| 摘要 |
PURPOSE:To eliminate necessity of prolong an undesired polling period by causing an 170 device to return pseudo status information to a host processing device if it is difficult to return status information. CONSTITUTION:If polling is issued repeatedly from the host processing device with a certain timing, an I/O control device 1 transfers it to a lower I/O device through a selector 4. If the fact occurs that the status information could not be returned properly to the host processing device because of execution of a command, the I/O control device 1 reads old status information stored in a status memory 3 and returns it to the host processing device through the selector 5 according to the instruction from a control division 2. |
