Electronic system and method for implementing functional redundancy checking by comparing signatures having relatively small numbers of signals

Abstract

An electronic system and method are presented for the implementation of functional redundancy checking (FRC) by comparing “signatures” produced by two different electronic devices, for example central processing units (CPUs). The signatures include a relatively small number of signals which reflect an internal state of each CPU. The electronic system includes a first and second CPU. Each CPU is configured to execute instructions and produce output signals. The first and second CPUs are preferably identical and execute instructions simultaneously such that their internal states and produced output signals should be the same at any given time. Each CPU includes a signature generator for generating the signature. The electronic system also includes a compare unit coupled to receive the signatures. The compare unit compares the signatures and produces an error signal if the signatures are not identical. The electronic system may be a computer system, further including a system bus and chip set logic. The system bus is adapted for coupling to one or more peripheral devices. The chip set logic is coupled between the first and second CPUs and the system bus, and functions as an interface between the first and second CPUs and the system bus. The first and second CPU are coupled to the chip set logic via separate processor buses. At least a portion of the signal lines of the separate processor buses are “point-to-point”, enabling the processor buses to achieve relatively high data transfer rates.