Format of DOS 4.0-6.0 disk buffer:
Offset Size Description )
00h WORD forward ptr, offset only, to next least recently used buffer
02h WORD backward pointer, offset only
04h BYTE drive (0=A,1=B, etc) if bit 7 clear
SFT index if bit 7 set
FFh if not in use
05h BYTE buffer flags (see #01656)
06h DWORD logical sector number (local buffers only)
0Ah BYTE number of copies to write
for FAT sectors, same as number of FATs
for data and directory sectors, usually 1
0Bh WORD offset in sectors between copies to write for FAT sectors
0Dh DWORD pointer to DOS Drive Parameter Block (see #01395 at AH=32h)
11h WORD size of data in buffer if remote buffer (see also #01656)
13h BYTE reserved (padding)
14h buffered data
Note: for DOS 4.x, all buffered sectors which have the same hash value
(computed as the sum of high and low words of the logical sector
number divided by the number of disk buffer chains) are on the same
doubly-linked circular chain; for DOS 5+, only a single circular
chain exists.
the links consist of offset addresses only, the segment being the same
for all buffers in the chain.
SeeAlso: #01649,#01650,#01652