DUPLEX SYSTEM USING STANDBY REDUNDANT CONFIGURATION

PURPOSE: To improve the throughput of the system by omitting the selection of the check point data that is performed by a CPU of operating system at a check point, the transfer of the check point data, etc. CONSTITUTION: A CPU 11 receives a store device full generation notification signal 91 and sends a check point instruction signal 92 to a data extension processor 60. The CPU 11 monitors a check point status signal 93 and starts execution of a task after the processing of the device 60 is completed. Then the CPU 11 produces the signal 92, and a data quantity counter of a data monitor device 30 is cleared. Furthermore, the change of the task management information 18 occurred at the CPU 11 is sent to a standby processor 2 from an operating processor 1. Then the device 60 extends the data stored in a data store device 50 into the task internal data stored in a main memory 22 and invalidates the signal 93.