Abstract: A duplex system has duplicated processor devices. Each of the processor devices has a first copying section which writes data written in a memory of the processor device, into a same address of a memory of the other processor device, a second copying section which divides all data in the memory of the processor device to sequentially write all data into the memory of the other processor device periodically, an error detecting section which checks the data written in the memory of the processor device, and an error check register which sets an error bit when the error detecting section detects an error. After the first copying section and the second copying section write data into a memory of the standby side processor device, the control side processor device checks an error bit of an error check register of the standby side processor device.

Abstract: A duplex system has duplicated processor devices. Each of the processor devices has a first copying section which writes data written in a memory of the processor device, into a same address of a memory of the other processor device, a second copying section which divides all data in the memory of the processor device to sequentially write all data into the memory of the other processor device periodically, an error detecting section which checks the data written in the memory of the processor device, and an error check register which sets an error bit when the error detecting section detects an error. After the first copying section and the second copying section write data into a memory of the standby side processor device, the control side processor device checks an error bit of an error check register of the standby side processor device.