NAME
        read -- read input from parallel port

   FUNCTION
        This command causes a stream of characters to be read from the
        parallel I/O register. The number of characters is specified in
        io_Length. The EOF and EOL modes are supported, but be warned that
        using these modes can result in a buffer overflow if the proper
        EOL or EOF character is not received in time. These modes should
        be used only when the sender and receiver have been designed to
        cooperate. A safety guard can be implemented to EOF by setting
        io_Length to a maximum allowed value. That cannot be done with EOL
        since the EOL mode is identified by io_Length=-1.

        The parallel.device has no internal buffer; if no read request has
        been made, pending input (i.e. handshake request) is not
        acknowledged.

   IO REQUEST
        io_Message      mn_ReplyPort initialized
        io_Device       set by opendevice
        io_Unit         set by opendevice
        io_Command      CMD_READ (02)
        io_Flags        If IOF_QUICK is set, driver will attempt Quick IO
        io_Length       number of characters to receive.
        io_Data         pointer where to put the data.

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

   SEE ALSO
        parallel.device/pdcmd_setparams