Abstract: The operation of an electronic system comprising a plurality of integrated circuits or other circuit elements is simulated using a software-based development tool that provides a generic framework for simultaneous simulation of multiple circuit elements having potentially different clock speeds, latencies or other characteristics. One or more interfaces provided in the software-based development tool permit registration of processing events associated with one or more of the circuit elements. The software-based development tool is further operative to determine a system clock for a given simulation, and to schedule execution of the associated processing events in a manner that takes into account differences between the system clock and one or more circuit element clocks, so as to maintain consistency in the execution of the processing events relative to the determined system clock.

Abstract: The operation of an electronic system comprising a plurality of integrated circuits or other circuit elements is simulated using a software-based development tool that provides a generic framework for simultaneous simulation of multiple circuit elements having potentially different clock speeds, latencies or other characteristics. One or more interfaces provided in the software-based development tool permit registration of processing events associated with one or more of the circuit elements. The software-based development tool is further operative to determine a system clock for a given simulation, and to schedule execution of the associated processing events in a manner that takes into account differences between the system clock and one or more circuit element clocks, so as to maintain consistency in the execution of the processing events relative to the determined system clock.

Abstract: A system area network computer system architecture is structured as a single system image cluster operating system to offer an opportunity to increase the availability to I/O devices in the system. The computing system comprises a number of processor units coupled to a plurality of input/output (I/O) elements by a routing fabric that provides each of the processor elements with access to any one of the I/O elements. Using a Transparent Network Computing extension to a highly available version of UNIX System V Release 4.2, the system provides a higher degree of availability to I/O devices by providing for the takeover of their controlling entity.

Abstract: A multiprocessor system includes a number of central processing unit (CPUs) and at least one input/output (I/O) device interconnected by routing apparatus for communicating packetized messages therebetween. The messages contain address information identifying the source and destination of the message, and may also contain requests to write to, or read from, storage of a CPU. Protection against errant reads or writes is provided by an access validation method that utilizes access validation information contained in plural entries maintained by each CPU. Each entry provides validation by identifying what elements of the system has read and/or write wccss to the memory of that CPU, without which memory access is denied.

Abstract: A multiprocessor system includes a number of sub-processor systems, each substantially identically constructed, and each comprising a central processing unit (CPU), and at least one I/O device, interconnected by routing apparatus that also interconnects the sub-processor systems. A CPU of any one of the sub-processor systems may communicate, through the routing elements, with any I/O device of the system, or with any CPU of the system. The CPUs are structured to operate in one of two modes: a simplex mode in which the two CPUs operate independently of each other, and a duplex mode in which the CPUs operate in lock-step synchronism to execute each instruction of identical instruction streams at substantially the same time. Communications between I/O devices and CPUs is by packetized messages. Interrupts from I/O devices are communicated from the I/O devices to the CPUs (or from one CPU to another CPU) as message packets. CPUs and I/O devices may write to, or read from, memory of a CPU of the system.

Abstract: A multiprocessor system includes a number of sub-processor systems, each substantially identically constructed, and each comprising a central processing unit (CPU), and at least one I/O device, interconnected by routing apparatus that also interconnects the sub-processor systems. A CPU of any one of the sub-processor systems may communicate, through the routing elements, with any I/O device of the system, or with any CPU of the system.Communications between I/O devices and CPUs is by packetized messages. Interrupts from I/O devices are communicated from the I/O devices to the CPUs (or from one CPU to another CPU) as message packets, and stored at an interrupt queue in memory. Storage of the interrupt data will initiate an internal interrupt to notify the receiving CPU. The receiving CPU can then access the interrupt queue, examine the interrupt data, and determine what action to take.