| 摘要 |
PROBLEM TO BE SOLVED: To surely detect an abnormality of software irrelevantly to the operation state of a CPU by monitoring whether or not a process was performed in a specific period for every plural processes and detecting an abnormality of the software when any process among the plural processes is performed out of the specific period. SOLUTION: If the software of a CPU 9 becomes abnormal, the process time of the CPU 9 becomes longer than that at abnormal time and since timing outputting an address 2a from the CPU 9 to an address bus 10 is delayed, the timing of a pulse 2b from an address comparator 2 is delayed from the normal time. Since the rise timing of the output 2c of a one-shot multivibrator 5 is therefore delayed from the normal time and a time interval is generated between pulses 1c and 2c, the output signal (d) of an OR circuit 7 is temporarily a low level. In this case, since a flip-flop circuit 8 is set, the flip-flop circuit 8 outputs an alarm.
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