PURPOSE: To eliminate the need of storage holding operations from a computer system and to enable the system to execute a processing which was executed by the system before a power failure occurs in a short time after the power supply is restored by using an SRAM as the main storage device of the system.

CONSTITUTION: An SRAM is used as the main storage device of this computer system. Accordingly, storage holding operations, such as power supply, etc., become unnecessary and the memory state of the main storage device before a power failure occurs can be maintained. The initializing programs of LSIs 4 for controlling peripheral devices are stored in a ROM 3. When the power supply is restored, the programs are loaded and the LSIs 4 for controlling peripheral equipments are initialized. Since the memory state of the main storage device 1 is maintained in the same state as the before the power failure occurs, an operating system and application program are immediately set to executable states. Therefore, the processing which was executed before the power failure occurs can be executed in a short time after the power supply is restored.