Patent ID: 8671300

Claim:
A processing unit including an operation unit to execute operation processing, wherein the processing unit is connected to another processing unit through system bus including serial signal communication line and synchronization signal communication line to be able to communicate therewith and the processing unit comprises: a synchronization unit to transmit, when the operation unit detects abnormal state in the processing unit, notification of detection of the abnormal state received from the operation unit to the other processing unit through the synchronization signal communication line and to supply the detection notification of abnormal state to a conversion unit; and the conversion unit to receive, when the detection notification of abnormal state is not received from the synchronization unit, data of operation processing result from the operation unit by parallel communication and to receive, when the detection notification of abnormal state is received from the synchronization unit, emergency data from the operation unit through important signal line for parallel communication different from signal line used for the parallel communication by parallel communication, the conversion unit converting the received parallel signal into serial signal to transmit the serial signal to the other processing unit through the serial signal communication line in any case.