Format of COMPAQ DOS 3.31 drive data table:
Offset	Size	Description	)
 00h	DWORD	pointer to next table (offset FFFFh if last table)
 04h	BYTE	physical unit number (for INT 13)
 05h	BYTE	logical drive number (0=A:)
 06h 25 BYTEs	BIOS Parameter Block (see #02603)
 1Fh  6 BYTEs	reserved fields from BPB above???
 25h	BYTE	flags
		bit 6: 16-bit FAT instead of 12-bit FAT
		bit 5: large volume???
 26h	WORD	device-open count???
 28h 11 BYTEs	volume label or "NO NAME    " if none (always "NO NAME" for
		  fixed media)
 33h	BYTE	terminating null for volume label
 34h	BYTE	device type (see #01561 at INT 21/AX=440Dh"DOS 3.2+")
 35h	WORD	bit flags describing drive (see #02604)
 37h	WORD	number of cylinders
 39h 25 BYTEs	BIOS parameter block for highest capacity drive supports
 52h  6 BYTEs	??? apparently always zeros
 58h	BYTE	least-significant byte of last-accessed cylinder number
---removable media---
 59h	DWORD	time of last access in clock ticks (FFFFFFFFh if never)
---fixed media---
 59h	WORD	partition (FFFFh = primary, 0001h = extended)
 5Bh	WORD	absolute cylinder number of partition's start on physical
		  drive (always FFFFh if primary partition)
SeeAlso: #02601,#02603