| 摘要 |
PURPOSE:To appropriately execute retry when an I/O(input/output) device can not receive an I/O instruction by providing the I/O with an I/O control device including a register for storing queue time and returning status including queue time information to the I/O instruction outputted from a central processing unit(CPU). CONSTITUTION:When the I/O controller 5 can not accept an I/O instruction received from the CPU 1 to the I/O 4, the device 5 returns status including queue time information to the CPU 1. The CPU 1 decides the status of the controller 5 in accordance with the returned queue time information and executes retrying operation after the lapse of the queue time, or executes proper processing such as the output of I/O abnormality information as the stall of the I/O. Thereby even when the I/O instruction outputted from the CPU 1 can not be received, an appropriate retry can be executed and the processing of the CPU 1 can be efficiently executed. |
