Information processing systems having a main CPU and a sub-CPU which controls the overall system to achieve power savings

摘要

An information processing system in which a sub-CPU is provided besides a main CPU to carry out those kinds of processing and power supply control that may be executed at time intervals of a short period, so that the power consumption of the information processing system can be reduced without lowering the processing speed of the information processing system. The sub-CPU of a type operating at a low speed, driven by a low voltage and consuming a small amount of power carries out those kinds of processing including monitoring an input from a keyboard, counting the output of a timer and monitoring and controlling a power supply control circuit, and, during waiting arrival of a key input, the main CPU is placed in its halt mode consuming a very small amount of power. The sub-CPU instructs to selectively turn off the power supply for an input/output unit not in use among a display unit, a modem, an FDD, an extension slot, etc., whereby the power consumption of the information processing system can be reduced without lowering the processing speed of the information processing system.