Fault-tolerance: The survival attribute of digital systems

Fault-tolerance is the architectural attribute of a digital system that keeps the logic machine doing its specified tasks when its host, the physical system, suffers various kinds of failures of its components. A more general concept of fault-tolerance also includes human mistakes committed during software and hardware implementation and during man/machine interaction among the causes of faults that are to be tolerated by the logic machine. This paper discusses the concept of faulttolerance, the reasons for its inclusion in digital system architecture, and the methods of its implementation. A chronological view of the evolution of fault-tolerant systems and an outline of some goals for its further development conclude the presentation.