Abstract: A streamlined cache coherency protocol system and method for a multiple processor single chip device. There are three primary memory unit (e.g., a cache line) states (modified, shared, and invalid) and three intermediate memory unit pending states. The pending states are used by the present invention to prevent race conditions that may develop during the completion of a transaction. The pending states “lock out” the memory unit (e.g., prevent access by other agents to a cache line) whose state is in transition between two primary states, thus ensuring coherency protocol correctness. Transitions between states are governed by a series of request and reply or acknowledgment messages. The memory unit is placed in a pending state while appropriate measures are taken to ensure access takes place at an appropriate time. For example, a modification occurs only when other agents can not access the particular memory unit (e.g., a cache line).

Abstract: The present invention provides a new crossbar switch which is implemented by a plurality of parallel chips. Each chip is completely programmable to couple to every node in the system, e.g., from one node to about one thousand nodes (corresponding to present-day technology limits of about one thousand I/O pins) although conventional systems typically support no more than 32 nodes. The crossbar switch can be implemented to support only one node, then one chip can be used to route all 64 bits in parallel for 64 bit microprocessors.

Abstract: The present invention provides a new crossbar switch which is implemented by a plurality of parallel chips. Each chip is completely programmable to couple to every node in the system, e.g., from one node to about one thousand nodes (corresponding to present-day technology limits of about one thousand I/O pins) although conventional systems typically support no more than 32 nodes. The crossbar switch can be implemented to support only one node, then one chip can be used to route all 64 bits in parallel for 64 bit microprocessors.

Abstract: A streamlined cache coherency protocol system and method for a multiple processor single chip device. There are three primary memory unit (e.g., a cache line) states ( modified, shared, and invalid) and three intermediate memory unit pending states. The pending states are used by the present invention to prevent race conditions that may develop during the completion of a transaction. The pending states “lock out” the memory unit (e.g., prevent access by other agents to a cache line) whose state is in transition between two primary states, thus ensuring coherency protocol correctness. Transitions between states are governed by a series of request and reply or acknowledgment messages. The memory unit is placed in a pending state while appropriate measures are taken to ensure access takes place at an appropriate time. For example, a modification occurs only when other agents can not access the particular memory unit (e.g., a cache line).

Abstract: A cache coherent multiple processor integrated circuit. The circuit includes a plurality of processor units. The processor units are each provided with a cache unit. An embedded RAM unit is included for storing instructions and data for the processor units. A cache coherent bus is coupled to the processor units and the embedded RAM unit. The bus is configured to provide cache coherent snooping commands to enable the processor units to ensure cache coherency between their respective cache units and the embedded RAM unit. The multiple processor integrated circuit can further include an input output unit coupled to the bus to provide input and output transactions for the processor units. The bus is configured to provide split transactions for the processor units coupled to the bus, providing better bandwidth utilization of the bus. The bus can be configured to transfer an entire cache line for the cache units of the processor units in a single clock cycle, wherein the bus is 256 bits wide.

Abstract: Multiple processors are mounted on a single die. The die is connected to a memory storing multiple operating systems or images of multiple operating systems. Each of the processors or a group of one or more of the processors is operable to execute a distinct one of the multiple operating systems. Therefore, resources for a single operating system may be dedicated to one processor or a group of processors. Consequently, a large number of processors mounted on a single die can operate efficiently.

Abstract: A distributed shared memory multi-processor system includes a System Control Unit (SCU) which is made up of a system control unit address section (SCUA) and system control unit data sections (SCUDs). The SCU is scalable by dividing the control and data flow functions of the SCU, and then parallelizing the data path. This allows the number of processors in the system to be increased or higher performance processors to be added by increasing the number of SCUDs and reprogramming crossbar switches incorporated in the SCUA and SCUDs. This results in the overall increase of the multi-processor system performance.

Abstract: A network of integrated communication switches and coherence controllers is provided which interconnected nodes in a cache-coherent multi-processor computer architecture. The nodes contain multiple processors operatively connected to associated memory units through memory controllers. The communication switches and coherence controllers has associated coherence directories which maintain coherence information for all memory lines that are “homed” in the nodes that are directly connected to the particular communication switch and coherence controller.

Abstract: The present invention provides a new crossbar switch which is implemented by a first plurality of chips. Each chip is completely programmable to couple to every node in the system, e.g., from one node to about one thousand nodes (corresponding to present-day technology limits of about one thousand I/O pins) although conventional systems typically support no more than 32 nodes. The crossbar switch can be implemented to support only one node, then one chip can be used to route all 64 bits in parallel for 64 bit microprocessors. A second plurality of chips in parallel provides the redundancy necessary for a high availability system.

Abstract: A monolithic integrated circuit chip preferably includes a pair of data busses capable of conducting in parallel the number of signals which can be processed simultaneously by the components on the chip. Signals on the busses are carried in a time-multiplexed manner, each bus having a predetermined number of time slots. Preferably, each component on the chip is connected to one or both of the busses and is assigned a particular time slot for the bus to which it is connected. The resulting chip is of a structured, rather than a custom, design. Accordingly, it can be readily expanded or contracted in the number of signals which can be simultaneously processed. The number of components which can be included on the chip is limited only by the number of time slots available on the bus to which it is connected. By providing two busses, such common circuit elements as two-input adder/subtractors can be readily accommodated by a chip designed according to the instant invention.