International Business Machines Corporation

Richard Strangwayes

Thomas Anthony Gregg

Leon Skarshinski

Salvatore A Calta

A channel subsystem with a conventional serial extender link that causes communications between a channel and a control unit to be delayed by the additional time to transmit a message in one direction and to transmit an acknowledgement in the other direction. The channel subsystem also has a buffer and associated components (called a channel outboard box) that are used for prefetching data from processor memory or from a peripheral device without waiting for the acknowledgment routines that are commonly used on both an interlocked data transfer and a non-interlocked transfer (called data streaming). A system of counters and other components and associated operations maintain the correct byte count that would otherwise be maintained in a system without the prefetch buffer and with only a short serial link. A system of count and status frames provides for sending byte count and other status information between the channel and the outboard box.

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Wappingers Falls, NY, United States of America

Richard Strangwayes