INT 7F - Alloy NTNX, MW386 - GET CHANNEL STATUS
        AH = 15h
        CL = 00h
        AL = channel number
        DX:DI -> status structure (see below)
Return: AL = status (00h-03h) (see AH=12h)
SeeAlso: AH=15h/CL=01h

Format of status structure:
Offset  Size    Description
 00h    BYTE    channel status
                bit 0: channel open
                bit 1: channel buffer contains received data
                bit 7: channel locked
 01h    BYTE    sender ID

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