hd2, AX = 7 (runix only)
  2947 000052C3 [4E530000]          <1> 	dd	cret ; hd3, AX = 8 (runix only)	
  2948 000052C7 [4E530000]          <1> 	dd	cret ; lpr, AX = 9 (runix)
  2949                              <1> 	;dd	error; lpr, AX = 9 (error !)
  2950                              <1> 	;;dd	offset ejec ;;lpr, AX = 9  
  2951 000052CB [02530000]          <1> 	dd	ccvt ; tty0, AX = 10 (runix)	  
  2952 000052CF [02530000]          <1> 	dd	ccvt ; tty1, AX = 11 (runix)	  
  2953 000052D3 [02530000]          <1> 	dd	ccvt ; tty2, AX = 12 (runix)	  
  2954 000052D7 [02530000]          <1> 	dd	ccvt ; tty3, AX = 13 (runix)	  
  2955 000052DB [02530000]          <1> 	dd	ccvt ; tty4, AX = 14 (runix)	  
  2956 000052DF [02530000]          <1> 	dd	ccvt ; tty5, AX = 15 (runix)	  
  2957 000052E3 [02530000]          <1> 	dd	ccvt ; tty6, AX = 16 (runix)	  
  2958 000052E7 [02530000]          <1> 	dd	ccvt ; tty7, AX = 17 (runix)	  
  2959 000052EB [02530000]          <1> 	dd	ccvt ; COM1, AX = 18 (runix only)	  
  2960 000052EF [02530000]          <1> 	dd	ccvt ; COM2, AX = 19 (runix only)
  2961                              <1> 
  2962                              <1> 	; 1:
  2963                              <1> 	;        ctty   / tty
  2964                              <1> 	;        cppt   / ppt
  2965                              <1> 	;        sret   / mem
  2966                              <1> 	;        sret   / rf0
  2967                              <1> 	;        sret   / rk0
  2968                              <1> 	;        sret   / tap0
  2969                              <1> 	;        sret   / tap1
  2970                              <1> 	;        sret   / tap2
  2971                              <1> 	;        sret   / tap3
  2972                              <1> 	;        sret   / tap4
  2973                              <1> 	;        sret   / tap5
  2974                              <1> 	;        sret   / tap6
  2975                              <1> 	;        sret   / tap7
  2976                              <1> 	;        ccvt   / tty0
  2977                              <1> 	;        ccvt   / tty1
  2978                              <1> 	;        ccvt   / tty2
  2979                              <1> 	;        ccvt   / tty3
  2980                              <1> 	;        ccvt   / tty4
  2981                              <1> 	;        ccvt   / tty5
  2982                              <1> 	;        ccvt   / tty6
  2983                              <1> 	;        ccvt   / tty7
  2984                              <1> 	;        error / crd
  2985                              <1> 
  2986                              <1> ;iclose_2: ; 2: / negative i-number
  2987                              <1> 	;neg	ax
  2988                              <1> 		;neg r1 / make it positive
  2989                              <1> 	;cmp	ax, 40
  2990                              <1> 		;cmp r1,$40. / is it a special file?
  2991                              <1>         ;ja	short @b
  2992                              <1> 		;bgt    3b / no. return
  2993                              <1> 	;push	ax
  2994                              <1> 		;mov r1,-(sp)
  2995                              <1> 	;movzx	ebx, al
  2996                              <1> 	;shl	bx, 1
  2997                              <1> 		;asl r1 / yes. compute jump address and transfer
  2998                              <1> 	;add	ebx, iclose_3 - 2
  2999                              <1> 	;jmp	dword [ebx]
  3000                              <1> 		;jmp *1f-2(r1) / figure out 
  3001                              <1> ;iclose_3:
  3002                              <1> 	;dd	ctty ; tty, AX = 1 (runix)
  3003                              <1> 	;dd	sret ; mem, AX = 2 (runix)
  3004                              <1> 	;dd	sret ; fd0, AX = 3 (runix only)
  3005                              <1> 	;dd	sret ; fd1, AX = 4 (runix only)
  3006                              <1> 	;dd	sret ; hd0, AX = 5 (runix only)
  3007                              <1> 	;dd	sret ; hd1, AX = 6 (runix only)	
  3008                              <1> 	;dd	sret ; hd2, AX = 7 (runix only)
  3009                              <1> 	;dd	sret ; hd3, AX = 8 (runix only)
  3010                              <1> 	 ;dd	sret ; lpr, AX = 9	
  3011                              <1> 	;dd	ejec ; lpr, AX = 9  (runix)
  3012                              <1> 	;dd	ccvt ; tty0, AX = 10 (runix)	  
  3013                              <1> 	;dd	ccvt ; tty1, AX = 11 (runix)	  
  3014                              <1> 	;dd	ccvt ; tty2, AX = 12 (runix)	  
  3015                              <1> 	;dd	ccvt ; tty3, AX = 13 (runix)	  
  3016                              <1> 	;dd	ccvt ; tty4, AX = 14 (runix)	  
  3017                              <1> 	;dd	ccvt ; tty5, AX = 15 (runix)	  
  3018                              <1> 	;dd	ccvt ; tty6, AX = 16 (runix)	  
  3019                              <1> 	;dd	ccvt ; tty7, AX = 17 (runix)	  
  3020                              <1> 	;dd	ccvt ; COM1, AX = 18 (runix only)	  
  3021                              <1> 	;dd	ccvt ; COM2, AX = 19 (runix only) 
  3022                              <1> 	
  3023                              <1> 	;1:
  3024                              <1> 	;      	ctty   / tty
  3025                              <1> 	;       leadr  / ppt
  3026                              <1> 	;       sret   / mem
  3027                              <1> 	;       sret   / rf0
  3028                              <1> 	;       sret   / rk0
  3029                              <1> 	;       sret   / tap0
  3030                              <1> 	;       sret   / tap1
  3031                              <1> 	;       sret   / tap2
  3032                              <1> 	;       sret   / tap3
  3033                              <1> 	;       sret   / tap4
  3034                              <1> 	;       sret   / tap5
  3035                              <1> 	;       sret   / tap6
  3036                              <1> 	;       sret   / tap7
  3037                              <1> 	;       ccvt   / tty0
  3038                              <1> 	;       ccvt   / tty1
  3039                              <1> 	;       ccvt   / tty2
  3040                              <1> 	;       ccvt   / tty3
  3041                              <1> 	;       ccvt   / tty4
  3042                              <1> 	;       ccvt   / tty5
  3043                              <1> 	;       ccvt   / tty6
  3044                              <1> 	;       ccvt   / tty7
  3045                              <1> 	;/      ejec   / lpr
  3046                              <1> 
  3047                              <1> ctty: ; / close console tty
  3048                              <1> 	; 26/02/2022
  3049                              <1> 	; 09/02/2022
  3050                              <1> 	; 06/02/2022
  3051                              <1> 	; 08/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  3052                              <1> 	; 18/05/2015 (Retro UNIX 386 v1 - Beginning)
  3053                              <1> 	; 21/05/2013 - 26/01/2014 (Retro UNIX 8086 v1)
  3054                              <1> 	;
  3055                              <1> 	; Retro UNIX 8086 v1 modification !
  3056                              <1> 	; (DL = 2 -> it is open for reading)
  3057                              <1> 	; (DL = 1 -> it is open for writing)
  3058                              <1> 	; (DL = 0 -> it is open for sysstty system call)
  3059                              <1> 	;
  3060                              <1> 	; 06/12/2013
  3061 000052F3 0FB61D[2B660000]    <1>         movzx   ebx, byte [u.uno] ; process number
  3062 000052FA 8A83[33630000]      <1>         mov     al, [ebx+p.ttyc-1]
  3063                              <1> 	; 13/01/2014
  3064                              <1> 	;jmp	short cttyp
  3065                              <1> 	; 06/02/2022
  3066 00005300 EB04                <1> 	jmp	short ctty_0
  3067                              <1> ccvt:
  3068 00005302 2C0A                <1> 	sub 	al, 10
  3069                              <1> cttyp:	; (call from sysstty)
  3070                              <1> 	; 08/01/2022
  3071 00005304 31DB                <1> 	xor	ebx, ebx
  3072                              <1> ctty_0: ; (ebx < 256)  ; 06/02/2022
  3073                              <1> 	; 08/01/2022
  3074                              <1> 	; 18/05/2015 (32 bit modifications)
  3075                              <1> 	; 16/08/2013 - 26/01/2014
  3076                              <1> 	;movzx 	ebx, al ; tty number (0 to 9)
  3077                              <1> 	; 08/01/2022
  3078 00005306 88C3                <1> 	mov	bl, al
  3079 00005308 D0E3                <1> 	shl 	bl, 1  ; aligned to word	
  3080                              <1> 	; 26/01/2014
  3081 0000530A 81C3[64620000]      <1> 	add 	ebx, ttyl
  3082 00005310 88C6                <1> 	mov 	dh, al ; tty number
  3083 00005312 668B03              <1> 	mov 	ax, [ebx]
  3084                              <1> 		   ; AL = lock value (0 or process number)
  3085                              <1> 		   ; AH = open count 
  3086 00005315 20E4                <1> 	and 	ah, ah
  3087 00005317 7514                <1> 	jnz	short ctty_ret
  3088                              <1>   	; 09/02/2022
  3089 00005319 80FA01              <1> 	cmp	dl, 1	; DL = 0 -> called by sysstty
  3090 0000531C 7231                <1> 	jb	short ctty_stc_retn ; cf=1
  3091                              <1> 	; iclose (dl=1 or dl=2)
  3092 0000531E C705[31660000]0A00- <1>         mov     dword [u.error], ERR_DEV_NOT_OPEN
  3092 00005326 0000                <1>
  3093                              <1> 			; device not open ! error
  3094                              <1> 	;jmp 	short ctty_err ; open count = 0, it is not open !
  3095 00005328 E9A4DEFFFF          <1> 	jmp	error
  3096                              <1> 	; 26/01/2014
  3097                              <1> ctty_ret:
  3098 0000532D FECC                <1> 	dec 	ah ; decrease open count
  3099 0000532F 7502                <1> 	jnz	short ctty_1
  3100 00005331 30C0                <1> 	xor	al, al ; unlock/free tty
  3101                              <1> ctty_1:
  3102 00005333 668903              <1> 	mov 	[ebx], ax ; close tty instance
  3103                              <1> 	;
  3104 00005336 BB[0C660000]        <1> 	mov	ebx, u.ttyp
  3105                              <1> 	;test	dl, 1 ; open for write sign
  3106                              <1> 	;jz	short ctty_2
  3107                              <1> 	; 26/02/2022
  3108 0000533B F6C202              <1> 	test	dl, 2 ; open for read sign
  3109 0000533E 7501                <1> 	jnz	short ctty_2
  3110 00005340 43                  <1> 	inc	ebx
  3111                              <1> ctty_2:
  3112 00005341 FEC6                <1> 	inc	dh ; tty number + 1
  3113 00005343 3A33                <1> 	cmp	dh, [ebx]
  3114                              <1> 	;jne	short cret
  3115 00005345 7503                <1> 	jne	short ctty_3 ; 09/02/2022
  3116                              <1> 	; Reset/Clear 'u.ttyp' ('the recent TTY') value
  3117 00005347 C60300              <1> 	mov	byte [ebx], 0
  3118                              <1> ctty_3:
  3119                              <1> 	; 09/02/2022
  3120 0000534A 08D2                <1> 	or	dl, dl ; sysstty system call check (DL=0)
  3121 0000534C 7401                <1> 	jz	short ctty_4
  3122                              <1> cret:
  3123                              <1> 	;pop	ax
  3124                              <1> 	; 08/01/2022
  3125 0000534E 58                  <1> 	pop	eax
  3126                              <1> ctty_stc_retn:	; 09/02/2022
  3127                              <1> ctty_4:
  3128 0000534F C3                  <1> 	retn
  3129                              <1> 
  3130                              <1> ;ctty_err: ; 13/01/2014
  3131                              <1> ;	or 	dl, dl ; DL = 0 -> called by sysstty
  3132                              <1> ;	jnz	error
  3133                              <1> ;	stc
  3134                              <1> ;	retn
  3135                              <1> 
  3136                              <1> 	; Original UNIX v1 'ctty' routine:
  3137                              <1> 	;	
  3138                              <1>         ;mov    tty+[ntty*8]-8+6,r5 
  3139                              <1> 	;		;/ point r5 to the console tty buffer
  3140                              <1>         ;decb   (r5) / dec number of processes using console tty
  3141                              <1>         ;br     sret / return via sret
  3142                              <1> 
  3143                              <1> ;ccvt:	; < close tty >
  3144                              <1> 	; 21/05/2013 - 13/01/2014 (Retro UNIX 8086 v1)
  3145                              <1> 	;
  3146                              <1> 	; Retro UNIX 8086 v1 modification !
  3147                              <1> 	; 
  3148                              <1> 	; In original UNIX v1, 'ccvt' routine 
  3149                              <1> 	;		(exactly different than this one)
  3150                              <1> 	;	was in 'u9.s' file.
  3151                              <1> 	;
  3152                              <1> 	; DL = 2 -> it is open for reading
  3153                              <1> 	; DL = 1 -> it is open for writing
  3154                              <1> 	;
  3155                              <1> 	; 17/09/2013
  3156                              <1> 	;sub 	al, 10
  3157                              <1> 	;cmp	al, 7
  3158                              <1> 	;jna	short cttyp
  3159                              <1> 	; 13/01/2014
  3160                              <1> 	;jmp	short cttyp
  3161                              <1> 
  3162                              <1> ;cppt: / close paper tape
  3163                              <1> ;        clrb   pptiflg / set pptiflg to indicate file not open
  3164                              <1> ;1:
  3165                              <1> ;        mov    $240,*$ps /set process or priority to 5
  3166                              <1> ;        jsr    r0,getc; 2 / remove all ppt input entries from clist
  3167                              <1> ;                          / and assign to free list
  3168                              <1> ;               br sret
  3169                              <1> ;        br     1b
  3170                              <1> 
  3171                              <1> ;ejec:	
  3172                              <1> ;	jmp	error
  3173                              <1> ;/ejec:
  3174                              <1> ;/       mov    $100,*$lps / set line printer interrupt enable bit
  3175                              <1> ;/       mov    $14,r1 / 'form feed' character in r1 (new page).
  3176                              <1> ;/       jsr    r0,lptoc / space the printer to a new page
  3177                              <1> ;/       br     sret / return to caller via 'sret'
  3178                              <1> 
  3179                              <1> ejec:
  3180                              <1> 	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  3181                              <1> 	;	     - Printer Initialization
  3182                              <1> lpt_init:	
  3183                              <1> 	; Ref: IBM PC-AT BIOS v3 - PRT.ASM - 15/11/1985
  3184                              <1> 	;
  3185                              <1> 	; Default printer port: 378h ; LPT1
  3186                              <1> 	
  3187 00005350 B401                <1>  	mov	ah, 1  ; INITIALIZE THE PRINTER PORT
  3188                              <1> 	;call	int17h
  3189 00005352 E8C3FAFFFF          <1> 	call	PRNOP
  3190 00005357 7414                <1> 	jz	short lpt_init_ok
  3191                              <1> 	
  3192                              <1> 	; replace error code with 'device not ready' error
  3193                              <1> 	; (this may be better for 'sysopen')
  3194 00005359 B80F000000          <1> 	mov	eax, ERR_PRN_NOT_RDY
  3195 0000535E A3[31660000]        <1> 	mov	[u.error], eax
  3196                              <1> 	;jmp	sysret ; (may be) ? ([u.r0] = file descriptor)
  3197 00005363 A3[DC650000]        <1> 	mov	[u.r0], eax
  3198 00005368 E964DEFFFF          <1> 	jmp	error ; (better)	
  3199                              <1> 	
  3200                              <1> lpt_init_ok:
  3201                              <1> 	;jmp	short cret
  3202 0000536D 58                  <1> 	pop	eax    ; inode number
  3203 0000536E C3                  <1> 	retn
  3204                              <1> 	
  2118                                  %include 'u8.s'        ; 11/06/2015
  2119                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.6) - SYS8.INC
  2120                              <1> ; Last Modification: 15/07/2022
  2121                              <1> ; ----------------------------------------------------------------------------
  2122                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2123                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2124                              <1> ;
  2125                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2126                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2127                              <1> ; <Bell Laboratories (17/3/1972)>
  2128                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2129                              <1> ;
  2130                              <1> ; Retro UNIX 8086 v1 - U8.ASM (18/01/2014) //// UNIX v1 -> u8.s
  2131                              <1> ;
  2132                              <1> ; ****************************************************************************
  2133                              <1> 
  2134                              <1> ; 15/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2135                              <1> ; 14/07/2022 - Retro UNIX 386 v1 (Kernel v0.2.0.22)
  2136                              <1> ;---------------------------------------------------------------------
  2137                              <1> ; Buffer Header: -8 bytes-
  2138                              <1> ; word 1 - byte 0 - device (disk index) number (0 to 5)
  2139                              <1> ;	   byte 1 - status bits
  2140                              <1> ;	 	bit 0 - valid buffer bit (1 = valid, 0 = invalid, new)
  2141                              <1> ;		bit 1 - write bit (also modified bit)
  2142                              <1> ;		bit 2 - read bit	
  2143                              <1> ;		bit 3 to bit 7 are not used
  2144                              <1> ; word 2 - byte & byte 3 not used
  2145                              <1> ; word 3 & word 4 - byte 3, byte 5, byte 6, byte 7:
  2146                              <1> ;		physical block/sector address (32 bit LBA)
  2147                              <1> ;---------------------------------------------------------------------
  2148                              <1> 
  2149                              <1> ;; I/O Buffer - Retro UNIX 386 v1 modification
  2150                              <1> ;;     (8+512 bytes, 8 bytes header, 512 bytes data)
  2151                              <1> ;; Word 1, byte 0 = device id
  2152                              <1> ;; Word 1, byte 1 = status bits (bits 8 to 15)
  2153                              <1> ;;          bit 9 = write bit
  2154                              <1> ;;	    bit 10 = read bit	  
  2155                              <1> ;;	    bit 12 = waiting to write bit	
  2156                              <1> ;;	    bit 13 = waiting to read bit
  2157                              <1> ;;	    bit 15 = inhibit bit
  2158                              <1> ;; Word 2 (byte 2 & byte 3) = reserved (for now - 07/06/2015)
  2159                              <1> ;; Word 3 + Word 4 (byte 4,5,6,7) = physical block number 
  2160                              <1> ;;		   (In fact, it is 32 bit LBA for Retro UNIX 386 v1)
  2161                              <1> ;;
  2162                              <1> ;; I/O Buffer ((8+512 bytes in original Unix v1))
  2163                              <1> ;;	      ((4+512 bytes in Retro UNIX 8086 v1))
  2164                              <1> ;;
  2165                              <1> ;; I/O Queue Entry (of original UNIX operating system v1)
  2166                              <1> ;; Word 1, Byte 0 = device id
  2167                              <1> ;; Word 1, Byte 1 = (bits 8 to 15)
  2168                              <1> ;;          bit 9 = write bit
  2169                              <1> ;;	    bit 10 = read bit	  
  2170                              <1> ;;	    bit 12 = waiting to write bit	
  2171                              <1> ;;	    bit 13 = waiting to read bit
  2172                              <1> ;;	    bit 15 = inhibit bit
  2173                              <1> ;; Word 2 = physical block number (In fact, it is LBA for Retro UNIX 8086 v1)
  2174                              <1> ;;
  2175                              <1> ;; Original UNIX v1 ->
  2176                              <1> ;;		Word 3 = number of words in buffer (=256) 		
  2177                              <1> ;; Original UNIX v1 -> 
  2178                              <1> ;;		Word 4 = bus address (addr of first word of data buffer)
  2179                              <1> ;;
  2180                              <1> ;; Retro UNIX 8086 v1 -> Buffer Header (I/O Queue Entry) size is 4 bytes !
  2181                              <1> ;;
  2182                              <1> ;; Device IDs (of Retro Unix 8086 v1)
  2183                              <1> ;;          0 = fd0
  2184                              <1> ;;	    1 = fd1
  2185                              <1> ;;	    2 = hd0
  2186                              <1> ;;	    3 = hd1
  2187                              <1> ;;	    4 = hd2
  2188                              <1> ;;	    5 = hd3
  2189                              <1> 
  2190                              <1> ; Retro UNIX 386 v1 - 32 bit modifications (rfd, wfd, rhd, whd) - 09/06/2015
  2191                              <1> 
  2192                              <1> 	; 08/02/2022
  2193                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2194                              <1> rfd:	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2195                              <1> 	; 26/04/2013
  2196                              <1>    	; 13/03/2013 Retro UNIX 8086 v1 device (not an original unix v1 device)	
  2197                              <1>    	;sub 	ax, 3 ; zero based device number (Floppy disk)
  2198                              <1>       	;jmp 	short bread ; **** returns to routine that called readi			
  2199                              <1> 
  2200                              <1> 	; 08/02/2022
  2201                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2202                              <1> rhd:	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2203                              <1> 	; 26/04/2013
  2204                              <1>    	; 14/03/2013 Retro UNIX 8086 v1 device (not an original unix v1 device)	
  2205                              <1>    	;sub 	ax, 3 ; zero based device number (Hard disk)
  2206                              <1>    	;jmp	short bread ; **** returns to routine that called readi	
  2207                              <1> 
  2208                              <1> bread: 
  2209                              <1> 	; 15/07/2022
  2210                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2211                              <1> 	; 08/02/2022
  2212                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2213                              <1> 	; 14/07/2015
  2214                              <1> 	; 10/07/2015
  2215                              <1> 	; 09/06/2015
  2216                              <1> 	; 07/06/2015 (Retro UNIX 386 v1 - Beginning)
  2217                              <1> 	; 13/03/2013 - 29/07/2013 (Retro UNIX 8086 v1)
  2218                              <1> 	;	
  2219                              <1> 	; / read a block from a block structured device
  2220                              <1> 	;
  2221                              <1> 	; INPUTS ->
  2222                              <1> 	;    [u.fofp] points to the block number
  2223                              <1> 	;    ECX = maximum block number allowed on device
  2224                              <1> 	;	 ; that was an arg to bread, in original Unix v1, but
  2225                              <1> 	;	 ; CX register is used instead of arg in Retro Unix 8086 v1 		
  2226                              <1> 	;    [u.count]	number of bytes to read in
  2227                              <1> 	; OUTPUTS ->
  2228                              <1> 	;    [u.base] starting address of data block or blocks in user area  	
  2229                              <1> 	;    [u.fofp] points to next consecutive block to be read
  2230                              <1> 	;
  2231                              <1> 	; ((Modified registers: EAX, EDX, ECX, EBX, ESI, EDI))
  2232                              <1> 	;
  2233                              <1> 	; NOTE: Original UNIX v1 has/had a defect/bug here, even if read
  2234                              <1> 	;       byte count is less than 512, block number in *u.fofp (u.off)
  2235                              <1> 	;	is increased by 1. For example: If user/program request 
  2236                              <1> 	;       to read 16 bytes in current block, 'sys read' increases
  2237                              <1> 	;  	the next block number just as 512 byte reading is done.
  2238                              <1> 	;       This wrong is done in 'bread'. So, in Retro UNIX 8086 v1, 
  2239                              <1> 	;       for user (u) structure compatibility (because 16 bit is not
  2240                              <1> 	;       enough to keep byte position/offset of the disk), this
  2241                              <1> 	;	defect will not be corrected, user/program must request
  2242                              <1> 	;	512 byte read per every 'sys read' call to block devices
  2243                              <1> 	;       for achieving correct result. In future version(s), 
  2244                              <1> 	;	this defect will be corrected by using different 
  2245                              <1> 	;       user (u) structure. 26/07/2013 - Erdogan Tan 	
  2246                              <1> 
  2247                              <1> 	   	; jsr r0,tstdeve / error on special file I/O 
  2248                              <1> 			       ; / (only works on tape)
  2249                              <1> 		; mov *u.fofp,r1 / move block number to r1
  2250                              <1> 		; mov $2.-cold,-(sp) / "2-cold" to stack
  2251                              <1> ;1:
  2252                              <1> 		; cmp r1,(r0) / is this block # greater than or equal to
  2253                              <1> 			    ; / maximum block # allowed on device
  2254                              <1> 		; jnb short @f
  2255                              <1> 		; bhis	1f / yes, 1f (error)
  2256                              <1> 		; mov r1,-(sp) / no, put block # on stack
  2257                              <1> 		; jsr r0,preread / read in the block into an I/O buffer
  2258                              <1> 		; mov (sp)+,r1 / return block # to r1
  2259                              <1> 		; inc r1 / bump block # to next consecutive block
  2260                              <1> 		; dec (sp) / "2-1-cold" on stack
  2261                              <1> 		; bgt 1b / 2-1-cold = 0?  No, go back and read in next block
  2262                              <1> ;1:
  2263                              <1> 		; tst (sp)+ / yes, pop stack to clear off cold calculation
  2264                              <1> 	;push	ecx ; **
  2265                              <1> 	; 26/04/2013
  2266                              <1> 	;sub	ax, 3 ; 3 to 8 -> 0 to 5
  2267 0000536F 2C03                <1> 	sub	al, 3
  2268                              <1> 		; AL = Retro Unix 8086 v1 disk (block device) number
  2269 00005371 A2[44660000]        <1> 	mov	[u.brwdev], al
  2270                              <1> 	; 09/06/2015
  2271                              <1> 	;movzx	ebx, al
  2272                              <1> 	;mov	ecx, [ebx+drv.size] ; disk size (in sectors)
  2273                              <1> 	; 12/01/2022 (BugFix)
  2274 00005376 C0E002              <1> 	shl	al, 2 ; * 4
  2275 00005379 8B88[425D0000]      <1> 	mov	ecx, [eax+drv.size] ; disk size (in sectors)
  2276                              <1> bread_0:
  2277 0000537F 51                  <1> 	push	ecx ; ** ; 09/06/2015 
  2278                              <1> 	; 10/07/2015 (Retro UNIX 386 v1 modification!)
  2279                              <1> 	; [u.fofp] points to byte position in disk, not sector/block !
  2280 00005380 8B1D[EC650000]      <1> 	mov	ebx, [u.fofp]
  2281 00005386 8B03                <1> 	mov	eax, [ebx]
  2282 00005388 C1E809              <1> 	shr	eax, 9 ; convert byte position to block/sector number
  2283                              <1> 		; mov *u.fofp,r1 / restore r1 to initial value of the
  2284                              <1> 			       ; / block #
  2285 0000538B 39C8                <1> 	cmp	eax, ecx
  2286                              <1> 		; cmp r1,(r0)+ / block # greater than or equal to maximum
  2287                              <1>        	                     ; / block number allowed
  2288                              <1> 	;jnb	error 	     ; 18/04/2013
  2289                              <1> 		; bhis error10 / yes, error
  2290                              <1> 	; 08/02/2022
  2291                              <1> 	;jb	short bread_1
  2292                              <1> 	;mov 	dword [u.error], ERR_DEV_VOL_SIZE  ; 'out of volume' error
  2293                              <1> 	;jmp	error
  2294 0000538D 7342                <1> 	jnb	short brw_oov_err ; 'out of volume' error
  2295                              <1> bread_1:
  2296                              <1> 	;inc 	dword [ebx] ; 10/07/2015 (Retro UNIX 386 v1 - modification!)
  2297                              <1> 		; inc *u.fofp / no, *u.fofp has next block number
  2298                              <1> 	; EAX = Block number (zero based)
  2299                              <1> 		;;jsr r0,preread / read in the block whose number is in r1
  2300                              <1> preread: ;; call preread
  2301 0000538F BF[44660000]        <1> 	mov	edi, u.brwdev ; block device number for direct I/O
  2302 00005394 E8D4010000          <1> 	call	bufaloc_0 ; 26/04/2013
  2303                              <1> 	;; jc 	error
  2304                              <1> 	; EBX = Buffer (Header) Address -Physical-
  2305                              <1>         ; EAX = Block/Sector number (r1)
  2306                              <1> 	       ; jsr r0,bufaloc / get a free I/O buffer (r1 has block number)
  2307                              <1> 	; 14/03/2013
  2308 00005399 7411                <1>         jz	short bread_2 ; Retro UNIX 8086 v1 modification
  2309                              <1>        		; br 1f / branch if block already in a I/O buffer
  2310 0000539B 66810B0004          <1> 	or	word [ebx], 400h ; set read bit (10) in I/O Buffer
  2311                              <1>         	; bis $2000,(r5) / set read bit (bit 10 in I/O buffer)
  2312 000053A0 E8A0010000          <1> 	call	poke
  2313                              <1>         	; jsr r0,poke / perform the read
  2314                              <1> 	;;jc	error ;2 0/07/2013
  2315                              <1> ; 1:
  2316                              <1>  		; clr *$ps / ps = 0
  2317                              <1>         	; rts r0
  2318                              <1> 	; 08/02/2022
  2319 000053A5 7305                <1> 	jnc	short bread_2
  2320 000053A7 E911010000          <1> 	jmp	dskrd_err
  2321                              <1> 	;
  2322                              <1> ;; return from preread
  2323                              <1> bread_2:
  2324                              <1> 	; 15/07/2022
  2325                              <1> 	;or	word [ebx], 4000h 
  2326                              <1> 	;	; bis $40000,(r5) 
  2327                              <1> 	;		; / set bit 14 of the 1st word of the I/O buffer
  2328                              <1> bread_3: ; 1:
  2329                              <1> 	; 15/07/2022
  2330                              <1> 	;test	word [ebx], 2400h
  2331                              <1> 	;	; bit $22000,(r5) / are 10th and 13th bits set (read bits)
  2332                              <1> 	;jz	short bread_4
  2333                              <1> 	;	; beq 1f / no
  2334                              <1> 	;	; cmp cdev,$1 / disk or drum?
  2335                              <1> 	;	; ble 2f / yes
  2336                              <1> 	;	; tstb uquant / is the time quantum = 0?
  2337                              <1> 	;	; bne 2f / no, 2f
  2338                              <1> 	;	; mov r5,-(sp) / yes, save r5 (buffer address)
  2339                              <1> 	;	; jsr r0,sleep; 31. 
  2340                              <1> 	;		; / put process to sleep in channel 31 (tape)
  2341                              <1> 	;	; mov (sp)+,r5 / restore r5
  2342                              <1> 	;	; br 1b / go back
  2343                              <1> ; 2: / drum or disk
  2344                              <1>         ;; mov     cx, [s.wait_]+2 ;; 29/07/2013
  2345                              <1> 	;call	idle
  2346                              <1> 	;	; jsr r0,idle; s.wait+2 / wait
  2347                              <1> 	;jmp	short bread_3
  2348                              <1>        	;	; br 1b
  2349                              <1> bread_4: ; 1: / 10th and 13th bits not set
  2350                              <1> 	;and	word [ebx], 0BFFFh ; 1011111111111111b
  2351                              <1> 	;	; bic $40000,(r5) / clear bit 14
  2352                              <1>        	;	; jsr r0,tstdeve / test device for error (tape)
  2353                              <1> 	; 15/07/2022
  2354 000053AC 83C308              <1> 	add	ebx, 8
  2355                              <1> 		; add $8,r5 / r5 points to data in I/O buffer
  2356                              <1> 	; 09/06/2015
  2357 000053AF 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0
  2358 000053B7 7705                <1> 	ja	short bread_5
  2359 000053B9 E898F8FFFF          <1> 	call	trans_addr_w ; translate virtual address to physical (w)
  2360                              <1> bread_5:
  2361                              <1> 	; EBX = system (I/O) buffer address
  2362 000053BE E870000000          <1> 	call	dioreg
  2363                              <1>        		; jsr r0,dioreg / do bookkeeping on u.count etc.
