Unisys Corporation

Richard A Schranz

Anthony P Gold

Michael K Benton

A system and method is provided for assigning job numbers to fetch requests that are sent to a memory system in order and completed by the memory system out-of-order. A unique set of job numbers represent addresses in a memory fetch list. A valid register maintains status bits associated with the set of job numbers that identify whether a job number is assigned or available. Bits in the valid register are set when an associated job number is assigned and reset when an associated job number is completed. On assignment, a priority encoder selects any lowest available job number based upon the status of the bits in the valid register. In the preferred embodiment, the lowest available job number is selected.

Out-of-order fetching

A method and a switching system for connecting multiple requestors to multiple memory units simultaneously. This is accomplished by a switching system that employs multiplexing logic, control logic, multiple data input and output ports and a unique system interconnection topology. Independent data input ports comprised of multiplexing logic controlled by a control logic, simultaneously channel multiple fetch and store commands from the requestors to the memory units. Similarly, independent data output ports comprised of a second multiplexing logic controlled by a second control logic, simultaneously channels multiple return signals from the memory units to the requestors. The switching system of the present invention incorporates the unique system interconnection topology concept of feed-through boards and modular backplane boards. The feed-through boards coupled to the foreplane side of the backplane of a computer system and the modular backplane boards coupled to the backplane side of the backplane of a computer system, both serve to extend and manage the communication paths between the requestors and the memory units.

Method and apparatus for simultaneous interconnection of multiple

Modular expansion of a backplane is achieved by means of a modular backplane circuit board that plugs into the backplane side of a backplane parallel to that backplane. The backplane board provides a parallel backplane path between boards on the computer system. When unit boards are added to the foreplane side which require additional electrical paths for connection purposes, a modular backplane board may be added to the backplane side of the backplane to provide such path. In the preferred embodiment a gate array is added to the backplane board to provide management functions in handling the electrical connections on the backplane board.

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Norristown, PA, United States of America

Richard A Schranz