INT 21 - DOS 2+ - GET DOS DRIVE PARAMETER BLOCK FOR SPECIFIC DRIVE
        AH = 32h
        DL = drive number (00h = default, 01h = A:, etc)
Return: AL = status
            00h successful
                DS:BX -> Drive Parameter Block (DPB) for specified drive
            FFh invalid or network drive
Notes:  the OS/2 compatibility box supports the DOS 3.3 version of this call
          except for the DWORD at offset 12h
        this call updates the DPB by reading the disk; the DPB may be accessed
          via the DOS list of lists (see AH=52h) if disk access is not
          desirable.
        undocumented prior to the release of DOS 5.0; only the DOS 4+ version
          of the DPB has been documented, however
SeeAlso: AH=52h

Format of DOS Drive Parameter Block:
Offset  Size    Description
 00h    BYTE    drive number (00h = A:, 01h = B:, etc)
 01h    BYTE    unit number within device driver
 02h    WORD    bytes per sector
 04h    BYTE    highest sector number within a cluster
 05h    BYTE    shift count to convert clusters into sectors
 06h    WORD    number of reserved sectors at beginning of drive
 08h    BYTE    number of FATs
 09h    WORD    number of root directory entries
 0Bh    WORD    number of first sector containing user data
 0Dh    WORD    highest cluster number (number of data clusters + 1)
                16-bit FAT if greater than 0FF6h, else 12-bit FAT
 0Fh    BYTE    number of sectors per FAT
 10h    WORD    sector number of first directory sector
 12h    DWORD   address of device driver header
 16h    BYTE    media ID byte
 17h    BYTE    00h if disk accessed, FFh if not
 18h    DWORD   pointer to next DPB
---DOS 2.x---
 1Ch    WORD    cluster containing start of current directory, 0000h=root,
                FFFFh = unknown
 1Eh 64 BYTEs   ASCIZ pathname of current directory for drive
---DOS 3.x---
 1Ch    WORD    cluster at which to start search for free space when writing
 1Eh    WORD    number of free clusters on drive, FFFFh = unknown
---DOS 4.0-5.0---
 0Fh    WORD    number of sectors per FAT
 11h    WORD    sector number of first directory sector
 13h    DWORD   address of device driver header
 17h    BYTE    media ID byte
 18h    BYTE    00h if disk accessed, FFh if not
 19h    DWORD   pointer to next DPB
 1Dh    WORD    cluster at which to start search for free space when writing,
                usually the last cluster allocated
 1Fh    WORD    number of free clusters on drive, FFFFh = unknown