JP2967219B

PURPOSE:To provide the external power source instantaneous interruption processing device which restarts a processing from data before instantaneous interruption even when an external power source is instantaneously interrupted. CONSTITUTION:A ROM, RAM and power source instantaneous interruptor flag register C are connected to the CPU of the external power source instantaneous interruption processing device. A power supply holding circuit A is connected to the RAM, a power source instantaneous interruption judging circuit B is connected to the power source instantaneous interruption flag register C, and an input voltage monitor circuit D is provided. A voltage transformer E and an inside voltage monitor circuit F are connected to the input voltage monitor circuit, and a power down interrupting signal G is transmitted to the CPU. Since the inside voltage monitor circuit transmits a power on reset signal H to the CPU, the contents of data before the instantaneous interruption written in the RAM are held even when the external power source J is instantaneously interrupted and when the power source is turned on again, it is judged whether the power source is turned on by the instantaneous interruption or not. When it is caused by the instantaneous interruption, the processing is restarted from the data before the instantaneous interruption.