| 摘要 |
PURPOSE:To omit the control of both a working system and a standby system by connecting a bus between an input/output device to the write/read accesses given from a computer of the working system and the read access given from a computer of a standby system and disconnecting a bus to the write access from the standby system computer to inhibit the access. CONSTITUTION:A conflict control circuit 113 decides the priority and permission for the read access given from a computer 2 of a standby system as well as the read/write accesses given from a computer 1 of a working system. Then an input/output bus 7 or 8 and an input/output bus 9 of an input/output device 5 are connected to each other via a gate 14 or 15. While the gate 15 is closed to the write access given to the device 5 from the computer 2 by the standby system computer 12 from the circuit 113 and a duplex control device 3A. At the same time, an answer control circuit 18 sends back an answer as if a write access were through normally. In such a way, the control is continued with switching perfectly carried out between the working and standby systems. Thus various control tasks can be omitted.
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