Format of DOS 4.01 (from UR 25066 Corrctive Services Disk on) disk buffer info |
| Offset | Size | Description | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
00h |
DWORD |
pointer to array of disk buffer hash chain heads (see #01654) | |||||||||
|
04h |
WORD |
number of disk buffer hash chains (referred to as NDBCH below) | |||||||||
|
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 |
01h, possibly to distinguish from pre-UR 25066 format | |||||||||
|
0Dh |
WORD |
??? EMS segment for BUFFERS (only with /XD) | |||||||||
|
0Fh |
WORD |
??? EMS physical page number of EMS seg above (only with /XD) | |||||||||
|
11h |
WORD |
??? EMS segment for ??? (only with /XD) | |||||||||
|
13h |
WORD |
??? EMS physical page number of above (only with /XD) | |||||||||
|
15h |
BYTE |
??? number of EMS page frames present (only with /XD) | |||||||||
|
16h |
WORD |
segment of one-sector workspace buffer allocated in main memory if BUFFERS/XS or /XD options in effect, possibly to avoid DMA into EMS | |||||||||
|
18h |
WORD |
EMS handle for buffers, zero if not in EMS | |||||||||
|
1Ah |
WORD |
EMS physical page number used for buffers (usually 255) | |||||||||
|
1Ch |
WORD |
??? appears always to be 0001h | |||||||||
|
1Eh |
WORD |
segment of EMS physical page frame | |||||||||
|
20h |
WORD |
??? appears always to be zero | |||||||||
|
22h |
BYTE |
|
|
See Also: |