INT 7F - Alloy NTNX, MW386 - CHANNEL CONTROL - LOCK ALL OPEN CHANNELS
        AH = 10h
        CL = 06h
Return: AL = status (00h-03h) (see AH=10h/CL=00h)
Note:   may not be invoked from within a hardware interrupt handler
SeeAlso: AH=10h/CL=02h,AH=10h/CL=08h

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