| 摘要 |
PURPOSE:To attain command chaining processing at high speed by using other idle channel to prefetch to a channel command word during data transfer between an input/output device and a main storage device thereby realizing parallel processing. CONSTITUTION:A channel input/output section 2 is used in common use for prefetching a channel control word CCW. A CCW prefetching CWGET routine reads the state of a byte multiplexer channel from a subchannel memory 14. When the channel input/output section 2 does not access a main storage 200 the intermission of operation is commanded to the channel input/output section 2. Then, a CCW address is read, the next CCW address is calculated and stored in a local storage 17. The input/output control section recieves it, accesses the main storage 200 by a memory access control section and the CWGET routine is stored in a local storage 17.
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