NAME
        write -- send output to parallel port

   FUNCTION
        This command causes a stream of characters to be written to the
        parallel output register. The number of characters is specified in
        io_Length, unless -1 is used, in which case output is sent until
        a zero byte occurs in the data. This is independent of, and may be
        used simultaneously with setting the EOFMODE in io_ParFlags and using
        the PTermArray to terminate the read or write.

   IO REQUEST
        io_Message      mn_ReplyPort initialized
        io_Device       set by opendevice
        io_Unit         set by opendevice
        io_Command      CMD_WRITE (03)
        io_Flags        If IOF_QUICK is set, driver will attempt Quick IO
        io_Length       number of characters to transmit, or if set
                        to -1 send until zero byte encountered
        io_Data         pointer to block of data to transmit

   RESULTS
        io_Error -- If the write succeded, then io_error will be null.
             If the write failed, then io_error will contain an error code.

   SEE ALSO
        parallel.device/pdcmd_setparams