| 摘要 |
PURPOSE:To improve the throughput of a system comprising a CPU and an I/O device by designating a bus connected to the I/O device to be selected with a sub number stored in a storage circuit to omit ecessive access of the bus. CONSTITUTION:A CPU agives an I/O selection command 1 including an identification number field as an I/O selection command signal and it is inputted to selection circuit 10-12 connected to buses 20-22 and a storage circuit 5. The circuit 5 outputs a signal corresponding to the identification number designated by the I/O selection command to a signal line 6, the circuits 10-12 designate one of the corresponding buses 20-22 and transmit the supplied identification number of the designated bus. The I/O device is selected by the command of I/O selection only once. |
