Since the first version of this survey of information on the development of the computer was published in 1971, a great deal has changed and much progress has been made. All the machines discussed in this book have actually been constructed and evaluated. The papers, wherever possible, are written by the specific machine architects or people closely associated with the architectures. Several are presented in elaborate detail, enabling the reader to appreciate the design complexities encountered and design methodologies employed by the architects. This volume favors depth over breadth, so it is not possible to discuss all important architectures (nor even all major manufacturers). However, the architectures that are included were carefully selected to uniformly cover the major design principles of computer structures. It is hoped that this book will serve as an educational resource for computer engineers designing physical systems, computer scientists concerned with programming and abstract views of information processing, and electrical engineers who sees computer systems as a part of a larger technology.