  2364                              <1> 	; esi = start address of the transfer (in the buffer)
  2365                              <1> 	; edi = [u.pbase], destination address in user's memory space
  2366                              <1> 	; ecx = transfer count (in bytes)
  2367                              <1> 	;
  2368                              <1> ;1: / r5 points to beginning of data in I/O buffer, r2 points to beginning
  2369                              <1> ;   / of users data
  2370 000053C3 F3A4                <1> 	rep	movsb
  2371                              <1> 		; movb (r5)+,(r2)+ / move data from the I/O buffer
  2372                              <1>        		; dec r3 / to the user's area in core starting at u.base
  2373                              <1>        		; bne 1b
  2374 000053C5 59                  <1> 	pop	ecx ; **
  2375 000053C6 833D[00660000]00    <1> 	cmp	dword [u.count], 0
  2376                              <1> 		; tst u.count / done
  2377 000053CD 77B0                <1> 	ja	short bread_0 ; 09/06/2015
  2378                              <1>        		; beq 1f / yes, return
  2379                              <1> 		; tst -(r0) / no, point r0 to the argument again
  2380                              <1>        		; br bread / read some more
  2381                              <1> ; 1:
  2382 000053CF 58                  <1> 	pop	eax ; ****
  2383                              <1>        		; mov (sp)+,r0
  2384 000053D0 C3                  <1>         retn		; 09/06/2015
  2385                              <1> 	;jmp	ret_ 
  2386                              <1> 		;jmp ret  / jump to routine that called readi
  2387                              <1> 
  2388                              <1> 	; 08/02/2022
  2389                              <1> brw_oov_err:
  2390 000053D1 C705[31660000]1000- <1> 	mov 	dword [u.error], ERR_DEV_VOL_SIZE  ; 'out of volume' error
  2390 000053D9 0000                <1>
  2391 000053DB E9F1DDFFFF          <1> 	jmp	error
  2392                              <1> 
  2393                              <1> 	; 08/02/2022
  2394                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2395                              <1> wfd:    ; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2396                              <1> 	; 26/04/2013
  2397                              <1>    	; 14/03/2013 Retro UNIX 8086 v1 device (not an original unix v1 device)	
  2398                              <1>    	;sub 	ax, 3 ; zero based device number (Hard disk)
  2399                              <1>    	;jmp	short bwrite ; **** returns to routine that called writei
  2400                              <1> 
  2401                              <1> 	; 08/02/2022
  2402                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)				
  2403                              <1> whd:	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2404                              <1>    	; 14/03/2013 Retro UNIX 8086 v1 device (not an original unix v1 device)	
  2405                              <1>    	;sub 	ax, 3 ; zero based device number (Hard disk)
  2406                              <1>    	;jmp 	short bwrite ; **** returns to routine that called writei ('jmp ret')
  2407                              <1> 
  2408                              <1> bwrite:
  2409                              <1> 	; 15/07/2022
  2410                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2411                              <1> 	; 08/02/2022
  2412                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2413                              <1> 	; 14/07/2015
  2414                              <1> 	; 10/07/2015
  2415                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2416                              <1> 	; 14/03/2013 - 20/07/2013 (Retro UNIX 8086 v1)
  2417                              <1> 	;	
  2418                              <1> 	;; / write on block structured device
  2419                              <1> 	;
  2420                              <1> 	; INPUTS ->
  2421                              <1> 	;    [u.fofp] points to the block number
  2422                              <1> 	;    ECX = maximum block number allowed on device
  2423                              <1> 	;	 ; that was an arg to bwrite, in original Unix v1, but
  2424                              <1> 	;	 ; CX register is used instead of arg in Retro Unix 8086 v1 		
  2425                              <1> 	;    [u.count]	number of bytes to user desires to write
  2426                              <1> 	; OUTPUTS ->
  2427                              <1> 	;    [u.fofp] points to next consecutive block to be written into
  2428                              <1> 	;
  2429                              <1> 	; ((Modified registers: EDX, ECX, EBX, ESI, EDI))
  2430                              <1> 	;
  2431                              <1> 	; NOTE: Original UNIX v1 has/had a defect/bug here, even if write
  2432                              <1> 	;       byte count is less than 512, block number in *u.fofp (u.off)
  2433                              <1> 	;	is increased by 1. For example: If user/program request 
  2434                              <1> 	;       to write 16 bytes in current block, 'sys write' increases
  2435                              <1> 	;  	the next block number just as 512 byte writing is done.
  2436                              <1> 	;       This wrong is done in 'bwrite'. So, in Retro UNIX 8086 v1, 
  2437                              <1> 	;       for user (u) structure compatibility (because 16 bit is not
  2438                              <1> 	;       enough to keep byte position/offset of the disk), this
  2439                              <1> 	;	defect will not be corrected, user/program must request
  2440                              <1> 	;	512 byte write per every 'sys write' call to block devices
  2441                              <1> 	;       for achieving correct result. In future version(s), 
  2442                              <1> 	;	this defect will be corrected by using different 
  2443                              <1> 	;       user (u) structure. 26/07/2013 - Erdogan Tan 	
  2444                              <1> 
  2445                              <1>        		; jsr r0,tstdeve / test the device for an error
  2446                              <1> 	;push	ecx ; **
  2447                              <1> 	; 26/04/2013
  2448                              <1> 	;sub	ax, 3 ; 3 to 8 -> 0 to 5
  2449 000053E0 2C03                <1> 	sub	al, 3
  2450                              <1> 		; AL = Retro Unix 8086 v1 disk (block device) number
  2451 000053E2 A2[44660000]        <1> 	mov	[u.brwdev], al
  2452                              <1> 	; 09/06/2015
  2453                              <1> 	;movzx	ebx, al
  2454                              <1> 	;mov	ecx, [ebx+drv.size] ; disk size (in sectors)
  2455                              <1> 	; 12/01/2022 (BugFix)
  2456 000053E7 C0E002              <1> 	shl	al, 2 ; * 4
  2457 000053EA 8B88[425D0000]      <1> 	mov	ecx, [eax+drv.size] ; disk size (in sectors)
  2458                              <1> bwrite_0:
  2459 000053F0 51                  <1> 	push	ecx ; ** ; 09/06/2015
  2460                              <1> 	; 10/07/2015 (Retro UNIX 386 v1 modification!)
  2461                              <1> 	; [u.fofp] points to byte position in disk, not sector/block !
  2462 000053F1 8B1D[EC650000]      <1> 	mov	ebx, [u.fofp]
  2463 000053F7 8B03                <1> 	mov	eax, [ebx]       
  2464 000053F9 C1E809              <1> 	shr	eax, 9 ; convert byte position to block/sector number
  2465                              <1> 		; mov *u.fofp,r1 / put the block number in r1
  2466 000053FC 39C8                <1> 	cmp	eax, ecx
  2467                              <1> 		; cmp r1,(r0)+ / does block number exceed maximum allowable #
  2468                              <1>        	                     ; / block number allowed
  2469                              <1> 	;jnb	error	     ; 18/04/2013
  2470                              <1> 		; bhis error10 / yes, error
  2471                              <1>      	; 08/02/2022
  2472                              <1> 	;jb	short bwrite_1
  2473                              <1> 	;mov 	dword [u.error], ERR_DEV_VOL_SIZE  ; 'out of volume' error
  2474                              <1> 	;jmp	error
  2475 000053FE 73D1                <1> 	jnb	short brw_oov_err ; 'out of volume' error
  2476                              <1> bwrite_1:
  2477                              <1> 	;inc 	dword [ebx] ; 10/07/2015 (Retro UNIX 386 v1 - modification!)
  2478                              <1> 		; inc *u.fofp / no, increment block number
  2479                              <1> 	; 09/06/2015 - 10/07/2015
  2480 00005400 66833D[41660000]00  <1> 	cmp	word [u.pcount], 0
  2481 00005408 7705                <1> 	ja	short bwrite_2
  2482 0000540A E843F8FFFF          <1> 	call	trans_addr_r ; translate virtual address to physical (r)
  2483                              <1> bwrite_2:
  2484 0000540F BF[44660000]        <1> 	mov	edi, u.brwdev  ; block device number for direct I/O
  2485 00005414 E8C5000000          <1>        	call	bwslot ; 26/04/2013 (wslot -> bwslot)	 				
  2486                              <1> 		; jsr r0,wslot / get an I/O buffer to write into
  2487                              <1> 		; add $8,r5 / r5 points to data in I/O buffer
  2488 00005419 E815000000          <1>         call	dioreg
  2489                              <1> 		; jsr r0,dioreg / do the necessary bookkeeping
  2490                              <1> 	; esi = destination address (in the buffer)
  2491                              <1> 	; edi = [u.pbase], start address of transfer in user's memory space
  2492                              <1> 	; ecx = transfer count (in bytes)
  2493                              <1> ; 1: / r2 points to the users data; r5 points to the I/O buffers data area
  2494 0000541E 87F7                <1> 	xchg 	esi, edi ; 14/07/2015
  2495 00005420 F3A4                <1> 	rep	movsb
  2496                              <1> 		; movb (r2)+,(r5)+ / ; r3, has the byte count
  2497                              <1>        		; dec r3 / area to the I/O buffer
  2498                              <1>        		; bne 1b
  2499 00005422 E8F0000000          <1> 	call	dskwr
  2500                              <1> 		; jsr r0,dskwr / write it out on the device
  2501 00005427 59                  <1> 	pop	ecx ; **
  2502 00005428 833D[00660000]00    <1>         cmp     dword [u.count], 0
  2503                              <1> 		; tst u.count / done
  2504 0000542F 77BF                <1> 	ja	short bwrite_0 ; 09/06/2015
  2505                              <1> 		; beq 1f / yes, 1f
  2506                              <1> 		; tst -(r0) / no, point r0 to the argument of the call
  2507                              <1>        		; br bwrite / go back and write next block
  2508                              <1> ; 1:
  2509 00005431 58                  <1> 	pop	eax ; ****
  2510                              <1>        		; mov (sp)+,r0
  2511 00005432 C3                  <1> 	retn		; 09/06/2015
  2512                              <1>         ;jmp	ret_ 
  2513                              <1> 		; jmp ret / return to routine that called writei
  2514                              <1> ;error10:
  2515                              <1> ;       jmp     error  ; / see 'error' routine
  2516                              <1> 
  2517                              <1> dioreg:
  2518                              <1> 	; 04/02/2022
  2519                              <1> 	; 14/07/2015
  2520                              <1> 	; 10/07/2015 (UNIX v1 bugfix - [u.fofp]: byte pos., not block)
  2521                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2522                              <1> 	; 14/03/2013 (Retro UNIX 8086 v1)
  2523                              <1> 	;	
  2524                              <1> 	; bookkeeping on block transfers of data
  2525                              <1> 	;
  2526                              <1> 	; * returns value of u.pbase before it gets updated, in EDI
  2527                              <1> 	; * returns byte count (to transfer) in ECX (<=512)
  2528                              <1> 	; 10/07/2015
  2529                              <1> 	; * returns byte offset from beginning of current sector buffer
  2530                              <1> 	; (beginning of data) in ESI
  2531                              <1> 	;
  2532 00005433 8B0D[00660000]      <1> 	mov	ecx, [u.count]
  2533                              <1> 		; mov u.count,r3 / move char count to r3
  2534                              <1> 	; 04/02/2022
  2535 00005439 31D2                <1> 	xor	edx, edx
  2536 0000543B B602                <1> 	mov	dh, 2
  2537                              <1> 	; edx = 512
  2538 0000543D 39D1                <1> 	cmp	ecx, edx ; 512
  2539                              <1> 	;cmp 	ecx, 512
  2540                              <1> 		; cmp r3,$512. / more than 512. char?
  2541 0000543F 7602                <1> 	jna	short dioreg_0
  2542                              <1> 		; blos 1f / no, branch
  2543 00005441 89D1                <1> 	mov	ecx, edx ; 512
  2544                              <1> 	;mov	ecx, 512
  2545                              <1> 		; mov $512.,r3 / yes, just take 512.
  2546                              <1> dioreg_0:
  2547                              <1> 	; 09/06/2015
  2548 00005443 663B0D[41660000]    <1> 	cmp	cx, [u.pcount]
  2549 0000544A 7607                <1> 	jna	short dioreg_1
  2550 0000544C 668B0D[41660000]    <1> 	mov	cx, [u.pcount]
  2551                              <1> dioreg_1:
  2552                              <1> ; 1:
  2553 00005453 8B15[FC650000]      <1> 	mov	edx, [u.base] ; 09/06/2015 (eax -> edx)
  2554                              <1> 	        ; mov u.base,r2 / put users base in r2
  2555 00005459 010D[04660000]      <1> 	add	[u.nread], ecx
  2556                              <1> 		; add r3,u.nread / add the number to be read to u.nread
  2557 0000545F 290D[00660000]      <1> 	sub	[u.count], ecx
  2558                              <1> 		; sub r3,u.count / update count
  2559 00005465 010D[FC650000]      <1> 	add	[u.base], ecx
  2560                              <1> 		; add r3,u.base / update base
  2561                              <1> 	; 10/07/2015
  2562                              <1> 	; Retro UNIX 386 v1 - modification !
  2563                              <1> 	; (File pointer points to byte position, not block/sector no.)
  2564                              <1> 	; (It will point to next byte position instead of next block no.)
  2565 0000546B 8B35[EC650000]      <1> 	mov	esi, [u.fofp] ; u.fopf points to byte position pointer  
  2566 00005471 8B06                <1> 	mov	eax, [esi] ; esi points to current byte pos. on the disk
  2567 00005473 010E                <1> 	add	[esi], ecx ; ecx is added to set the next byte position
  2568 00005475 25FF010000          <1> 	and	eax, 1FFh  ; get offset from beginning of current block	
  2569 0000547A 89DE                <1> 	mov	esi, ebx   ; beginning of data in sector/block buffer
  2570 0000547C 01C6                <1> 	add	esi, eax   ; esi contains start address of the transfer
  2571                              <1> 	; 09/06/2015 - 10/07/2015
  2572 0000547E 66290D[41660000]    <1> 	sub	[u.pcount], cx
  2573 00005485 81E2FF0F0000        <1> 	and	edx, PAGE_OFF ; 0FFFh
  2574 0000548B 8B3D[3D660000]      <1> 	mov	edi, [u.pbase]
  2575 00005491 81E700F0FFFF        <1> 	and	edi, ~PAGE_OFF
  2576 00005497 01D7                <1> 	add	edi, edx
  2577 00005499 893D[3D660000]      <1> 	mov	[u.pbase], edi
  2578 0000549F 010D[3D660000]      <1> 	add	[u.pbase], ecx ; 14/07/2015
  2579 000054A5 C3                  <1> 	retn
  2580                              <1> 		; rts r0 / return
  2581                              <1> 
  2582                              <1> dskrd:
  2583                              <1> 	; 15/07/2022
  2584                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2585                              <1> 	; 08/02/2022 (Retro UNIX 386 v1.1)
  2586                              <1> 	; 18/08/2015
  2587                              <1> 	; 02/07/2015
  2588                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2589                              <1> 	; 14/03/2013 - 29/07/2013 (Retro UNIX 8086 v1)
  2590                              <1> 	;
  2591                              <1> 	; 'dskrd' acquires an I/O buffer, puts in the proper
  2592                              <1> 	; I/O queue entries (via bufaloc) then reads a block
  2593                              <1> 	; (number specified in r1) in the acquired buffer.)
  2594                              <1> 	; If the device is busy at the time dskrd is called,	
  2595                              <1> 	; dskrd calls idle.
  2596                              <1> 	; 
  2597                              <1> 	; INPUTS ->
  2598                              <1> 	;    r1 - block number
  2599                              <1> 	;    cdev - current device number 
  2600                              <1> 	; OUTPUTS ->
  2601                              <1> 	;    r5 - points to first data word in I/O buffer
  2602                              <1> 	;
  2603                              <1> 	; ((AX = R1)) input/output
  2604                              <1> 	; ((BX = R5)) output 
  2605                              <1> 	;
  2606                              <1>         ; ((Modified registers: EDX, ECX, EBX, ESI, EDI))  
  2607                              <1> 	;
  2608 000054A6 E8B5000000          <1> 	call 	bufaloc
  2609                              <1> 		; jsr r0,bufaloc / shuffle off to bufaloc; 
  2610                              <1> 			       ; / get a free I/O buffer
  2611                              <1> 	;;jc	error ; 20/07/2013
  2612 000054AB 740C                <1> 	jz	short dskrd_1 ; Retro UNIX 8086 v1 modification
  2613                              <1>        		; br 1f / branch if block already in a I/O buffer
  2614                              <1> 
  2615                              <1> 	; 15/07/2022
  2616                              <1> 	; (buffer header byte 1, bit 2 is disk read bit/flag)
  2617                              <1> dskrd_0: ; 10/07/2015 (wslot)
  2618 000054AD 66810B0004          <1> 	or	word [ebx], 400h ; set read bit (10) in I/O Buffer
  2619                              <1>         	; bis $2000,(r5) / set bit 10 of word 1 of 
  2620                              <1> 		               ; / I/O queue entry for buffer
  2621 000054B2 E88E000000          <1> 	call	poke
  2622                              <1> 		; jsr r0,poke / just assigned in bufaloc, 
  2623                              <1> 			    ; /	bit 10=1 says read
  2624                              <1> 	; 09/06/2015
  2625                              <1> 	;jnc	short dskrd_1
  2626                              <1> 	;mov	dword [u.error], ERR_DRV_READ ; disk read error !
  2627                              <1> 	;jmp	error
  2628                              <1> 	; 08/02/2022
  2629 000054B7 7204                <1> 	jc	short dskrd_3
  2630                              <1> dskrd_1: ; 1:
  2631                              <1>        	; 15/07/2022
  2632                              <1> 	;
  2633                              <1> 	;	;clr *$ps
  2634                              <1>        	;test	word [ebx], 2400h
  2635                              <1> 	;	; bit $22000,(r5) / if either bits 10, or 13 are 1; 
  2636                              <1> 	;			; / jump to idle
  2637                              <1>        	;jz	short dskrd_2
  2638                              <1> 	;	; beq 1f
  2639                              <1>         ;;;mov   ecx, [s.wait_]
  2640                              <1>        	;call	idle
  2641                              <1> 	;	; jsr r0,idle; s.wait+2
  2642                              <1> 	;jmp 	short dskrd_1
  2643                              <1>        	;	; br 1b
  2644                              <1> dskrd_2: ; 1:
  2645 000054B9 83C308              <1>         add	ebx, 8
  2646                              <1> 		; add $8,r5 / r5 points to first word of data in block 
  2647                              <1> 			  ; / just read in
  2648 000054BC C3                  <1>        	retn
  2649                              <1> 		; rts r0
  2650                              <1> dskrd_err: 
  2651                              <1> 	; 08/02/2022
  2652                              <1> 	; (jump from 'bread' error)	
  2653                              <1> dskrd_3:	
  2654                              <1> 	; 08/02/2022
  2655 000054BD 803D[44660000]FF    <1> 	cmp	byte [u.brwdev], 0FFh ; is error code set in [u.error] ?
  2656 000054C4 7509                <1> 	jne	short dskrd_4 ; no
  2657                              <1> 	; yes, clear [u.brwdev] for next check and jump to 'error'
  2658 000054C6 C605[44660000]00    <1> 	mov	byte [u.brwdev], 0
  2659 000054CD EB0A                <1> 	jmp	short dskrd_5
  2660                              <1> dskrd_4:
  2661 000054CF C705[31660000]1100- <1> 	mov	dword [u.error], ERR_DRV_READ ; disk read error !
  2661 000054D7 0000                <1>
  2662                              <1> dskrd_5:
  2663 000054D9 E9F3DCFFFF          <1> 	jmp	error
  2664                              <1> 
  2665                              <1> bwslot:
  2666                              <1> 	; 15/07/2022
  2667                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2668                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2669                              <1> 	; 10/07/2015
  2670                              <1> 	;	If the block/sector is not placed in a buffer
  2671                              <1> 	;	before 'wslot', it must be read before
  2672                              <1> 	;	it is written! (Otherwise transfer counts less
  2673                              <1> 	;	than 512 bytes will be able to destroy existing 
  2674                              <1> 	;	data on disk.)
  2675                              <1> 	;
  2676                              <1> 	; 11/06/2015 (Retro UNIX 386 v1 - Beginning)
  2677                              <1> 	; 26/04/2013(Retro UNIX 8086 v1)
  2678                              <1> 	; Retro UNIX 8086 v1 modification !
  2679                              <1> 	; ('bwslot' will be called from 'bwrite' only!)
  2680                              <1> 	; INPUT -> EDI - points to device id (in u.brwdev)	
  2681                              <1> 	;	-> EAX = block number
  2682                              <1> 	;
  2683 000054DE E88A000000          <1> 	call	bufaloc_0
  2684 000054E3 742A                <1> 	jz	short wslot_0 ; block/sector already is in the buffer
  2685                              <1> 	; 12/01/2022
  2686                              <1> 	; ebx = buffer header address
  2687                              <1> bwslot_0:
  2688                              <1> 	; 10/07/2015
  2689 000054E5 8B35[EC650000]      <1> 	mov	esi, [u.fofp]
  2690 000054EB 8B06                <1> 	mov	eax, [esi]
  2691 000054ED 25FF010000          <1> 	and	eax, 1FFh ; offset from beginning of the sector/block
  2692 000054F2 750C                <1> 	jnz 	short bwslot_1 ; it is not a full sector write
  2693                              <1> 		       ; recent disk data must be placed in the buffer
  2694 000054F4 813D[00660000]0002- <1> 	cmp	dword [u.count], 512
  2694 000054FC 0000                <1>
  2695 000054FE 730F                <1> 	jnb	short wslot_0	
  2696                              <1> bwslot_1:
  2697 00005500 E8A8FFFFFF          <1> 	call	dskrd_0
  2698                              <1> 	; 12/01/2022
  2699                              <1> 	; ebx = buffer data address = buffer header address + 8
  2700 00005505 83EB08              <1> 	sub	ebx, 8 ; set ebx to the buffer header address again
  2701 00005508 EB05                <1> 	jmp 	short wslot_0
  2702                              <1> 
  2703                              <1> wslot:
  2704                              <1> 	; 15/07/2022
  2705                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2706                              <1> 	;
  2707                              <1> 	; 11/06/2015 (Retro UNIX 386 v1 - Beginning)
  2708                              <1> 	; 		(32 bit modifications)
  2709                              <1> 	; 14/03/2013 - 29/07/2013(Retro UNIX 8086 v1)
  2710                              <1> 	;
  2711                              <1> 	; 'wslot' calls 'bufaloc' and obtains as a result, a pointer
  2712                              <1> 	; to the I/O queue of an I/O buffer for a block structured
  2713                              <1> 	; device. It then checks the first word of I/O queue entry.	
  2714                              <1> 	; If bits 10 and/or 13 (read bit, waiting to read bit) are set,
  2715                              <1> 	; wslot calls 'idle'. When 'idle' returns, or if bits 10 
  2716                              <1> 	; and/or 13 are not set, 'wslot' sets bits 9 and 15 of the first
  2717                              <1> 	; word of the I/O queue entry (write bit, inhibit bit).
  2718                              <1> 	;
  2719                              <1> 	; INPUTS ->
  2720                              <1>  	;    r1 - block number
  2721                              <1> 	;    cdev - current (block/disk) device number
  2722                              <1>  	;
  2723                              <1> 	; OUTPUTS ->
  2724                              <1> 	;    bufp - bits 9 and 15 are set, 
  2725                              <1> 	;           the remainder of the word left unchanged
  2726                              <1> 	;    r5 - points to first data word in I/O buffer
  2727                              <1> 	;
  2728                              <1> 	; ((AX = R1)) input/output
  2729                              <1> 	; ((BX = R5)) output 
  2730                              <1> 	;
  2731                              <1>         ; ((Modified registers: EDX, ECX, EBX, ESI, EDI)) 
  2732                              <1> 
  2733 0000550A E851000000          <1> 	call	bufaloc
  2734                              <1> 	; 10/07/2015
  2735                              <1> 		; jsr r0,bufaloc / get a free I/O buffer; pointer to first
  2736                              <1>         	; br 1f / word in buffer in r5
  2737                              <1> 	; EBX = Buffer (Header) Address (r5) (ES=CS=DS, system/kernel segment)
  2738                              <1>         ; EAX = Block/Sector number (r1)
  2739                              <1> wslot_0: ;1:
  2740                              <1> 	; 14/07/2022
  2741                              <1> 	;
  2742                              <1>      	;test	word [ebx], 2400h
  2743                              <1> 	;	; bit $22000,(r5) / check bits 10, 13 (read, waiting to read)
  2744                              <1> 	;			; / of I/O queue entry
  2745                              <1> 	;jz	short wslot_1
  2746                              <1>         ;       ; beq 1f  / branch if 10, 13 zero (i.e., not reading, 
  2747                              <1> 	;	       ; / or not waiting to read)
  2748                              <1> 	;
  2749                              <1> 	;;mov	ecx, [s.wait_] ; 29/07/2013
  2750                              <1> 	;call	idle
  2751                              <1> 	;	; jsr r0,idle; / if buffer is reading or writing to read,
  2752                              <1>        	;                   ; / idle
  2753                              <1> 	;jmp	short wslot_0
  2754                              <1> 	;	; br 1b / till finished
  2755                              <1> wslot_1: ;1:
  2756                              <1> 	;or	word [ebx], 8200h
  2757                              <1>        	;	; bis $101000,(r5) / set bits 9, 15 in 1st word of I/O queue
  2758                              <1>         ;			; / (write, inhibit bits)
  2759                              <1> 	;	; clr *$ps / clear processor status
  2760                              <1> 
  2761                              <1> 	; 15/07/2022
  2762                              <1> 	; (set disk write bit/flag)
  2763                              <1> 	;or	word [ebx], 200h	
  2764 0000550F 43                  <1> 	inc	ebx
  2765 00005510 800B02              <1> 	or	byte [ebx], 2
  2766 00005513 83C307              <1> 	add	ebx, 7
  2767                              <1> 
  2768                              <1> 	;add	ebx, 8 ; 11/06/2015
  2769                              <1> 		; add $8,r5 / r5 points to first word in data area 
  2770                              <1> 			  ; / for this block
  2771                              <1> dskwr_1:	; 08/02/2022
  2772 00005516 C3                  <1>        	retn
  2773                              <1> 		; rts r0
  2774                              <1> dskwr:
  2775                              <1> 	; 15/07/2022
  2776                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2777                              <1> 	; 08/02/2022 (Retro UNIX 386 v1.1)
  2778                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2779                              <1> 	; 14/03/2013 - 03/08/2013 (Retro UNIX 8086 v1)
  2780                              <1> 	;
  2781                              <1> 	; 'dskwr' writes a block out on disk, via ppoke. The only
  2782                              <1> 	; thing dskwr does is clear bit 15 in the first word of I/O queue
  2783                              <1> 	; entry pointed by 'bufp'. 'wslot' which must have been called
  2784                              <1> 	; previously has supplied all the information required in the
  2785                              <1> 	; I/O queue entry.
  2786                              <1> 	;
  2787                              <1> 	; (Modified registers: ECX, EDX, EBX, ESI, EDI)
  2788                              <1> 	;
  2789                              <1> 	;
  2790 00005517 8B1D[98650000]      <1> 	mov	ebx, [bufp]
  2791                              <1> 	; 15/07/2022
  2792                              <1> 	;and	word [ebx], 7FFFh ; 0111111111111111b
  2793                              <1> 	;	; bic $100000,*bufp / clear bit 15 of I/O queue entry at
  2794                              <1>                                   ; / bottom of queue
  2795                              <1> 	; 15/07/2022
  2796                              <1> 	; (set disk write bit)
  2797                              <1> 	; ('wslot' already sets disk write bit/flag)
  2798                              <1> 	;mov	word [ebx], 200h
  2799                              <1> 	
  2800 0000551D E823000000          <1> 	call	poke
  2801                              <1> 	; 09/06/2015
  2802 00005522 73F2                <1> 	jnc	short dskwr_1
  2803                              <1> 	; 08/02/2022
  2804 00005524 803D[44660000]FF    <1> 	cmp	byte [u.brwdev], 0FFh ; is error code set in [u.error] ?
  2805 0000552B 7509                <1> 	jne	short dskwr_0 ; no
  2806                              <1> 	; yes, clear [u.brwdev] for next check and jump to 'error'
  2807 0000552D C605[44660000]00    <1> 	mov	byte [u.brwdev], 0
  2808 00005534 EB0A                <1> 	jmp	short dskwr_2
  2809                              <1> dskwr_0:
  2810 00005536 C705[31660000]1200- <1> 	mov	dword [u.error], ERR_DRV_WRITE ; disk write error !
  2810 0000553E 0000                <1>
  2811                              <1> dskwr_2:
  2812 00005540 E98CDCFFFF          <1> 	jmp	error
  2813                              <1> ;dskwr_1:
  2814                              <1> ;	retn
  2815                              <1> 
  2816                              <1> ;ppoke:
  2817                              <1>        		; mov $340,*$ps
  2818                              <1>        		; jsr r0,poke
  2819                              <1>        		; clr *$ps
  2820                              <1> 		; rts r0
  2821                              <1> 
  2822                              <1> poke:
  2823                              <1> 	; 15/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2824                              <1> 	; 14/07/2022
  2825                              <1> 	;	! Major Modification !
  2826                              <1> 	;	Retro UNIX 386 v1 (Kernel v0.2.0.22)
  2827                              <1> 	;
  2828                              <1> 	; 04/02/2022 (32 bit reg push pop)
  2829                              <1> 	; 24/10/2015
  2830                              <1> 	; 20/08/2015
  2831                              <1> 	; 18/08/2015
  2832                              <1> 	; 02/07/2015
  2833                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2834                              <1> 	; 15/03/2013 - 18/01/2014 (Retro UNIX 8086 v1)
  2835                              <1> 	;
  2836                              <1> 	; (NOTE: There are some disk I/O code modifications & extensions
  2837                              <1> 	; & exclusions on original 'poke' & other device I/O procedures of 
  2838                              <1> 	; UNIX v1 OS for performing disk I/O functions by using IBM PC 
  2839                              <1> 	; compatible rombios calls in Retro UNIX 8086 v1 kernel.)
  2840                              <1> 	;
  2841                              <1> 	; Basic I/O functions for all block structured devices
  2842                              <1> 	;
  2843                              <1>         ; (Modified registers: ECX, EDX, ESI, EDI)
  2844                              <1> 	;
  2845                              <1> 	; 20/07/2013 modifications
  2846                              <1> 	;            (Retro UNIX 8086 v1 features only !)
  2847                              <1> 	; INPUTS -> 
  2848                              <1> 	;        EBX = buffer header address
  2849                              <1> 	; OUTPUTS ->
  2850                              <1> 	;	 cf=0 -> successed r/w (at least, for the caller's buffer) 
  2851                              <1> 	;	 cf=1 -> error, word [EBX] = 0FFFFh
  2852                              <1> 	;		(drive not ready or r/w error!)
  2853                              <1> 	;	 (dword [EBX+4] <> 0FFFFFFFFh indicates r/w success)	
  2854                              <1> 	;	 (dword [EBX+4] = 0FFFFFFFFh means RW/IO error)
  2855                              <1> 	;        (also it indicates invalid buffer data)
  2856                              <1> 	
  2857                              <1> 	; 15/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  2858                              <1> 	; 14/07/2022 - Retro UNIX 386 v1 (Kernel v0.2.0.22)
  2859                              <1> 	; Buffer header:
  2860                              <1> 	;	byte 0 - device/disk (index) number
  2861                              <1> 	;	byte 1 - status
  2862                              <1> 	;	    before 'poke'	
  2863                              <1> 	;		bit 0 - valid bit 
  2864                              <1> 	;		   (0 for new buffer)
  2865                              <1> 	;		   (1 for existing buffer)	
  2866                              <1> 	;		bit 1 - write (modified) bit, disk write flag
  2867                              <1> 	;		bit 2 - read bit, disk read flag
  2868                              <1> 	;	    after 'poke'
  2869                              <1> 	;		if disk r/w is successed
  2870                              <1> 	;		   bit 0 = 1
  2871                              <1> 	;		   bit 1 = 0
  2872                              <1> 	;		   bit 2 = 0
  2873                              <1> 	;		if disk r/w is failed
  2874                              <1> 	;		   bit 0 = 0 (invalid buffer)
  2875                              <1> 	;		   bit 1 = 0 (write bit)
  2876                              <1> 	;		   bit 2 = 0 (read bit)	
  2877                              <1>  	;
  2878                              <1> 	;	byte 2 & byte 3 - not used
  2879                              <1> 	;	byte 4 to byte 7 - disk block/sector address
  2880                              <1> 	
  2881                              <1> 	; 04/02/2022
  2882 00005545 50                  <1> 	push	eax
  2883 00005546 E896000000          <1> 	call	diskio ; Retro UNIX 8086 v1 Only !
  2884 0000554B 58                  <1> 	pop	eax
  2885 0000554C 730D                <1> 	jnc	short seta ; 14/07/2022
  2886                              <1> 	
  2887                              <1> 	; 14/07/2022
  2888                              <1> 	; (invalidate buffer)
  2889                              <1> 	
  2890                              <1> 	; 02/07/2015 (32 bit modification)
  2891                              <1> 	; 20/07/2013
  2892 0000554E C74304FFFFFFFF      <1> 	mov	dword [ebx+4], 0FFFFFFFFh ; -1 
  2893                              <1>        		; mov $-1,2(r1) / destroy associativity
  2894 00005555 66C703FF00          <1> 	mov	word [ebx], 0FFh ; 20/08/2015 
  2895                              <1> 		; clrb 1(r1) / do not do I/O
  2896                              <1> 	;stc
  2897 0000555A C3                  <1> 	retn
  2898                              <1>         	; rts r0
  2899                              <1> seta: 
  2900 0000555B C6430101            <1> 	mov	byte [ebx+1], 1 ; clear write/read bits, set valid bit
  2901                              <1> 	;clc
  2902 0000555F C3                  <1> 	retn
  2903                              <1> 
  2904                              <1> %if 0
  2905                              <1> 
  2906                              <1> poke:
  2907                              <1> 	; 24/12/2021 (32 bit reg push-pop)
  2908                              <1> 	; 24/10/2015
  2909                              <1> 	; 20/08/2015
  2910                              <1> 	; 18/08/2015
  2911                              <1> 	; 02/07/2015
  2912                              <1> 	; 09/06/2015 (Retro UNIX 386 v1 - Beginning)
  2913                              <1> 	; 15/03/2013 - 18/01/2014 (Retro UNIX 8086 v1)
  2914                              <1> 	;
  2915                              <1> 	; (NOTE: There are some disk I/O code modifications & extensions
  2916                              <1> 	; & exclusions on original 'poke' & other device I/O procedures of 
  2917                              <1> 	; UNIX v1 OS for performing disk I/O functions by using IBM PC 
  2918                              <1> 	; compatible rombios calls in Retro UNIX 8086 v1 kernel.)
