SUPERVISORY UNIT FOR CPU ABNORMALITY

摘要

PURPOSE:To recognize quickly the abnormality of a CPU by enabling a specific CPU control the resetting of another CPU and also informing periodically the specific CPU that other CPU are normal. CONSTITUTION:When one of plural CPU is abnormal, it is impossible to inform the normal state to a host CPU. Thus the host CPU can recognize the abnormal ity of a lower CPU and furthermore can control the state of the lower CPU. In other words, a CPU 1 of a lower system image pickup part A writes the normal status of its own to a shared memory 7 once every two minutes. While a CPU 2 at the side of a communication control part B reads out the status showing that the CPU 1 is normal once every five minutes and erases this status at each time. In such a way, the erased status is never written again after the abnormality of the CPU 1 is confirmed. Thus the CPU 2 can know that the CPU 1 has a runaway.