| 摘要 |
PURPOSE:To simplify the double structure control by providing a bus controller between the system bus of a computer and to input/output devices having the same function and proper addresses respectively. CONSTITUTION:A system bus 3 of a CPU (not shwow in the diagram) is connected to two input/output devices 1 and 2 having the same function and different addresses via a bus controller 7. The data is transferred between the bus 3 and controllers 1a and 2a of the devices 1 and 2 by the controller 7 in response to the control signal given from the CPU. As shown in the diagram A, the data can be transferred via the controller 7 with devices 1 and 2 defined as devices different from each other. Otherwise the devices 1 and 2 are duplicated to transfer the same data as shown in the diagram B. In the case of duplication, the addresses are apparently coincident with each other for devices 1 and 2. Then the CPU performs reading/writing with just a single acess. In such a way, a double structure is easily obtained for two input/output devices. |
