INT 2F - Jim Harper's CD-ROM redirector SCSI driver - DO COMMAND
        AX = 7F01h
        DS:DX -> command record (see below)
Return: AL = status
            00h successful
            else error code
SeeAlso: AX=7F00h,AX=7F02h,INT 11/AH=FFh"SDLP",INT 21/AX=4402h"ASPI"
SeeAlso: INT 4F/AX=8100h

Format of command record:
Offset  Size    Description
 00h    BYTE    ID
 01h 10 BYTEs   CDB (Command Descriptor Block) for operation
 0Bh    WORD    segment of buffer
 0Dh    WORD    offset of buffer
 0Fh    BYTE    status
 10h    BYTE    sense
 12h    WORD    count

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