| 摘要 |
PURPOSE:To decrease the burden of a CPU and improve the rate of response to input-output devices by enabling executing to be started only when predetermined conditions are satisfied only by the response from a lower device as an input-output instruction. CONSTITUTION:A collating circuit 14 selects one out of the registers 12, 13 or 8 displayed by the data D2 transmitted from a condition decoder 10 and applies the output thereof to an instruction CCW execution circuit 5 that the channel perse is ought to execute. When the contents of the I/O state register 8 are decidied to be BUSY in the circuit 14 and the nonestablishment of conditions are announced to the circuit 5, the circuit 5 informs of that effect to a CPU. Thereafter, the circuit 5 successively monitors the operation state of the input-output devices through the control signal line, not shown. Here, if the contents of the lower device register 8 are informed to the circuit 5 as the condition establishment in the circuit 14, the circuit 5 reads out the information from a main memory MEM and starts processing based on the instruction. Thereby, the burden of the CPU is reduced and the response speed to the device 8 is increased. |
