Fail-fast, fail-functional, fault-tolerant multiprocessor system

摘要

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. Memory protection is provided by an access validation method maintained by each CPU in which CPUs and/or I/O devices are provided with a validation to read/write memory of that CPU, without which memory access is denied.