INT 7F - Alloy NTNX (Host) - GET SHARED DRIVE INFO
        AH = 06h
        AL = drive number (1=A:, 2=B:, etc)
        ES:DI -> drive info record (see below)
Return: AX = status
            0000h successful
                ES:DI buffer filled
            0001h not shared drive

Format of drive info record:
Offset  Size    Description
 00h    WORD    segment of drive IO-REQUEST structure (MSDOS DPB)
 02h    WORD    segment of allocation map (owner table)
                one byte per FAT entry, containing user ID owning that entry
 04h    WORD    segment of master FAT for drive (copy of FAT on disk)
 06h    WORD    pointer to configuration file
 08h    WORD    total number of clusters
 0Ah    WORD    bytes per sector
 0Ch    WORD    sectors per cluster
 0Eh    BYTE    FAT type (0Ch = 12-bit, 10h = 16-bit)