  2919                              <1> 	;
  2920                              <1> 	; Basic I/O functions for all block structured devices
  2921                              <1> 	;
  2922                              <1>         ; (Modified registers: ECX, EDX, ESI, EDI)
  2923                              <1> 	;
  2924                              <1> 	; 20/07/2013 modifications
  2925                              <1> 	;            (Retro UNIX 8086 v1 features only !)
  2926                              <1> 	; INPUTS -> 
  2927                              <1> 	;        (EBX = buffer header address)
  2928                              <1> 	; OUTPUTS ->
  2929                              <1> 	;	 cf=0 -> successed r/w (at least, for the caller's buffer) 
  2930                              <1> 	;	 cf=1 -> error, word [EBX] = 0FFFFh
  2931                              <1> 	;		(drive not ready or r/w error!)
  2932                              <1> 	;	 (dword [EBX+4] <> 0FFFFFFFFh indicates r/w success)	
  2933                              <1> 	;	 (dword [EBX+4] = 0FFFFFFFFh means RW/IO error)
  2934                              <1> 	;        (also it indicates invalid buffer data)
  2935                              <1> 	;
  2936                              <1> 	push	ebx
  2937                              <1>        		; mov r1,-(sp)
  2938                              <1>        		; mov r2,-(sp)
  2939                              <1>        		; mov r3,-(sp)
  2940                              <1> 	push 	eax ; Physical Block Number (r1) (mget)
  2941                              <1> 	;
  2942                              <1> 	; 09/06/2015
  2943                              <1> 	; (permit read/write after a disk  R/W error)
  2944                              <1> 	mov	cl, [ebx] ; device id (0 to 5)
  2945                              <1> 	mov	al, 1
  2946                              <1> 	shl	al, cl
  2947                              <1> 	test 	al, [active] ; busy ? (error)
  2948                              <1> 	jz	short poke_0
  2949                              <1> 	not	al
  2950                              <1> 	and	[active], al ; reset busy bit for this device only
  2951                              <1> poke_0:
  2952                              <1>         mov     esi, bufp + (4*(nbuf+2)) 
  2953                              <1> 		; mov $bufp+nbuf+nbuf+6,r2 / r2 points to highest priority
  2954                              <1> 					 ; / I/O queue pointer
  2955                              <1> poke_1: ; 1:
  2956                              <1>         sub	esi, 4
  2957                              <1> 	mov	ebx, [esi]
  2958                              <1> 		; mov -(r2),r1 / r1 points to an I/O queue entry
  2959                              <1> 	mov	ax, [ebx] ; 17/07/2013
  2960                              <1>        	test	ah, 06h
  2961                              <1> 	;test	word [ebx], 600h ; 0000011000000000b
  2962                              <1> 		; bit $3000,(r1) / test bits 9 and 10 of word 1 of I/O 
  2963                              <1> 			       ; / queue entry
  2964                              <1>         jz      short poke_5
  2965                              <1> 		; beq 2f / branch to 2f if both are clear
  2966                              <1> 	; 31/07/2013
  2967                              <1> 	;test	ah, 0B0h ; (*)
  2968                              <1> 	;;test	word [ebx], 0B000h ; 1011000000000000b
  2969                              <1> 		; bit $130000,(r1) / test bits 12, 13, and 15
  2970                              <1>         ;jnz	short poke_5 ; 31/07/2013 (*)
  2971                              <1> 		; bne 2f / branch if any are set
  2972                              <1> 	;movzx	ecx, byte [ebx] ; 09/06/2015 ; Device Id
  2973                              <1>     		; movb (r1),r3 / get device id
  2974                              <1> 	movzx	ecx, al ; 18/08/2015
  2975                              <1> 	;mov	edi, ecx ; 26/04/2013
  2976                              <1> 	xor 	eax, eax ; 0
  2977                              <1> 	;cmp 	[edi+drv.error], al ; 0
  2978                              <1> 		; tstb deverr(r3) / test for errors on this device
  2979                              <1>        	;jna	short poke_2 
  2980                              <1> 		; beq 3f / branch if no errors
  2981                              <1> 	; 02/07/2015
  2982                              <1> 	;dec	eax
  2983                              <1> 	;mov	[ebx+4], ax ; 0FFFFFFFFh ; -1 
  2984                              <1>        		; mov $-1,2(r1) / destroy associativity
  2985                              <1> 	;shr	eax, 24
  2986                              <1> 	;mov	[ebx], eax ; 000000FFh, reset
  2987                              <1> 		; clrb 1(r1) / do not do I/O
  2988                              <1> 	;jmp	short poke_5
  2989                              <1>         ;       ; br 2f
  2990                              <1>                 ; rts r0
  2991                              <1> poke_2: ; 3:
  2992                              <1> 	; 02/07/2015
  2993                              <1> 	inc	cl ; 0FFh -> 0
  2994                              <1> 	jz	short poke_5
  2995                              <1> 	inc	al ; mov ax, 1
  2996                              <1> 	dec	cl
  2997                              <1> 	jz	short poke_3
  2998                              <1> 	; 26/04/2013 Modification
  2999                              <1> 	;inc	al ; mov ax, 1
  3000                              <1> 	;or	cl, cl ; Retro UNIX 8086 v1 device id.
  3001                              <1> 	;jz	short poke_3 ; cl = 0
  3002                              <1> 	shl	al, cl ; shl ax, cl
  3003                              <1> poke_3:
  3004                              <1> 	;test	[active], ax
  3005                              <1> 	test	[active], al
  3006                              <1> 		; bit $2,active / test disk busy bit
  3007                              <1> 	jnz     short poke_5
  3008                              <1> 		; bne 2f / branch if bit is set
  3009                              <1> 	;or	[active], ax
  3010                              <1> 	or	[active], al
  3011                              <1> 		; bis $2,active / set disk busy bit
  3012                              <1> 	;push	ax
  3013                              <1> 	; 24/12/2021
  3014                              <1> 	push	eax
  3015                              <1> 	call	diskio ; Retro UNIX 8086 v1 Only !
  3016                              <1> 	;mov    [edi+drv.error], ah
  3017                              <1> 	; 24/12/2021
  3018                              <1> 	pop	eax
  3019                              <1> 	;pop	ax
  3020                              <1> 	jnc	short poke_4 ; 20/07/2013
  3021                              <1> 	;cmp 	[edi+drv.error], al ; 0	
  3022                              <1> 	;jna	short poke_4
  3023                              <1> 		; tstb deverr(r3) / test for errors on this device
  3024                              <1>        		; beq 3f / branch if no errors
  3025                              <1> 	; 02/07/2015 (32 bit modification)
  3026                              <1> 	; 20/07/2013
  3027                              <1> 	mov	dword [ebx+4], 0FFFFFFFFh ; -1 
  3028                              <1>        		; mov $-1,2(r1) / destroy associativity
  3029                              <1> 	mov	word [ebx], 0FFh ; 20/08/2015 
  3030                              <1> 		; clrb 1(r1) / do not do I/O
  3031                              <1> 	jmp     short poke_5
  3032                              <1> poke_4:	; 20/07/2013
  3033                              <1> 	; 17/07/2013
  3034                              <1> 	not 	al 
  3035                              <1> 	and	[active], al ; reset, not busy
  3036                              <1> 	; EBX = system I/O buffer header (queue entry) address
  3037                              <1> seta: ; / I/O queue bookkeeping; set read/write waiting bits.
  3038                              <1> 	mov	ax, [ebx]
  3039                              <1>        		; mov (r1),r3 / move word 1 of I/O queue entry into r3
  3040                              <1>         and	ax, 600h
  3041                              <1> 		; bic $!3000,r3 / clear all bits except 9 and 10
  3042                              <1> 	and 	word [ebx], 0F9FFh
  3043                              <1>        		; bic $3000,(r1) / clear only bits 9 and 10
  3044                              <1> 	shl	ah, 3
  3045                              <1>        		; rol r3
  3046                              <1>                 ; rol r3
  3047                              <1>                 ; rol r3	
  3048                              <1> 	or	[ebx], ax
  3049                              <1> 		; bis r3,(r1) / or old value of bits 9 and 10 with 
  3050                              <1> 			   ; bits 12 and 13
  3051                              <1> 	call	idle ; 18/01/2014
  3052                              <1> 	;; sti
  3053                              <1> 	;hlt 	; wait for a hardware interrupt
  3054                              <1> 	;; cli
  3055                              <1> 	; NOTE: In fact, disk controller's 'disk I/O completed' 
  3056                              <1>         ; interrupt would be used to reset busy bits, but INT 13h
  3057                              <1> 	; returns when disk I/O is completed. So, here, as temporary
  3058                              <1> 	; method, this procedure will wait for a time according to
  3059                              <1> 	; multi tasking and time sharing concept.
  3060                              <1> 	;
  3061                              <1> 	; 24/10/2015
  3062                              <1> 	;not	ax 
  3063                              <1> 	mov 	ax, 0FFh ; 24/10/2015 (temporary)
  3064                              <1> 	and	[ebx], ax ; clear bits 12 and 13
  3065                              <1> poke_5: ;2:
  3066                              <1>         cmp     esi, bufp
  3067                              <1> 		; cmp r2,$bufp / test to see if entire I/O queue 
  3068                              <1>                             ; / has been scanned
  3069                              <1> 	ja      short poke_1
  3070                              <1> 		; bhi 1b
  3071                              <1> 	; 24/03/2013
  3072                              <1>        		; mov (sp)+,r3
  3073                              <1>        		; mov (sp)+,r2
  3074                              <1>        		; mov (sp)+,r1
  3075                              <1>         pop 	eax  ; Physical Block Number (r1) (mget)
  3076                              <1> 	pop 	ebx
  3077                              <1> 	; 02/07/2015 (32 bit modification)
  3078                              <1> 	; 20/07/2013
  3079                              <1> 	;cmp 	dword [ebx+4], 0FFFFFFFFh
  3080                              <1> 	cmp	byte [ebx], 0FFh ; 20/08/2015
  3081                              <1> 	;	
  3082                              <1> 	; 'poke' returns with cf=0 if the requested buffer is read 
  3083                              <1> 	; or written successfully; even if an error occurs while
  3084                              <1> 	; reading to or writing from other buffers. 20/07/2013
  3085                              <1> 	;
  3086                              <1> 	; 09/06/2015
  3087                              <1> 	cmc
  3088                              <1> 	retn
  3089                              <1>                 ; rts r0
  3090                              <1> 
  3091                              <1> %endif
  3092                              <1> 
  3093                              <1> bufaloc:
  3094                              <1> 	; 15/07/2022
  3095                              <1> 	;	Retro UNIX 386 v1.1 (Kernel v0.2.1.6)
  3096                              <1> 	; 14/07/2022
  3097                              <1> 	;	Retro UNIX 386 v1 (Kernel v0.2.0.22)
  3098                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  3099                              <1> 	; 20/08/2015
  3100                              <1> 	; 19/08/2015
  3101                              <1> 	; 02/07/2015
  3102                              <1> 	; 11/06/2015 (Retro UNIX 386 v1 - Beginning)
  3103                              <1> 	;	     (32 bit modifications)	
  3104                              <1> 	; 13/03/2013 - 29/07/2013 (Retro UNIX 8086 v1)
  3105                              <1> 	;
  3106                              <1> 	; bufaloc - Block device I/O buffer allocation
  3107                              <1> 	; 
  3108                              <1> 	; INPUTS ->
  3109                              <1> 	;    r1 - block number
  3110                              <1> 	;    cdev - current (block/disk) device number
  3111                              <1> 	;    bufp+(2*n)-2 --- n = 1 ... nbuff
  3112                              <1> 	; OUTPUTS ->
  3113                              <1> 	;    r5 - pointer to buffer allocated
  3114                              <1> 	;    bufp ... bufp+12 --- (bufp), (bufp)+2
  3115                              <1> 	;
  3116                              <1> 	; ((AX = R1)) input/output
  3117                              <1> 	; ((BX = R5)) output
  3118                              <1>         ;    ((Modified registers: DX, CX, BX, SI, DI, BP))
  3119                              <1> 	;    zf=1 -> block already in a I/O buffer
  3120                              <1> 	;    zf=0 -> a new I/O buffer has been allocated
  3121                              <1> 	;    ((DL = Device ID))
  3122                              <1> 	;    (((DH = 0 or 1)))
  3123                              <1> 	;    (((CX = previous value of word ptr [bufp])))
  3124                              <1> 	;    ((CX and DH will not be used after return)))
  3125                              <1> 
  3126                              <1> 	; 14/07/2022
  3127                              <1> 	;	Modified registers: EBX, ECX, EDX, ESI, EDI
  3128                              <1> 
  3129                              <1> 	;;push 	esi ; ***
  3130                              <1> 		; mov r2,-(sp) / save r2 on stack
  3131                              <1>        		; mov $340,*$ps / set processor priority to 7
  3132                              <1> 	; 20/07/2013
  3133                              <1> 	; 26/04/2013
  3134                              <1> 	;movzx	ebx, byte [cdev] ; 0 or 1
  3135                              <1> 	;mov	edi, rdev ; offset mdev = offset rdev + 1
  3136                              <1> 	;add	edi, ebx
  3137                              <1> 	; 09/01/2022
  3138 00005560 0FB63D[C3650000]    <1> 	movzx	edi, byte [cdev] ; 0 or 1
  3139 00005567 81C7[C4650000]      <1> 	add	edi, rdev
  3140                              <1> bufaloc_0: ; 26/04/2013 !! here is called from bread or bwrite !!
  3141                              <1> 			;; EDI points to device id.
  3142 0000556D 0FB61F              <1> 	movzx	ebx, byte [edi] ; [EDI] -> rdev/mdev or brwdev
  3143                              <1> 	; 11/06/2015
  3144 00005570 80BB[5E5D0000]F0    <1> 	cmp 	byte [ebx+drv.status], 0F0h ; Drive not ready !
  3145 00005577 720F                <1> 	jb	short bufaloc_9
  3146 00005579 C705[31660000]0F00- <1> 	mov	dword [u.error], ERR_DRV_NOT_RDY
  3146 00005581 0000                <1>
  3147 00005583 E949DCFFFF          <1> 	jmp	error
  3148                              <1> bufaloc_9:
  3149 00005588 89DA                <1> 	mov	edx, ebx ; dh = 0, dl = device number (0 to 5)
  3150                              <1> bufaloc_10: ; 02/07/2015
  3151                              <1> 	; 14/07/2022
  3152                              <1> 	;xor 	ebp, ebp ; 0
  3153                              <1> 	;push	ebp ; 0
  3154                              <1>         ;mov	ebp, esp	
  3155 0000558A 31FF                <1> 	xor	edi, edi ; 0	
  3156 0000558C 57                  <1> 	push	edi
  3157                              <1> bufaloc_1: ;1:
  3158                              <1> 		; clr -(sp) / vacant buffer
  3159 0000558D BE[98650000]        <1>         mov 	esi, bufp
  3160                              <1> 		; mov $bufp,r2 / bufp contains pointers to I/O queue 
  3161                              <1> 			     ; / entrys in buffer area
  3162                              <1> bufaloc_2: ;2:
  3163 00005592 8B1E                <1> 	mov	ebx, [esi]
  3164                              <1>        		; mov (r2)+,r5 / move pointer to word 1 of an I/O 
  3165                              <1> 			    ; queue entry into r5
  3166                              <1> 	; 14/07/2022
  3167 00005594 8B0B                <1> 	mov	ecx, [ebx]	
  3168                              <1> 	;test	word [ebx], 0F600h
  3169                              <1> 	; 15/07/2022
  3170 00005596 F6C501              <1> 	test	ch, 1 ; valid buffer (content) ?
  3171                              <1> 		; bit $173000,(r5) / lock+keep+active+outstanding
  3172 00005599 7505                <1>         jnz	short bufaloc_3 ; yes
  3173                              <1> 		; bne 3f / branch when 
  3174                              <1> 		       ; / any of bits 9,10,12,13,14,15 are set
  3175                              <1>                        ; / (i.e., buffer busy)
  3176                              <1> 	;mov    [ebp], esi ; pointer to I/0 queue entry
  3177                              <1> 	; 14/07/2022
  3178                              <1> 	; save free buffer pointer 
  3179 0000559B 893424              <1> 	mov	[esp], esi
  3180                              <1>                 ; mov r2,(sp) ;/ save pointer to last non-busy buffer
  3181                              <1> 			; / found points to word 2 of I/O queue entry)
  3182                              <1> 	; continue to see if requested sector/block buffer
  3183                              <1> 	;	already is one of existing (valid) buffers
  3184                              <1> 	;jmp	short bufaloc_4
  3185 0000559E EB0E                <1> 	jmp	short bufaloc_11 ; 14/07/2022
  3186                              <1> bufaloc_3: ;3:
  3187                              <1> 	;mov	dl, [edi] ; 26/04/2013
  3188                              <1> 	;
  3189 000055A0 38D1                <1> 	cmp	cl, dl ; 14/07/2022
  3190                              <1> 	;cmp	[ebx], dl	
  3191                              <1> 		; cmpb (r5),cdev / is device in I/O queue entry same 
  3192                              <1> 			       ; / as current device
  3193 000055A2 7508                <1> 	jne	short bufaloc_4
  3194                              <1>        		; bne 3f
  3195 000055A4 394304              <1> 	cmp	[ebx+4], eax
  3196                              <1>        		; cmp 2(r5),r1 / is block number in I/O queue entry, 
  3197                              <1> 			     ; / same as current block number
  3198 000055A7 7503                <1>        	jne	short bufaloc_4
  3199                              <1> 		; bne 3f
  3200                              <1> 	;add	esp, 4
  3201 000055A9 59                  <1> 	pop	ecx
  3202                              <1>        		; tst (sp)+ / bump stack pointer
  3203 000055AA EB1D                <1> 	jmp	short bufaloc_7 ; Retro Unix 8086 v1 modification
  3204                              <1> 				; jump to bufaloc_6 in original Unix v1
  3205                              <1>        		; br 1f / use this buffer
  3206                              <1> bufaloc_4: ;3:
  3207                              <1> 	; 14/07/2022
  3208                              <1> 	; save last valid buffer 
  3209                              <1> 	; (will be used if there is not a free buffer)
  3210 000055AC 89F7                <1> 	mov	edi, esi	
  3211                              <1> bufaloc_11:
  3212 000055AE 83C604              <1> 	add	esi, 4 ; 20/08/2015
  3213                              <1> 	;
  3214 000055B1 81FE[B8650000]      <1> 	cmp	esi, bufp + (nbuf*4)
  3215                              <1> 		; cmp r2,$bufp+nbuf+nbuf
  3216 000055B7 72D9                <1> 	jb	short bufaloc_2
  3217                              <1> 		; blo 2b / go to 2b if r2 less than bufp+nbuf+nbuf (all
  3218                              <1>                        ; / buffers not checked)
  3219 000055B9 5E                  <1>         pop	esi
  3220                              <1> 		; mov (sp)+,r2 / once all bufs are examined move pointer
  3221                              <1> 			     ; / to last free block
  3222 000055BA 09F6                <1>        	or	esi, esi 
  3223 000055BC 7502                <1> 	jnz	short bufaloc_5
  3224                              <1> 		; bne 2f / if (sp) is non zero, i.e., 
  3225                              <1> 	        ; / if a free buffer is found branch to 2f
  3226                              <1> 
  3227                              <1> 	; 14/07/2022        
  3228                              <1> 	; if there is not a free buffer
  3229                              <1> 	; we can use last valid buffer (the oldest buffer)
  3230                              <1> 	; ((ptr to new buffer is located at head of buff ptr chain))
  3231 000055BE 89FE                <1> 	mov	esi, edi
  3232                              <1> 
  3233                              <1> 	;;mov  ecx, [s.wait_]
  3234                              <1> 	;call	idle
  3235                              <1> 	;	; jsr r0,idle; s.wait+2 / idle if no free buffers
  3236                              <1> 	;jmp 	short bufaloc_10 ; 02/07/2015
  3237                              <1>        	;	; br 1b
  3238                              <1> bufaloc_5: ;2:
  3239                              <1> 		; tst (r0)+ / skip if warmed over buffer
  3240                              <1> 	; 14/07/2022
  3241                              <1> 	;inc	dh ; Retro UNIX 8086 v1 modification
  3242                              <1> bufaloc_6: ;1:
  3243 000055C0 8B1E                <1>         mov    	ebx, [esi] 
  3244                              <1> 		; mov -(r2),r5 / put pointer to word 1 of I/O queue 
  3245                              <1> 			     ; / entry in r5
  3246                              <1> 	;; 26/04/2013
  3247                              <1>         ;;mov	dl, [edi] ; byte [rdev] or byte [mdev]
  3248                              <1> 	;mov 	[ebx], dl
  3249                              <1> 		; movb cdev,(r5) / put current device number 
  3250                              <1> 				 ; / in I/O queue entry
  3251                              <1> 	; 14/07/2022
  3252                              <1> 	; invalidate buffer before r/w (new) disk sector/block
  3253                              <1> 	;mov	[ebx+1], dh ; 0
  3254                              <1> 	; 14/07/2022
  3255 000055C2 8913                <1> 	mov	[ebx], edx  ; dh = 0
  3256                              <1> 	
  3257 000055C4 894304              <1> 	mov 	[ebx+4], eax
  3258                              <1> 		; mov r1,2(r5) / move block number into word 2 
  3259                              <1> 			     ; / of I/O queue entry
  3260                              <1> 	; 14/07/2022
  3261 000055C7 FEC6                <1> 	inc	dh ; dh = 1
  3262                              <1> bufaloc_7: ;1:
  3263 000055C9 81FE[98650000]      <1>         cmp	esi, bufp
  3264                              <1> 		; cmp r2,$bufp / bump all entrys in bufp 
  3265                              <1> 			     ; / and put latest assigned
  3266 000055CF 760B                <1> 	jna	short bufaloc_8	
  3267                              <1>        		; blos 1f / buffer on the top 
  3268                              <1> 			; / (this makes if the lowest priority)
  3269                              <1> 	; 14/07/2022
  3270 000055D1 89F7                <1> 	mov	edi, esi
  3271 000055D3 83EE04              <1> 	sub	esi, 4
  3272 000055D6 8B0E                <1> 	mov	ecx, [esi]
  3273 000055D8 890F                <1> 	mov	[edi], ecx ; 14/07/2022
  3274                              <1> 	;mov	[esi+4], ecx
  3275                              <1> 		; mov -(r2),2(r2) / job for a particular device
  3276 000055DA EBED                <1> 	jmp 	short bufaloc_7        
  3277                              <1> 		; br 1b
  3278                              <1> bufaloc_8: ;1:
  3279 000055DC 891E                <1>         mov	[esi], ebx
  3280                              <1> 		; mov r5,(r2)
  3281                              <1> 	;;pop	esi ; ***
  3282                              <1>        		; mov (sp)+,r2 / restore r2
  3283 000055DE 08F6                <1>        	or 	dh, dh ; 0 or 1 ?
  3284                              <1> 		; Retro UNIX 8086 v1 modification
  3285                              <1> 		; zf=1 --> block already is in an I/O buffer
  3286                              <1> 		; zf=0 --> a new I/O buffer has been allocated
  3287 000055E0 C3                  <1> 	retn
  3288                              <1> 		; rts r0
  3289                              <1> 
  3290                              <1> diskio:
  3291                              <1> 	; 12/07/2022
  3292                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3293                              <1> 	;	((simplified and shortened 'diskio.s' code))
  3294                              <1> 	; 12/02/2022
  3295                              <1> 	; 10/02/2022
  3296                              <1> 	; 08/02/2022
  3297                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1 2022, Kernel v0.2.1.2)
  3298                              <1> 	; 10/07/2015
  3299                              <1> 	; 02/07/2015
  3300                              <1> 	; 16/06/2015
  3301                              <1> 	; 11/06/2015 (Retro UNIX 386 v1 - Beginning)
  3302                              <1> 	;	     (80386 protected mode modifications)	
  3303                              <1> 	; 15/03/2013 - 29/04/2013 (Retro UNIX 8086 v1)
  3304                              <1> 	;
  3305                              <1> 	; Retro UNIX 8086 v1 feature only !
  3306                              <1> 	;
  3307                              <1> 	; Derived from proc_chs_read procedure of TRDOS DISKIO.ASM (2011)
  3308                              <1> 	; 04/07/2009 - 20/07/2011
  3309                              <1> 	;
  3310                              <1> 	; NOTE: Reads only 1 block/sector (sector/block size is 512 bytes)
  3311                              <1> 	;
  3312                              <1>         ; INPUTS ->
  3313                              <1> 	; 	   EBX = System I/O Buffer header address
  3314                              <1> 	;
  3315                              <1>         ; OUTPUTS -> cf=0 --> done 
  3316                              <1> 	; 	     cf=1 --> error code in AH
  3317                              <1> 	;	     ; 08/02/2022
  3318                              <1> 	;	     cf=1 & [u.brwdev] = 0FFh -->
  3319                              <1> 	;		error code in [u.error]
  3320                              <1> 	;		
  3321                              <1> 	; (Modified registers: EAX, ECX, EDX)
  3322                              <1> 	
  3323                              <1> ;rw_disk_sector:
  3324                              <1> 	; 12/07/2022
  3325                              <1> 	; 08/07/2022
  3326                              <1> 	; 12/02/2022
  3327                              <1> 	; 10/02/2022
  3328                              <1> 	; 08/02/2022
  3329                              <1> 	; 10/07/2015
  3330                              <1> 	; 02/07/2015
  3331                              <1> 	; 11/06/2015 - Retro UNIX 386 v1 - 'u8.s' 
  3332                              <1> 	; 21/02/2015 ('dsectpm.s', 'read_disk_sector')
  3333                              <1> 	; 16/02/2015 (Retro UNIX 386 v1 test - 'unix386.s')
  3334                              <1> 	; 01/12/2014 - 18/01/2015 ('dsectrm2.s')
  3335                              <1> 	;
  3336                              <1> 	;;mov	dx, 0201h ; Read 1 sector/block
  3337                              <1> 	;mov	dh, 2
  3338                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3339 000055E1 B602                <1> 	mov	dh, 2 ; Write 1 sector/block
  3340 000055E3 668B03              <1> 	mov	ax, [ebx] 
  3341                              <1> 	;
  3342 000055E6 56                  <1> 	push	esi ; ****
  3343 000055E7 53                  <1> 	push	ebx ; ***
  3344                              <1> 	;
  3345 000055E8 0FB6C8              <1> 	movzx	ecx, al
  3346 000055EB 89CE                <1> 	mov	esi, ecx
  3347                              <1> 	;
  3348 000055ED 38F1                <1> 	cmp	cl, dh ; 2
  3349 000055EF 7202                <1> 	jb	short rwdsk0
  3350 000055F1 047E                <1> 	add	al, 7Eh  ; 80h, 81h, 82h, 83h
  3351                              <1> rwdsk0:
  3352                              <1> 	; 12/07/2022
  3353                              <1> 	;mov	[drv], al
  3354 000055F3 81C6[5E5D0000]      <1> 	add	esi, drv.status
  3355                              <1> 	; 11/06/2015
  3356 000055F9 803EF0              <1> 	cmp	byte [esi], 0F0h 
  3357 000055FC 7204                <1> 	jb      short rwdsk1
  3358                              <1> 	; 'drive not ready' error
  3359                              <1> 	; 10/02/2022
  3360                              <1> 	; 08/02/2022
  3361                              <1> 	;mov	byte [u.brwdev], 0FFh ; error code in [u.error]
  3362                              <1> 	;mov	dword [u.error], ERR_DRV_NOT_RDY
  3363                              <1> 	;;jmp	error
  3364                              <1> 	;stc	; cf = 1
  3365                              <1> 	;retn
  3366                              <1> 	; 10/02/2022
  3367 000055FE B10F                <1> 	mov	cl, ERR_DRV_NOT_RDY
  3368 00005600 EB1F                <1> 	jmp	short rwdsk_err1
  3369                              <1> rwdsk1:
  3370                              <1> 	;test	ah, 2
  3371                              <1> 	;;test	ax, 200h ; Bit 9 of word 0 (status word)
  3372                              <1> 	;		 ; write bit
  3373                              <1> 	;jz	short rwdsk2
  3374                              <1> 	
  3375                              <1> 	;;test	ah, 4
  3376                              <1> 	;;;test	ax, 400h ; Bit 10 of word 0 (status word)
  3377                              <1> 	;;		 ; read bit
  3378                              <1> 	;;jz	short diskio_ret
  3379                              <1> 
  3380                              <1> 	;inc	dh ; 03h = write
  3381                              <1> 
  3382                              <1> 	; 08/07/2022
  3383 00005602 84F4                <1> 	test	ah, dh ; test ah, 2
  3384 00005604 7502                <1> 	jnz	short rwdsk2 ; dh = 02h = write
  3385 00005606 FECE                <1> 	dec	dh
  3386                              <1> 		; dh = 01h = read
  3387                              <1> rwdsk2:
  3388 00005608 88C2                <1> 	mov	dl, al
  3389 0000560A 83C304              <1> 	add	ebx, 4 ; sector/block address/number pointer
  3390 0000560D 8B03                <1> 	mov	eax, [ebx] ; sector/block number (LBA)
  3391 0000560F C0E102              <1> 	shl	cl, 2
  3392 00005612 81C1[425D0000]      <1> 	add	ecx, drv.size ; disk size
  3393 00005618 3B01                <1> 	cmp	eax, [ecx] ; Last sector + 1 (number of secs.)
  3394 0000561A 7214                <1> 	jb      short rwdsk3
  3395                              <1>  	; 'out of volume' error
  3396                              <1> 	; 10/02/2022
  3397                              <1> 	; 08/02/2022
  3398                              <1> 	;mov	byte [u.brwdev], 0FFh ; error code in [u.error]
  3399                              <1> 	;mov 	dword [u.error], ERR_DEV_VOL_SIZE
  3400                              <1> 	;;jmp	error
  3401                              <1> 	;stc	; cf = 1
  3402                              <1> 	;retn
  3403                              <1> 	; 10/02/2022
  3404 0000561C B910000000          <1> 	mov	ecx, ERR_DEV_VOL_SIZE
  3405                              <1> rwdsk_err1:
  3406 00005621 C605[44660000]FF    <1> 	mov	byte [u.brwdev], 0FFh
  3407 00005628 890D[31660000]      <1> 	mov 	[u.error], ecx ; 12/02/2022
  3408 0000562E EB27                <1> 	jmp	short rwdsk_err2
  3409                              <1> rwdsk3:
  3410                              <1> 	; 11/06/2015
  3411 00005630 83C304              <1> 	add	ebx, 4 ; buffer address
  3412 00005633 C605[62660000]04    <1> 	mov	byte [retry_count], 4
  3413                              <1> 	; 12/07/2022
  3414                              <1> 	;test	byte [esi], 1 ; LBA ready ?
  3415                              <1>         ;jz	short rwdsk_chs
  3416                              <1> rwdsk_lba:
  3417                              <1> 	; LBA read/write (with private LBA function) 
  3418                              <1> 	;((Retro UNIX 386 v1 - DISK I/O code by Erdogan Tan))
  3419 0000563A 83C607              <1>         add     esi, drv.error - drv.status ; 10/07/2015
  3420 0000563D 89C1                <1> 	mov	ecx, eax ; sector number
  3421                              <1> 	; ebx = buffer (data) address
  3422                              <1> 	; dl = physical drive number (0, 1, 80h, 81h, 82h, 83h)
  3423                              <1> rwdsk_lba_retry:
  3424                              <1> 	;mov	dl, [drv]
  3425                              <1> 		; Function 1Bh = LBA read, 1Ch = LBA write
  3426                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3427                              <1> 	;;mov	ah, 1Ch - 03h ; LBA write function number - 3
  3428                              <1> 	;mov	ah, 2 ; LBA write function number - 2
  3429                              <1> 	;add	ah, dh		
  3430                              <1> 	;mov	al, 1
  3431                              <1> 	;int	13h
  3432                              <1> 	;call	int13h
  3433                              <1> 	; 12/07/2022
  3434 0000563F 88F0                <1> 	mov	al, dh	; function (1 or 2)
  3435                              <1> 			; (1 = read, 2 = write )
  3436                              <1> 	; ecx = disk sector address (LBA)
  3437                              <1> 	; ebx = buffer address
  3438                              <1> 	;  dl = (physical) disk number
  3439                              <1> 	;  al = function (r/w)
  3440 00005641 E80ECAFFFF          <1> 	call	DISK_IO
  3441                              <1> 
  3442 00005646 8826                <1> 	mov	[esi], ah ; error code ; 10/07/2015
  3443 00005648 730E                <1> 	jnc	short rwdsk_lba_ok
  3444 0000564A 80FC80              <1> 	cmp	ah, 80h ; time out ?
