Prioritized unidirectional distributed bus accessing system
First Claim
1. A bus communication system, comprising:
- (a) a plurality of segments of a unidirectional transmit bus;
(b) a unidirectional receive bus such that information packets from said transmit bus are placed on said receive bus; and
(c) a plurality of bus interface units (BIUs) coupled in series with successive segments, respectively, of said transmit bus, each said BIU including a transmit bus input and a transmit bus output, said transmit bus input of each BIU being coupled, respectively, to the transmit bus output of the next upstream BIU, each said BIU also including a receive bus input connected to said receive bus, each said BIU being capable of transmitting an information packet of predetermined priority on said transmit bus, each said BIU including;
(1) a memory for storing a plurality of information packets to be transmitted; and
(2) a control circuit associated with said memory for selectively operating said BIU in an active and a passive mode, said control circuit causing said BIU to operate as a repeater during said passive mode such that packets received on said transmit bus input are retransmitted on said transmit bus output and causing said BIU to operate as a transmitter during said active mode such that said BIU sequentially transmits said information packets stored in its said memory in accordance with said predetermined priority.
1 Assignment
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Accused Products
Abstract
A plurality of bus interface units (BIUs), capable of placing information packets on a unidirectional transmit bus, are coupled to the transmit bus at locations spaced therealong. Each BIU comprises a transmit bus input port and a transmit bus output port, wherein the transmit bus input port of each BIU is coupled to the transmit bus output port of the next upstream BIU, and a receive bus input port connected to a receive bus. Each BIU includes a memory for storing at least one information packet to be transmitted and a control circuit associated with the memory. In a passive mode, the control circuit operates the BIU like a repeater, wherein packets received on its transmit bus input are reconstituted and retransmitted on its transmit bus output. In an active mode, the control circuit causes the BIU to transmit information packets stored in its memory. Each information packet may have a predetermined priority. The control circuit aborts transmission of an information packet whenever the BIU receives a higher or equal priority packet than it is transmitting and transmits the received packet in lieu of the aborted packet. Packets received during transmission, having lower priority than the packet being transmitted, are stored in memory for later transmission.
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Citations
38 Claims
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1. A bus communication system, comprising:
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(a) a plurality of segments of a unidirectional transmit bus; (b) a unidirectional receive bus such that information packets from said transmit bus are placed on said receive bus; and (c) a plurality of bus interface units (BIUs) coupled in series with successive segments, respectively, of said transmit bus, each said BIU including a transmit bus input and a transmit bus output, said transmit bus input of each BIU being coupled, respectively, to the transmit bus output of the next upstream BIU, each said BIU also including a receive bus input connected to said receive bus, each said BIU being capable of transmitting an information packet of predetermined priority on said transmit bus, each said BIU including; (1) a memory for storing a plurality of information packets to be transmitted; and (2) a control circuit associated with said memory for selectively operating said BIU in an active and a passive mode, said control circuit causing said BIU to operate as a repeater during said passive mode such that packets received on said transmit bus input are retransmitted on said transmit bus output and causing said BIU to operate as a transmitter during said active mode such that said BIU sequentially transmits said information packets stored in its said memory in accordance with said predetermined priority. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A bus interface unit (BIU) for data communication systems, comprising:
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(a) a transmit bus output for placing data on said data bus; (b) a transmit bus input for receiving data from said data bus; (c) memory means for storing said data in accordance with a predetermined priority; (d) a receive bus input for receiving data from a receive data bus; (e) control means coupled to said memory means for transmitting said data stored in said memory means in accordance with said predetermined priority; and (f) switching means for controllably coupling said transmit bus output, said transmit bus input, and said receive bus input to said memory means, said switching means being operable in response to said control means. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for transmitting information packets among a plurality of bus interface units (BIUs) spaced along and coupled to a unidirectional transmit bus and a unidirectional receive bus wherein each BIU comprises a transmit bus input and a transmit bus output, said transmit bus input of each BIU being coupled to said transmit bus output of the next upstream BIU, respectively, each of said BIUs also comprising a receive bus input connected to said receive bus, each of said BIUs including a memory for storing a plurality of information packets to be transmitted, said transmit bus being coupled to said receive bus such that information packets from said transmit bus are placed on said receive bus, said method comprising the steps of:
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(a) operating a selected one of said BIUs in a passive mode when said selected BIU has no information packet stored in its said memory to be transmitted, said selected BIU acting as a repeater during said passive mode wherein information packets received on its said transmit bus input are retransmitted on its said transmit bus output; and (b) operating said selected BIU in an active mode when said selected BIU has one or more information packets stored in said memory to be transmitted, said selected BIU transmitting said information packets stored in its associated said memory during said active mode in a predetermined sequence in accordance with the priority of said stored information packets. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method for transmitting information packets among a plurality of bus interface units (BIUs), each of said BIUs having a unique designation of a source and destination, said BIUs being spaced along and coupled to a unidirectional transmit bus and a unidirectional receive bus and capable of placing information packets from said transmit bus onto said receive bus, each packet having source and destination indicators encoded therein, comprising:
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(a) sensing at each BIU the transmit and receive buses to determine if information packets are on the transmit and receive buses; (b) initiating placement of a first information packet from a BIU on the transmit bus at an instant when no information packets are sensed on both the transmit and receive bus; and (c) removing a second information packet subsequently sensed on the transmit bus from the transmit bus while placing said first information packet on the transmit bus and storing the removed second information packet. - View Dependent Claims (35, 36, 37, 38)
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Specification