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    Read -- read input from parallel port

    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

    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.

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


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