Format of DOS 1.1 and MS-DOS 1.25 drive parameter block:
Offset	Size	Description	)
 00h	BYTE	sequential device ID
 01h	BYTE	logical drive number (0=A:)
 02h	WORD	bytes per sector
 04h	BYTE	highest sector number within a cluster
 05h	BYTE	shift count to convert clusters into sectors
 06h	WORD	starting sector number of first FAT
 08h	BYTE	number of copies of FAT
 09h	WORD	number of directory entries
 0Bh	WORD	number of first data sector
 0Dh	WORD	highest cluster number (number of data clusters + 1)
 0Fh	BYTE	sectors per FAT
 10h	WORD	starting sector of directory
 12h	WORD	address of allocation table
Note:	the DOS 1.0 table is the same except that the first and last fields
	  are missing; see INT 21/AH=32h for the DOS 2+ version
SeeAlso: #01395,#04039