  3445 0000564D 7408                <1>         je      short rwdsk_lba_fails
  3446 0000564F FE0D[62660000]      <1> 	dec	byte [retry_count]
  3447 00005655 7504                <1>         jnz     short rwdsk_lba_reset ; 10/07/2015
  3448                              <1> rwdsk_err2:	; 10/02/2022
  3449                              <1> rwdsk_lba_fails:
  3450 00005657 F9                  <1> 	stc
  3451                              <1> rwdsk_lba_ok:
  3452 00005658 5B                  <1> 	pop	ebx ; ***
  3453 00005659 5E                  <1> 	pop	esi ; ****
  3454 0000565A C3                  <1> 	retn
  3455                              <1> rwdsk_lba_reset:
  3456                              <1> 	;mov	ah, 0Dh ; Alternate reset
  3457                              <1> 	;int	13h
  3458                              <1> 	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3459                              <1> 	;mov	ah, 5 ; Alternate reset	 
  3460                              <1> 	;call	int13h
  3461                              <1> 	;jnc	short rwdsk_lba_retry
  3462                              <1> 	; 12/07/2022
  3463 0000565B 30C0                <1> 	xor	al, al ; 0 ; reset
  3464 0000565D E8F2C9FFFF          <1> 	call	DISK_IO
  3465 00005662 73DB                <1> 	jnc	short rwdsk_lba_retry
  3466                              <1> 
  3467 00005664 8826                <1> 	mov	[esi], ah ; error code ; 10/07/2015
  3468 00005666 EBF0                <1> 	jmp	short rwdsk_lba_ok
  3469                              <1> 
  3470                              <1> 	; 12/07/2022 
  3471                              <1> 	;	(CHS Read/Write setup is not needed here.)
  3472                              <1> 	; 	(LBA address will be converted to CHS parameters 
  3473                              <1> 	;	in 'DISK_IO' procedure when/if it is required.)
  3474                              <1>  
  3475                              <1> ;	; CHS read (convert LBA address to CHS values)	
  3476                              <1> ;rwdsk_chs:
  3477                              <1> ;	; 10/07/2015
  3478                              <1> ;	sub	esi, drv.status
  3479                              <1> ;	mov	ecx, esi
  3480                              <1> ;	add 	esi, drv.error
  3481                              <1> ;	; 02/07/2015
  3482                              <1> ;	; 16/06/2015
  3483                              <1> ;	; 11/06/2015 
  3484                              <1> ;	push	ebx ; ** ; buffer
  3485                              <1> ;	shl	ecx, 1
  3486                              <1> ;	push	ecx ; * 
  3487                              <1> ;	;
  3488                              <1> ;	mov	ebx, ecx
  3489                              <1> ;	mov	[rwdsk], dh ; 02/07/2015
  3490                              <1> ;	xor	edx, edx ; 0
  3491                              <1> ;	; 09/01/2022
  3492                              <1> ;	;sub	ecx, ecx 
  3493                              <1> ;       add     ebx, drv.spt
  3494                              <1> ;	mov	cx, [ebx] ; sector per track
  3495                              <1> ;		; EDX:EAX = LBA
  3496                              <1> ;	div	ecx
  3497                              <1> ;	mov	cl, dl	; sector number - 1
  3498                              <1> ;	inc	cl	; sector number (1 based)
  3499                              <1> ;	pop	ebx ; * ; 11/06/2015
  3500                              <1> ;	;push	cx
  3501                              <1> ;	; 09/01/2022
  3502                              <1> ;	push	ecx
  3503                              <1> ;	add     ebx, drv.heads
  3504                              <1> ;	mov	cx, [ebx] ; heads
  3505                              <1> ;	xor	edx, edx
  3506                              <1> ;		; EAX = cylinders * heads + head
  3507                              <1> ;	div	ecx
  3508                              <1> ;	;pop	cx     ; sector number
  3509                              <1> ;	; 09/01/2022
  3510                              <1> ;	pop	ecx
  3511                              <1> ;	mov	dh, dl ; head number
  3512                              <1> ;	mov	dl, [drv]
  3513                              <1> ;	mov	ch, al ; cylinder (bits 0-7)
  3514                              <1> ;	shl	ah, 6
  3515                              <1> ;	or	cl, ah ; cylinder (bits 8-9)
  3516                              <1> ;		       ; sector (bits 0-7)
  3517                              <1> ;	pop	ebx ; ** ; buffer ; 11/06/2015
  3518                              <1> ;		; CL = sector (bits 0-5)
  3519                              <1> ;		;      cylinder (bits 8-9 -> bits 6-7)
  3520                              <1> ;		; CH = cylinder (bits 0-7)
  3521                              <1> ;		; DH = head
  3522                              <1> ;		; DL = drive
  3523                              <1> ;	;
  3524                              <1> ;	mov	byte [retry_count], 4
  3525                              <1> ;rwdsk_retry:	
  3526                              <1> ;	;mov	ah, [rwdsk] ; 02h = read, 03h = write
  3527                              <1> ;	; 08/07/2022
  3528                              <1> ;	mov	ah, [rwdsk] ; 01h = read, 02h = write
  3529                              <1> ;	mov	al, 1 ; sector count	
  3530                              <1> ;	;int	13h
  3531                              <1> ;	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3532                              <1> ;	call	int13h
  3533                              <1> ;	mov	[esi], ah ; error code ; 10/07/2015
  3534                              <1> ;	jnc	short rwdsk_ok ; ah = 0
  3535                              <1> ;	cmp	ah, 80h ; time out ?
  3536                              <1> ;	je	short rwdsk_fails
  3537                              <1> ;	dec	byte [retry_count]
  3538                              <1> ;	jnz	short rwdsk_reset
  3539                              <1> ;rwdsk_fails:
  3540                              <1> ;	stc
  3541                              <1> ;rwdsk_ok:
  3542                              <1> ;	pop	ebx ; ***
  3543                              <1> ;	pop	esi ; ****
  3544                              <1> ;	retn
  3545                              <1> ;rwdsk_reset:
  3546                              <1> ;	; 02/02/2015
  3547                              <1> ;	sub	ah, ah
  3548                              <1> ;	cmp	dl, 80h
  3549                              <1> ;	jb	short rwdsk_fd_reset
  3550                              <1> ;	;mov	ah, 0Dh ; Alternate reset
  3551                              <1> ;	; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  3552                              <1> ;	mov	ah, 5  ; Alternate reset
  3553                              <1> ;rwdsk_fd_reset:
  3554                              <1> ;	;int	13h
  3555                              <1> ;	call	int13h
  3556                              <1> ;	jnc	short rwdsk_retry
  3557                              <1> ;	mov	[esi], ah ; error code ; 10/07/2015
  3558                              <1> ;	jmp 	short rwdsk_ok
  3559                              <1> 
  3560                              <1> ; Original UNIX v1 - drum (& disk) interrupt routine
  3561                              <1> ;	(Equivalent to IRQ 14 & IRQ 15 disk/hardware interrupts)
  3562                              <1> ;
  3563                              <1> ; This feature is not used in Retro UNIX 386 (& 8086) for now.
  3564                              <1> ; Because, current Retro UNIX 386 disk I/O -INT13H- routine is 
  3565                              <1> ; derived from IBM PC AT -infact: XT286- BIOS source code, int 13h
  3566                              <1> ; that uses hardware -transfer has been completed-  interrupt inside it. 
  3567                              <1> ; In a next Retro UNIX 386 version, these interrupts
  3568                              <1> ; (fdc_int, hdc1_int, hdc2_int) will be handled by a separate routine
  3569                              <1> ; as in original unix v1.
  3570                              <1> ; I am not removing IBM BIOS source code derivatives -compatible code-
  3571                              <1> ; for now, regarding the new/next 32 bit TRDOS project by me
  3572                              <1> ; (to keep source code files easy adaptable to 32 bit TRDOS.)
  3573                              <1> ;
  3574                              <1> ; Erdogan tan (10/07/2015) 
  3575                              <1> 
  3576                              <1> ;drum: / interrupt handler
  3577                              <1> ;       jsr     r0,setisp / save r1,r2,r3, and clockp on the stack
  3578                              <1> ;       jsr     r0,trapt; dcs; rfap; 1 / check for stray interrupt or
  3579                              <1> ;                                      / error
  3580                              <1> ;               br 3f / no, error
  3581                              <1> ;       br      2f / error
  3582                              <1> ;
  3583                              <1> ;disk:
  3584                              <1> ;       jsr     r0,setisp / save r1,r2,r3, and clockp on the stack
  3585                              <1> ;       jmp     *$0f
  3586                              <1> ;0:
  3587                              <1> ;       jsr     r0,trapt; rkcs; rkap; 2
  3588                              <1> ;      	        br 3f / no, errors
  3589                              <1> ;       mov     $115,(r2) / drive reset, errbit was set
  3590                              <1> ;       mov     $1f,0b-2 / next time jmp *$0f is executed jmp will be
  3591                              <1> ;                        / to 1f
  3592                              <1> ;       br      4f
  3593                              <1> ;1:
  3594                              <1> ;       bit     $20000,rkcs
  3595                              <1> ;       beq     4f / wait for seek complete
  3596                              <1> ;       mov     $0b,0b-2
  3597                              <1> ;       mov     rkap,r1
  3598                              <1> ;2:
  3599                              <1> ;       bit     $3000,(r1) / are bits 9 or 10 set in the 1st word of
  3600                              <1> ;                          / the disk buffer
  3601                              <1> ;       bne     3f / no, branch ignore error if outstanding
  3602                              <1> ;       inc     r1
  3603                              <1> ;       asr     (r1)
  3604                              <1> ;       asr     (r1)
  3605                              <1> ;       asr     (r1) / reissue request
  3606                              <1> ;       dec     r1
  3607                              <1> ;3:
  3608                              <1> ;       bic     $30000,(r1) / clear bits 12 and 13 in 1st word of buffer
  3609                              <1> ;       mov     ac,-(sp)
  3610                              <1> ;       mov     mq,-(sp) / put these on the stack
  3611                              <1> ;       mov     sc,-(sp)
  3612                              <1> ;       jsr     r0,poke
  3613                              <1> ;       mov     (sp)+,sc
  3614                              <1> ;       mov     (sp)+,mq / pop them off stack
  3615                              <1> ;       mov     (sp)+,ac
  3616                              <1> ;4:
  3617                              <1> ;       jmp     retisp / u4-3
  3618                              <1> ;
  3619                              <1> ;trapt:                  / r2 points to the
  3620                              <1> ;       mov     (r0)+,r2 / device control register
  3621                              <1> ;       mov     *(r0)+,r1 / transaction pointer points to buffer
  3622                              <1> ;       tst     (sp)+
  3623                              <1> ;       tstb    (r2) / is ready bit of dcs set?
  3624                              <1> ;       bge     4b / device still active so branch
  3625                              <1> ;       bit     (r0),active / was device busy?
  3626                              <1> ;       beq     4b / no, stray interrupt
  3627                              <1> ;       bic     (r0)+,active / yes, set active to zero
  3628                              <1> ;       tst     (r2) / test the err(bit is) of dcs
  3629                              <1> ;       bge     2f / if no error jump to 2f
  3630                              <1> ;       tst     (r0)+ / skip on error
  3631                              <1> ; 2:
  3632                              <1> ;       jmp     (r0)
  2119                                  %include 'u9.s'        ; 29/06/2015
  2120                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.4) - SYS9.INC
  2121                              <1> ; Last Modification: 13/06/2022
  2122                              <1> ; ----------------------------------------------------------------------------
  2123                              <1> ; Derived from 'Retro UNIX 8086 v1' source code by Erdogan Tan
  2124                              <1> ; (v0.1 - Beginning: 11/07/2012)
  2125                              <1> ;
  2126                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2127                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2128                              <1> ; <Bell Laboratories (17/3/1972)>
  2129                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2130                              <1> ;
  2131                              <1> ; Retro UNIX 8086 v1 - U9.ASM (01/09/2014) //// UNIX v1 -> u9.s
  2132                              <1> ;
  2133                              <1> ; ****************************************************************************
  2134                              <1> 
  2135                              <1> getch:
  2136                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2137                              <1> 	; 30/06/2015
  2138                              <1> 	; 18/02/2015 - Retro UNIX 386 v1 - feature only!
  2139 00005668 28C0                <1> 	sub	al, al ; 0
  2140                              <1> getch_q: ; 06/08/2015
  2141 0000566A 8A25[46620000]      <1> 	mov 	ah, [ptty] ; active (current) video page
  2142 00005670 EB06                <1>         jmp     short getc_n
  2143                              <1> 
  2144                              <1> getc: 
  2145                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2146                              <1> 	; 12/11/2015
  2147                              <1> 	; 15/09/2015
  2148                              <1> 	; 01/07/2015
  2149                              <1> 	; 30/06/2015
  2150                              <1> 	; 18/02/2015 (Retro UNIX 386 v1 - Beginning)
  2151                              <1> 	; 13/05/2013 - 04/07/2014 (Retro UNIX 8086 v1)
  2152                              <1> 	;
  2153                              <1> 	; Retro UNIX 8086 v1 modification !
  2154                              <1> 	; 
  2155                              <1> 	; 'getc' gets (next) character 
  2156                              <1> 	;	 from requested TTY (keyboard) buffer 
  2157                              <1> 	; INPUTS ->
  2158                              <1> 	;     [u.ttyn] = tty number (0 to 7) (8 is COM1, 9 is COM2)	
  2159                              <1> 	;     AL=0 -> Get (next) character from requested TTY buffer
  2160                              <1> 	;	(Keyboard buffer will point to 
  2161                              <1> 	;			next character at next call)
  2162                              <1> 	;     AL=1 -> Test a key is available in requested TTY buffer
  2163                              <1> 	;	(Keyboard buffer will point to 
  2164                              <1> 	;			current character at next call)
  2165                              <1> 	; OUTPUTS ->
  2166                              <1> 	;     (If AL input is 1) ZF=1 -> 'empty buffer' (no chars)
  2167                              <1> 	;     			 ZF=0 -> AX has (current) character
  2168                              <1> 	;      AL = ascii code
  2169                              <1> 	;      AH = scan code	(AH = line status for COM1 or COM2)	 			
  2170                              <1> 	; 		        (cf=1 -> error code/flags in AH)
  2171                              <1> 	; Original UNIX V1 'getc': 
  2172                              <1> 	;		get a character off character list
  2173                              <1> 	;
  2174                              <1> 	; ((Modified registers: eAX, eBX, eCX, eDX, eSI, eDI))	
  2175                              <1> 	;
  2176                              <1> 	; 30/06/2015 (32 bit modifications)
  2177                              <1> 	; 16/07/2013
  2178                              <1> 	; mov 	[getctty], ah
  2179                              <1> 	;
  2180                              <1> 
  2181 00005672 8A25[30660000]      <1> 	mov	ah, [u.ttyn] 	; 28/07/2013
  2182                              <1> getc_n:
  2183                              <1> 	; 30/06/2015
  2184 00005678 08E4                <1> 	or	ah, ah
  2185 0000567A 740D                <1> 	jz	short getc0 
  2186 0000567C D0E4                <1> 	shl	ah, 1
  2187 0000567E 0FB6DC              <1> 	movzx	ebx, ah
  2188 00005681 81C3[48620000]      <1> 	add	ebx, ttychr
  2189 00005687 EB05                <1> 	jmp	short getc1
  2190                              <1> getc0:
  2191 00005689 BB[48620000]        <1> 	mov	ebx, ttychr
  2192                              <1> getc1:
  2193 0000568E 668B0B              <1> 	mov	cx, [ebx] 	; ascii & scan code
  2194                              <1> 				; (by kb_int)	
  2195 00005691 6609C9              <1> 	or	cx, cx
  2196 00005694 7507                <1> 	jnz	short getc2
  2197 00005696 20C0                <1> 	and 	al, al
  2198 00005698 7415                <1> 	jz	short getc_s
  2199                              <1> 	;xor	ax, ax
  2200                              <1> 	; 24/12/2021
  2201 0000569A 31C0                <1> 	xor	eax, eax
  2202 0000569C C3                  <1> 	retn
  2203                              <1> getc2:	
  2204 0000569D 20C0                <1> 	and	al, al
  2205 0000569F 6689C8              <1> 	mov	ax, cx
  2206 000056A2 66B90000            <1> 	mov	cx, 0
  2207 000056A6 7506                <1> 	jnz	short getc3
  2208                              <1> getc_sn:
  2209 000056A8 66890B              <1> 	mov	[ebx], cx ; 0, reset
  2210 000056AB 6639C8              <1> 	cmp	ax, cx  ; zf = 0
  2211                              <1> getc3:
  2212 000056AE C3                  <1> 	retn
  2213                              <1> getc_s:
  2214                              <1> 	; 12/11/2015
  2215                              <1> 	; 15/09/2015
  2216                              <1> 	; 01/07/2015
  2217                              <1> 	; 30/06/2015 (Retro UNIX 386 v1 - Beginning)
  2218                              <1> 	; 16/07/2013 - 14/02/2014 (Retro UNIX 8086 v1)
  2219                              <1> 	;
  2220                              <1> 	; tty  of the current process is not 
  2221                              <1> 	; current tty (ptty); so, current process only 
  2222                              <1> 	; can use keyboard input when its tty becomes 
  2223                              <1> 	; current tty (ptty).
  2224                              <1> 	; 'sleep' is for preventing an endless lock
  2225                              <1> 	; during this tty input request.
  2226                              <1> 	; (Because, the user is not looking at the video page
  2227                              <1> 	; of the process to undersand there is a keyboard
  2228                              <1> 	; input request.)
  2229                              <1> 	;
  2230                              <1> 	;((Modified registers: eAX, eBX, eCX, eDX, eSI, eDI))
  2231                              <1> 	;
  2232                              <1> 	; 05/10/2013
  2233                              <1> 	; ah = byte ptr [u.ttyn] ; (tty number)
  2234                              <1> 	;
  2235                              <1> 	; 10/10/2013
  2236                              <1> gcw0:
  2237 000056AF B10A                <1> 	mov	cl, 10 ; ch = 0
  2238                              <1> gcw1:	
  2239                              <1> 	; 12/11/2015
  2240 000056B1 E828DCFFFF          <1> 	call intract ; jumps to 'sysexit' if [u.quit] = FFFFh
  2241                              <1> 	; 10/10/2013
  2242 000056B6 E8C4EFFFFF          <1> 	call	idle
  2243 000056BB 668B03              <1> 	mov	ax, [ebx] 	; ascii & scan code
  2244                              <1> 				; (by kb_int)
  2245 000056BE 6609C0              <1> 	or	ax, ax
  2246                              <1> ;	jnz	short gcw3
  2247 000056C1 7519                <1> 	jnz	short gcw2 ; 15/09/2015
  2248                              <1> 	; 30/06/2015
  2249 000056C3 FEC9                <1> 	dec	cl
  2250 000056C5 75EA                <1> 	jnz	short gcw1
  2251                              <1> 	;
  2252 000056C7 8A25[30660000]      <1> 	mov	ah, [u.ttyn] 	; 20/10/2013
  2253                              <1> ;	; 10/12/2013
  2254                              <1> ;	cmp 	ah, [ptty]
  2255                              <1> ;	jne	short gcw2
  2256                              <1> ;	; 14/02/2014
  2257                              <1> ;	cmp	byte [u.uno], 1
  2258                              <1> ;	jna	short gcw0		
  2259                              <1> ;gcw2:
  2260 000056CD E83AF0FFFF          <1> 	call	sleep
  2261                              <1> 	;
  2262                              <1> 	; 20/09/2013
  2263 000056D2 8A25[30660000]      <1> 	mov	ah, [u.ttyn]
  2264 000056D8 30C0                <1> 	xor 	al, al
  2265 000056DA EB9C                <1> 	jmp	short getc_n
  2266                              <1> ;gcw3:
  2267                              <1> gcw2: 	; 15/09/2015
  2268                              <1> 	; 10/10/2013
  2269 000056DC 30C9                <1> 	xor	cl, cl
  2270 000056DE EBC8                <1> 	jmp	short getc_sn
  2271                              <1> 
  2272                              <1> putc:	
  2273                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2274                              <1> 	; 13/08/2015
  2275                              <1> 	; 30/06/2015 (Retro UNIX 386 v1 - Beginning)
  2276                              <1> 	; 15/05/2013 - 27/07/2014 (Retro UNIX 8086 v1)
  2277                              <1> 	;
  2278                              <1> 	; Retro UNIX 8086 v1 modification !
  2279                              <1> 	; 
  2280                              <1> 	; 'putc' puts a character 
  2281                              <1> 	;	 onto requested (tty) video page or
  2282                              <1> 	;	 serial port
  2283                              <1> 	; INPUTS ->
  2284                              <1> 	;     AL = ascii code of the character
  2285                              <1> 	;     AH = video page (tty) number (0 to 7)
  2286                              <1> 	;			  (8 is COM1, 9 is COM2)	
  2287                              <1> 	; OUTPUTS ->
  2288                              <1> 	;    (If AL input is 1) ZF=1 -> 'empty buffer' (no chars)
  2289                              <1> 	;      			ZF=0 -> AX has (current) character
  2290                              <1> 	;     cf=0 and AH = 0 -> no error
  2291                              <1> 	;     cf=1 and AH > 0 -> error (only for COM1 and COM2)		 			
  2292                              <1> 	; 
  2293                              <1> 	; Original UNIX V1 'putc': 
  2294                              <1> 	;     put a character at the end of character list
  2295                              <1> 	;
  2296                              <1> 	; ((Modified registers: eAX, eBX, eCX, eDX, eSI, eDI))
  2297                              <1> 	;
  2298 000056E0 80FC07              <1> 	cmp	ah, 7
  2299                              <1>         ;ja	sndc
  2300 000056E3 770A                <1>         ja      short sndc ; 24/12/2024
  2301                              <1> 	; 30/06/2015
  2302 000056E5 0FB6DC              <1> 	movzx	ebx, ah
  2303                              <1> 	; 13/08/2015
  2304 000056E8 B407                <1> 	mov	ah, 07h ; black background, light gray character color
  2305 000056EA E9B3BCFFFF          <1> 	jmp	write_tty ; 'video.inc'
  2306                              <1> 
  2307                              <1> sndc:   ; <Send character>
  2308                              <1> 	;
  2309                              <1> 	; 12/01/2022
  2310                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2311                              <1> 	; 17/11/2015
  2312                              <1> 	; 16/11/2015
  2313                              <1> 	; 11/11/2015
  2314                              <1> 	; 10/11/2015
  2315                              <1> 	; 09/11/2015
  2316                              <1> 	; 08/11/2015
  2317                              <1> 	; 07/11/2015
  2318                              <1> 	; 06/11/2015 (serial4.asm, 'sendchr')	
  2319                              <1> 	; 29/10/2015
  2320                              <1> 	; 30/06/2015 (Retro UNIX 386 v1 - Beginning)
  2321                              <1> 	; 14/05/2013 - 28/07/2014 (Retro UNIX 8086 v1)
  2322                              <1> 	;
  2323                              <1> 	; Retro UNIX 8086 v1 feature only !
  2324                              <1> 	;
  2325                              <1> 	; ah = [u.ttyn]
  2326                              <1> 	;
  2327                              <1> 	; 30/06/2015
  2328 000056EF 80EC08              <1> 	sub	ah, 8 ; ; 0 = tty8 or 1 = tty9
  2329                              <1> 	; 07/11/2015
  2330 000056F2 0FB6DC              <1> 	movzx	ebx, ah ; serial port index (0 or 1)
  2331                              <1> sndc0:
  2332                              <1> 	; 07/11/2015
  2333 000056F5 E860F0FFFF          <1> 	call	isintr ; quit (ctrl+break) check
  2334 000056FA 7405                <1> 	jz	short sndc1
  2335 000056FC E8DDDBFFFF          <1> 	call	intract ; quit (ctrl+break) check
  2336                              <1> 	; CPU will jump to 'sysexit' if 'u.quit' = 0FFFFh (yes)
  2337                              <1> sndc1:
  2338                              <1> 	; 16/11/2015
  2339                              <1> 	;mov	cx, ax	; *** al = character (to be sent)
  2340                              <1> 	; 24/12/2021
  2341 00005701 89C1                <1> 	mov	ecx, eax ; *** al = character (to be sent)
  2342                              <1> sndcx:
  2343 00005703 8A83[8A620000]      <1> 	mov	al, [ebx+schar] ; last sent character
  2344 00005709 8AA3[88620000]      <1> 	mov	ah, [ebx+rchar] ; last received character
  2345                              <1> 	;
  2346                              <1> 	; 17/11/2015
  2347                              <1> 	; check 'request for response' status
  2348 0000570F 80BB[84620000]00    <1> 	cmp	byte [ebx+req_resp], 0
  2349 00005716 740A                <1> 	jz	short query
  2350                              <1> response:
  2351 00005718 FE05[87620000]      <1> 	inc 	byte [comqr] ; query or response status
  2352 0000571E B0FF                <1> 	mov	al, 0FFh	 
  2353 00005720 EB14                <1> 	jmp	short sndc3
  2354                              <1> query:
  2355 00005722 08C0                <1> 	or 	al, al  ; 0 = query (also end of text)
  2356 00005724 750E                <1> 	jnz 	short sndc2 ; normal character
  2357                              <1> 	;cmp 	ah, 0FFh     ; is it responded by terminal ?
  2358                              <1> 	;je	short sndc2  ; yes, already responded
  2359                              <1> 	; 16/11/2015
  2360                              <1> 	; query: request for response (again)
  2361 00005726 8883[88620000]      <1> 	mov	[ebx+rchar], al ; 0 ; reset
  2362 0000572C FE05[87620000]      <1> 	inc 	byte [comqr] ; query or response status
  2363 00005732 EB02                <1> 	jmp	short sndc3
  2364                              <1> sndc2:
  2365 00005734 88C8                <1> 	mov	al, cl 	; *** character (to be sent)
  2366                              <1> sndc3:
  2367 00005736 8883[8A620000]      <1> 	mov	[ebx+schar], al ; current character (to be sent)
  2368 0000573C 88D8                <1> 	mov	al, bl ; 0 or 1 (serial port index)
  2369                              <1> 	; 30/06/2015
  2370 0000573E E844D5FFFF          <1> 	call	sp_status ; get serial port status
  2371                              <1> 	; AL = Line status, AH = Modem status
  2372                              <1> 	; 07/11/2015
  2373 00005743 A880                <1> 	test	al, 80h
  2374 00005745 7504                <1> 	jnz	short sndc4
  2375 00005747 A820                <1> 	test	al, 20h	; Transmitter holding register empty ?
  2376 00005749 751A                <1> 	jnz	short sndc5
  2377                              <1> sndc4: 	; Check line status again
  2378                              <1> 	; 16/11/2015
  2379                              <1> 	;push	cx
  2380                              <1> 	; 24/12/2021
  2381 0000574B 51                  <1> 	push	ecx
  2382                              <1> 	;mov	ecx, 6 ; 6*30 micro seconds (~5556 chars/second)
  2383                              <1> 	; 12/01/2022
  2384 0000574C 31C9                <1> 	xor	ecx, ecx
  2385 0000574E B106                <1> 	mov	cl, 6
  2386 00005750 E844BDFFFF          <1> 	call	WAITF
  2387                              <1> 	;pop	cx
  2388                              <1> 	; 24/12/1021
  2389 00005755 59                  <1> 	pop	ecx
  2390                              <1> 	;
  2391 00005756 88D8                <1> 	mov	al, bl ; 0 or 1 (serial port index)
  2392 00005758 E82AD5FFFF          <1> 	call	sp_status ; get serial port status
  2393                              <1> 	; 16/11/2015
  2394                              <1> 	; 09/11/2015
  2395                              <1> 	; 08/11/2015
  2396 0000575D A880                <1> 	test	al, 80h	; time out error
  2397 0000575F 7565                <1>         jnz     short sndc7
  2398 00005761 A820                <1> 	test	al, 20h	; Transmitter holding register empty ?
  2399 00005763 7461                <1>         jz	short sndc7
  2400                              <1> sndc5:  
  2401 00005765 8A83[8A620000]      <1> 	mov	al, [ebx+schar] ; character (to be sent)
  2402 0000576B 66BAF803            <1> 	mov	dx, 3F8h   ; data port (COM2)
  2403 0000576F 28DE                <1> 	sub	dh, bl
  2404 00005771 EE                  <1> 	out	dx, al	   ; send on serial port
  2405                              <1> 	; 10/11/2015
  2406                              <1> 	; delay for 3*30 (3*(15..80)) micro seconds
  2407                              <1> 	; (to improve text flow to the terminal)
  2408                              <1> 	; ('diskette.inc': 'WAITF')
  2409                              <1> 	; Uses port 61h, bit 4 to have CPU speed independent waiting.
  2410                              <1> 	; (refresh periods = 1 per 30 microseconds on most machines)
  2411                              <1> 	;push	cx
  2412                              <1> 	; 24/12/2021
  2413 00005772 51                  <1> 	push	ecx
  2414                              <1> 	;mov	ecx, 6 ; 6*30 micro seconds (~5556 chars/second)
  2415                              <1> 	; 12/01/2022
  2416 00005773 29C9                <1> 	sub	ecx, ecx
  2417 00005775 B106                <1> 	mov	cl, 6
  2418 00005777 E81DBDFFFF          <1> 	call	WAITF
  2419                              <1> 	;pop	cx
  2420                              <1> 	; 24/12/1021
  2421 0000577C 59                  <1> 	pop	ecx
  2422                              <1>     	;
  2423                              <1> 	; 07/11/2015
  2424 0000577D 88D8                <1> 	mov	al, bl ; al = 0 (tty8) or 1 (tty9)
  2425                              <1> 	;
  2426 0000577F E803D5FFFF          <1> 	call	sp_status ; get serial port status
  2427                              <1> 	; AL = Line status, AH = Modem status
  2428                              <1> 	;
  2429 00005784 E8D1EFFFFF          <1> 	call	isintr ; quit (ctrl+break) check
  2430 00005789 7405                <1> 	jz	short sndc6
  2431 0000578B E84EDBFFFF          <1> 	call	intract ; quit (ctrl+break) check
  2432                              <1> 	; CPU will jump to 'sysexit' if 'u.quit' = 0FFFFh (yes)
  2433                              <1> sndc6:
  2434 00005790 3C80                <1> 	cmp	al, 80h
  2435 00005792 7332                <1> 	jnb	short sndc7		
  2436                              <1> 	;
  2437 00005794 803D[87620000]01    <1> 	cmp	byte [comqr], 1 ; 'query or response' ?
  2438 0000579B 7244                <1> 	jb	short sndc8 	; no, normal character
  2439 0000579D 883D[87620000]      <1> 	mov 	byte [comqr], bh ; 0 ; reset
  2440                              <1> 	; 17/11/2015
  2441 000057A3 E8D7EEFFFF          <1> 	call	idle
  2442                              <1> 	;
  2443 000057A8 38BB[8A620000]      <1> 	cmp	[ebx+schar], bh ; 0 ; query ?
  2444                              <1>         ;ja	sndc2       ; response (will be followed by
  2445                              <1> 			    ; a normal character)
  2446                              <1> 	; 24/12/2021
  2447 000057AE 7602                <1> 	jna	short sndc_10
  2448 000057B0 EB82                <1> 	jmp	sndc2
  2449                              <1> sndc_10:
  2450                              <1> 	; Query request must be responded by the terminal
  2451                              <1> 	; before sending a normal character !
  2452 000057B2 53                  <1> 	push	ebx
  2453                              <1> 	;push	cx ; *** cl = character (to be sent)
  2454                              <1> 	; 24/12/2021
  2455 000057B3 51                  <1> 	push	ecx ; *** cl = character (to be sent)
  2456 000057B4 8A25[30660000]      <1> 	mov	ah, [u.ttyn]
  2457 000057BA E84DEFFFFF          <1> 	call	sleep ; this process will be awakened by
  2458                              <1> 		      ; received data available interrupt
  2459                              <1> 	;pop	cx ; *** cl = character (to be sent)
  2460                              <1> 	; 24/12/2021
  2461 000057BF 59                  <1> 	pop	ecx ; *** cl = character (to be sent) 
  2462 000057C0 5B                  <1> 	pop	ebx
  2463 000057C1 E93DFFFFFF          <1>         jmp	sndcx
  2464                              <1> sndc7:
  2465                              <1> 	 ; 16/11/2015
  2466 000057C6 803D[87620000]01    <1> 	cmp	byte [comqr], 1 ; 'query or response' ?
