List of Lists
DOS 3.xx and Above
-08h DWORD Current buffer in BUFFERS= chain
-04h WORD Offset within current buffer
DOS 2.xx and Above
-02h WORD Segment of first Memory Control Block
00h DWORD Pointer to first Drive Parameter Block
04h DWORD Pointer to first DCB (system file table)
08h DWORD Pointer to CLOCK$ device driver
0Ch DWORD Pointer to CON device driver
DOS 2.xx Only
10h BYTE Number of Logical Drives
11h WORD Maximum bytes per sector on any block device
13h DWORD Pointer to start of disk buffer chain
17h Begining of NUL device driver
DOS 3.xx and Above
10h WORD Maximum bytes per sector on any block device
12h DWORD Pointer to start of disk buffer chain
16h DWORD Pointer to logical drive table
1Ah DWORD Pointer to start of DOS's FCB chain
1Eh WORD Number of FCB's to keep when swapping
20h BYTE Number of block devices
21h BYTE Number of logical drives (default=5, or LASTDRIVE=)
22h Beginning of NUL device driver
DOS 4.xx
12h DWORD Changed to pointer to EMS link record, which in
turn points to start of disk buffer chain
Logical Drive Table
00h 2 BYTEs Actual drive designator and ":"
02h 65 BYTEs Current ASCIIZ path for this drive; includes
root directory "\"
43h WORD Current status of drive:
| Drive
Status |
| Bit |
Dec |
Hex |
Description |
| 0 |
1 |
0001h |
Unknown |
| 1 |
2 |
0002h |
| 2 |
4 |
0004h |
| 3 |
8 |
0008h |
| 4 |
16 |
0010h |
| 5 |
32 |
0020h |
| 6 |
64 |
0040h |
| 7 |
128 |
0080h |
| 8 |
256 |
0100h |
| 9 |
512 |
0200h |
| 10 |
1024 |
0400h |
| 11 |
2048 |
0800h |
| 12 |
4096 |
1000h |
SUBSTed unit |
| 13 |
8192 |
2000h |
Unknown |
| 14 |
16384 |
4000h |
Ready for use |
| 15 |
32768 |
8000h |
Unknown |
45h DWORD Pointer to DOS DPB for drive
49h WORD First cluster of current directory; FFFFh if drive
never accessed, 0000h if root directory
4Bh WORD Unknown
4Dh WORD Unknown
4Fh WORD Number of bytes to skip over when reporting
directory; 0002h for normal drive, more for a
SUBSTed unit
DOS 4.xx
51h 7 BYTEs Unknown, default values of 0 |