Abstract: Upon detection of service interruption, the power supply unit gives a notice of the occurrence of service interruption to the processor unit to instruct save operation from the memory unit to the storage device, then instructs power disconnection to the second power supply section to discontinue supply of power, and continues supply of power from the power supply section to the memory unit and the storage device for save operation. The power supply control unit gives an advance notice of power disconnection to the memory unit prior to the instruction of power disconnection to the second power supply section to start save operation from the memory unit to the storage device, and upon the lapse of a prescribed period of time from the advance notice, instructs power disconnection of the second power supply section. Upon receipt of an end notice of save operation from the memory unit, the power supply control unit instructs the first power supply section to disconnect to discontinue supply of power.

Abstract: A commercially available clock IC which is easily influenced by a temperature change or the like is used as it is, thereby easily allowing the clock IC to function as a high precision clock IC. A high precision oscillator is provided separately from a clock circuit as a clock IC. On the basis of a clock signal from the high precision oscillator, a predetermined time, for example, one minute is measured by a high precision clock control circuit. A correction signal is transmitted to the clock circuit as a clock IC from a high precision control circuit every measurement of such a predetermined time, thereby allowing the correcting operation of the time information to be executed. The clock circuit is, consequently, made operative at a precision of the high precision oscillating circuit.