Format of DOS 5.0-6.0 disk buffer info |
| Offset | Size | Description | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
00h |
DWORD |
pointer to least-recently-used buffer header (may be in HMA) (see #01655) | |||||||||
|
04h |
WORD |
number of dirty disk buffers | |||||||||
|
06h |
DWORD |
pointer to lookahead buffer, zero if not present | |||||||||
|
0Ah |
WORD |
number of lookahead sectors, else zero (the y in BUFFERS=x,y) | |||||||||
|
0Ch |
BYTE |
buffer location
|
|||||||||
|
0Dh |
DWORD |
pointer to one-segment workspace buffer in base memory | |||||||||
|
11h |
3 BYTEs |
unused | |||||||||
|
14h |
WORD |
??? | |||||||||
|
16h |
BYTE |
flag: INT 24 fail while making an I/O status call | |||||||||
|
17h |
BYTE |
temp storage for user memory allocation strategy during EXEC | |||||||||
|
18h |
BYTE |
counter: number of INT 21 calls for which A20 is off | |||||||||
|
19h |
BYTE |
bit flags
|
|||||||||
|
1Ah |
WORD |
offset of unpack code start (used only during INT 21/AX=4B05h) | |||||||||
|
1Ch |
BYTE |
bit 0 set iff UMB MCB chain linked to normal MCB chain | |||||||||
|
1Dh |
WORD |
minimum paragraphs of memory required by program being EXECed | |||||||||
|
1Fh |
WORD |
segment of first MCB in upper memory blocks or
FFFFh if DOS memory chain in base 640K only (first UMB MCB usually at 9FFFh,
locking out video memory with a DOS-owned memory block) the MCB this word points at contains a valid link into high memory even if it is marked with a 'Z' indicating the last memory block |
|||||||||
|
21h |
WORD |
paragraph from which to start scanning during memory allocation |
|
See Also: |