For the editors of this book, as well as for many other researchers in the area of fault-tolerant computing, Dr. William Caswell Carter is one of the key figures in the formation and development of this important field. We felt that the IFIP Working Group 10.4 at Baden, Austria, in June 1986, which coincided with an important step in Bill's career, was an appropriate occasion to honor Bill's contributions and achievements by organizing a one day "Symposium on the Evolution of Fault-Tolerant Computing" in the honor of William C. Carter. The Symposium, held on June 30, 1986, brought together a group of eminent scientists from all over the world to discuss the evolu tion, the state of the art, and the future perspectives of the field of fault-tolerant computing. Historic developments in academia and industry were presented by individuals who themselves have actively been involved in bringing them about. The Symposium proved to be a unique historic event and these Proceedings, which contain the final versions of the papers presented at Baden, are an authentic reference document."