Ncr Corporation

Marti D Miller

Edward A McDonald

Thomas F Heil

Gene F Young

James M Ottinger

Craig A Walrath

A retry scheme for optimizing use of a first bus in a computer system which includes a plurality of bus masters connected through the first bus to an interface circuit and second bus. The interface circuit includes logic for generating a busy signal when the second bus is in a busy state and logic for generating a retry signal when the interface circuit is addressed by a bus master while the second bus is in a busy state. Each bus master includes logic for receiving the retry signal and relinquishing control of the common bus upon receipt of the retry signal from the interface circuit. A bus arbiter includes logic for receiving the busy signal and preventing any bus master seeking access to the second bus from participating in arbitration for control of the common first bus until the busy signal has been negated. Thus, during the term of the busy signal the first bus may be controlled by any bus master not requiring access to the shared resource. Upon negation of the busy signal, all bus masters will be permitted to compete for ownership of the bus.

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Hudwon, WI, United States of America

Marti D Miller