Digital Equipment Corporation

Jay C Stickney

Raj K Ramanujan

Paul J Lemmon

James B Keller

David J Sager

Steven Ho

Anne S Valiton

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.

Method of controlling a shared memory bus in a multiprocessor system for

The invention is directed to a method by which data from a first synchronous subsystem is transmitted to a second synchronous subsystem physically spaced from the first subsystem such that the system clock is skewed relative to the two subsystems. Pursuant to the invention, the transmitted data cycle time is multiple of the common system cycle time and a clock signal is forwarded with the data from the first subsystem to the second subsystem. The clock signal forwarded with the data provides an indication to the second subsystem of the instants of time at which received data changes. The data change instants are used to generate a binary signal that inverts its value at each such instant. The binary signal is transmitted through a synchronizer to produce a logic signal in the second subsystem. The logic signal is utilized to transmit the received data into the second subsystem in synchronization with the clock of the second subsystem.

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Derry, NH, United States of America

Jay C Stickney