  2467 000057CD 7213                <1> 	jb	short sndc9 	; no
  2468                              <1> 	;
  2469 000057CF 88BB[88620000]      <1> 	mov	[ebx+rchar], bh ; 0 ; reset
  2470 000057D5 88BB[8A620000]      <1> 	mov	[ebx+schar], bh ; 0 ; reset
  2471                              <1> 	;
  2472 000057DB 883D[87620000]      <1> 	mov	byte [comqr], bh ; 0 ; reset  
  2473                              <1> sndc8:
  2474 000057E1 F5                  <1> 	cmc  ; jnc -> jc, jb -> jnb
  2475                              <1> sndc9:
  2476                              <1> 	; AL = Line status, AH = Modem status
  2477 000057E2 C3                  <1> 	retn
  2478                              <1> 
  2479                              <1> get_cpos:
  2480                              <1> 	; 29/06/2015 (Retro UNIX 386 v1)
  2481                              <1> 	; 04/12/2013 (Retro UNIX 8086 v1 - 'sysgtty')
  2482                              <1> 	;
  2483                              <1> 	; INPUT -> bl = video page number
  2484                              <1> 	; RETURN -> dx = cursor position
  2485                              <1> 
  2486 000057E3 53                  <1> 	push	ebx
  2487 000057E4 83E30F              <1> 	and	ebx, 0Fh ; 07h ; tty0 to tty7
  2488 000057E7 D0E3                <1> 	shl	bl, 1
  2489 000057E9 81C3[36620000]      <1> 	add	ebx, cursor_posn
  2490 000057EF 668B13              <1> 	mov	dx, [ebx]
  2491 000057F2 5B                  <1> 	pop	ebx
  2492 000057F3 C3                  <1> 	retn
  2493                              <1> 
  2494                              <1> read_ac_current:
  2495                              <1> 	; 29/06/2015 (Retro UNIX 386 v1)
  2496                              <1> 	; 04/12/2013 (Retro UNIX 8086 v1 - 'sysgtty')
  2497                              <1> 	;
  2498                              <1> 	; INPUT -> bl = video page number
  2499                              <1> 	; RETURN -> ax = character (al) and attribute (ah)
  2500                              <1> 
  2501 000057F4 E80FBDFFFF          <1> 	call 	find_position ; 'video.inc'
  2502                              <1> 	; dx = status port
  2503                              <1> 	; esi = cursor location/address
  2504 000057F9 81C600800B00        <1> 	add	esi, 0B8000h	; 30/08/2014 (Retro UNIX 386 v1)
  2505 000057FF 668B06              <1> 	mov 	ax, [esi]	; get the character and attribute
  2506 00005802 C3                  <1> 	retn
  2507                              <1> 
  2508                              <1> syssleep:
  2509                              <1> 	; 29/06/2015 - (Retro UNIX 386 v1)
  2510                              <1> 	; 11/06/2014 - (Retro UNIX 8086 v1)
  2511                              <1> 	;
  2512                              <1> 	; Retro UNIX 8086 v1 feature only
  2513                              <1> 	; (INPUT -> none)
  2514                              <1> 	;
  2515 00005803 0FB61D[2B660000]    <1> 	movzx	ebx, byte [u.uno] ; process number
  2516 0000580A 8AA3[33630000]      <1> 	mov	ah, [ebx+p.ttyc-1] ; current/console tty
  2517 00005810 E8F7EEFFFF          <1> 	call	sleep
  2518 00005815 E9D7D9FFFF          <1> 	jmp	sysret
  2519                              <1> 
  2520                              <1> 	; 27/02/2022
  2521                              <1> 	; (u1.s, 'wttyc' & 'wpc_clr')
  2522                              <1> %if 0
  2523                              <1> 
  2524                              <1> vp_clr:
  2525                              <1> 	; Reset/Clear Video Page
  2526                              <1> 	;
  2527                              <1> 	; 24/12/2021 - (Retro UNIX 386 v1.1)
  2528                              <1> 	; 30/06/2015 - (Retro UNIX 386 v1)
  2529                              <1> 	; 21/05/2013 - 30/10/2013(Retro UNIX 8086 v1) (U0.ASM)
  2530                              <1> 	;
  2531                              <1> 	; Retro UNIX 8086 v1 feature only !
  2532                              <1> 	;
  2533                              <1> 	; INPUTS -> 
  2534                              <1> 	;   BL = video page number	 
  2535                              <1> 	;
  2536                              <1> 	; OUTPUT ->
  2537                              <1> 	;   none
  2538                              <1> 	; ((Modified registers: eAX, BH, eCX, eDX, eSI, eDI))
  2539                              <1> 	;
  2540                              <1> 	; 04/12/2013
  2541                              <1> 	sub	al, al
  2542                              <1> 	; al = 0 (clear video page)
  2543                              <1> 	; bl = video page
  2544                              <1> 	mov	ah, 07h
  2545                              <1> 	; ah = 7 (attribute/color)
  2546                              <1> 	;xor 	cx, cx ; 0, left upper column (cl) & row (cl)
  2547                              <1> 	; 24/12/2021
  2548                              <1> 	xor	ecx, ecx
  2549                              <1> 	mov	dx, 184Fh ; right lower column & row (dl=24, dh=79)
  2550                              <1> 	call	scroll_up
  2551                              <1> 	; bl = video page
  2552                              <1> 	;xor	dx, dx ; 0 (cursor position) 
  2553                              <1> 	; 24/12/2021
  2554                              <1> 	xor	edx, edx 
  2555                              <1> 	jmp 	set_cpos
  2556                              <1> 
  2557                              <1> %endif
  2558                              <1> 
  2559                              <1> sysmsg:
  2560                              <1> 	; 24/12/2021 (Retro UNIX 386 v1.1)
  2561                              <1> 	; 11/11/2015
  2562                              <1> 	; 01/07/2015 - (Retro UNIX 386 v1 feature only!)
  2563                              <1> 	; Print user-application message on user's console tty
  2564                              <1> 	;
  2565                              <1> 	; Input -> EBX = Message address
  2566                              <1> 	;	   ECX = Message length (max. 255)
  2567                              <1> 	;	   DL = Color (IBM PC Rombios color attributes)
  2568                              <1> 	;
  2569 0000581A 81F9FF000000        <1> 	cmp	ecx, MAX_MSG_LEN ; 255
  2570                              <1> 	;ja	sysret ; nothing to do with big message size
  2571 00005820 7779                <1> 	ja	short sysmsg8 ; 24/12/2021
  2572 00005822 08C9                <1> 	or	cl, cl
  2573                              <1> 	;jz	sysret
  2574 00005824 7475                <1> 	jz	short sysmsg8 ; 24/12/2021
  2575 00005826 20D2                <1> 	and	dl, dl
  2576 00005828 7502                <1> 	jnz	short sysmsg0
  2577 0000582A B207                <1> 	mov	dl, 07h ; default color
  2578                              <1> 		; (black background, light gray character)
  2579                              <1> sysmsg0:
  2580 0000582C 891D[FC650000]      <1> 	mov	[u.base], ebx
  2581 00005832 8815[47620000]      <1> 	mov	[ccolor], dl ; color attributes
  2582 00005838 89E5                <1> 	mov	ebp, esp
  2583 0000583A 31DB                <1> 	xor	ebx, ebx ; 0
  2584 0000583C 891D[04660000]      <1> 	mov	[u.nread], ebx ; 0
  2585                              <1> 	;
  2586 00005842 381D[43660000]      <1> 	cmp	[u.kcall], bl ; 0
  2587 00005848 7772                <1> 	ja	short sysmsgk ; Temporary (01/07/2015)
  2588                              <1> 	;
  2589 0000584A 890D[00660000]      <1> 	mov	[u.count], ecx
  2590 00005850 41                  <1> 	inc	ecx ; + 00h ; ASCIIZ
  2591                              <1> 	; 24/12/2021
  2592                              <1> 	; (dword alignment for esp)
  2593 00005851 F6C103              <1> 	test	cl, 3
  2594 00005854 7404                <1> 	jz	short sysmsg_7
  2595 00005856 80C903              <1> 	or	cl, 3
  2596 00005859 41                  <1> 	inc	ecx
  2597                              <1> sysmsg_7:
  2598 0000585A 29CC                <1> 	sub	esp, ecx
  2599 0000585C 89E7                <1> 	mov	edi, esp
  2600 0000585E 89E6                <1> 	mov	esi, esp
  2601 00005860 66891D[41660000]    <1> 	mov	[u.pcount], bx ; reset page (phy. addr.) counter
  2602                              <1> 	; 11/11/2015
  2603 00005867 8A25[0C660000]      <1> 	mov 	ah, [u.ttyp] ; recent open tty
  2604                              <1> 	; 0 = none
  2605 0000586D FECC                <1> 	dec	ah
  2606 0000586F 790C                <1> 	jns	short sysmsg1 
  2607 00005871 8A1D[2B660000]      <1> 	mov	bl, [u.uno] ; process number	
  2608 00005877 8AA3[33630000]      <1> 	mov	ah, [ebx+p.ttyc-1] ; user's (process's) console tty
  2609                              <1> sysmsg1:
  2610 0000587D 8825[30660000]      <1> 	mov	[u.ttyn], ah
  2611                              <1> sysmsg2:
  2612 00005883 E851F6FFFF          <1> 	call	cpass
  2613 00005888 7416                <1> 	jz	short sysmsg5
  2614 0000588A AA                  <1> 	stosb
  2615 0000588B 20C0                <1> 	and	al, al
  2616 0000588D 75F4                <1> 	jnz	short sysmsg2
  2617                              <1> sysmsg3:
  2618 0000588F 80FC07              <1> 	cmp	ah, 7 ; tty number
  2619 00005892 7711                <1> 	ja	short sysmsg6 ; serial port
  2620 00005894 E83E000000          <1> 	call	print_cmsg
  2621                              <1> sysmsg4:
  2622 00005899 89EC                <1> 	mov	esp, ebp	
  2623                              <1> sysmsg8: ; 24/12/2021	
  2624 0000589B E951D9FFFF          <1> 	jmp	sysret
  2625                              <1> sysmsg5:
  2626 000058A0 C60700              <1> 	mov	byte [edi], 0
  2627 000058A3 EBEA                <1> 	jmp	short sysmsg3
  2628                              <1> sysmsg6:
  2629 000058A5 8A06                <1> 	mov	al, [esi]
  2630 000058A7 E843FEFFFF          <1> 	call	sndc
  2631 000058AC 72EB                <1> 	jc	short sysmsg4
  2632 000058AE 803E00              <1> 	cmp	byte [esi], 0  ; 0 is stop character
  2633 000058B1 76E6                <1> 	jna	short sysmsg4
  2634 000058B3 46                  <1> 	inc 	esi
  2635 000058B4 8A25[30660000]      <1> 	mov	ah, [u.ttyn]
  2636 000058BA EBE9                <1> 	jmp	short sysmsg6
  2637                              <1> 
  2638                              <1> sysmsgk: ; Temporary (01/07/2015)
  2639                              <1> 	; The message has been sent by Kernel (ASCIIZ string)
  2640                              <1> 	; (ECX -character count- will not be considered)
  2641 000058BC 8B35[FC650000]      <1> 	mov	esi, [u.base]
  2642 000058C2 8A25[46620000]      <1> 	mov	ah, [ptty] ; present/current screen (video page)
  2643 000058C8 8825[30660000]      <1> 	mov	[u.ttyn], ah
  2644 000058CE C605[43660000]00    <1> 	mov	byte [u.kcall], 0
  2645 000058D5 EBB8                <1> 	jmp	short sysmsg3
  2646                              <1> 	
  2647                              <1> print_cmsg: 
  2648                              <1> 	; 01/07/2015 (retro UNIX 386 v1 feature only !)
  2649                              <1> 	;
  2650                              <1> 	; print message (on user's console tty) 
  2651                              <1> 	;	with requested color
  2652                              <1> 	;
  2653                              <1> 	; INPUTS:
  2654                              <1> 	;	esi = message address
  2655                              <1> 	;	[u.ttyn] = tty number (0 to 7)
  2656                              <1> 	;	[ccolor] = color attributes (IBM PC BIOS colors)
  2657                              <1> 	;
  2658 000058D7 AC                  <1> 	lodsb
  2659                              <1> pcmsg1:
  2660 000058D8 56                  <1> 	push 	esi
  2661 000058D9 0FB61D[30660000]    <1>         movzx   ebx, byte [u.ttyn]
  2662 000058E0 8A25[47620000]      <1> 	mov	ah, [ccolor]
  2663 000058E6 E8B7BAFFFF          <1> 	call 	write_tty
  2664 000058EB 5E                  <1> 	pop	esi
  2665 000058EC AC                  <1> 	lodsb
  2666 000058ED 20C0                <1> 	and 	al, al  ; 0
  2667 000058EF 75E7                <1> 	jnz 	short pcmsg1
  2668 000058F1 C3                  <1> 	retn
  2669                              <1> 
  2670                              <1> sysgeterr:
  2671                              <1> 	; 16/02/2022 - Retro UNIX 386 v1.1
  2672                              <1> 	; 09/12/2015
  2673                              <1> 	; 21/09/2015 - (Retro UNIX 386 v1 feature only!)
  2674                              <1> 	; Get last error number or page fault count
  2675                              <1> 	; (for debugging)
  2676                              <1> 	;
  2677                              <1> 	; Input -> EBX = return type
  2678                              <1> 	;	   0 = last error code (which is in 'u.error')	
  2679                              <1> 	;	   FFFFFFFFh = page fault count for running process
  2680                              <1> 	;	   FFFFFFFEh = total page fault count
  2681                              <1> 	;	   1 .. FFFFFFFDh = undefined 
  2682                              <1> 	;
  2683                              <1> 	; Output -> EAX = last error number or page fault count
  2684                              <1> 	;	   (depending on EBX input)
  2685                              <1> 	; 	
  2686 000058F2 21DB                <1> 	and 	ebx, ebx
  2687 000058F4 750F                <1> 	jnz	short glerr_2
  2688                              <1> glerr_0:
  2689 000058F6 A1[31660000]        <1> 	mov	eax, [u.error]
  2690                              <1> glerr_1:
  2691 000058FB A3[DC650000]        <1> 	mov	[u.r0], eax
  2692                              <1>  	;retn
  2693                              <1> 	; 16/02/2022 (BugFix)
  2694 00005900 E9ECD8FFFF          <1> 	jmp	sysret
  2695                              <1> glerr_2:
  2696 00005905 43                  <1> 	inc	ebx ; FFFFFFFFh -> 0, FFFFFFFEh -> FFFFFFFFh
  2697 00005906 74FD                <1> 	jz	short glerr_2 ; page fault count for process
  2698 00005908 43                  <1> 	inc	ebx ; FFFFFFFFh -> 0	
  2699 00005909 75EB                <1> 	jnz	short glerr_0
  2700 0000590B A1[CC620000]        <1> 	mov	eax, [PF_Count] ; total page fault count
  2701 00005910 EBE9                <1>         jmp     short glerr_1
  2702                              <1> glerr_3:
  2703 00005912 A1[45660000]        <1> 	mov 	eax, [u.pfcount]
  2704 00005917 EBE2                <1> 	jmp	short glerr_1
  2705                              <1> 
  2706                              <1> ; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2707                              <1> ;	     - PRINTER BIOS (Functions)		
  2708                              <1> 
  2709                              <1> ;;; IBM PC-AT BIOS v3 - PRT.ASM - 15/11/1985 ;;; 
  2710                              <1> ;
  2711                              <1> ;--- INT 17 H ------------------------------------------------------------------
  2712                              <1> ; PRINTER_IO								       :
  2713                              <1> ;	THIS ROUTINE PROVIDES COMMUNICATION WITH THE PRINTER		       :
  2714                              <1> ; INPUT 								       :
  2715                              <1> ;	(AH)= 00H  PRINT THE CHARACTER IN (AL)				       :
  2716                              <1> ;		    ON RETURN, (AH)= 1 IF CHARACTER NOT BE PRINTED (TIME OUT)  :
  2717                              <1> ;		    OTHER BITS SET AS ON NORMAL STATUS CALL		       :
  2718                              <1> ;	(AH)= 01H  INITIALIZE THE PRINTER PORT				       :
  2719                              <1> ;		    RETURNS WITH (AH) SET WITH PRINTER STATUS		       :
  2720                              <1> ;	(AH)= 02H  READ THE PRINTER STATUS INTO (AH)			       :
  2721                              <1> ;		   7	   6	   5	   4	   3	   2-1	   0	       :
  2722                              <1> ;		   |	   |	   |	   |	   |	   |	   |_TIME OUT  :
  2723                              <1> ;		   |	   |	   |	   |	   |	   |		       :
  2724                              <1> ;		   |	   |	   |	   |	   |	   |_ UNUSED	       :
  2725                              <1> ;		   |	   |	   |	   |	   |			       :
  2726                              <1> ;		   |	   |	   |	   |	   |_ 1 = I/O ERROR	       :
  2727                              <1> ;		   |	   |	   |	   |				       :
  2728                              <1> ;		   |	   |	   |	   |_ 1 = SELECTED		       :
  2729                              <1> ;		   |	   |	   |					       :
  2730                              <1> ;		   |	   |	   |_ 1 = OUT OF PAPER			       :
  2731                              <1> ;		   |	   |						       :
  2732                              <1> ;		   |	   |_ 1 = ACKNOWLEDGE				       :
  2733                              <1> ;		   |							       :
  2734                              <1> ;		   |_ 1 = NOT BUSY					       :
  2735                              <1> ;									       :
  2736                              <1> ;	(DX) = PRINTER TO BE USED (0,1,2) CORRESPONDING TO ACTUAL VALUES       :
  2737                              <1> ;		IN @PRINTER_BASE AREA					       :
  2738                              <1> ; DATA AREA @PRINTER_BASE CONTAINS THE BASE ADDRESS OF THE PRINTER CARD(S)     :
  2739                              <1> ; AVAILABLE (LOCATED AT BEGINNING OF DATA SEGMENT, 408H ABSOLUTE, 3 WORDS)     :
  2740                              <1> ;									       :
  2741                              <1> ; DATA AREA @PRINT_TIM_OUT (BYTE) MAY BE CHANGED TO CAUSE DIFFERENT	       :
  2742                              <1> ; TIME OUT WAITS. DEFAULT=20 * 4					       :
  2743                              <1> ;									       :
  2744                              <1> ; REGISTERS	(AH) IS MODIFIED WITH STATUS INFORMATION		       :
  2745                              <1> ;		ALL OTHERS UNCHANGED					       :
  2746                              <1> ;-------------------------------------------------------------------------------
  2747                              <1> 
  2748                              <1> int17h:
  2749                              <1> 	; 13/06/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.4)
  2750                              <1> 	; (Derived from: IBM PC-AT BIOS v3 - PRT.ASM - 15/11/1985)
  2751                              <1> 	;
  2752                              <1> 	; (Default printer port: 378h) ; LPT1
  2753                              <1> 	; (Number of printers = 1)
  2754                              <1> 	
  2755                              <1> 	PRINTER_BASE equ 378h ; LPT1
  2756                              <1> 	;PRINT_TIM_OUT equ 4*80*65536 
  2757                              <1> 			; (Ref: IBM PC-AT BIOS v2 PRT.ASM)	 
  2758                              <1> 
  2759                              <1> 	PRINT_TIM_OUT equ 36000 ; WAIT_PRN_NBUSY
  2760                              <1> 			; (Ref: AWARD BIOS 1999 ATORGS.ASM)		
  2761                              <1> 
  2762                              <1> 	; INPUT:
  2763                              <1> 	;	ah = 0 -> print the character in AL 
  2764                              <1> 	;		 (sys write with write count >0)
  2765                              <1> 	;	ah = 1 -> initialize printer port
  2766                              <1> 	;		 (sys open)	
  2767                              <1> 	;	ah = 2 -> read the printer status 
  2768                              <1> 	;		 (sys write with write count = 0)
  2769                              <1> 	; OUTPUT:
  2770                              <1> 	;	ah = printer status
  2771                              <1> 
  2772                              <1> 	; Modified registers: eax, ecx, edx
  2773                              <1> 
  2774                              <1> PRINTER_IO_1:
  2775 00005919 08E4                <1> 	or	ah, ah
  2776 0000591B 7417                <1> 	jz	short _b20
  2777 0000591D FECC                <1> 	dec	ah
  2778 0000591F 7444                <1> 	jz	short _b80
  2779                              <1> 	;dec 	ah
  2780                              <1> 	;jz	short _b50
  2781                              <1> _b50:
  2782                              <1> 	;-----	PRINTER STATUS
  2783                              <1> B50:
  2784 00005921 50                  <1> 	push	eax		; SAVE (AL) REGISTER
  2785                              <1> B60:
  2786 00005922 66BA7903            <1> 	mov	dx, PRINTER_BASE+1
  2787                              <1> 				; GET PRINTER ATTACHMENT BASE ADDRESS
  2788                              <1> 				; POINT TO CONTROL PORT
  2789 00005926 EC                  <1> 	in	al, dx		; PRE-CHARGE +BUSY LINE IF FLOATING
  2790 00005927 EC                  <1> 	in	al, dx		; GET PRINTER STATUS HARDWARE BITS
  2791 00005928 88C4                <1> 	mov	ah, al		; SAVE
  2792 0000592A 80E4F8              <1> 	and	ah, 0F8h	; TURN OFF UNUSED BITS
  2793                              <1> B70:
  2794 0000592D 5A                  <1> 	pop	edx		; RECOVER (AL) REGISTER
  2795 0000592E 88D0                <1> 	mov	al, dl		; MOVE CHARACTER INTO (AL)
  2796 00005930 80F448              <1> 	xor	ah, 48h		; FLIP A COUPLE OF BITS
  2797                              <1> B10:
  2798 00005933 C3                  <1> 	retn			; RETURN FROM ROUTINE WITH STATUS IN AH
  2799                              <1> _b20:
  2800                              <1> 	;-----	PRINT THE CHARACTER IN (AL)
  2801 00005934 B9A08C0000          <1> 	mov	ecx, PRINT_TIM_OUT ; (1 second)
  2802                              <1> B20:
  2803 00005939 50                  <1> 	push	eax		; SAVE VALUE TO PRINT
  2804 0000593A 66BA7803            <1> 	mov	dx, PRINTER_BASE
  2805 0000593E EE                  <1> 	out	dx, al		; OUTPUT CHARACTER TO DATA PORT
  2806 0000593F FEC2                <1> 	inc	dl		; POINT TO STATUS PORT
  2807                              <1> 
  2808                              <1> 	;-----	CHECK FOR PRINTER BUSY
  2809                              <1> B25:
  2810                              <1> 	;-----	WAIT BUSY
  2811                              <1> B35:
  2812 00005941 EC                  <1> 	in	al, dx		; GET STATUS
  2813 00005942 88C4                <1> 	mov	ah, al		; STATUS TO (AH) ALSO
  2814 00005944 A880                <1> 	test	al, 80h		; IS THE PRINTER CURRENTLY BUSY? (*)
  2815 00005946 750F                <1> 	jnz	short B40	; GO TO OUTPUT STROBE
  2816 00005948 E831000000          <1> 	call	WAIT_REFRESH	; (wait for 30 micro seconds)
  2817 0000594D E2F2                <1> 	loop	B35		; LOOP IF YES (*)
  2818                              <1> 
  2819 0000594F 80CC01              <1> 	or	ah, 1		; SET ERROR FLAG
  2820 00005952 80E4F9              <1> 	and	ah, 0F9h	; TURN OFF THE UNUSED BITS
  2821 00005955 EBD6                <1> 	jmp	short B70	; RETURN WITH ERROR FLAG SET
  2822                              <1> 
  2823                              <1> B40:				; SEND STROBE PULSE
  2824 00005957 B00D                <1> 	mov	al, 0Dh		; SET THE STROBE LOW (BIT ON)
  2825 00005959 6642                <1> 	inc	dx		; OUTPUT STROBE TO CONTROL PORT
  2826 0000595B FA                  <1> 	cli			; PREVENT INTERRUPT PULSE STRETCHING
  2827 0000595C EE                  <1> 	out	dx, al		; OUTPUT STROBE BIT > 1us < 5us
  2828                              <1> 	; IODELAY
  2829                              <1> 	;jmp	short $+2	; I/O DELAY TO ALLOW FOR LINE LOADING
  2830                              <1> 	;jmp	short $+2	; AND FOR CORRECT PULSE WIDTH
  2831                              <1> 	; NEWIODELAY
  2832 0000595D E6EB                <1> 	out	0EBh, al
  2833                              <1> 
  2834 0000595F B00C                <1> 	mov	al, 0Ch		; SET THE -STROBE HIGH
  2835 00005961 EE                  <1> 	out	dx, al
  2836 00005962 FB                  <1> 	sti			; INTERRUPTS BACK ON
  2837                              <1> 	;pop	eax		; RECOVER THE OUTPUT CHAR
  2838                              <1> 	;jmp	short B50
  2839 00005963 EBBD                <1> 	jmp	short B60
  2840                              <1> 
  2841                              <1> _b80:
  2842                              <1> 	;-----	INITIALIZE THE PRINTER PORT
  2843                              <1> B80:
  2844 00005965 50                  <1> 	push	eax		; SAVE (AL)
  2845 00005966 66BA7A03            <1> 	mov	dx, PRINTER_BASE+2 ; POINT TO OUTPUT PORT
  2846 0000596A B008                <1> 	mov	al, 8		; SET INIT LINE LOW
  2847 0000596C EE                  <1> 	out	dx, al
  2848                              <1> 	;mov	eax, 1000*4	; ADJUST FOR INITIALIZATION DELAY LOOP
  2849 0000596D B989080000          <1> 	mov	ecx, WAIT_PRN_INIT ; (65536 micro seconds)
  2850                              <1> B90:				; INIT_LOOP
  2851                              <1> 	;dec	eax		; LOOP FOR RESET TO TAKE
  2852                              <1> 	;jnz	short B90	; INIT_LOOP
  2853 00005972 E807000000          <1> 	call	WAIT_REFRESH	; (wait for 30 micro seconds)
  2854 00005977 E2F9                <1> 	loop	B90	
  2855 00005979 B00C                <1> 	mov	al, 0Ch		; NO INTERRUPTS, NON AUTO LF, INIT HIGH
  2856 0000597B EE                  <1> 	out	dx, al
  2857 0000597C EBA4                <1> 	jmp	short B60	; EXIT THROUGH STATUS ROUTINE
  2858                              <1> 
  2859                              <1> 
  2860                              <1> ; (According to) AWARD BIOS 1999 - ATORGS.ASM (dw -> equ, db -> equ)
  2861                              <1> ; -------------------------------------------------------------------
  2862                              <1> ;
  2863                              <1> ;;Wait while printer initializes should be 65,536 microseconds.
  2864                              <1> ;;65536/30 = 2185
  2865                              <1> ;			PUBLIC	WAIT_PRN_INIT_LO
  2866                              <1> ;WAIT_PRN_INIT_LO	DW	2185
  2867                              <1> ;			PUBLIC	WAIT_PRN_INIT_HI
  2868                              <1> ;WAIT_PRN_INIT_HI	DW	0
  2869                              <1> ;
  2870                              <1> WAIT_PRN_INIT equ 2185 ; 12/06/2022
  2871                              <1> ;
  2872                              <1> ;;Wait for printer not busy should be 1,080,000 microseconds.
  2873                              <1> ;;Memory refresh =15 us, therefore memory refresh period = 30 Us.
  2874                              <1> ;;1,080,000 / 30 = 36,000
  2875                              <1> ;			PUBLIC	WAIT_PRN_NBUSY_LO
  2876                              <1> ;WAIT_PRN_NBUSY_LO	DW	36000
  2877                              <1> ;			PUBLIC	WAIT_PRN_NBUSY_HI
  2878                              <1> ;WAIT_PRN_NBUSY_HI	DB	0
  2879                              <1> ;
  2880                              <1> ;WAIT_PRN_NBUSY	equ 36000 ; 12/06/2022
  2881                              <1> 
  2882                              <1> ; AWARD BIOS - 1999 - ATORGS.ASM (27/5/1999)
  2883                              <1> ; ------------------------------------------
  2884                              <1> ;WAIT_REFRESH:  Uses port 61, bit 4 to have CPU speed independent waiting.
  2885                              <1> ;   	INPUT: BX:CX = number of refresh periods to wait
  2886                              <1> ;     	       (refresh periods = 1 per 30 microseconds on most machines)
  2887                              <1> ;	OUTPUT: BX:CX destroyed.
  2888                              <1> ;
  2889                              <1> ;	SAVES:	AX (except when NO STACK)
  2890                              <1> ;
  2891                              <1> ;	NOTES:	This routine can be (and is) used with no stack. When
  2892                              <1> ;		used this way, AX is assumed to be destroyed.
