| 摘要 |
PURPOSE:To prevent lowering of the processing capability caused by selection of a data transfer destination in case that the data transfer destination of an input/output control device is changed. CONSTITUTION:If no IO processing request exists, the processing request of the first preference circuit 7 is selected by the inversion signal of a microprogram instruction output mu-1. At the time when execution of the processing request of the first processing queuing circuit 7 is completed, mu-2 is energized, and control is returned to an idle routine in the mu program. Since the idle routine outputs mu-3 to energize the second preference circuit 210, a processing request accumulared in the second processing queuing circuit 91 is selected and executed. The microprogram instruction output mu-1 is made to logical 0 at a proper time by the mu program performing this processing to stop temporarily execution of the prcessing request of the second processing queuing circuit 91, and a processing request IO of an input/output is executed. |
