.TL PREFACE .LP This Eighth Edition manual describes the lineal descendant of the original operating system pioneered by Ken Thompson and Dennis Ritchie in the Computing Science Research Center at AT&T Bell Laboratories. It is an experimental system, not a commercial prototype, which incorporates facilities from the Seventh Edition, System V, and Berkeley BSD 4.1. The distinctive theme of the Eighth Edition is distributed computing: Ritchie's coroutine-based stream IO system and the Datakit\u\fH\s-2TM\s0\fP\d virtual circuit switch realization by Lee McMahon and Bill Marshall provide the basis for networking, Peter Weinberger's remote file systems make it painless, and Rob Pike's software for the Teletype 5620 moves system action right out to the terminal. These facilities have spurred a host of programs for remote information services, interactive graphics, debugging, and simple fun. Many other people have contributed significantly, including, but not limited to L. Cardelli, T. A. Cargill, L. L. Cherry, R. J. Elliot, S. I. Feldman, F. T. Grampp, A. G. Hume, B. W. Kernighan, T. Killian, A. R. Koenig, M. E. Lesk, J. P. Linderman, B. N. Locanthi, M. S. Manasse, R. T. Morris, T. Pavlidis, D. L. Presotto, J. D. Reiser, M. J. Shannon, B. Stroustrup, and N. Wilson. .sp 2 .in 4i M. D. McIlroy .br February, 1985 .in 0