  2893                              <1> 
  2894                              <1> WAIT_REFRESH:
  2895                              <1> 	; 13/06/2022
  2896                              <1> 	; Modified for Retro UNIX 386 v1.1
  2897                              <1> 	
  2898                              <1> 	; (wait for 30 micro seconds)
  2899                              <1> 
  2900                              <1> 	SYS1	equ 61h ; PORT_B
  2901                              <1> 
  2902                              <1> WR_SHORT:
  2903 0000597E 50                  <1> 	push	eax
  2904                              <1> WR_STAT_0:
  2905 0000597F E461                <1> 	in	al, SYS1	; wait for high to low
  2906 00005981 A810                <1> 	test	al, 10h		; transition on memory
  2907 00005983 75FA                <1> 	jnz	short WR_STAT_0 
  2908                              <1> WR_STAT_1:
  2909 00005985 E461                <1> 	in	al, SYS1
  2910 00005987 A810                <1> 	test	al, 10h
  2911 00005989 74FA                <1> 	jz	short WR_STAT_1
  2912 0000598B 58                  <1> 	pop	eax
  2913 0000598C C3                  <1> 	retn
  2120                                  
  2121                                  ; 07/03/2015
  2122                                  ; Temporary Code
  2123                                  display_disks:
  2124 0000598D 803D[3C5D0000]00        	cmp 	byte [fd0_type], 0
  2125 00005994 7605                    	jna 	short ddsks1
  2126 00005996 E87D000000              	call	pdskm
  2127                                  ddsks1:
  2128 0000599B 803D[3D5D0000]00        	cmp	byte [fd1_type], 0
  2129 000059A2 760C                    	jna	short ddsks2
  2130 000059A4 C605[035F0000]31        	mov	byte [dskx], '1'
  2131 000059AB E868000000              	call	pdskm
  2132                                  ddsks2:
  2133 000059B0 803D[3E5D0000]00        	cmp	byte [hd0_type], 0
  2134 000059B7 7654                    	jna	short ddsk6
  2135 000059B9 66C705[015F0000]68-     	mov	word [dsktype], 'hd'
  2135 000059C1 64                 
  2136 000059C2 C605[035F0000]30        	mov	byte [dskx], '0'
  2137 000059C9 E84A000000              	call	pdskm
  2138                                  ddsks3:
  2139 000059CE 803D[3F5D0000]00        	cmp	byte [hd1_type], 0
  2140 000059D5 7636                    	jna	short ddsk6
  2141 000059D7 C605[035F0000]31        	mov	byte [dskx], '1'
  2142 000059DE E835000000              	call	pdskm
  2143                                  ddsks4:
  2144 000059E3 803D[405D0000]00        	cmp	byte [hd2_type], 0
  2145 000059EA 7621                    	jna	short ddsk6
  2146 000059EC C605[035F0000]32        	mov	byte [dskx], '2'
  2147 000059F3 E820000000              	call	pdskm
  2148                                  ddsks5:
  2149 000059F8 803D[415D0000]00        	cmp	byte [hd3_type], 0
  2150 000059FF 760C                    	jna	short ddsk6
  2151 00005A01 C605[035F0000]33        	mov	byte [dskx], '3'
  2152 00005A08 E80B000000              	call	pdskm
  2153                                  ddsk6:
  2154 00005A0D BE[125F0000]            	mov	esi, nextline
  2155 00005A12 E806000000              	call	pdskml
  2156                                  pdskm_ok:
  2157 00005A17 C3                      	retn
  2158                                  pdskm:
  2159 00005A18 BE[FF5E0000]            	mov	esi, dsk_ready_msg
  2160                                  pdskml:	
  2161 00005A1D AC                      	lodsb
  2162 00005A1E 08C0                    	or	al, al
  2163 00005A20 74F5                    	jz	short pdskm_ok
  2164 00005A22 56                      	push	esi
  2165 00005A23 31DB                    	xor	ebx, ebx ; 0
  2166                                  			; Video page 0 (bl=0)
  2167 00005A25 B407                    	mov	ah, 07h ; Black background, 
  2168                                  			; light gray forecolor
  2169 00005A27 E876B9FFFF              	call	write_tty
  2170 00005A2C 5E                      	pop	esi
  2171 00005A2D EBEE                    	jmp	short pdskml
  2172                                  
  2173 00005A2F 90                      align 16
  2174                                  
  2175                                  gdt:	; Global Descriptor Table
  2176                                  	; (30/07/2015, conforming cs)
  2177                                  	; (26/03/2015)
  2178                                  	; (24/03/2015, tss)
  2179                                  	; (19/03/2015)
  2180                                  	; (29/12/2013)
  2181                                  	;
  2182 00005A30 0000000000000000        	dw 0, 0, 0, 0		; NULL descriptor
  2183                                  	; 18/08/2014
  2184                                  			; 8h kernel code segment, base = 00000000h		
  2185 00005A38 FFFF0000009ACF00        	dw 0FFFFh, 0, 9A00h, 00CFh	; KCODE
  2186                                  			; 10h kernel data segment, base = 00000000h	
  2187 00005A40 FFFF00000092CF00        	dw 0FFFFh, 0, 9200h, 00CFh	; KDATA
  2188                                  			; 1Bh user code segment, base address = 400000h ; CORE
  2189 00005A48 FFFB000040FACF00        	dw 0FBFFh, 0, 0FA40h, 00CFh	; UCODE 
  2190                                  			; 23h user data segment, base address = 400000h ; CORE
  2191 00005A50 FFFB000040F2CF00        	dw 0FBFFh, 0, 0F240h, 00CFh	; UDATA
  2192                                  			; Task State Segment
  2193 00005A58 6700                    	dw 0067h ; Limit = 103 ; (104-1, tss size = 104 byte, 
  2194                                  			       ;  no IO permission in ring 3)
  2195                                  gdt_tss0:
  2196 00005A5A 0000                    	dw 0  ; TSS base address, bits 0-15 
  2197                                  gdt_tss1:
  2198 00005A5C 00                      	db 0  ; TSS base address, bits 16-23 
  2199                                  	      		; 49h	
  2200 00005A5D E9                      	db 11101001b ; E9h => P=1/DPL=11/0/1/0/B/1 --> B = Task is busy (1)
  2201 00005A5E 00                      	db 0 ; G/0/0/AVL/LIMIT=0000 ; (Limit bits 16-19 = 0000) (G=0, 1 byte)
  2202                                  gdt_tss2:
  2203 00005A5F 00                      	db 0  ; TSS base address, bits 24-31 
  2204                                  
  2205                                  gdt_end:
  2206                                  	;; 9Ah = 1001 1010b (GDT byte 5) P=1/DPL=00/1/TYPE=1010, 
  2207                                  					;; Type= 1 (code)/C=0/R=1/A=0
  2208                                  		; P= Present, DPL=0=ring 0,  1= user (0= system)
  2209                                  		; 1= Code C= non-Conforming, R= Readable, A = Accessed
  2210                                  
  2211                                  	;; 92h = 1001 0010b (GDT byte 5) P=1/DPL=00/1/TYPE=1010, 
  2212                                  					;; Type= 0 (data)/E=0/W=1/A=0
  2213                                  		; P= Present, DPL=0=ring 0,  1= user (0= system)
  2214                                  		; 0= Data E= Expansion direction (1= down, 0= up)
  2215                                  		; W= Writeable, A= Accessed
  2216                                  	
  2217                                  	;; FAh = 1111 1010b (GDT byte 5) P=1/DPL=11/1/TYPE=1010, 
  2218                                  					;; Type= 1 (code)/C=0/R=1/A=0
  2219                                  		; P= Present, DPL=3=ring 3,  1= user (0= system)
  2220                                  		; 1= Code C= non-Conforming, R= Readable, A = Accessed
  2221                                  
  2222                                  	;; F2h = 1111 0010b (GDT byte 5) P=1/DPL=11/1/TYPE=0010, 
  2223                                  					;; Type= 0 (data)/E=0/W=1/A=0
  2224                                  		; P= Present, DPL=3=ring 3,  1= user (0= system)
  2225                                  		; 0= Data E= Expansion direction (1= down, 0= up)
  2226                                  	
  2227                                  	;; CFh = 1100 1111b (GDT byte 6) G=1/B=1/0/AVL=0, Limit=1111b (3)
  2228                                  
  2229                                  		;; Limit = FFFFFh (=> FFFFFh+1= 100000h) // bits 0-15, 48-51 //
  2230                                  		;	 = 100000h * 1000h (G=1) = 4GB
  2231                                  		;; Limit = FFBFFh (=> FFBFFh+1= FFC00h) // bits 0-15, 48-51 //
  2232                                  		;	 = FFC00h * 1000h (G=1) = 4GB - 4MB
  2233                                  		; G= Granularity (1= 4KB), B= Big (32 bit), 
  2234                                  		; AVL= Available to programmers	
  2235                                  
  2236                                  gdtd:
  2237 00005A60 2F00                            dw gdt_end - gdt - 1    ; Limit (size)
  2238 00005A62 [305A0000]                      dd gdt			; Address of the GDT
  2239                                  
  2240                                  	; 20/08/2014
  2241                                  idtd:
  2242 00005A66 FF01                            dw idt_end - idt - 1    ; Limit (size)
  2243 00005A68 [B05F0000]                      dd idt			; Address of the IDT
  2244                                  
  2245                                  Align 4
  2246                                  
  2247                                  	; 21/08/2014
  2248                                  ilist:
  2249                                  	;times 	32 dd cpu_except ; INT 0 to INT 1Fh
  2250                                  	;
  2251                                  	; Exception list
  2252                                  	; 25/08/2014	
  2253 00005A6C [05080000]              	dd	exc0	; 0h,  Divide-by-zero Error
  2254 00005A70 [0C080000]              	dd	exc1	
  2255 00005A74 [13080000]              	dd 	exc2	
  2256 00005A78 [1A080000]              	dd	exc3	
  2257 00005A7C [1E080000]              	dd	exc4	
  2258 00005A80 [22080000]              	dd	exc5	
  2259 00005A84 [26080000]              	dd 	exc6	; 06h,  Invalid Opcode
  2260 00005A88 [2A080000]              	dd	exc7	
  2261 00005A8C [2E080000]              	dd	exc8	
  2262 00005A90 [32080000]              	dd	exc9	
  2263 00005A94 [36080000]              	dd 	exc10	
  2264 00005A98 [3A080000]              	dd	exc11
  2265 00005A9C [3E080000]              	dd	exc12
  2266 00005AA0 [42080000]              	dd	exc13	; 0Dh, General Protection Fault
  2267 00005AA4 [46080000]              	dd 	exc14	; 0Eh, Page Fault
  2268 00005AA8 [4A080000]              	dd	exc15
  2269 00005AAC [4E080000]              	dd	exc16
  2270 00005AB0 [52080000]              	dd	exc17
  2271 00005AB4 [56080000]              	dd 	exc18
  2272 00005AB8 [5A080000]              	dd	exc19
  2273 00005ABC [5E080000]              	dd 	exc20
  2274 00005AC0 [62080000]              	dd	exc21
  2275 00005AC4 [66080000]              	dd	exc22
  2276 00005AC8 [6A080000]              	dd	exc23
  2277 00005ACC [6E080000]              	dd 	exc24
  2278 00005AD0 [72080000]              	dd	exc25
  2279 00005AD4 [76080000]              	dd	exc26
  2280 00005AD8 [7A080000]              	dd	exc27
  2281 00005ADC [7E080000]              	dd 	exc28
  2282 00005AE0 [82080000]              	dd	exc29
  2283 00005AE4 [86080000]              	dd 	exc30
  2284 00005AE8 [8A080000]              	dd	exc31
  2285                                  	; Interrupt list
  2286 00005AEC [40060000]              	dd	timer_int	; INT 20h
  2287                                  		;dd	irq0	
  2288 00005AF0 [440B0000]              	dd	keyb_int	; 27/08/2014
  2289                                  		;dd	irq1
  2290 00005AF4 [5F070000]              	dd	irq2
  2291                                  		; COM2 int
  2292 00005AF8 [63070000]              	dd	irq3
  2293                                  		; COM1 int
  2294 00005AFC [6E070000]              	dd	irq4
  2295 00005B00 [79070000]              	dd	irq5
  2296                                  ;DISKETTE_INT: ;06/02/2015
  2297 00005B04 [B61F0000]              	dd	fdc_int		; 16/02/2015, IRQ 6 handler	
  2298                                  		;dd	irq6
  2299                                  ; Default IRQ 7 handler against spurious IRQs (from master PIC)
  2300                                  ; 25/02/2015 (source: http://wiki.osdev.org/8259_PIC)
  2301 00005B08 [F50A0000]              	dd	default_irq7	; 25/02/2015
  2302                                  		;dd	irq7
  2303                                  ; Real Time Clock Interrupt
  2304 00005B0C [93090000]              	dd	rtc_int		; 23/02/2015, IRQ 8 handler
  2305                                  		;dd	irq8	; INT 28h
  2306 00005B10 [89070000]              	dd	irq9
  2307 00005B14 [8D070000]              	dd	irq10
  2308 00005B18 [91070000]              	dd	irq11
  2309 00005B1C [95070000]              	dd	irq12
  2310 00005B20 [99070000]              	dd	irq13
  2311                                  ;HDISK_INT1:  ;06/02/2015 	
  2312 00005B24 [80240000]              	dd	hdc1_int 	; 21/02/2015, IRQ 14 handler		
  2313                                  		;dd	irq14
  2314                                  ;HDISK_INT2:  ;06/02/2015
  2315 00005B28 [A3240000]              	dd	hdc2_int 	; 21/02/2015, IRQ 15 handler		
  2316                                  		;dd	irq15	; INT 2Fh
  2317                                  		; 14/08/2015
  2318 00005B2C [D9300000]              	dd	sysent		; INT 30h (system calls)
  2319                                  	
  2320                                  	;dd	ignore_int
  2321 00005B30 00000000                	dd	0
  2322                                  
  2323                                  ;;;
  2324                                  ;;; 11/03/2015
  2325                                  %include 'kybdata.inc'	; KEYBOARD (BIOS) DATA
  2326                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.4) - KYBDATA.INC
  2327                              <1> ; Last Modification: 13/06/2022
  2328                              <1> ;		 (Data Section for 'KEYBOARD.INC')	
  2329                              <1> ;
  2330                              <1> ; ///////// KEYBOARD DATA ///////////////
  2331                              <1> 
  2332                              <1> ; 11/03/2015
  2333                              <1> ; 05/12/2014
  2334                              <1> ; 04/12/2014 (derived from pc-xt-286 bios source code -1986-) 
  2335                              <1> ; 03/06/86  KEYBOARD BIOS
  2336                              <1> 
  2337                              <1> ;---------------------------------------------------------------------------------
  2338                              <1> ;	KEY IDENTIFICATION SCAN TABLES
  2339                              <1> ;---------------------------------------------------------------------------------
  2340                              <1> 
  2341                              <1> ;-----	TABLES FOR ALT CASE ------------
  2342                              <1> ;-----	ALT-INPUT-TABLE 
  2343 00005B34 524F50514B          <1> K30:	db	82,79,80,81,75
  2344 00005B39 4C4D474849          <1> 	db	76,77,71,72,73		; 10 NUMBER ON KEYPAD
  2345                              <1> ;-----	SUPER-SHIFT-TABLE 
  2346 00005B3E 101112131415        <1> 	db	16,17,18,19,20,21	; A-Z TYPEWRITER CHARS
  2347 00005B44 161718191E1F        <1> 	db	22,23,24,25,30,31
  2348 00005B4A 202122232425        <1> 	db	32,33,34,35,36,37
  2349 00005B50 262C2D2E2F30        <1> 	db	38,44,45,46,47,48
  2350 00005B56 3132                <1> 	db	49,50
  2351                              <1> 
  2352                              <1> ;-----	TABLE OF SHIFT KEYS AND MASK VALUES
  2353                              <1> ;-----	KEY_TABLE 
  2354 00005B58 52                  <1> _K6:    db      INS_KEY                 ; INSERT KEY
  2355 00005B59 3A4546381D          <1> 	db	CAPS_KEY,NUM_KEY,SCROLL_KEY,ALT_KEY,CTL_KEY
  2356 00005B5E 2A36                <1>         db      LEFT_KEY,RIGHT_KEY
  2357                              <1> _K6L    equ     $-_K6
  2358                              <1> 
  2359                              <1> ;-----	MASK_TABLE
  2360 00005B60 80                  <1> _K7:    db      INS_SHIFT               ; INSERT MODE SHIFT
  2361 00005B61 4020100804          <1> 	db	CAPS_SHIFT,NUM_SHIFT,SCROLL_SHIFT,ALT_SHIFT,CTL_SHIFT
  2362 00005B66 0201                <1> 	db	LEFT_SHIFT,RIGHT_SHIFT
  2363                              <1> 
  2364                              <1> ;-----	TABLES FOR CTRL CASE		;---- CHARACTERS ------
  2365 00005B68 1BFF00FFFFFF        <1> _K8:	db	27,-1,0,-1,-1,-1	; Esc, 1, 2, 3, 4, 5
  2366 00005B6E 1EFFFFFFFF1F        <1> 	db 	30,-1,-1,-1,-1,31	; 6, 7, 8, 9, 0, -
  2367                              <1> 	;db	-1,127,-1,17,23,5	; =, Bksp, Tab, Q, W, E
  2368 00005B74 FF7F94111705        <1> 	db	-1,127,148,17,23,5 ; 13/06/2022
  2369 00005B7A 12141915090F        <1> 	db	18,20,25,21,9,15	; R, T, Y, U, I, O
  2370 00005B80 101B1D0AFF01        <1> 	db	16,27,29,10,-1,1	; P, [, ], Enter, Ctrl, A
  2371 00005B86 13040607080A        <1> 	db	19,4,6,7,8,10		; S, D, F, G, H, J
  2372 00005B8C 0B0CFFFFFFFF        <1> 	db	11,12,-1,-1,-1,-1	; K, L, :, ', `, LShift
  2373 00005B92 1C1A18031602        <1> 	db	28,26,24,3,22,2		; Bkslash, Z, X, C, V, B
  2374 00005B98 0E0DFFFFFFFF        <1> 	db	14,13,-1,-1,-1,-1	; N, M, ,, ., /, RShift
  2375 00005B9E 96FF20FF            <1> 	db	150,-1,' ',-1		; *, ALT, Spc, CL
  2376                              <1> 	;				;----- FUNCTIONS ------		
  2377 00005BA2 5E5F60616263        <1> 	db 	94,95,96,97,98,99	; F1 - F6
  2378 00005BA8 64656667FFFF        <1> 	db	100,101,102,103,-1,-1	; F7 - F10, NL, SL
  2379 00005BAE 778D848E738F        <1> 	db	119,141,132,142,115,143	; Home, Up, PgUp, -, Left, Pad5
  2380 00005BB4 749075917692        <1> 	db 	116,144,117,145,118,146 ; Right, +, End, Down, PgDn, Ins
  2381 00005BBA 93FFFFFF898A        <1> 	db	147,-1,-1,-1,137,138	; Del, SysReq, Undef, WT, F11, F12
  2382                              <1> 
  2383                              <1> ;-----	TABLES FOR LOWER CASE ----------
  2384 00005BC0 1B3132333435363738- <1> K10:	db 	27,'1234567890-=',8,9
  2384 00005BC9 39302D3D0809        <1>
  2385 00005BCF 71776572747975696F- <1> 	db 	'qwertyuiop[]',13,-1,'asdfghjkl;',39
  2385 00005BD8 705B5D0DFF61736466- <1>
  2385 00005BE1 67686A6B6C3B27      <1>
  2386 00005BE8 60FF5C7A786376626E- <1> 	db	96,-1,92,'zxcvbnm,./',-1,'*',-1,' ',-1
  2386 00005BF1 6D2C2E2FFF2AFF20FF  <1>
  2387                              <1> ;-----	LC TABLE SCAN
  2388 00005BFA 3B3C3D3E3F          <1> 	db	59,60,61,62,63		; BASE STATE OF F1 - F10
  2389 00005BFF 4041424344          <1> 	db	64,65,66,67,68
  2390 00005C04 FFFF                <1> 	db	-1,-1			; NL, SL
  2391                              <1> 
  2392                              <1> ;-----	KEYPAD TABLE
  2393 00005C06 474849FF4BFF        <1> K15:	db	71,72,73,-1,75,-1	; BASE STATE OF KEYPAD KEYS
  2394 00005C0C 4DFF4F50515253      <1> 	db	77,-1,79,80,81,82,83
  2395 00005C13 FFFF5C8586          <1> 	db	-1,-1,92,133,134	; SysRq, Undef, WT, F11, F12
  2396                              <1> 
  2397                              <1> ;-----	TABLES FOR UPPER CASE ----------
  2398 00005C18 1B21402324255E262A- <1> K11:	db 	27,'!@#$%',94,'&*()_+',8,0
  2398 00005C21 28295F2B0800        <1>
  2399 00005C27 51574552545955494F- <1> 	db 	'QWERTYUIOP{}',13,-1,'ASDFGHJKL:"'
  2399 00005C30 507B7D0DFF41534446- <1>
  2399 00005C39 47484A4B4C3A22      <1>
  2400 00005C40 7EFF7C5A584356424E- <1> 	db	126,-1,'|ZXCVBNM<>?',-1,'*',-1,' ',-1
  2400 00005C49 4D3C3E3FFF2AFF20FF  <1>
  2401                              <1> ;-----	UC TABLE SCAN
  2402 00005C52 5455565758          <1> K12:	db	84,85,86,87,88		; SHIFTED STATE OF F1 - F10
  2403 00005C57 595A5B5C5D          <1> 	db	89,90,91,92,93
  2404 00005C5C FFFF                <1> 	db	-1,-1			; NL, SL
  2405                              <1> 
  2406                              <1> ;-----	NUM STATE TABLE
  2407 00005C5E 3738392D3435362B31- <1> K14:	db 	'789-456+1230.'		; NUMLOCK STATE OF KEYPAD KEYS
  2407 00005C67 3233302E            <1>
  2408                              <1> 	;
  2409 00005C6B FFFF7C8788          <1> 	db	-1,-1,124,135,136	; SysRq, Undef, WT, F11, F12
  2410                              <1> 
  2411                              <1> Align	4
  2412                              <1> ;----------------------------------------
  2413                              <1> ;	VIDEO DISPLAY DATA AREA		;
  2414                              <1> ;----------------------------------------
  2415 00005C70 03                  <1> CRT_MODE	db	3	; CURRENT DISPLAY MODE (TYPE)
  2416 00005C71 29                  <1> CRT_MODE_SET	db	29h	; CURRENT SETTING OF THE 3X8 REGISTER
  2417                              <1> 				; (29h default setting for video mode 3)
  2418                              <1> 				; Mode Select register Bits
  2419                              <1> 				;   BIT 0 - 80x25 (1), 40x25 (0)
  2420                              <1> 				;   BIT 1 - ALPHA (0), 320x200 GRAPHICS (1)
  2421                              <1> 				;   BIT 2 - COLOR (0), BW (1)
  2422                              <1> 				;   BIT 3 - Video Sig. ENABLE (1), DISABLE (0)
  2423                              <1> 				;   BIT 4 - 640x200 B&W Graphics Mode (1)
  2424                              <1> 				;   BIT 5 - ALPHA mode BLINKING (1)
  2425                              <1> 				;   BIT 6, 7 - Not Used
  2426                              <1> 
  2427                              <1> ; Mode 0 - 2Ch = 101100b	; 40x25 text, 16 gray colors
  2428                              <1> ; Mode 1 - 28h = 101000b	; 40x25 text, 16 fore colors, 8 back colors
  2429                              <1> ; Mode 2 - 2Dh = 101101b	; 80x25 text, 16 gray colors	
  2430                              <1> ; MODE 3 - 29h = 101001b	; 80x25 text, 16 fore color, 8 back color
  2431                              <1> ; Mode 4 - 2Ah = 101010b	; 320x200 graphics, 4 colors
  2432                              <1> ; Mode 5 - 2Eh = 101110b	; 320x200 graphics, 4 gray colors
  2433                              <1> ; Mode 6 - 1Eh = 011110b	; 640x200 graphics, 2 colors
  2434                              <1> ; Mode 7 - 29h = 101001b	; 80x25 text, black & white colors
  2435                              <1> ; Mode & 37h = Video signal OFF
  2436                              <1> 			
  2437                              <1> 
  2438                              <1> ; 26/08/2014
  2439                              <1> ; Retro UNIX 8086 v1 - UNIX.ASM (03/03/2014)
  2440                              <1> ; Derived from IBM "pc-at" 
  2441                              <1> ; rombios source code (06/10/1985)
  2442                              <1> ; 'dseg.inc'
  2443                              <1> 
  2444                              <1> ;---------------------------------------;
  2445                              <1> ;	SYSTEM DATA AREA		;
  2446                              <1> ;----------------------------------------
  2447 00005C72 00                  <1> BIOS_BREAK	db	0		; BIT 7=1 IF BREAK KEY HAS BEEN PRESSED
  2448                              <1> 
  2449                              <1> ;----------------------------------------
  2450                              <1> ;	KEYBOARD DATA AREAS		;
  2451                              <1> ;----------------------------------------
  2452                              <1> 
  2453 00005C73 00                  <1> KB_FLAG		db	0		; KEYBOARD SHIFT STATE AND STATUS FLAGS
  2454 00005C74 00                  <1> KB_FLAG_1	db	0		; SECOND BYTE OF KEYBOARD STATUS
  2455 00005C75 00                  <1> KB_FLAG_2	db	0		; KEYBOARD LED FLAGS
  2456 00005C76 00                  <1> KB_FLAG_3	db	0		; KEYBOARD MODE STATE AND TYPE FLAGS
  2457 00005C77 00                  <1> ALT_INPUT	db	0		; STORAGE FOR ALTERNATE KEY PAD ENTRY
  2458 00005C78 [885C0000]          <1> BUFFER_START	dd	KB_BUFFER 	; OFFSET OF KEYBOARD BUFFER START
  2459 00005C7C [A85C0000]          <1> BUFFER_END	dd	KB_BUFFER + 32	; OFFSET OF END OF BUFFER
  2460 00005C80 [885C0000]          <1> BUFFER_HEAD	dd	KB_BUFFER 	; POINTER TO HEAD OF KEYBOARD BUFFER
  2461 00005C84 [885C0000]          <1> BUFFER_TAIL	dd	KB_BUFFER 	; POINTER TO TAIL OF KEYBOARD BUFFER
  2462                              <1> ; ------	HEAD = TAIL	INDICATES THAT THE BUFFER IS EMPTY
  2463 00005C88 0000<rep 10h>       <1> KB_BUFFER	times	16 dw 0		; ROOM FOR 16 SCAN CODE ENTRIES
  2464                              <1> 
  2465                              <1> ; /// End Of KEYBOARD DATA ///
  2326                                  %include 'vidata.inc'	; VIDEO (BIOS) DATA
  2327                              <1> ; Retro UNIX 386 v1 Kernel - VIDATA.INC
  2328                              <1> ; Last Modification: 11/03/2015
  2329                              <1> ;		    (Data section for 'VIDEO.INC')	
  2330                              <1> ;
  2331                              <1> ; ///////// VIDEO DATA ///////////////
  2332                              <1> 
  2333                              <1> video_params:
  2334                              <1> 	; 02/09/2014 (Retro UNIX 386 v1)
  2335                              <1> 	;ORGS.ASM ----- 06/10/85   COMPATIBILITY MODULE
  2336                              <1> 	; VIDEO MODE 3
  2337 00005CA8 71505A0A1F0619      <1> 	db	71h,50h,5Ah,0Ah,1Fh,6,19h	; SET UP FOR 80X25
  2338 00005CAF 1C02070607          <1> 	db	1Ch,2,7,6,7	; cursor start = 6, cursor stop = 7
  2339 00005CB4 00000000            <1> 	db	0,0,0,0
  2340                              <1> 
  2341                              <1> ; /// End Of VIDEO DATA ///
  2327                                  %include 'diskdata.inc'	; DISK (BIOS) DATA (initialized)
  2328                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.5) - DISKDATA.INC
  2329                              <1> ; Last Modification: 11/07/2022
  2330                              <1> ;	(Initialized Disk Parameters Data section for 'DISKIO.INC') 
  2331                              <1> ;
  2332                              <1> ; *****************************************************************************
  2333                              <1> 
  2334                              <1> ;----------------------------------------
  2335                              <1> ;	80286 INTERRUPT LOCATIONS	:
  2336                              <1> ;	REFERENCED BY POST & BIOS	:
  2337                              <1> ;----------------------------------------
  2338                              <1> 
  2339 00005CB8 [1B5D0000]          <1> DISK_POINTER:	dd	MD_TBL6		; Pointer to Diskette Parameter Table
  2340                              <1> 
  2341                              <1> ; IBM PC-XT Model 286 source code ORGS.ASM (06/10/85) - 14/12/2014
  2342                              <1> ;----------------------------------------------------------------
  2343                              <1> ; DISK_BASE							:
  2344                              <1> ;	THIS IS THE SET OF PARAMETERS REQUIRED FOR		:
  2345                              <1> ;	DISKETTE OPERATION. THEY ARE POINTED AT BY THE		:
  2346                              <1> ;	DATA VARIABLE @DISK_POINTER. TO MODIFY THE PARAMETERS,	:
  2347                              <1> ;	BUILD ANOTHER PARAMETER BLOCK AND POINT AT IT		:
  2348                              <1> ;----------------------------------------------------------------
  2349                              <1> 
  2350                              <1> ;DISK_BASE:	
  2351                              <1> ;	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2352                              <1> ;	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2353                              <1> ;	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2354                              <1> ;	DB	2		; 512 BYTES/SECTOR
  2355                              <1> ;	;DB	15		; EOT (LAST SECTOR ON TRACK)
  2356                              <1> ;	db	18		; (EOT for 1.44MB diskette)
  2357                              <1> ;	DB	01BH		; GAP LENGTH
  2358                              <1> ;	DB	0FFH		; DTL
  2359                              <1> ;	;DB	054H		; GAP LENGTH FOR FORMAT
  2360                              <1> ;	db	06ch		; (for 1.44MB dsikette)
  2361                              <1> ;	DB	0F6H		; FILL BYTE FOR FORMAT
  2362                              <1> ;	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2363                              <1> ;	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2364                              <1> 
  2365                              <1> ;----------------------------------------
  2366                              <1> ;	ROM BIOS DATA AREAS		:
  2367                              <1> ;----------------------------------------
  2368                              <1> 
  2369                              <1> ;DATA		SEGMENT AT 40H		; ADDRESS= 0040:0000
  2370                              <1> 
  2371                              <1> ;@EQUIP_FLAG	DW	?		; INSTALLED HARDWARE FLAGS
  2372                              <1> 
  2373                              <1> ;----------------------------------------
  2374                              <1> ;	DISKETTE DATA AREAS		:
  2375                              <1> ;----------------------------------------
  2376                              <1> 
  2377                              <1> ;@SEEK_STATUS	DB	?		; DRIVE RECALIBRATION STATUS
  2378                              <1> ;					; BIT 3-0 = DRIVE 3-0 RECALIBRATION
  2379                              <1> ;					; BEFORE NEXT SEEK IF BIT IS = 0
  2380                              <1> ;@MOTOR_STATUS	DB	?		; MOTOR STATUS
  2381                              <1> ;					; BIT 3-0 = DRIVE 3-0 CURRENTLY RUNNING
  2382                              <1> ;					; BIT 7 = CURRENT OPERATION IS A WRITE
  2383                              <1> ;@MOTOR_COUNT	DB	?		; TIME OUT COUNTER FOR MOTOR(S) TURN OFF
  2384                              <1> ;@DSKETTE_STATUS DB	?		; RETURN CODE STATUS BYTE
  2385                              <1> ;					; CMD_BLOCK  IN STACK FOR DISK OPERATION
  2386                              <1> ;@NEC_STATUS	DB	7 DUP(?)	; STATUS BYTES FROM DISKETTE OPERATION
  2387                              <1> 
  2388                              <1> ;----------------------------------------
  2389                              <1> ;	POST AND BIOS WORK DATA AREA	:
  2390                              <1> ;----------------------------------------
  2391                              <1> 
  2392                              <1> ;@INTR_FLAG	DB	?		; FLAG INDICATING AN INTERRUPT HAPPENED
  2393                              <1> 
  2394                              <1> ;----------------------------------------
  2395                              <1> ;	TIMER DATA AREA 		:
  2396                              <1> ;----------------------------------------
  2397                              <1> 
  2398                              <1> ; 17/12/2014  (IRQ 0 - INT 08H)
  2399                              <1> ;TIMER_LOW	equ	46Ch		; Timer ticks (counter)  @ 40h:006Ch
  2400                              <1> ;TIMER_HIGH	equ	46Eh		; (18.2 timer ticks per second)
  2401                              <1> ;TIMER_OFL	equ	470h		; Timer - 24 hours flag  @ 40h:0070h
  2402                              <1> 
  2403                              <1> ;----------------------------------------
  2404                              <1> ;	ADDITIONAL MEDIA DATA		:
  2405                              <1> ;----------------------------------------
  2406                              <1> 
  2407                              <1> ;@LASTRATE	DB	?		; LAST DISKETTE DATA RATE SELECTED
  2408                              <1> ;@DSK_STATE	DB	?		; DRIVE 0 MEDIA STATE
  2409                              <1> ;		DB	?		; DRIVE 1 MEDIA STATE
  2410                              <1> ;		DB	?		; DRIVE 0 OPERATION START STATE
  2411                              <1> ;		DB	?		; DRIVE 1 OPERATION START STATE
  2412                              <1> ;@DSK_TRK	DB	?		; DRIVE 0 PRESENT CYLINDER
  2413                              <1> ;		DB	?		; DRIVE 1 PRESENT CYLINDER
  2414                              <1> 
  2415                              <1> ;DATA		ENDS			; END OF BIOS DATA SEGMENT
  2416                              <1> 
  2417                              <1> ;--------------------------------------------------------
  2418                              <1> ;	DRIVE TYPE TABLE				:
  2419                              <1> ;--------------------------------------------------------
  2420                              <1> 		; 16/02/2015 (unix386.s, 32 bit modifications)
  2421                              <1> DR_TYPE:
  2422 00005CBC 01                  <1> 		DB	01		;DRIVE TYPE, MEDIA TABLE
  2423                              <1>                 ;DW      MD_TBL1
  2424 00005CBD [DA5C0000]          <1> 		dd	MD_TBL1
  2425 00005CC1 82                  <1> 		DB	02+BIT7ON
  2426                              <1> 		;DW      MD_TBL2
  2427 00005CC2 [E75C0000]          <1>                 dd      MD_TBL2
  2428 00005CC6 02                  <1> DR_DEFAULT:	DB	02
  2429                              <1>                 ;DW      MD_TBL3
  2430 00005CC7 [F45C0000]          <1> 		dd      MD_TBL3
  2431 00005CCB 03                  <1> 		DB	03
  2432                              <1>                 ;DW      MD_TBL4
  2433 00005CCC [015D0000]          <1> 		dd      MD_TBL4
  2434 00005CD0 84                  <1> 		DB	04+BIT7ON
  2435                              <1>                 ;DW      MD_TBL5
  2436 00005CD1 [0E5D0000]          <1> 		dd      MD_TBL5
  2437 00005CD5 04                  <1> 		DB	04
  2438                              <1>                 ;DW      MD_TBL6
  2439 00005CD6 [1B5D0000]          <1> 		dd      MD_TBL6
  2440                              <1> DR_TYPE_E       equ $                   ; END OF TABLE
  2441                              <1> ;DR_CNT		EQU	(DR_TYPE_E-DR_TYPE)/3
  2442                              <1> DR_CNT		equ	(DR_TYPE_E-DR_TYPE)/5
  2443                              <1> ;--------------------------------------------------------
  2444                              <1> ;	MEDIA/DRIVE PARAMETER TABLES			:
  2445                              <1> ;--------------------------------------------------------
  2446                              <1> ;--------------------------------------------------------
  2447                              <1> ;	360 KB MEDIA IN 360 KB DRIVE			:
  2448                              <1> ;--------------------------------------------------------
  2449                              <1> MD_TBL1:        
  2450 00005CDA DF                  <1> 	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2451 00005CDB 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2452 00005CDC 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2453 00005CDD 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2454 00005CDE 09                  <1> 	DB	09		; EOT (LAST SECTOR ON TRACK)
  2455 00005CDF 2A                  <1> 	DB	02AH		; GAP LENGTH
  2456 00005CE0 FF                  <1> 	DB	0FFH		; DTL
  2457 00005CE1 50                  <1> 	DB	050H		; GAP LENGTH FOR FORMAT
  2458 00005CE2 F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2459 00005CE3 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2460 00005CE4 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2461 00005CE5 27                  <1> 	DB	39		; MAX. TRACK NUMBER
  2462 00005CE6 80                  <1> 	DB	RATE_250	; DATA TRANSFER RATE
  2463                              <1> ;--------------------------------------------------------
