PROJECT: SINGLIX Operating System Issue: 4 Revision: 12 Date: 19/05/2009 OWNER: ERDOĞAN TAN / Istanbul / Turkiye
ROOT DIRECTORY DESCRIPTION TABLE format of SINGLIX FS1,FS2 file systems
Offset	Item	DATA	Type	Size	Description of Item
0	RDT Sign	‘RDT’	Char	3 byte	TR-SINGLIX Root Directory Descriptor
3	FS RDT Version	XXh	Byte	1 byte	Must be 0 for Current/This RDT Version
4	Sector Size	XXXXh	Word	2 byte	Bytes per Sector (FS1=512, FS2=2048)
6	RDT Number	XXXXh	Word	2 byte	RDT (Sequence) Number of Root Dir.
8	Directory Number	XXXXXXXXh	Dword	4 byte	The 1st RDT Address of Root Dir. (LBA)
12	Next RDT Number	XXXXXXXXh	Dword	4 byte	RDT address of the next section (LBA)
16	Sector Count	XXXXXXXXh	Dword	4 byte	Number of Sectors in this section
20	Beginning Sector	XXXXXXXXh	Dword	4 byte	Volume Beginning Sector (LBA) Addr.
24*	Reserved	XXXXXXXXh	Dword	4 byte	Reserved for TR-MULTIX (must be 0)
28	Volume Serial No.	XXXXXXXXh	Dword	4 byte	Volume (Root Dir.) Serial No. (Tick Count)
32	Entry Size	04h	Byte	1 byte	Directory Entry Size ( = 4 bytes)
33	Reserved	00h	Byte	1 byte	Reserved (Must be ZERO)
34*	Reserved	12 bytes	Byte	12 byte	Reserved for TR-MULTIX (must be 0)
46	Country	XXh	Byte	1 byte	Language, Date, Text Format (default = 0)
47	Time Zone	XXh	Byte	1 byte	-11 to +12  (GMT = 0, default = 0)
48	Creating Year	XXXXh (CCYY)	Word	2 byte	Year in Binary Coded Decimal (BCD)
50	Creating Month	XXh	Bute	1 byte	Month in Binary Coded Decimal (BCD)
51	Creating Day	XXh	Byte	1 byte	Day in Binary Coded Decimal (BCD)
52	Creating Hour	XXh	Byte	1 byte	Hour in Binary Coded Decimal (BCD)
53	Creating Minute	XXh	Byte	1 byte	Minute in Binary Coded Decimal (BCD)
54	Creating Second	XXh	Byte	1 byte	Second in Binary Coded Decimal (BCD)
55	C. Time Mode	XXh	Byte	1 byte	0 = Standard Time, 1 = Daylight Saving
56	Last Modif. Date	XXXXXXXXh	Dword	4 byte	The Last Modification/Write Date (BCD)
60	Last Modif. Time	XXXXXXh	Byte	3 byte	The Last Modification/Write Time (BCD)
63	L. M. Time Mode	XXh	Byte	1 byte	0 = Standard, 1 = Daylight Saving Time
64	Volume Name	64 Chars	Char	64 byte	FS Volume Name String (Zero Padded)
128	Reserved	?	Byte	128 byte	128 byte Reserved/Optional Data Field
256	Reserved	?	Byte	256 byte	256 byte Reserved/Optional Data Field
512**	Reserved	?	Byte	1536 byte	Optional/Reserved Area for FS2 Files
* Used by TR-MULTIX (Multi User, Multi Tasking) Operating System, only! ** 1536 byte extra description for 2048 bytes per sector File System (FS2), only ! Optional ! NOTE: Root Dir. Entry: FFFFFFFFh is erased entry, 0 is end of root dir. entries. Root dir. entries are the 1st FDT or DDT addresses of files or sub dirs. (32 bit sector offset number which is > 0 and < FFFFFFFFh) Root directory is the parent directory of all sub directory level 1 signed directories (of course if they are recorded in root directory entries.) Directory Description Table Offset 33 is for Sub Directory Level. The ZERO value at RDT Offset 33 shows it is ROOT directory (also ‘RDT’ identifier shows that). The Operating System Software/Kernel or a program which uses this SINGLIX FS, must check the letter “R” and “DT” letters at the beginning of directory descriptor table. (At Offset 0, “D” for sub directories, “F” for files. “DE” shows that directory/files is actually deleted, can not be undeleted because of it is removed from UNDELETE directory. And Disk Allocation Table shows the sectors of that directory/file as DELETED/FreeForUse. When the file/directory is in UNDELETE/restore directory, Disk Allocation Table pointers point that directory/file sectors as normal dir/file allocated sectors as decription table or dir/file data.) When SINGLIX FS freesectors will be calculated, only Disk Allocation Table pointers will be used for calculation. For example: the DAT pointer bytes with ZERO value (absolute free/unused sector) or a “Free For Use” or “Deleted” value shows free sectors. Root/Parent Dir. Serial used for that purpose: When a dir or file is deleted, it will be removed from root/parent dir entries by replacing child directory or file number to FFFFFFFFh = deleted entry sign. And, it will be located in UNDELETE Directory as a new deleted file entry. When user want to undelete this file, if parent dir serial number same with in the parent directory descriptor table (as number) declared in child dir/file decriptor table, the deleted directory or file will be restored in the root directory. Directory serial number is just a tick count which always different by the computer’s timer ticks. (as like as volume serial number.) That checkup is performed for preventing accidental/wrong restore operations. Because, a directory can be deleted, then, a new directory description table can be created on same disk sector, only serial number check (because of serial number is the timer tick count) will provide determining of that DDT is actually the parent directory’s description table or a new directory description table. Also, Root Directory Serial Number is (same with) Volume (File System) Serial Number. Root Directory Serial Number is not neeed for undelete procedure. (There is only one root directory in a FS and it can not be deleted.)