Software Diversity is one of the fault-tolerance means to achieve dependable systems. In this volume, some experimental systems as well as real-life applications of software diversity are presented. The history, the current state-of-the-art and future perspectives are given. Although this technique is used quite successfully in industrial applications, further research is necessary to solve some open questions. We hope to report on new results and applications in another volume of this series within some years. Acknowledgements The idea of the workshop was put forward by the chairpersons of IFIP WG lOA, J. -c. Laprie, J. F. Meyer and Y. Tohma, in January 1986, and the edi­ tor of this volume was asked to organize the workshop. This volume was edited with the assistance of the editors of the series, A. AviZienis, H. Kopetz and J. -C. Laprie, who also had the function of reviewers. Karlsruhe, October 1987 U. Voges, Editor Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. Introduction U. Voges 2. Railway Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 ERICSSON Safety System for Railway Control . . . . . . . . . . . . . . . . . . 11 G. Hagelin 3. Nuclear Applications . . . . . . . . . . . . . . . . . . . . . . 23 Use of Diversity in Experimental Reactor Safety Systems . 29 U. Voges The PODS Diversity Experiment . 51 P. G. Bishop 4. Flight Applications . . . . . . . . . . . . . . . . . . . . . . . . . 85 AIRBUS and ATR System Architecture and Specification. . 95 P. Traverse 5. University Research . . . . . . . . . . . . . . . . . . . 105 Tolerating Software Design Faults in a Command and Control System . . . . . . . . . . . . . . . . . . . . . . 109 T. Anderson, P. A. Barrett, D. N. Halliwell, M. R. MouldingDEDIX 87 - A Supervisory System for Design Diversity Experiments at UCLA . . . . . . . . . . . . . . . . . .