Notes on the "Worm" programs -- some early experience with a distributed computation by John F. Shoch and Jon A. Hupp SSL-80-3 and IEN 159 May 1980, revised September 1980 (c) Xerox Corporation 1980 [Note: This file, IEN-159.TXT, contains only the abstract from the paper. For a complete version of the paper, please send a message to Shoch@Parc, or send a note to: SSL Publications Coordinator Xerox Parc 3333 Coyote Hill Road Palo Alto, California 94304. Alternatively, people who can print files in "Press" format may directly retrieve [Maxc]IEN-159.press.] Abstract: The "Worm" programs were an experiment in the development of distributed computations -- programs that would span machine boundaries, and also replicate themselves in idle machines. A "worm" is composed of multiple "segments" each running on a different machine. The underlying worm maintenance mechanisms were responsible for maintaining the worm -- finding free machines when needed, and replicating the program for each additional segment. The worm control procedures require some careful design, but this mechanism made each worm a very dynamic and robust program. These techniques were then used to support several real applications, ranging from a simple multi-machine test program to a more sophisticated real-time animation system harnessing multiple machines. The worm programs have helped to demonstrate that the tools are at hand for experimenting with distributed computations. CR Categories: 3.81. Key words and phrases: Distributed computations, distributed computing, multi-machine programs, Ethernet local network, Pup internetwork architecture. This paper is to be presented at the Workshop on Fundamental Issues in Distributed Computing, ACM/SIGOPS and ACM/SIGPLAN, Pala Mesa Resort, December 1980.