Digital Equipment Corporation

Hewlett-packard Development Company, L.p.

Paul J Lemmon

Raj K Ramanujan

Jay C Stickney

James B Keller

Steven Ho

A computer system is adapted to transfer write data from a central processing unit to one of a plurality of memory modules in a memory array by transferring a block of write data to a memory control logic device. The memory control logic device transfers the block of data in a plurality of data bursts interspaced by a preselected number of bus cycles. During the interspaced preselected number of bus cycles, the memory control logic device sends pending read commands to an available memory module thereby overlapping read and write operations on the memory bus, thus, lowering memory read latency.

Interleaving read and write operations on a bus and minimizing buffering on a memory module in a computer system

The bandwidth of a first bus and a second bus, unequal due to differences in protocol overheads and cycle times between the buses, are equalized without sacrificing any bandwidth on the lower bandwidth bus and without introducing any buffering in a control logic device. The control logic device equalizes the bandwidths of the buses by instructing a device coupled to the second bus to insert a partial dead bus cycle in a read transmission thereby dynamically adjusting read timing on the second bus when the second bus is heavily loaded.

Method and apparatus for the dynamic adjustment of data transfer timing

A system and method for controlling a shared memory bus in a computer of a multi-processor system prevents collisions on the shared bus and ensures that the bus is full at system start-up. Steady state operations are maintained without the need for a queuing mechanism in the system's memory controller and in view of the memory modules of the shared memory having different read access times, with the system and method being implemented in a system that includes a central unit and multiple uni-directional buses that are disposed between a shared memory and a plurality of processors, with the central unit controlling access to, and use of, the shared buses of the system.

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West Townsend, MA, United States of America

Paul J Lemmon