  2464                              <1> ;	360 KB MEDIA IN 1.2 MB DRIVE			:
  2465                              <1> ;--------------------------------------------------------
  2466                              <1> MD_TBL2:        
  2467 00005CE7 DF                  <1> 	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2468 00005CE8 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2469 00005CE9 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2470 00005CEA 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2471 00005CEB 09                  <1> 	DB	09		; EOT (LAST SECTOR ON TRACK)
  2472 00005CEC 2A                  <1> 	DB	02AH		; GAP LENGTH
  2473 00005CED FF                  <1> 	DB	0FFH		; DTL
  2474 00005CEE 50                  <1> 	DB	050H		; GAP LENGTH FOR FORMAT
  2475 00005CEF F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2476 00005CF0 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2477 00005CF1 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2478 00005CF2 27                  <1> 	DB	39		; MAX. TRACK NUMBER
  2479 00005CF3 40                  <1> 	DB	RATE_300	; DATA TRANSFER RATE
  2480                              <1> ;--------------------------------------------------------
  2481                              <1> ;	1.2 MB MEDIA IN 1.2 MB DRIVE			:
  2482                              <1> ;--------------------------------------------------------
  2483                              <1> MD_TBL3:
  2484 00005CF4 DF                  <1> 	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2485 00005CF5 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2486 00005CF6 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2487 00005CF7 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2488 00005CF8 0F                  <1> 	DB	15		; EOT (LAST SECTOR ON TRACK)
  2489 00005CF9 1B                  <1> 	DB	01BH		; GAP LENGTH
  2490 00005CFA FF                  <1> 	DB	0FFH		; DTL
  2491 00005CFB 54                  <1> 	DB	054H		; GAP LENGTH FOR FORMAT
  2492 00005CFC F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2493 00005CFD 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2494 00005CFE 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2495 00005CFF 4F                  <1> 	DB	79		; MAX. TRACK NUMBER
  2496 00005D00 00                  <1> 	DB	RATE_500	; DATA TRANSFER RATE
  2497                              <1> ;--------------------------------------------------------
  2498                              <1> ;	720 KB MEDIA IN 720 KB DRIVE			:
  2499                              <1> ;--------------------------------------------------------
  2500                              <1> MD_TBL4:
  2501 00005D01 DF                  <1> 	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2502 00005D02 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2503 00005D03 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2504 00005D04 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2505 00005D05 09                  <1> 	DB	09		; EOT (LAST SECTOR ON TRACK)
  2506 00005D06 2A                  <1> 	DB	02AH		; GAP LENGTH
  2507 00005D07 FF                  <1> 	DB	0FFH		; DTL
  2508 00005D08 50                  <1> 	DB	050H		; GAP LENGTH FOR FORMAT
  2509 00005D09 F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2510 00005D0A 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2511 00005D0B 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2512 00005D0C 4F                  <1> 	DB	79		; MAX. TRACK NUMBER
  2513 00005D0D 80                  <1> 	DB	RATE_250	; DATA TRANSFER RATE
  2514                              <1> ;--------------------------------------------------------
  2515                              <1> ;	720 KB MEDIA IN 1.44 MB DRIVE			:
  2516                              <1> ;--------------------------------------------------------
  2517                              <1> MD_TBL5:
  2518 00005D0E DF                  <1> 	DB	11011111B	; SRT=D, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2519 00005D0F 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2520 00005D10 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2521 00005D11 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2522 00005D12 09                  <1> 	DB	09		; EOT (LAST SECTOR ON TRACK)
  2523 00005D13 2A                  <1> 	DB	02AH		; GAP LENGTH
  2524 00005D14 FF                  <1> 	DB	0FFH		; DTL
  2525 00005D15 50                  <1> 	DB	050H		; GAP LENGTH FOR FORMAT
  2526 00005D16 F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2527 00005D17 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2528 00005D18 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2529 00005D19 4F                  <1> 	DB	79		; MAX. TRACK NUMBER
  2530 00005D1A 80                  <1> 	DB	RATE_250	; DATA TRANSFER RATE
  2531                              <1> ;--------------------------------------------------------
  2532                              <1> ;	1.44 MB MEDIA IN 1.44 MB DRIVE			:
  2533                              <1> ;--------------------------------------------------------
  2534                              <1> MD_TBL6:
  2535 00005D1B AF                  <1> 	DB	10101111B	; SRT=A, HD UNLOAD=0F - 1ST SPECIFY BYTE
  2536 00005D1C 02                  <1> 	DB	2		; HD LOAD=1, MODE=DMA - 2ND SPECIFY BYTE
  2537 00005D1D 25                  <1> 	DB	MOTOR_WAIT	; WAIT TIME AFTER OPERATION TILL MOTOR OFF
  2538 00005D1E 02                  <1> 	DB	2		; 512 BYTES/SECTOR
  2539 00005D1F 12                  <1> 	DB	18		; EOT (LAST SECTOR ON TRACK)
  2540 00005D20 1B                  <1> 	DB	01BH		; GAP LENGTH
  2541 00005D21 FF                  <1> 	DB	0FFH		; DTL
  2542 00005D22 6C                  <1> 	DB	06CH		; GAP LENGTH FOR FORMAT
  2543 00005D23 F6                  <1> 	DB	0F6H		; FILL BYTE FOR FORMAT
  2544 00005D24 0F                  <1> 	DB	15		; HEAD SETTLE TIME (MILLISECONDS)
  2545 00005D25 08                  <1> 	DB	8		; MOTOR START TIME (1/8 SECONDS)
  2546 00005D26 4F                  <1> 	DB	79		; MAX. TRACK NUMBER
  2547 00005D27 00                  <1> 	DB	RATE_500	; DATA TRANSFER RATE
  2548                              <1> 
  2549                              <1> 
  2550                              <1> ; << diskette.inc >>
  2551                              <1> ; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2552                              <1> ;
  2553                              <1> ;----------------------------------------
  2554                              <1> ;	ROM BIOS DATA AREAS		:
  2555                              <1> ;----------------------------------------
  2556                              <1> 
  2557                              <1> ;DATA		SEGMENT AT 40H		; ADDRESS= 0040:0000
  2558                              <1> 
  2559                              <1> ;----------------------------------------
  2560                              <1> ;	FIXED DISK DATA AREAS		:
  2561                              <1> ;----------------------------------------
  2562                              <1> 
  2563                              <1> ;DISK_STATUS1:	DB	0		; FIXED DISK STATUS
  2564                              <1> ;HF_NUM:		DB	0		; COUNT OF FIXED DISK DRIVES
  2565                              <1> ;CONTROL_BYTE:	DB	0		; HEAD CONTROL BYTE
  2566                              <1> ;@PORT_OFF	DB	?		;  RESERVED (PORT OFFSET)
  2567                              <1> 
  2568                              <1> ;----------------------------------------
  2569                              <1> ;	ADDITIONAL MEDIA DATA		:
  2570                              <1> ;----------------------------------------
  2571                              <1> 
  2572                              <1> ;@LASTRATE	DB	?		; LAST DISKETTE DATA RATE SELECTED
  2573                              <1> ;HF_STATUS	DB	0		; STATUS REGISTER
  2574                              <1> ;HF_ERROR	DB	0		; ERROR REGISTER
  2575                              <1> ;HF_INT_FLAG	DB	0		; FIXED DISK INTERRUPT FLAG
  2576                              <1> ;HF_CNTRL	DB	0		; COMBO FIXED DISK/DISKETTE CARD BIT 0=1
  2577                              <1> ;@DSK_STATE	DB	?		; DRIVE 0 MEDIA STATE
  2578                              <1> ;		DB	?		; DRIVE 1 MEDIA STATE
  2579                              <1> ;		DB	?		; DRIVE 0 OPERATION START STATE
  2580                              <1> ;		DB	?		; DRIVE 1 OPERATION START STATE
  2581                              <1> ;@DSK_TRK	DB	?		; DRIVE 0 PRESENT CYLINDER
  2582                              <1> ;		DB	?		; DRIVE 1 PRESENT CYLINDER
  2583                              <1> 
  2584                              <1> ;DATA		ENDS			; END OF BIOS DATA SEGMENT
  2585                              <1> ;
  2586                              <1> ; +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2587                              <1> 
  2588                              <1> ERR_TBL:
  2589 00005D28 E0                  <1> 	db	NO_ERR
  2590 00005D29 024001BB            <1> 	db	BAD_ADDR_MARK,BAD_SEEK,BAD_CMD,UNDEF_ERR
  2591 00005D2D 04BB100A            <1> 	db	RECORD_NOT_FND,UNDEF_ERR,BAD_ECC,BAD_SECTOR
  2592                              <1> 
  2593                              <1> ; 11/07/2022
  2594                              <1> ; 17/12/2014 (mov ax, [cfd])
  2595                              <1> ; 11/12/2014
  2596                              <1> ;cfd:		db 0			; current floppy drive (for GET_PARM)
  2597                              <1> ; 17/12/2014				; instead of 'DISK_POINTER'
  2598                              <1> ;pfd:		db 1			; previous floppy drive (for GET_PARM)
  2599                              <1> 					; (initial value of 'pfd 
  2600                              <1> 					; must be different then 'cfd' value
  2601                              <1> 					; to force updating/initializing
  2602                              <1> 					; current drive parameters) 
  2603                              <1> 
  2604                              <1> ;; 11/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2605 00005D31 FF                  <1> pfd:		db 0FFh
  2606                              <1> 
  2607                              <1> align 2
  2608                              <1> 
  2609 00005D32 F001                <1> HF_PORT:	dw 	1F0h  ; Default = 1F0h
  2610                              <1> 			      ; (170h)
  2611 00005D34 F603                <1> HF_REG_PORT:	dw	3F6h  ; HF_PORT + 206h
  2612                              <1> 
  2613                              <1> ; 05/01/2015 
  2614 00005D36 00                  <1> hf_m_s:         db      0     ; (0 = Master, 1 = Slave)
  2615                              <1> 
  2616                              <1> ; *****************************************************************************
  2328                                  ;;;
  2329                                  
  2330 00005D37 90                      Align 2
  2331                                  
  2332                                  ; 12/11/2014 (Retro UNIX 386 v1)
  2333 00005D38 00                      boot_drv:    db 0 ; boot drive number (physical)
  2334                                  ; 24/11/2014
  2335 00005D39 00                      drv:	     db 0 
  2336 00005D3A 00                      last_drv:    db 0 ; last hdd
  2337 00005D3B 00                      hdc:         db 0  ; number of hard disk drives
  2338                                  		     ; (present/detected)
  2339                                  ;
  2340                                  ; 24/11/2014 (Retro UNIX 386 v1)
  2341                                  ; Physical drive type & flags
  2342 00005D3C 00                      fd0_type:    db 0  ; floppy drive type
  2343 00005D3D 00                      fd1_type:    db 0  ; 4 = 1.44 Mb, 80 track, 3.5" (18 spt)
  2344                                  		     ; 6 = 2.88 Mb, 80 track, 3.5" (36 spt)
  2345                                  		     ; 3 = 720 Kb, 80 track, 3.5" (9 spt)
  2346                                  		     ; 2 = 1.2 Mb, 80 track, 5.25" (15 spt)
  2347                                  		     ; 1 = 360 Kb, 40 track, 5.25" (9 spt)		
  2348 00005D3E 00                      hd0_type:    db 0  ; EDD status for hd0 (bit 7 = present flag)
  2349 00005D3F 00                      hd1_type:    db 0  ; EDD status for hd1 (bit 7 = present flag)
  2350 00005D40 00                      hd2_type:    db 0  ; EDD status for hd2 (bit 7 = present flag)
  2351 00005D41 00                      hd3_type:    db 0  ; EDD status for hd3 (bit 7 = present flag)
  2352                                  		     ; bit 0 - Fixed disk access subset supported
  2353                                  		     ; bit 1 - Drive locking and ejecting
  2354                                  		     ; bit 2 - Enhanced disk drive support
  2355                                  		     ; bit 3 = Reserved (64 bit EDD support)
  2356                                  		     ; (If bit 0 is '1' Retro UNIX 386 v1
  2357                                  		     ; will interpret it as 'LBA ready'!)		
  2358                                  
  2359                                  ; 12/07/2022
  2360                                  ; (drv.cylinders, drv.spt, drv.spt will not be used now on)
  2361                                  ; ('diskio.inc')
  2362                                  ; ((spt and heads and cylinder counts will be taken from DPT))
  2363                                  
  2364                                  ; 11/03/2015 - 10/07/2015
  2365                                  ;drv.cylinders: dw 0,0,0,0,0,0,0
  2366                                  ;drv.heads:     dw 0,0,0,0,0,0,0
  2367                                  ;drv.spt:       dw 0,0,0,0,0,0,0
  2368                                  ; 12/07/2022 - 11/03/2015
  2369 00005D42 000000000000000000-     drv.size:      dd 0,0,0,0,0,0,0
  2369 00005D4B 000000000000000000-
  2369 00005D54 000000000000000000-
  2369 00005D5D 00                 
  2370 00005D5E 00000000000000          drv.status:    db 0,0,0,0,0,0,0
  2371 00005D65 00000000000000          drv.error:     db 0,0,0,0,0,0,0
  2372                                  ;
  2373                                  
  2374                                  ; 27/08/2014
  2375                                  scr_row:
  2376 00005D6C E0810B00                	dd 0B8000h + 0A0h + 0A0h + 0A0h ; Row 3
  2377                                  scr_col:
  2378 00005D70 00000000                	dd 0
  2379                                  
  2380                                  ;; 14/08/2015
  2381                                  ;;msgPM:
  2382                                  ;;      db "Protected mode and paging are ENABLED ... ", 0
  2383                                  msgKVER:
  2384                                  	;;;;db "Retro UNIX 386 v1.1 - Kernel v0.2.1.2 [29/04/2022]", 0
  2385                                  	;;;db "Retro UNIX 386 v1.1 - Kernel v0.2.1.3 [02/06/2022]", 0
  2386                                  	;;db "Retro UNIX 386 v1.1 - Kernel v0.2.1.4 [14/06/2022]", 0
  2387                                  	;db "Retro UNIX 386 v1.1 - Kernel v0.2.1.5 [12/07/2022]", 0
  2388 00005D74 526574726F20554E49-     	db "Retro UNIX 386 v1.1 - Kernel v0.2.1.6 [18/07/2022]", 0
  2388 00005D7D 58203338362076312E-
  2388 00005D86 31202D204B65726E65-
  2388 00005D8F 6C2076302E322E312E-
  2388 00005D98 36205B31382F30372F-
  2388 00005DA1 323032325D00       
  2389                                  
  2390 00005DA7 90                      Align 2
  2391                                  
  2392                                  ; 20/08/2014
  2393                                    ; /* This is the default interrupt "handler" :-) */ 
  2394                                    ; Linux v0.12 (head.s)
  2395                                  int_msg:
  2396 00005DA8 556E6B6E6F776E2069-     	db "Unknown interrupt ! ", 0
  2396 00005DB1 6E7465727275707420-
  2396 00005DBA 212000             
  2397                                  
  2398 00005DBD 90                      Align 2  
  2399                                  
  2400                                  ; 21/08/2014
  2401                                  timer_msg:
  2402 00005DBE 49525120302028494E-     	db "IRQ 0 (INT 20h) ! Timer Interrupt : "
  2402 00005DC7 542032306829202120-
  2402 00005DD0 54696D657220496E74-
  2402 00005DD9 657272757074203A20 
  2403                                  tcountstr:
  2404 00005DE2 303030303020            	db "00000 "
  2405 00005DE8 00                      	db 0
  2406                                  
  2407 00005DE9 90                      Align 2
  2408                                  	; 21/08/2014
  2409                                  exc_msg:
  2410 00005DEA 435055206578636570-     	db "CPU exception ! "
  2410 00005DF3 74696F6E202120     
  2411                                  excnstr: 		; 25/08/2014
  2412 00005DFA 3F3F68202045495020-     	db "??h", "  EIP : "
  2412 00005E03 3A20               
  2413                                  EIPstr: ; 29/08/2014
  2414 00005E05 00<rep Ch>              	times 12 db 0
  2415                                  rtc_msg:
  2416 00005E11 5265616C2054696D65-     	db "Real Time Clock - "
  2416 00005E1A 20436C6F636B202D20 
  2417                                  datestr:
  2418 00005E23 30302F30302F303030-     	db "00/00/0000"
  2418 00005E2C 30                 
  2419 00005E2D 20                      	db " "
  2420                                  daystr:
  2421 00005E2E 44415920                	db "DAY "
  2422                                  timestr:	
  2423 00005E32 30303A30303A3030                db "00:00:00"
  2424 00005E3A 20                      	db " "
  2425 00005E3B 00                      	db 0 
  2426                                  
  2427                                  daytmp:
  2428                                  	; 28/02/2015
  2429 00005E3C 3F3F3F2053554E204D-     	db "??? SUN MON TUE WED THU FRI SAT "
  2429 00005E45 4F4E20545545205745-
  2429 00005E4E 442054485520465249-
  2429 00005E57 2053415420         
  2430                                  
  2431 00005E5C FF                      ptime_seconds: db 0FFh
  2432                                  
  2433                                  	; 23/02/2015
  2434                                  	; 25/08/2014
  2435                                  ;scounter:
  2436                                  ;	db 5
  2437                                  ;	db 19
  2438                                  
  2439                                  ; 02/01/2022
  2440                                  ; 05/11/2014
  2441                                  ;msg_out_of_memory:
  2442                                  ;	db 	07h, 0Dh, 0Ah
  2443                                  ;       db	'Insufficient memory ! (Minimum 2 MB memory is needed.)'
  2444                                  ; 	db	0Dh, 0Ah, 0
  2445                                  	;
  2446                                  setup_error_msg:
  2447 00005E5D 0D0A                    	db 0Dh, 0Ah
  2448 00005E5F 4469736B2053657475-     	db 'Disk Setup Error!' 
  2448 00005E68 70204572726F7221   
  2449 00005E70 0D0A00                  	db 0Dh, 0Ah,0
  2450                                  
  2451                                  ; 02/09/2014 (Retro UNIX 386 v1)
  2452                                  ;crt_ulc : db 0 ; upper left column (for scroll) 
  2453                                  ;	  db 0 ; upper left row (for scroll)	
  2454                                  
  2455                                  ;crt_lrc : db 79 ; lower right column (for scroll) 
  2456                                  ;	  db 24 ; lower right row (for scroll)
  2457                                  
  2458                                  
  2459                                  ; 06/11/2014 (Temporary Data)
  2460                                  ; Memory Information message
  2461                                  ; 14/08/2015
  2462                                  msg_memory_info:
  2463 00005E73 07                      	db	07h
  2464 00005E74 0D0A                    	db	0Dh, 0Ah
  2465                                  	;db 	"MEMORY ALLOCATION INFO", 0Dh, 0Ah, 0Dh, 0Ah
  2466 00005E76 546F74616C206D656D-     	db	"Total memory : "
  2466 00005E7F 6F7279203A20       
  2467                                  mem_total_b_str: ; 10 digits
  2468 00005E85 303030303030303030-     	db	"0000000000 bytes", 0Dh, 0Ah
  2468 00005E8E 302062797465730D0A 
  2469 00005E97 202020202020202020-     	db	"               ", 20h, 20h, 20h
  2469 00005EA0 202020202020202020 
  2470                                  mem_total_p_str: ; 7 digits
  2471 00005EA9 303030303030302070-     	db	"0000000 pages", 0Dh, 0Ah
  2471 00005EB2 616765730D0A       
  2472 00005EB8 0D0A                    	db 	0Dh, 0Ah
  2473 00005EBA 46726565206D656D6F-     	db	"Free memory  : "
  2473 00005EC3 727920203A20       
  2474                                  free_mem_b_str:  ; 10 digits
  2475 00005EC9 3F3F3F3F3F3F3F3F3F-     	db	"?????????? bytes", 0Dh, 0Ah
  2475 00005ED2 3F2062797465730D0A 
  2476 00005EDB 202020202020202020-     	db	"               ", 20h, 20h, 20h
  2476 00005EE4 202020202020202020 
  2477                                  free_mem_p_str:  ; 7 digits
  2478 00005EED 3F3F3F3F3F3F3F2070-     	db	"??????? pages", 0Dh, 0Ah
  2478 00005EF6 616765730D0A       
  2479 00005EFC 0D0A00                  	db	0Dh, 0Ah, 0
  2480                                  
  2481                                  dsk_ready_msg:
  2482 00005EFF 0D0A                    	db 	0Dh, 0Ah
  2483                                  dsktype:
  2484 00005F01 6664                    	db	'fd'
  2485                                  dskx:
  2486 00005F03 30                      	db	'0'
  2487 00005F04 20                      	db	20h
  2488 00005F05 697320524541445920-     	db 	'is READY ...'
  2488 00005F0E 2E2E2E             
  2489 00005F11 00                      	db 	0
  2490                                  nextline:
  2491 00005F12 0D0A00                  	db 	0Dh, 0Ah, 0
  2492                                  
  2493                                  ; KERNEL - SYSINIT Messages
  2494                                  ; 24/08/2015
  2495                                  ; 13/04/2015 - (Retro UNIX 386 v1 Beginning)
  2496                                  ; 14/07/2013
  2497                                  ;kernel_init_err_msg:
  2498                                  ;	db 0Dh, 0Ah
  2499                                  ;	db 07h
  2500                                  ;	db 'Kernel initialization ERROR !'
  2501                                  ;	db 0Dh, 0Ah, 0 
  2502                                  ; 24/08/2015
  2503                                  ;;; (temporary kernel init message has been removed
  2504                                  ;;;  from 'sys_init' code)
  2505                                  ;kernel_init_ok_msg: 
  2506                                  ;	db 0Dh, 0Ah
  2507                                  ;	db 07h
  2508                                  ;	db 'Welcome to Retro UNIX 386 v1.1 Operating System !'
  2509                                  ;	db 0Dh, 0Ah
  2510                                  ;       db 'by Erdogan Tan - 04/02/2016 (v0.2.1.0)'
  2511                                  ;	db 0Dh, 0Ah, 0
  2512                                  panic_msg:
  2513 00005F15 0D0A07                  	db 0Dh, 0Ah, 07h
  2514 00005F18 4552524F523A204B65-     	db 'ERROR: Kernel Panic !'
  2514 00005F21 726E656C2050616E69-
  2514 00005F2A 632021             
  2515 00005F2D 0D0A00                  	db 0Dh, 0Ah, 0
  2516                                  etc_init_err_msg:
  2517 00005F30 0D0A                    	db 0Dh, 0Ah
  2518 00005F32 07                      	db 07h
  2519 00005F33 4552524F523A202F65-     	db 'ERROR: /etc/init !?'
  2519 00005F3C 74632F696E69742021-
  2519 00005F45 3F                 
  2520 00005F46 0D0A00                  	db 0Dh, 0Ah, 0
  2521                                  
  2522                                  ; 10/05/2015
  2523                                  badsys_msg:
  2524 00005F49 0D0A                    	db 0Dh, 0Ah
  2525 00005F4B 07                      	db 07h
  2526 00005F4C 496E76616C69642053-     	db 'Invalid System Call !'
  2526 00005F55 797374656D2043616C-
  2526 00005F5E 6C2021             
  2527 00005F61 0D0A                    	db 0Dh, 0Ah
  2528 00005F63 4541583A20              	db 'EAX: '
  2529                                  bsys_msg_eax:
  2530 00005F68 303030303030303068      	db '00000000h'
  2531 00005F71 0D0A                    	db 0Dh, 0Ah
  2532 00005F73 4549503A20              	db 'EIP: '
  2533                                  bsys_msg_eip:
  2534 00005F78 303030303030303068      	db '00000000h' 
  2535 00005F81 0D0A00                  	db 0Dh, 0Ah, 0
  2536                                  
  2537                                  BSYS_M_SIZE equ $ - badsys_msg
  2538                                  
  2539                                  
  2540                                  align 2
  2541                                  
  2542                                  ; EPOCH Variables
  2543                                  ; 13/04/2015 - Retro UNIX 386 v1 Beginning
  2544                                  ; 09/04/2013 epoch variables
  2545                                  ; Retro UNIX 8086 v1 Prototype: UNIXCOPY.ASM, 10/03/2013
  2546                                  ;
  2547 00005F84 B207                    year: 	dw 1970
  2548                                  ;month: dw 1
  2549                                  ;day: 	dw 1
  2550                                  ;hour: 	dw 0
  2551                                  ;minute: dw 0
  2552                                  ;second: dw 0
  2553                                  ; 02/06/2022
  2554 00005F86 01                      month:	db 1
  2555 00005F87 01                      day:	db 1
  2556 00005F88 01                      hour:	db 1
  2557 00005F89 01                      minute: db 1
  2558 00005F8A 01                      second:	db 1
  2559 00005F8B 01                      	db 1
  2560                                  
  2561                                  DMonth:
  2562 00005F8C 0000                    	dw 0
  2563 00005F8E 1F00                    	dw 31
  2564 00005F90 3B00                    	dw 59
  2565 00005F92 5A00                    	dw 90
  2566 00005F94 7800                    	dw 120
  2567 00005F96 9700                    	dw 151
  2568 00005F98 B500                    	dw 181
  2569 00005F9A D400                    	dw 212
  2570 00005F9C F300                    	dw 243
  2571 00005F9E 1101                    	dw 273
  2572 00005FA0 3001                    	dw 304
  2573 00005FA2 4E01                    	dw 334
  2574                                  
  2575                                  ; 02/01/2022 (Retro UNIX 386 v1.1, Runix Kernel v0.2.1.2)
  2576                                  ; 04/11/2014 (Retro UNIX 386 v1)
  2577 00005FA4 0000                    mem_1m_1k:   dw 0  ; Number of contiguous KB between
  2578                                  		   ;   1 and 16 MB, max. 3C00h = 15 MB.
  2579 00005FA6 0000                    	     dw 0  ; 02/01/2022 (Retro UNIX 386 v1.2)
  2580 00005FA8 0000                    mem_16m_64k: dw 0  ; Number of contiguous 64 KB blocks
  2581                                  		   ;   between 16 MB and 4 GB.
  2582 00005FAA 0000                    	     dw 0  ; 02/01/2022 (Retro UNIX 386 v1.2)
  2583                                  
  2584                                  ; 02/01/2022
  2585                                  KEND:
  2586                                  
  2587 00005FAC 90<rep 4h>              align 16
  2588                                  
  2589                                  bss_start:
  2590                                  
  2591                                  ABSOLUTE bss_start
  2592                                  
  2593                                  	; 11/03/2015
  2594                                  	; Interrupt Descriptor Table (20/08/2014)
  2595                                  idt:
  2596 00005FB0 <res 200h>              	resb	64*8 ; INT 0 to INT 3Fh
  2597                                  idt_end:
  2598                                  
  2599                                  ;alignb 4
  2600                                  
  2601                                  task_state_segment:
  2602                                  	; 24/03/2015
  2603 000061B0 ????                    tss.link:   resw 1
  2604 000061B2 ????                    	    resw 1
  2605                                  ; tss offset 4	
  2606 000061B4 ????????                tss.esp0:   resd 1
  2607 000061B8 ????                    tss.ss0:    resw 1
  2608 000061BA ????                    	    resw 1	
  2609 000061BC ????????                tss.esp1:   resd 1
  2610 000061C0 ????                    tss.ss1:    resw 1
  2611 000061C2 ????                    	    resw 1 	
  2612 000061C4 ????????                tss.esp2:   resd 1
  2613 000061C8 ????                    tss.ss2:    resw 1
  2614 000061CA ????                    	    resw 1
  2615                                  ; tss offset 28
  2616 000061CC ????????                tss.CR3:    resd 1
  2617 000061D0 ????????                tss.eip:    resd 1
  2618 000061D4 ????????                tss.eflags: resd 1
  2619                                  ; tss offset 40
  2620 000061D8 ????????                tss.eax:    resd 1		 		
  2621 000061DC ????????                tss.ecx:    resd 1
  2622 000061E0 ????????                tss.edx:    resd 1
  2623 000061E4 ????????                tss.ebx:    resd 1
  2624 000061E8 ????????                tss.esp:    resd 1
  2625 000061EC ????????                tss.ebp:    resd 1
  2626 000061F0 ????????                tss.esi:    resd 1
  2627 000061F4 ????????                tss.edi:    resd 1
  2628                                  ; tss offset 72
  2629 000061F8 ????                    tss.ES:     resw 1
  2630 000061FA ????                    	    resw 1	
  2631 000061FC ????                    tss.CS:	    resw 1
  2632 000061FE ????                    	    resw 1
  2633 00006200 ????                    tss.SS:	    resw 1
  2634 00006202 ????                    	    resw 1
  2635 00006204 ????                    tss.DS:	    resw 1
  2636 00006206 ????                    	    resw 1
  2637 00006208 ????                    tss.FS:	    resw 1
  2638 0000620A ????                    	    resw 1
  2639 0000620C ????                    tss.GS:	    resw 1
  2640 0000620E ????                    	    resw 1		
  2641 00006210 ????                    tss.LDTR:   resw 1
  2642 00006212 ????                    	    resw 1
  2643                                  ; tss offset 100		
  2644 00006214 ????                    	    resw 1		
  2645 00006216 ????                    tss.IOPB:   resw 1
  2646                                  ; tss offset 104 
  2647                                  tss_end:
  2648                                  
  2649 00006218 ????????                k_page_dir:  resd 1 ; Kernel's (System) Page Directory address
  2650                                  		  ;   (Physical address = Virtual address)	 	
  2651 0000621C ????????                memory_size: resd 1 ; memory size in pages
  2652 00006220 ????????                free_pages:  resd 1 ; number of free pages		
  2653 00006224 ????????                next_page:   resd 1 ; offset value in M.A.T. for
  2654                                  		  ;   first free page search
  2655 00006228 ????????                last_page:   resd 1 ; offset value in M.A.T. which
  2656                                  		  ;   next free page search will be
  2657                                  		  ; stopped after it. (end of M.A.T.)
  2658 0000622C ????????                first_page:  resd 1 ;   offset value in M.A.T. which
  2659                                  		  ; first free page search
  2660                                  		  ;   will be started on it. (for user)
  2661 00006230 ????????                mat_size:    resd 1 ; Memory Allocation Table size in pages		
  2662                                  
  2663                                  ;;;
  2664                                  ; 02/09/2014 (Retro UNIX 386 v1)
  2665                                  ; 04/12/2013 (Retro UNIX 8086 v1)
  2666 00006234 ????                    CRT_START:   resw 1 	  ; starting address in regen buffer
  2667                                  			  ; NOTE: active page only
  2668 00006236 <res 10h>               cursor_posn: resw 8 	  ; cursor positions for video pages
  2669                                  active_page: 
  2670 00006246 ??                      ptty: 	     resb 1 	  ; current tty
  2671                                  ; 01/07/2015
  2672 00006247 ??                      ccolor:	     resb 1	  ; current color attributes ('sysmsg')	
  2673                                  ; 26/10/2015
  2674                                  ; 07/09/2014
  2675 00006248 <res 14h>               ttychr:      resw ntty+2  ; Character buffer (multiscreen)
  2676                                  
  2677                                  ; 21/08/2014
  2678 0000625C ????????                tcount:	     resd 1
  2679                                  
  2680                                  ; 18/05/2015 (03/06/2013 - Retro UNIX 8086 v1 feature only!)
  2681 00006260 ????????                p_time:      resd 1     ; present time (for systime & sysmdate)
  2682                                  
  2683                                  ; 18/05/2015 (16/08/2013 - Retro UNIX 8086 v1 feature only !)
  2684                                  ; (open mode locks for pseudo TTYs)
  2685                                  ; [ major tty locks (return error in any conflicts) ]
  2686 00006264 <res 14h>               ttyl:        resw ntty+2 ; opening locks for TTYs.
  2687                                  
  2688                                  ; 15/04/2015 (Retro UNIX 386 v1)
  2689                                  ; 22/09/2013 (Retro UNIX 8086 v1)
  2690 00006278 <res Ah>                wlist:       resb ntty+2 ; wait channel list (0 to 9 for TTYs)
  2691                                  ; 15/04/2015 (Retro UNIX 386 v1)
  2692                                  ;; 12/07/2014 -> sp_init set comm. parameters as 0E3h
  2693                                  ;; 0 means serial port is not available 
  2694                                  ;;comprm: ; 25/06/2014
  2695 00006282 ??                      com1p:       resb 1  ;;0E3h
  2696 00006283 ??                      com2p:       resb 1  ;;0E3h
  2697                                  
  2698                                  ; 17/11/2015
  2699                                  ; request for response (from the terminal)	
  2700 00006284 ????                    req_resp:     resw 1 			
  2701                                  ; 07/11/2015
  2702 00006286 ??                      ccomport:    resb 1 ; current COM (serial) port
  2703                                  		    ; (0= COM1, 1= COM2)
  2704                                  ; 09/11/2015
  2705 00006287 ??                      comqr:	     resb 1 ; 'query or response' sign (u9.s, 'sndc')
  2706                                  ; 07/11/2015
  2707 00006288 ????                    rchar:	     resw 1 ; last received char for COM 1 and COM 2		
  2708 0000628A ????                    schar:	     resw 1 ; last sent char for COM 1 and COM 2
  2709                                  
  2710                                  ; 23/10/2015
  2711                                  ; SERIAL PORTS - COMMUNICATION MODES
  2712                                  ; (Retro UNIX 386 v1 feature only!)
