INT 69 - DECnet DOS CTERM - STATUS
        AX = 0103h
        DX = session handle
Return: AH status flags
            bit 7 session has been aborted
                6 DECnet error
                1 trace data available
                0 receive data available
        AL = reason code if DECnet error
            00h normal disconnect
            01h unknown message from host
            02h protocol violation from host
            03h could not process the initiate message
            04h error receiving message from host
            05h error sending message to host
            06h error checking for message from host
            07h remote system does not support CTERM
            08h remote system does not support correct protocol version
            09h did not receive BIND message from host
            0Ah could not send BIND message to host
            0Bh no more sessions available
            0Ch session does not exist
            0Dh not enough memory to complete operation
            0Eh connection has broken