| 摘要 |
PURPOSE:To make the control of I/O devices possible by providing two kinds of flag corresponding to the number of I/O devices on the main memory and regarding contents of flags and setting or resetting flags. CONSTITUTION:Channel control block CCB is provided as control information for devices. Flag A is provided for preventing information other than CCB from being read out erroneously from the main memory and the needless CCB processing from being repeated, for example, i case that data is inputted erroneously from a device which CCB is not prepared previously for or interruption is caused to CCB after the completion of the processing for this CCB. Flag B is provided for confirming the completion of the device-side output operation at a WRITE operation time, and is generated immediately after the completion of the output operation to complete the CCB processing. |
