Data processing system employing broadcast packet switching
First Claim
1. In a data processing system having a plurality of subsystems and employing broadcast packet switching for delivering a message from one of said subsystems to another of said subsystems over a system bus, said system bus including a star coupler and pairs of first and second transmission lines, with said pairs of transmission lines linked by said star coupler so that a message from one of said subsystems may be carried along said first transmission line in one of said pairs of transmission lines to said star coupler and passed through said star coupler to said second transmission line in all of said pairs of transmission lines, the improvement wherein:
- plural subsystems are each separately connected along at least one of said pairs of transmission lines so that said first transmission line in that one of said pairs carries signals transmitted by any one of its connected subsystems to said star coupler and said second transmission line in that one of said pairs carries signals to be received at all of its connected subsystems, and so that the number of subsystems in said data processing system is greater than the number of pairs of transmission lines linked by said star coupler; and
each of said connected subsystems comprises a processor and a local memory each operatively connected to said one of said pairs of transmission lines, said local memory for storing data to be processed by said processor.
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Abstract
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.
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Citations
20 Claims
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1. In a data processing system having a plurality of subsystems and employing broadcast packet switching for delivering a message from one of said subsystems to another of said subsystems over a system bus, said system bus including a star coupler and pairs of first and second transmission lines, with said pairs of transmission lines linked by said star coupler so that a message from one of said subsystems may be carried along said first transmission line in one of said pairs of transmission lines to said star coupler and passed through said star coupler to said second transmission line in all of said pairs of transmission lines, the improvement wherein:
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plural subsystems are each separately connected along at least one of said pairs of transmission lines so that said first transmission line in that one of said pairs carries signals transmitted by any one of its connected subsystems to said star coupler and said second transmission line in that one of said pairs carries signals to be received at all of its connected subsystems, and so that the number of subsystems in said data processing system is greater than the number of pairs of transmission lines linked by said star coupler; and each of said connected subsystems comprises a processor and a local memory each operatively connected to said one of said pairs of transmission lines, said local memory for storing data to be processed by said processor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a local data processing network having a plurality of subsystems, a system bus for linking said subsystems, the improvement wherein:
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said system bus comprises; pairs of first and second unidirectional transmission lines, each pair associated with plural ones of said subsystems, each of said first transmission lines for carrying signals transmitted from each of its associated subsystems and each of said second transmission lines for carrying signals to be received by each of its associated subsystems; and a star coupler connected to each of said pairs of first and second transmission lines so that a signal received at said star coupler along one of said first transmission lines from one of its associated subsystems is directed to all said second transmission lines so that all of said subsystems receive the signal, including the subsystem transmitting the signal; and each of said plurality of subsystems comprises; one of a processor subsystem, a memory subsystem and an input/output (I/O) subsystem, operatively connected to its associated pair of transmission lines, each said processor subsystem having a work processor for executing tasks and a local processor memory for storing data for use by said work processor, each said memory subsystem having a memory processor and a local memory for storing data managed by said memory processor, and each said I/O subsystem having an I/O processor and a local I/O memory for storing data for being transferred between said I/O memory and a peripheral device by said I/O processor.
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13. In a data processing system:
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a plurality of physically separated stations, each station including a cabinet and a plurality of subsystems within the cabinet; an optical star coupler; and a pair of first and second optical transmission lines associated with each station, with said first optical transmission line carrying optical signals to said optical star coupler generated by any subsystem in its associated station and said second optical transmission line carrying optical signals from the optical star coupler to all of the subsystems in its associated station; with said optical star coupler receiving optical signals from said first optical transmission line in any said pair of first and second optical transmission lines and passing the optical signals to said second optical transmission line in each said pair of first and second optical transmission lines; and with each of said subsystems in each station including a processor and a local memory operatively connected to said pair of first and second optical transmission lines associated with that station, said local memory for storing data to be processed by said processor. - View Dependent Claims (14, 15)
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16. In a data processing system, the improvement comprising:
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a group of subsystems located at a station, said subsystems each coupled within the station to a first internal transmission line for carrying signals transmitted by any one of said group of subsystems and to a second internal transmission line for carrying signals to be received by all of said group of subsystems, each of said subsystems comprising a processor and a local memory each operatively connected to said first and second internal transmission lines, said local memory for storing data to be processed by said processor, the station enclosed by a computer cabinet and adapted to be linked to other stations by a pair of first and second external transmission lines, with the first external transmission line coupled to said first internal transmission line for carrying the signals on the first internal transmission line to a star coupler and with the second external transmission line coupled to said second internal transmission line for carrying signals from the star coupler to be received by all of said group of subsystems; and means for connecting said first internal transmission line to said second internal transmission line within said station so that when the station is not linked to other stations, all the signals generated by any one of said group of subsystems on said first internal transmission line are provided directly to said second internal transmission line to be received by all of said group of subsystems, including the subsystem transmitting the signals.
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17. A data processing system, comprising:
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a plurality of stations, each station including a group of subsystems located within a cabinet; a system bus, said system bus including; a pair of oppositely directed, unidirectional internal signal paths at each station coupled to each of the group of subsystems at that station, said pair of internal signal paths including an outbound path for receiving any signal transmitted from one of the group of subsystems at that station and an inbound path for providing the transmitted signal to each of the group of subsystems at that station; with the group of subsystems at each station including a processor and a local memory each connected to said pair of internal signal paths at that station, said local memory for storing data to be processed by said processor; a star coupler; and a pair of oppositely directed, unidirectional external signals paths associated with each station, said pair of external signal paths connecting its associated station to said star coupler and including an outbound path for receiving any signal from the outbound path of said pair of internal signal path at its associated station and an inbound path for receiving a signal from said star coupler and providing the signal to the inbound path of said pair of internal signal paths at its associated station; said star coupler for receiving a signal from the outbound path of any said pair of external signal paths and providing the signal to the inbound path of each said pair of external signal paths so that a signal transmitted by any subsystem on its internal outbound path is provided to the inbound path of each external signal path; and a system bus interface coupling each subsystem to the outbound path and inbound path of said pair of internal signal paths at each station, said system bus interface comprising; means for sensing an idle condition of said system bus at the inbound path of said pair of internal signal paths at its station; means for selectively providing a signal in the form of an information packet to the outbound path of said pair of internal signal paths at its station, the information packet provided only when said system bus interface senses the idle condition; means for receiving a signal in the form of an information packet from the inbound path of said pair of internal signal paths at its station; means for monitoring the information packets received from the inbound path of said pair of internal signals paths at its station, to sense more than one information packet on said system bus; and means for disabling said providing means when said monitoring means senses two information packets on said system bus. - View Dependent Claims (18, 19, 20)
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Specification