INT 21 - CD-ROM device driver - IOCTL OUTPUT
        AX = 4403h
        BX = file handle referencing character device for CD-ROM driver
        CX = number of bytes to write
        DS:DX -> control block (see below)
Return: CF clear if successful
            AX = number of bytes actually written
        CF set on error
            AX = error code (01h,05h,06h,0Dh) (see AH=59h)
SeeAlso: AX=4402h"CD-ROM",INT 2F/AX=0802h

Format of control block:
Offset  Size    Description
 00h    BYTE    function code
                00h eject disk
                01h lock/unlock door
                02h reset drive
                03h control audio channel
                04h write device control string
                05h close tray
---functions 00h,02h,05h---
 no further fields
---function 01h---
 01h    BYTE    lock function
                00h unlock door
                01h lock door
---function 03h---
 01h    BYTE    input channel (0-3) for output channel 0
 02h    BYTE    volume for output channel 0
 03h    BYTE    input channel (0-3) for output channel 1
 04h    BYTE    volume for output channel 1
 05h    BYTE    input channel (0-3) for output channel 2
 06h    BYTE    volume for output channel 2
 07h    BYTE    input channel (0-3) for output channel 3
 08h    BYTE    volume for output channel 3
Note:   output channels 0 and 1 are left and right, 2 and 3 are left prime and
          right prime; a volume of 00h is off
---function 04h---
 01h  N BYTEs   bytes to send directly to the CD-ROM drive without
                interpretation

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