Patent ID: 7999953

Claim:
A printer comprising: a data receiving unit which is configured to receive data sent from a host computer; a data transmission unit which is configured to send data to said host computer; a receive buffer which is configured to temporarily store data received by said data receiving unit; an interpreting unit which is configured to interpret data stored in said receive buffer; a print buffer which is configured to store a print image generated in response to print data among said data stored in said receive buffer; a print mechanism which is configured to print said print image stored in said print buffer; and control means for controlling said data receiving unit, said data transmission unit, said receive buffer, said interpreting unit, said print buffer, and said print mechanism; wherein said control means is for causing said data receiving unit to start discarding received data and clearing said data stored in said receive buffer when an off-line error occurs, for causing said data receiving unit to stop discarding said received data and causing said data transmission unit to send an on-line status report to said host computer when said printer returns to an on-line state, for clearing said receive buffer again in response to a clear buffer command which is sent from said host computer in response to the on-line status report; for causing said data transmission unit to send a buffer clearing completion report to said host computer when said data receiving unit receives said clear buffer command, and to print based on print data received from said host computer after sending said buffer clearing completion report.