  2713                                  ; 0 - command mode (default/initial mode)
  2714                                  ; 1 - terminal mode (Retro UNIX 386 v1 terminal, ascii chars)
  2715                                  ;;; communication modes for futre versions:  
  2716                                  ; // 2 - keyboard mode (ascii+scancode input)
  2717                                  ; // 3 - mouse mode
  2718                                  ; // 4 - device control (output) mode
  2719                                  ; VALID COMMANDS for current version:
  2720                                  ; 	'LOGIN'
  2721                                  ;  Login request: db 0FFh, 'LOGIN', 0 
  2722                                  ;	 ("Retro UNIX 386 v1 terminal requests login")
  2723                                  ;  Login response: db 0FFh, 'login', 0
  2724                                  ;	 ("login request accepted, wait for login prompt") 
  2725                                  ; When a login requests is received and acknowledged (by
  2726                                  ; serial port interrupt handler (communication procedure),
  2727                                  ; Retro UNIX 386 v1 operating system will start terminal mode
  2728                                  ; (login procedure) by changing comm. mode to 1 (terminal mode)
  2729                                  ; and then running 'etc/getty' for tty8 (COM1) or tty9 (COM2)
  2730                                  ; 
  2731                                  ; 'sys connect' system call is used to change communication mode
  2732                                  ; except 'LOGIN' command which is used to start terminal mode
  2733                                  ; by using (COM port) terminal.
  2734                                  
  2735                                  ;com1own:     resb 1 ; COM1 owner (u.uno)
  2736                                  ;com2own:     resb 1 ; COM2 owner (u.uno)
  2737                                  ;com1mode:    resb 1 ; communication mode for COM1
  2738                                  ;com1com:     resb 1 ; communication command for COM1
  2739                                  ;com2mode:    resb 1 ; communication mode for COM1
  2740                                  ;com2com      resb 1 ; communication command for COM1
  2741                                  ;com1cbufp:   resb 8 ; COM1 command buffer char pointer	
  2742                                  ;com2cbufp:   resb 8 ; COM2 command buffer char pointer	
  2743                                  ;com1cbuf:    resb 8 ; COM2 command buffer
  2744                                  ;com2cbuf:    resb 8 ; COM2 command buffer
  2745                                  
  2746                                  ; 22/08/2014 (RTC)
  2747                                  ; (Packed BCD)
  2748 0000628C ??                      time_seconds: resb 1
  2749 0000628D ??                      time_minutes: resb 1
  2750 0000628E ??                      time_hours:   resb 1
  2751 0000628F ??                      date_wday:    resb 1
  2752 00006290 ??                      date_day:     resb 1
  2753 00006291 ??                      date_month:   resb 1			
  2754 00006292 ??                      date_year:    resb 1
  2755 00006293 ??                      date_century: resb 1
  2756                                  
  2757                                  %include 'diskbss.inc'	; UNINITIALIZED DISK (BIOS) DATA
  2758                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.5) - DISKBSS.INC
  2759                              <1> ; Last Modification: 10/07/2022
  2760                              <1> ;	(Uninitialized Disk Parameters Data section for 'DISKIO.INC') 
  2761                              <1> ;
  2762                              <1> ; *****************************************************************************
  2763                              <1> 
  2764                              <1> alignb 2
  2765                              <1> 
  2766                              <1> ;----------------------------------------
  2767                              <1> ;	TIMER DATA AREA 		:
  2768                              <1> ;----------------------------------------
  2769                              <1> 
  2770                              <1> TIMER_LH:	; 16/02/205
  2771 00006294 ????                <1> TIMER_LOW:      resw	1               ; LOW WORD OF TIMER COUNT
  2772 00006296 ????                <1> TIMER_HIGH:     resw	1               ; HIGH WORD OF TIMER COUNT
  2773 00006298 ??                  <1> TIMER_OFL:      resb 	1               ; TIMER HAS ROLLED OVER SINCE LAST READ
  2774                              <1> 
  2775                              <1> ;----------------------------------------
  2776                              <1> ;	DISKETTE DATA AREAS		:
  2777                              <1> ;----------------------------------------
  2778                              <1> 
  2779 00006299 ??                  <1> SEEK_STATUS:	resb	1
  2780 0000629A ??                  <1> MOTOR_STATUS:	resb	1
  2781 0000629B ??                  <1> MOTOR_COUNT:	resb	1
  2782 0000629C ??                  <1> DSKETTE_STATUS:	resb	1
  2783 0000629D ??????????????      <1> NEC_STATUS:	resb	7
  2784                              <1> 
  2785                              <1> ;----------------------------------------
  2786                              <1> ;	ADDITIONAL MEDIA DATA		:
  2787                              <1> ;----------------------------------------
  2788                              <1> 
  2789 000062A4 ??                  <1> LASTRATE:	resb 	1
  2790 000062A5 ??                  <1> HF_STATUS:	resb 	1
  2791                              <1> ;HF_ERROR:	resb 	1  ; 10/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)	
  2792 000062A6 ??                  <1> HF_INT_FLAG:	resb	1
  2793                              <1> ;HF_CNTRL:	resb 	1  ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2794                              <1> ;DSK_STATE:	resb 	4
  2795 000062A7 ????                <1> DSK_STATE:	resb 	2  ; 08/07/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.5)
  2796 000062A9 ????                <1> DSK_TRK:	resb 	2
  2797                              <1> 
  2798                              <1> ;----------------------------------------
  2799                              <1> ;	FIXED DISK DATA AREAS		:
  2800                              <1> ;----------------------------------------
  2801                              <1> 
  2802 000062AB ??                  <1> DISK_STATUS1:	resb 	1		; FIXED DISK STATUS
  2803 000062AC ??                  <1> HF_NUM:		resb 	1		; COUNT OF FIXED DISK DRIVES
  2804 000062AD ??                  <1> CONTROL_BYTE:	resb 	1		; HEAD CONTROL BYTE
  2805                              <1> ;@PORT_OFF	resb	1		; RESERVED (PORT OFFSET)
  2806                              <1> ;port1_off	resb	1		; Hard disk controller 1 - port offset
  2807                              <1> ;port2_off	resb	1		; Hard disk controller 2 - port offset
  2808                              <1> 
  2809 000062AE ????                <1> alignb 4
  2810                              <1> 
  2811                              <1> ;HF_TBL_VEC:	resd	1 		; Primary master disk param. tbl. pointer
  2812                              <1> ;HF1_TBL_VEC:	resd	1		; Primary slave disk param. tbl. pointer
  2813                              <1> HF_TBL_VEC: ; 22/12/2014	
  2814 000062B0 ????????            <1> HDPM_TBL_VEC:	resd	1 		; Primary master disk param. tbl. pointer
  2815 000062B4 ????????            <1> HDPS_TBL_VEC:	resd	1		; Primary slave disk param. tbl. pointer
  2816 000062B8 ????????            <1> HDSM_TBL_VEC:	resd	1 		; Secondary master disk param. tbl. pointer
  2817 000062BC ????????            <1> HDSS_TBL_VEC:	resd	1		; Secondary slave disk param. tbl. pointer
  2818                              <1> 
  2819                              <1> ; 03/01/2015
  2820 000062C0 ??                  <1> LBAMode:     	resb	1
  2821                              <1> 
  2822                              <1> ; *****************************************************************************
  2758                                  
  2759                                  ;;; Real Mode Data (10/07/2015 - BSS)
  2760                                  
  2761                                  ;alignb 2
  2762                                  
  2763                                  ; 02/01/2022
  2764                                  ;%include 'ux.s' ; 12/04/2015 (unix system/user/process data)
  2765                                  
  2766                                  ; 24/12/2021
  2767                                  ; (memory page swap parameters are disabled as temporary)
  2768                                  ;
  2769                                  ;; Memory (swap) Data (11/03/2015)
  2770                                  ; 09/03/2015
  2771                                  ;swpq_count: resw 1 ; count of pages on the swap que
  2772                                  ;swp_drv:    resd 1 ; logical drive description table address of the swap drive/disk
  2773                                  ;swpd_size:  resd 1 ; size of swap drive/disk (volume) in sectors (512 bytes).	
  2774                                  ;swpd_free:  resd 1 ; free page blocks (4096 bytes) on swap disk/drive (logical)
  2775                                  ;swpd_next:  resd 1 ; next free page block
  2776                                  ;swpd_last:  resd 1 ; last swap page block	
  2777                                  	
  2778 000062C1 ??????                  alignb 4
  2779                                  
  2780                                  ; 10/07/2015
  2781                                  ; 28/08/2014
  2782 000062C4 ????????                error_code:	resd 1
  2783                                  ; 29/08/2014
  2784 000062C8 ????????                FaultOffset: 	resd 1
  2785                                  ; 21/09/2015
  2786 000062CC ????????                PF_Count:	resd 1	; total page fault count
  2787                                  		       	; (for debugging - page fault analyze)
  2788                                  		 	; 'page _fault_handler' (memory.inc)
  2789                                  			; 'sysgeterr' (u9.s)
  2790                                  ; 26/02/2022
  2791 000062D0 ????????                rtc_ticks:	resd 1  ; (temporary! this rtc counter value may be used 
  2792                                  			;  for a system call in next retro unix 386 version)
  2793                                  			; -2 ticks per second-
  2794                                  ;; 21/08/2015
  2795                                  ;;buffer: resb (nbuf*520) ;; sysdefs.inc, ux.s
  2796                                  
  2797                                  ; 02/01/2022
  2798                                  %include 'ux.s' ; 12/04/2015 (unix system/user/process data)
  2799                              <1> ; Retro UNIX 386 v1 Kernel (v0.2.1.6) - SYSX.INC (ux.s)
  2800                              <1> ; Last Modification: 15/07/2022
  2801                              <1> ; ----------------------------------------------------------------------------
  2802                              <1> ; ///////// RETRO UNIX 386 V1 SYSTEM DEFINITIONS ///////////////
  2803                              <1> ; (Modified from 
  2804                              <1> ;	Retro UNIX 8086 v1 system definitions in 'UNIX.ASM', 01/09/2014)
  2805                              <1> ; ((UNIX.ASM (RETRO UNIX 8086 V1 Kernel), 11/03/2013 - 01/09/2014))
  2806                              <1> ; ----------------------------------------------------------------------------
  2807                              <1> ; Derived from UNIX Operating System (v1.0 for PDP-11) 
  2808                              <1> ; (Original) Source Code by Ken Thompson (1971-1972)
  2809                              <1> ; <Bell Laboratories (17/3/1972)>
  2810                              <1> ; <Preliminary Release of UNIX Implementation Document>
  2811                              <1> ; (Section E10 (17/3/1972) - ux.s)
  2812                              <1> ; ****************************************************************************
  2813                              <1> ; 04/12/2015
  2814                              <1> 
  2815                              <1> alignb 2
  2816                              <1> 
  2817                              <1> inode:
  2818                              <1> 	; 11/03/2013. 
  2819                              <1> 	;Derived from UNIX v1 source code 'inode' structure (ux).
  2820                              <1> 	;i.
  2821                              <1> 
  2822 000062D4 ????                <1> 	i.flgs:	 resw 1
  2823 000062D6 ??                  <1> 	i.nlks:	 resb 1
  2824 000062D7 ??                  <1> 	i.uid:	 resb 1
  2825 000062D8 ????                <1>         i.size:  resw 1 ; size
  2826 000062DA <res 10h>           <1> 	i.dskp:	 resw 8 ; 16 bytes
  2827 000062EA ????????            <1> 	i.ctim:	 resd 1
  2828 000062EE ????????            <1> 	i.mtim:	 resd 1
  2829 000062F2 ????                <1> 	i.rsvd:  resw 1 ; Reserved (ZERO/Undefined word for UNIX v1.)
  2830                              <1> 
  2831                              <1> I_SIZE	equ $ - inode 
  2832                              <1> 
  2833                              <1> process:
  2834                              <1> 	; 26/02/2022
  2835                              <1> 	; 12/01/2022 (Retro UNIX 386 v1.1) 
  2836                              <1> 	; 06/05/2015
  2837                              <1> 	; 11/03/2013 - 05/02/2014
  2838                              <1> 	;Derived from UNIX v1 source code 'proc' structure (ux).
  2839                              <1> 	;p.
  2840                              <1> 	
  2841 000062F4 <res 20h>           <1>         p.pid:   resw nproc
  2842 00006314 <res 20h>           <1>         p.ppid:  resw nproc
  2843                              <1> 	;p.break: resw nproc ; 12/01/2022 (p.break is not used)
  2844 00006334 <res 10h>           <1>         p.ttyc:  resb nproc ; console tty in Retro UNIX 8086 v1.
  2845                              <1> 	; 26/02/2022 (p.waitc is not used)
  2846                              <1> 	;p.waitc: resb nproc ; waiting channel in Retro UNIX 8086 v1.
  2847 00006344 <res 10h>           <1> 	p.link:	 resb nproc
  2848 00006354 <res 10h>           <1> 	p.stat:	 resb nproc
  2849                              <1> 
  2850                              <1> 	; 06/05/2015 (Retro UNIX 386 v1 fetaure only !) 
  2851 00006364 <res 40h>           <1> 	p.upage: resd nproc ; Physical address of the process's
  2852                              <1> 			    ; 'user' structure	
  2853                              <1> 
  2854                              <1> P_SIZE	equ $ - process
  2855                              <1> 
  2856                              <1> ; fsp table (original UNIX v1)
  2857                              <1> ;
  2858                              <1> ;Entry
  2859                              <1> ;          15                                      0
  2860                              <1> ;  1     |---|---------------------------------------|
  2861                              <1> ;        |r/w|       i-number of open file           |
  2862                              <1> ;        |---|---------------------------------------| 
  2863                              <1> ;        |               device number               |
  2864                              <1> ;        |-------------------------------------------|
  2865                              <1> ;    (*) | offset pointer, i.e., r/w pointer to file |
  2866                              <1> ;        |-------------------------------------------| 
  2867                              <1> ;        |  flag that says    | number of processes  |
  2868                              <1> ;        |   file deleted     | that have file open  |
  2869                              <1> ;        |-------------------------------------------| 
  2870                              <1> ;  2     |                                           |
  2871                              <1> ;        |-------------------------------------------| 
  2872                              <1> ;        |                                           |
  2873                              <1> ;        |-------------------------------------------|
  2874                              <1> ;        |                                           |
  2875                              <1> ;        |-------------------------------------------|
  2876                              <1> ;        |                                           |
  2877                              <1> ;        |-------------------------------------------| 
  2878                              <1> ;  3     |                                           | 
  2879                              <1> ;        |                                           |  
  2880                              <1> ;
  2881                              <1> ; (*) Retro UNIX 386 v1 modification: 32 bit offset pointer 
  2882                              <1> 
  2883                              <1> ; 15/04/2015
  2884 000063A4 <res 1F4h>          <1> fsp:	 resb nfiles*10 ; 11/05/2015 (8 -> 10)
  2885 00006598 <res 28h>           <1> bufp:	 resd (nbuf+2) ; will be initialized 
  2886 000065C0 ????                <1> ii:	 resw 1
  2887                              <1> ;idev:	 resw 1 ; device number is 1 byte in Retro UNIX 8086 v1 !
  2888                              <1> ;cdev:	 resw 1 ; device number is 1 byte in Retro UNIX 8086 v1 !
  2889                              <1> ; 11/01/2022
  2890 000065C2 ??                  <1> idev:	 resb 1
  2891 000065C3 ??                  <1> cdev:	 resb 1
  2892                              <1> ; 18/05/2015
  2893                              <1> ; 26/04/2013 device/drive parameters (Retro UNIX 8086 v1 feature only!)
  2894                              <1> ; 'UNIX' device numbers (as in 'cdev' and 'u.cdrv')
  2895                              <1> ;	0 -> root device (which has Retro UNIX 8086 v1 file system)
  2896                              <1> ; 	1 -> mounted device (which has Retro UNIX 8086 v1 file system)
  2897                              <1> ; 'Retro UNIX 8086 v1' device numbers: (for disk I/O procedures)
  2898                              <1> ;	0 -> fd0 (physical drive, floppy disk 1), physical drive number = 0
  2899                              <1> ;	1 -> fd1 (physical drive, floppy disk 2), physical drive number = 1
  2900                              <1> ;	2 -> hd0 (physical drive, hard disk 1), physical drive number = 80h
  2901                              <1> ;	3 -> hd1 (physical drive, hard disk 2), physical drive number = 81h
  2902                              <1> ;	4 -> hd2 (physical drive, hard disk 3), physical drive number = 82h
  2903                              <1> ;	5 -> hd3 (physical drive, hard disk 4), physical drive number = 83h
  2904 000065C4 ??                  <1> rdev:	 resb 1 ; root device number ; Retro UNIX 8086 v1 feature only!
  2905                              <1> 	        ; as above, for physical drives numbers in following table
  2906 000065C5 ??                  <1> mdev:	 resb 1 ; mounted device number ; Retro UNIX 8086 v1 feature only!
  2907                              <1> ; 15/04/2015
  2908                              <1> ;active: resb 1 ; 15/07/2022
  2909                              <1> ;	 resb 1 ; 09/06/2015
  2910 000065C6 ????                <1> mnti:	 resw 1
  2911 000065C8 ????                <1> mntp:	 resw 1 ; 15/05/2022 ; (parent dir inumber of [mnti])
  2912 000065CA ????                <1> mpid:	 resw 1
  2913 000065CC ????                <1> rootdir: resw 1
  2914                              <1> ; 14/02/2014
  2915                              <1> ; Major Modification: Retro UNIX 8086 v1 feature only!
  2916                              <1> ;		      Single level run queue
  2917                              <1> ;		      (in order to solve sleep/wakeup lock)
  2918 000065CE ????                <1> runq:	 resw 1
  2919 000065D0 ??                  <1> imod:	 resb 1
  2920 000065D1 ??                  <1> smod:	 resb 1
  2921 000065D2 ??                  <1> mmod:	 resb 1
  2922 000065D3 ??                  <1> sysflg:	 resb 1
  2923                              <1> 
  2924                              <1> alignb 4
  2925                              <1> 
  2926                              <1> user:
  2927                              <1> 	; 09/01/2022 (Retro UNIX 386 v1.1, Kernel v0.2.1.2)
  2928                              <1> 	; 04/12/2015 
  2929                              <1> 	; 18/10/2015
  2930                              <1> 	; 12/10/2015
  2931                              <1> 	; 21/09/2015
  2932                              <1> 	; 24/07/2015
  2933                              <1> 	; 16/06/2015
  2934                              <1> 	; 09/06/2015
  2935                              <1> 	; 11/05/2015
  2936                              <1> 	; 16/04/2015 (Retro UNIX 386 v1 - 32 bit modifications)
  2937                              <1> 	; 10/10/2013
  2938                              <1> 	; 11/03/2013. 
  2939                              <1> 	;Derived from UNIX v1 source code 'user' structure (ux).
  2940                              <1> 	;u.
  2941                              <1> 
  2942 000065D4 ????????            <1> 	u.sp:	  resd 1 ; esp (kernel stack at the beginning of 'sysent')
  2943 000065D8 ????????            <1> 	u.usp:	  resd 1 ; esp (kernel stack points to user's registers)
  2944 000065DC ????????            <1> 	u.r0:	  resd 1 ; eax
  2945 000065E0 ????                <1> 	u.cdir:	  resw 1
  2946 000065E2 <res Ah>            <1> 	u.fp:	  resb 10
  2947 000065EC ????????            <1> 	u.fofp:	  resd 1
  2948 000065F0 ????????            <1> 	u.dirp:	  resd 1
  2949 000065F4 ????????            <1> 	u.namep:  resd 1
  2950 000065F8 ????????            <1> 	u.off:	  resd 1
  2951 000065FC ????????            <1> 	u.base:	  resd 1
  2952 00006600 ????????            <1> 	u.count:  resd 1
  2953 00006604 ????????            <1> 	u.nread:  resd 1
  2954 00006608 ????????            <1> 	u.break:  resd 1 ; break
  2955 0000660C ????                <1> 	u.ttyp:	  resw 1 
  2956 0000660E <res 10h>           <1> 	u.dirbuf: resb 16 ; 04/12/2015 (10 -> 16) 
  2957                              <1> 	;u.pri:	  resw 1 ; 14/02/2014
  2958 0000661E ??                  <1> 	u.quant:  resb 1 ; Retro UNIX 8086 v1 Feature only ! (uquant)
  2959 0000661F ??                  <1> 	u.pri:	  resb 1 ; 
  2960 00006620 ????                <1> 	u.intr:	  resw 1
  2961 00006622 ????                <1> 	u.quit:	  resw 1
  2962                              <1> 	;u.emt:	  resw 1 ; 10/10/2013
  2963 00006624 ????                <1> 	u.ilgins: resw 1
  2964                              <1> 	;u.cdrv:  resw 1 ; cdev
  2965 00006626 ??                  <1> 	u.cdrv:   resb 1 ; 09/01/2022
  2966 00006627 ??                  <1> 		  resb 1 ; 09/01/2022 (dword alignment)
  2967 00006628 ??                  <1> 	u.uid:	  resb 1 ; uid
  2968 00006629 ??                  <1> 	u.ruid:	  resb 1
  2969 0000662A ??                  <1> 	u.bsys:	  resb 1
  2970 0000662B ??                  <1> 	u.uno:	  resb 1
  2971 0000662C ????????            <1>         u.upage:  resd 1 ; 16/04/2015 - Retro Unix 386 v1 feature only !
  2972                              <1> 	; tty number (rtty, rcvt, wtty)
  2973 00006630 ??                  <1> 	u.ttyn:	  resb 1 ; 28/07/2013 - Retro Unix 8086 v1 feature only !
  2974                              <1> 	; last error number
  2975 00006631 ????????            <1> 	u.error:  resd 1 ; 28/07/2013 - 09/03/2015 
  2976                              <1> 		        ; Retro UNIX 8086/386 v1 feature only!
  2977 00006635 ????????            <1> 	u.pgdir:  resd 1 ; 09/03/2015 (page dir addr of process)
  2978 00006639 ????????            <1> 	u.ppgdir: resd 1 ; 06/05/2015 (page dir addr of the parent process)
  2979 0000663D ????????            <1> 	u.pbase:  resd 1 ; 20/05/2015 (physical base/transfer address)
  2980 00006641 ????                <1> 	u.pcount: resw 1 ; 20/05/2015 (byte -transfer- count for page)
  2981                              <1> 	;u.pncount: resw 1 
  2982                              <1> 		; 16/06/2015 (byte -transfer- count for page, 'namei', 'mkdir')
  2983                              <1> 	;u.pnbase:  resd 1 
  2984                              <1> 		; 16/06/2015 (physical base/transfer address, 'namei', 'mkdir')
  2985                              <1> 			 ; 09/06/2015
  2986 00006643 ??                  <1> 	u.kcall:  resb 1 ; The caller is 'namei' (dskr) or 'mkdir' (dskw) sign		
  2987 00006644 ??                  <1> 	u.brwdev: resb 1 ; Block device number for direct I/O (bread & bwrite)
  2988                              <1> 			 ; 24/07/2015 - 24/06/2015
  2989                              <1> 	;u.args:  resd 1 ; arguments list (line) offset from start of [u.upage]
  2990                              <1> 			 ; (arg list/line is from offset [u.args] to 4096 in [u.upage])
  2991                              <1> 			 ; ([u.args] points to argument count -argc- address offset)
  2992                              <1>  			 ; 24/06/2015	  	
  2993                              <1> 	;u.core:  resd 1 ; physical start address of user's memory space (for sys exec)
  2994                              <1> 	;u.ecore: resd 1 ; physical end address of user's memory space (for sys exec)
  2995                              <1> 			 ; 21/09/2015 (debugging - page fault analyze)
  2996 00006645 ????????            <1> 	u.pfcount: resd 1 ; page fault count for (this) process (for sys geterr)
  2997                              <1> 
  2998 00006649 ??????              <1> alignb 4
  2999                              <1> 
  3000                              <1> U_SIZE	equ $ - user
  3001                              <1> 
  3002                              <1> ; 18/10/2015 - Retro UNIX 386 v1 (local variables for 'namei' and 'sysexec')
  3003 0000664C ????????            <1> pcore:  resd 1 ; physical start address of user's memory space (for sys exec)
  3004 00006650 ????????            <1> ecore:  resd 1 ; physical start address of user's memory space (for sys exec)
  3005 00006654 ????????            <1> nbase:	resd 1	; physical base address for 'namei' & 'sysexec'
  3006 00006658 ????                <1> ncount: resw 1	; remain byte count in page for 'namei' & 'sysexec'
  3007                              <1> ;argc:	resw 1	; argument count for 'sysexec'
  3008 0000665A ??                  <1> argc:	resb 1	; 12/01/2022 - Retro UNIX 386 v1.1 (Kernel v0.2.1.2)
  3009 0000665B ??                  <1> 	resb 1 
  3010 0000665C ????????            <1> argv:	resd 1	; argument list (recent) address for 'sysexec'
  3011                              <1> 
  3012                              <1> ; 03/06/2015 - Retro UNIX 386 v1 Beginning
  3013                              <1> ; 07/04/2013 - 31/07/2013 - Retro UNIX 8086 v1
  3014 00006660 ??                  <1> rw: 	 resb 1 ;; Read/Write sign (iget)
  3015 00006661 ??                  <1> rwdsk:	 resb 1 ;; Read/Write function number (diskio) - 16/06/2015
  3016 00006662 ??                  <1> retry_count: resb 1 ; Disk I/O retry count - 11/06/2015
  3017 00006663 ??                  <1> 	 resb 1 ;; Reserved (16/06/2015) 
  3018                              <1> 
  3019                              <1> ;alignb 4
  3020                              <1> 
  3021                              <1> ; 22/08/2015
  3022 00006664 <res 1040h>         <1> buffer: resb nbuf * 520
  3023                              <1> 
  3024 000076A4 ????????????????    <1> sb0:	resd 2
  3025                              <1> ;s:
  3026                              <1> ; (root disk) super block buffer
  3027                              <1> systm:
  3028                              <1> 	; 13/11/2015 (Retro UNIX 386 v1)	
  3029                              <1> 	; 11/03/2013. 
  3030                              <1> 	;Derived from UNIX v1 source code 'systm' structure (ux).
  3031                              <1> 	;s.
  3032                              <1> 
  3033 000076AC ????                <1> 	resw 1
  3034 000076AE <res 168h>          <1> 	resb 360 ; 2880 sectors ; original UNIX v1 value: 128
  3035 00007816 ????                <1> 	resw 1
  3036 00007818 <res 20h>           <1> 	resb 32	 ; 256+40 inodes ; original UNIX v1 value: 64
  3037                              <1> eofitab equ $ - systm ; 11/02/2022 (end of inode table)
  3038 00007838 ????????            <1> 	s.time:	 resd 1
  3039 0000783C ????????            <1> 	s.syst:	 resd 1
  3040 00007840 ????????            <1>         s.wait_: resd 1 ; wait
  3041 00007844 ????????            <1> 	s.idlet: resd 1
  3042 00007848 ????????            <1> 	s.chrgt: resd 1
  3043 0000784C ????                <1> 	s.drerr: resw 1
  3044                              <1> 
  3045                              <1> S_SIZE	equ $ - systm
  3046                              <1> 
  3047 0000784E <res 5Eh>           <1> 	resb 512-S_SIZE ; 03/06/2015	 
  3048                              <1> 
  3049 000078AC ????????????????    <1> sb1:	resd 2
  3050                              <1> ; (mounted disk) super block buffer
  3051                              <1> mount:	
  3052 000078B4 <res 200h>          <1> 	resb 512  ; 03/06/2015
  3053                              <1> 
  3054                              <1> ;/ ux -- unix
  3055                              <1> ;
  3056                              <1> ;systm:
  3057                              <1> ;
  3058                              <1> ;	.=.+2
  3059                              <1> ;	.=.+128.
  3060                              <1> ;	.=.+2
  3061                              <1> ;	.=.+64.
  3062                              <1> ;	s.time: .=.+4
  3063                              <1> ;	s.syst: .=.+4
  3064                              <1> ;	s.wait: .=.+4
  3065                              <1> ;	s.idlet:.=.+4
  3066                              <1> ;	s.chrgt:.=.+4
  3067                              <1> ;	s.drerr:.=.+2
  3068                              <1> ;inode:
  3069                              <1> ;	i.flgs: .=.+2
  3070                              <1> ;	i.nlks: .=.+1
  3071                              <1> ;	i.uid:  .=.+1
  3072                              <1> ;	i.size: .=.+2
  3073                              <1> ;	i.dskp: .=.+16.
  3074                              <1> ;	i.ctim: .=.+4
  3075                              <1> ;	i.mtim: .=.+4
  3076                              <1> ;	. = inode+32.
  3077                              <1> ;mount:	.=.+1024.
  3078                              <1> ;proc:
  3079                              <1> ;	p.pid:  .=.+[2*nproc]
  3080                              <1> ;	p.dska: .=.+[2*nproc]
  3081                              <1> ;	p.ppid: .=.+[2*nproc]
  3082                              <1> ;	p.break:.=.+[2*nproc]
  3083                              <1> ;	p.link: .=.+nproc
  3084                              <1> ;	p.stat: .=.+nproc
  3085                              <1> ;tty:
  3086                              <1> ;	. = .+[ntty*8.]
  3087                              <1> ;fsp:	.=.+[nfiles*8.]
  3088                              <1> ;bufp:	.=.+[nbuf*2]+6
  3089                              <1> ;sb0:	.=.+8
  3090                              <1> ;sb1:	.=.+8
  3091                              <1> ;swp:	.=.+8
  3092                              <1> ;ii:	.=.+2
  3093                              <1> ;idev:	.=.+2
  3094                              <1> ;cdev:	.=.+2
  3095                              <1> ;deverr: .=.+12.
  3096                              <1> ;active: .=.+2
  3097                              <1> ;rfap:	.=.+2
  3098                              <1> ;rkap:	.=.+2
  3099                              <1> ;tcap:	.=.+2
  3100                              <1> ;tcstate:.=.+2
  3101                              <1> ;tcerrc: .=.+2
  3102                              <1> ;mnti:	.=.+2
  3103                              <1> ;mntd:	.=.+2
  3104                              <1> ;mpid:	.=.+2
  3105                              <1> ;clockp: .=.+2
  3106                              <1> ;rootdir:.=.+2
  3107                              <1> ;toutt:	.=.+16.
  3108                              <1> ;touts: .=.+32.
  3109                              <1> ;runq:	.=.+6
  3110                              <1> ;
  3111                              <1> ;wlist:	.=.+40.
  3112                              <1> ;cc:	.=.+30.
  3113                              <1> ;cf:	.=.+31.
  3114                              <1> ;cl:	.=.+31.
  3115                              <1> ;clist:	.=.+510.
  3116                              <1> ;imod:	.=.+1
  3117                              <1> ;smod:	.=.+1
  3118                              <1> ;mmod:	.=.+1
  3119                              <1> ;uquant: .=.+1
  3120                              <1> ;sysflg: .=.+1
  3121                              <1> ;pptiflg:.=.+1
  3122                              <1> ;ttyoch: .=.+1
  3123                              <1> ; .even
  3124                              <1> ; .=.+100.; sstack:
  3125                              <1> ;buffer: .=.+[ntty*140.]
  3126                              <1> ;	.=.+[nbuf*520.]
  3127                              <1> ;
  3128                              <1> ; . = core-64.
  3129                              <1> ;user:
  3130                              <1> ;	u.sp:    .=.+2
  3131                              <1> ;	u.usp:   .=.+2
  3132                              <1> ;	u.r0:    .=.+2
  3133                              <1> ;	u.cdir:  .=.+2
  3134                              <1> ;	u.fp:    .=.+10.
  3135                              <1> ;	u.fofp:  .=.+2
  3136                              <1> ;	u.dirp:  .=.+2
  3137                              <1> ;	u.namep: .=.+2
  3138                              <1> ;	u.off:   .=.+2
  3139                              <1> ;	u.base:  .=.+2
  3140                              <1> ;	u.count: .=.+2
  3141                              <1> ;	u.nread: .=.+2
  3142                              <1> ;	u.break: .=.+2
  3143                              <1> ;	u.ttyp:  .=.+2
  3144                              <1> ;	u.dirbuf:.=.+10.
  3145                              <1> ;	u.pri:   .=.+2
  3146                              <1> ;	u.intr:  .=.+2
  3147                              <1> ;	u.quit:  .=.+2
  3148                              <1> ;	u.emt:   .=.+2
  3149                              <1> ;	u.ilgins:.=.+2
  3150                              <1> ;	u.cdev:  .=.+2
  3151                              <1> ;	u.uid:   .=.+1
  3152                              <1> ;	u.ruid:  .=.+1
  3153                              <1> ;	u.bsys:  .=.+1
  3154                              <1> ;	u.uno:   .=.+1
  3155                              <1> ;. = core
  2799                                  
  2800                                  ; 27/12/2021
  2801                                  ;buffer: resb (nbuf*520)
  2802                                  
  2803                                  bss_end:
  2804                                  
  2805                                  ; 02/01/2022
  2806                                  BSS_SIZE equ bss_end - bss_start
  2807                                  
  2808                                  ; 27/12/2013
  2809                                  _end:  ; end of kernel code (and read only data, just before bss)
