Format of DOS 4.0-6.0 disk buffer

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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.
See Also:	#01649,#01650,#01652