System including single host buffer for transmit and receive data and reception buffer in interface device having stand-by area for use by host buffer when abnormal state is detected

摘要

In the event that a host device does not have a transmitting FIFO and receiving FIFO independently, but shares one FIFO for both transmission and reception, and an error occurs at the destination of transmission, the host cannot receive error information unless the FIFO is emptied. Accordingly, the printer according to the present invention secures a stand-by area in the reception buffer that is the same capacity as the FIFO at the host. In the event that an error occurs, transmission of data from the host is stopped, and if there is no available area except for the stand-by area within the reception buffer, the stand-by area is released to empty the FIFO.