Ncr Corporation

Daniel J Marro

David B Schuck

James E Kocol

Robert O Gunderson

A data processing system employing broadcast packet switching and having a plurality of subsystems and a system bus for linking the subsystems. The subsystems are grouped within stations that are each enclosed by a computer cabinet. The system bus includes a star coupler, first and second external transmission lines connecting each station to the star coupler, and first and second internal transmission lines within each station that are coupled to the first and second external transmission lines. The subsystems within each station are each coupled to the first and second internal transmission lines by a system bus interface. The system bus interface monitors the system bus for an idle condition, and passes a message from its subsystem to the system bus only when it detects an idle condition on the system bus. Each message on the system bus includes a postamble that is garbled by any system bus interface that detects an error in any message on the system bus. Each subsystem has a local memory that includes a mailbox for storing header information of messages that are to be copied by that subsystem. DMA circuitry in each system bus interface manages the operation of the mailbox in its subsystem. In alternate embodiments, the star coupler may be a magnetic star coupler or an electrical star coupler, and the system bus may be comprised of two channels, each channel including a star coupler and pairs of transmission lines connecting each station to the star coupler.

Data processing system wherein at least one subsystem has a local memory

A pipelined computer which executes high level language instructions is disclosed. The pipelined computer includes a memory for storing the high level language instructions therein. A plurality of microprogrammed digital computers are coupled in parallel to the memory, and are also intercoupled via an interlocking bus. The microprogrammed computers, in conjunction with the interlocking bus, form a pipeline for executing the high level language instructions. Each of the computers is a separately microprogrammable stage of the pipeline.

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Escondido, CA, United States of America

Daniel J Marro