| 摘要 |
PURPOSE:To reduce the overhead of a CPU by preparing a queue from a queue header table and a queue connecting table and setting a flip-flop to start an I/O instruction. CONSTITUTION:When the channel number of a channel controlling device CHC 3 is effective, the CHC 3 always receives an I/O instruction from the CPU, registers the instruction in an I/O instruction queue and sets an I/O instruction execution waiting flip-flop after preparing the queue. When each of channels 4-1- 4-N is made idle, the channel checks said flip-flop and when the flip-flop is set, generates an interruption to the CHC 3 to request the starting of execution. The CHC 3 removes I/O devices which are registered in the queue and enabled to execute the I/O instruction at present in sequence from the queue and executes the I/O instruction specified to the devices. |
