JPS57170000A - Redundancy constitution of memory and operating system - Google Patents

Abstract

PURPOSE:To achieve memory switching without interruption and to eliminate the need for the initial program loading at memory destruction, by switching the operating state from a cold standby system to active system and from hot standby system to the active system, according to the status through the use of three or the like memories. CONSTITUTION:Three memories 11a-11c are accessed by taking the same address space via processors 13a and 13b, and system control circuits 12a and 12b selecting the memories as required. The memory 11a acts like an active system making read/write, the memory 11b acts like a hot standby system only with write and the memory 11c acts like a cold standby system only with the initial loading. At the memories 11a and 11b destruction due to software runaway, the memory 11c becomes the active system via the circuits 12a and 12b, and when the memory 11b is guaranteed, the memory 11b is switched to the active system, the initial program load at memory destruction is unnecessary and the memories are switched without interruption, allowing to prevent the lowering in the processing speed.