Power backed-up dual memory system

摘要

A dual memory system consists of two memory units each having volatile memory devices, backup power storage means and backup monitoring facility which memorizes a signal indicative of whether backup is successful or failing. When the contents of one memory unit are copied to another memory unit, the receiving memory unit has the monitor signal in a state which is made coincident with the signal state of the sending memory unit. Consequently, the receiving memory unit will have the same state of the monitor signal as of the sending memory unit at the end of copying, and thus both memory units are in a successful backup state only when the sending memory unit is in a successful backup state.