Format of DOS 3.1-3.3x, DR DOS 5.0-6.0 system file tables and FCB tables: Offset Size Description ) 00h DWORD pointer to next file table (offset FFFFh if last) 04h WORD number of files in this table 06h 35h bytes per file Offset Size Description 00h WORD number of file handles referring to this file 02h WORD file open mode (see AX=6C00h, #01402 at AH=3Dh) bit 15 set if this file opened via FCB 04h BYTE file attribute (see #01420 at AX=4301h) 05h WORD device info word (see #01423 at AX=4400h) bit 15 set if remote file bit 14 set means do not set file date/time on closing bit 12 set means don't inherit on EXEC bits 5-0 drive number for disk files 07h DWORD pointer to device driver header if character device else pointer to DOS Drive Parameter Block (see #01395 at AH=32h) 0Bh WORD starting cluster of file 0Dh WORD file time in packed format (see #01665 at AX=5700h) not used for character devices in DR DOS 0Fh WORD file date in packed format (see #01666 at AX=5700h) not used for character devices in DR DOS 11h DWORD file size ---system file table--- 15h DWORD current offset in file (may be larger than size of file; INT 21/AH=42h does not check new position) ---FCB table--- 15h WORD counter for last I/O to FCB 17h WORD counter for last open of FCB (these are separate to determine the times of the latest I/O and open) --- 19h WORD relative cluster within file of last cluster accessed 1Bh WORD absolute cluster number of last cluster accessed 0000h if file never read or written??? 1Dh WORD number of sector containing directory entry (see #01352) 1Fh BYTE number of dir entry within sector (byte offset/32) 20h 11 BYTEs filename in FCB format (no path/period, blank-padded) 2Bh DWORD (SHARE.EXE) pointer to previous SFT sharing same file 2Fh WORD (SHARE.EXE) network machine number which opened file (Windows Enhanced mode DOSMGR uses the virtual machine ID as the machine number; see INT 2F/AX=1683h) 31h WORD PSP segment of file's owner (see #01378 at AH=26h) (first three entries for AUX/CON/PRN contain segment of IO.SYS startup code) 33h WORD offset within SHARE.EXE code segment of sharing record (see #01637) 0000h = none SeeAlso: #01639,#01640,#01642