DUPLEX CONTROLLER

PROBLEM TO BE SOLVED: To provide a duplex controller capable of checking an address defect by the equalization of a redundant control part. SOLUTION: This duplex controller is provided with first and second control parts 1 and 2 having memories 12 and 22 of which one becomes a control side and the other becomes a standby side, and a redundant control part 3 for equalizing the contents of the memory on the control side between these first and second control parts to the memory on the standby side between the first and second control parts. In this case, a fixed pattern is written in continuous addresses in the memory on the control side between the first and second control parts and an equalization check is performed corresponding to the contents in the memory on the standby side between the first and second control parts.