INT 13 U - Compaq DESKPRO/i - GET CURRENT MEDIA FORMAT
        AH = 20h
        DL = drive number (00h,01h)
Return: CF clear if successful
            AL = media type (see below)
        CF set on error
            AH = error code
                31h no such drive
                32h incorrect drive type stored in CMOS
Note:   this function is supported by the 3/8/93 ROM BIOS, but only partially
          (AL is always 00h when successful) by the 8/3/93 version

Values for media type:
 03h    720K
 04h    1.44M
 06h    2.88M
 0Ch    360K
 0Dh    1.2M
 0Eh    ???
 0Fh    ??? (1024-byte sectors)

.