Abstract: A memory protection method includes setting a memory area in at least one address setting register; setting a trap type in a trap type setting register corresponding to the address setting register; generating a trap of the trap type set in the trap type setting register in accordance with an access request to the memory area set at the address setting register; setting a size of an inaccessible area in a memory; allocating, in accordance with a memory allocation request from an application, a memory area to the application as an accessible area and an inaccessible area having the inaccessible area size right after the accessible area; setting the inaccessible area in a first address setting register and a first trap type in a first trap type setting register; and generating a memory image of the application and closing the application when a trap of the first trap type occurred.

Abstract: If a failure is detected in a system, it is automatically judged which operation mode should be selected, a system-down mode or a dynamic degeneracy mode. If a failed device is severed from the system, the severance of the device is reported by making a device control unit access the device or changing the state of the device.