JPS5922297A - Method for writing stored content in duplicated device - Google Patents

Abstract

PURPOSE:To write data in a spare system immediately by writing the same content as a current system in the spare system at the same timing on the basis of clock at the writing in the current system. CONSTITUTION:When a device A is used at present, a clock (a) is applied to the device A as a writing clock (b) and a writing clock b' is also applied to the spare system. Since an FF5 is normally in a reset state, both selectors 2, 2' select and output the clock (a) on the basis of the output (g) of the FF5 and are enabled to write data at the same timing and clock. At the writing in a memory 4, the clock (b) is acted as a write timing signal and a control circuit 3 supplies address data writing data (c), but in the spare system, the clock b' is acted as the write timing signal for a memory 4' and the memory 4' receives the same data (d) as the data (c). Consequently, the same contents are written in both the systems at the same timing.