| 摘要 |
PURPOSE:To significantly decrease the probability of the occurrence of the data overrun and the command overrun by executing the channel command word prefetching processing with the channel command work prefetching process. CONSTITUTION:A priority circuit 19, when the processing requests to the process of the second priority level B executed by a flip-flop 110 and a processing request line 111 are plural, is the circuit to select one request in accordance with the priority sequence specified beforehand. The flip-flop 110 can execute the setting and the presetting by the microprogram, and executes the processing request to the channel command word prefetching process at the time of the setting condition. The processing request by the flip-flop 110 has the highest priority sequence in the second priority level B. For a processing request line 111, there are respective processing request lines of a low speed page jumping- over, a low speed chain data, a low speed service, the communication between processors and the constitution control.
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