Patent ID: 8392656

Claim:
A parameter copying method for a duplex system in which a micro processing unit (MPU) and a main memory are duplicated and duplex operations of a hot standby system are performed, the duplex system having an MPU and a main memory at a control side and an MPU and a main memory at a standby side, comprising steps of: cache reading data in a cache access area of the main memory corresponding to the MPU at the control side; cache writing the data read in the cache reading step into a cache memory at the control side; and writing the data into the main memory corresponding to the MPU at the control side by a block write, and also writing the same data into the main memory corresponding to the MPU at the standby side by the block write on a basis of a mirrored write; wherein the step of writing the data by the block write is applied to the cache access area of the main memory corresponding to the MPU at the control side and to a cache access area of the main memory corresponding to the MPU at the standby side.