The newcastle connection or UNIXes of the world unite!

Abstract In this paper we describe a software subsystem that can be added to each of a set of physically interconnected UNIX or UNIX look‐alike systems, so as to construct a distributed system which is functionally indistinguishable at both the user and the program level from a conventional single‐processor UNIX system. The techniques used are applicable to a variety and multiplicity of both local and wide area networks, and enable all issues of inter‐processor communication, network protocols, etc., to be hidden. A brief account is given of experience with such a distributed system, which is currently operational on a set of PDPlls connected by a Cambridge Ring. The final sections compare our scheme to various precursor schemes and discuss its potential relevance to other operating systems.