Format of DOS 3.30 drive data table:
Offset Size Description )
00h DWORD pointer to next table (offset FFFFh if last table)
04h BYTE physical unit number (for INT 13)
05h BYTE logical drive number (0=A:)
06h 19 BYTEs BIOS Parameter Block (see also INT 21/AH=53h)
Offset Size Description
00h WORD bytes per sector
02h BYTE sectors per cluster, FFh if unknown
03h WORD number of reserved sectors
05h BYTE number of FATs
06h WORD number of root dir entries
08h WORD total sectors
0Ah BYTE media descriptor, 00h if unknown
0Bh WORD sectors per FAT
0Dh WORD sectors per track
0Fh WORD number of heads
11h WORD number of hidden sectors
19h BYTE flags
bit 6: 16-bit FAT instead of 12-bit FAT
1Ah WORD number of DEVICE OPEN calls without corresponding DEVICE CLOSE
1Ch 11 BYTEs volume label or "NO NAME " if none (always "NO NAME" for
fixed media)
27h BYTE terminating null for volume label???
28h BYTE device type (see #01561 at INT 21/AX=440Dh"DOS 3.2+")
29h WORD bit flags describing drive (see #02604)
2Bh WORD number of cylinders
2Dh 19 BYTEs BIOS Parameter Block for highest capacity supported
40h 3 BYTEs ???
43h 9 BYTEs filesystem type???, default = "NO NAME "
(apparently only MS-DOS 3.30 fixed media, nulls for removable
media and PC-DOS 3.30)
4Ch BYTE least-significant byte of last-accessed cylinder number
---removable media---
4Dh DWORD time of last access in clock ticks (FFFFFFFFh if never)
---fixed media---
4Dh WORD partition (FFFFh = primary, 0001h = extended)
4Fh WORD absolute cylinder number of partition's start on physical
drive (always FFFFh if primary partition)
SeeAlso: #02602,#02603