Format of DOS 4.0-7.0 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 also INT 21/AH=53h)
		Offset	Size	Description
		 00h	WORD	bytes per sector
		 02h	BYTE	sectors per cluster, FFh if unknown
		 03h	WORD	number of reserved sectors
		 05h	BYTE	number of FATs
		 06h	WORD	number of root dir entries
		 08h	WORD	total sectors (refer to offset 15h if zero)
		 0Ah	BYTE	media descriptor, 00h if unknown
		 0Bh	WORD	sectors per FAT
		 0Dh	WORD	sectors per track
		 0Fh	WORD	number of heads
		 11h	DWORD	number of hidden sectors
		 15h	DWORD	total sectors if WORD at 08h is zero
 1Fh	BYTE	flags
		bit 6: 16-bit FAT instead of 12-bit
		bit 7: unsupportable disk (all accesses will return Not Ready)
 20h	WORD	device-open count
 22h	BYTE	device type (see #01561 at INT 21/AX=440Dh"DOS 3.2+")
 23h	WORD	bit flags describing drive (see #02604)
 25h	WORD	number of cylinders (for partition only, if hard disk)
 27h 25 BYTEs	BIOS Parameter Block for default (highest) capacity supported
 40h  6 BYTEs	reserved (part of BPB above)
 46h	BYTE	last track accessed
---removable media---
 47h	DWORD	time of last access in clock ticks (FFFFFFFFh if never)
---fixed media---
 47h	WORD	partition (FFFFh = primary, 0001h = extended)
		always 0001h for DOS 5+
 49h	WORD	absolute cylinder number of partition's start on physical drive
		(FFFFh if primary partition in DOS 4.x)
------
 4Bh 11 BYTEs	volume label or "NO NAME    " if none (apparently taken from
		  extended boot record rather than root directory)
 56h	BYTE	terminating null for volume label
 57h	DWORD	serial number
 5Bh  8 BYTEs	filesystem type ("FAT12	  " or "FAT16	")
 63h	BYTE	terminating null for filesystem type
SeeAlso: #02601,#02602