The error-resistant interactively consistent architecture (ERICA)

The authors present an analysis of modularly redundant computer systems and various theoretical, as well as implementation, aspects of a highly reliable computer system with a relatively small amount of redundant hardware. From the evaluation of modularly redundant systems it is concluded that the (4, 2)-concept computer system compares favorably with a triple modular redundant and doubled system, with respect to cost, as well as to reliability. In order to cope with the Byzantine Generals problem, a hardware implementation of the algorithm is presented. The (4, 2)-concept is used in the Philips business communication switch SOPHO S-2500 and in a broadband switch (the Philips H1-switch). The prototype computer system presented can be used as a controller (e.g. in a telephone switching system), as a computer system for online transaction processing, or as a general-purpose computer.<>