| 摘要 |
PURPOSE:To rapidly and surely detect the run away of CPU by making CPU execute a program, monitoring the execution order and outputting a detection signal or a time-up signal, which is generated earlier, when the execution order is detected not a right order. CONSTITUTION:When CPU executes only OUT instruction without executing a specified instruction by its run away, etc., an output f of an undergate 5 becomes active and a detection signal f is generated as an output b of Q of 1 instruction window generation circuit 16 is '0'. When a specified instruction or OUT instruction is not executed, a timer circuit 1 continues counting operation and outputs a time-up signal h. Therefore, an OR-gate 7 outputs the time-up signal h or the detection signal f, which is generated earlier, to 11 for CPU reset output. Then, CPU receives this signal as a reset signal or an interruption signaland executes proper processing such as initialization, etc. Thus, the run way of CPU is rapidly and surely detected without loading a program. |
