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       Query -- query serial port/line status

       This command return the status of the serial port lines and
       registers. The number of unread bytes in the serial device's
       read buffer is shown in io_Actual.

	The break send & received flags are cleared by a query, and
	whenever a read IORequest is returned with a error
	in io_Error.

       io_Message      mn_ReplyPort initialized
       io_Device       preset by OpenDevice
       io_Unit         preset by OpenDevice
       io_Command      SDCMD_QUERY

       io_Status        BIT  ACTIVE  FUNCTION

              LSB       0    ---    reserved
                        1    ---    reserved
                        2    high   parallel "sel" on the A1000
                                    On the A500 & A2000, "sel" is also
                                    connected to the serial port's
                                    "Ring Indicator".  Be cautious when
                                    making cables.
                        3    low    Data Set Ready
                        4    low    Clear To Send
                        5    low    Carrier Detect
                        6    low    Ready To Send
                        7    low    Data Terminal Ready
              MSB       8    high   hardware overrun
                        9    high   break sent (most recent output)
                       10    high   break received (as latest input)
                       11    high   transmit x-OFFed
                       12    high   receive x-OFFed
                    13-15    ---    reserved

       io_Actual       set to count of unread input characters

       io_Error -- Query will always succeded.

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