UNIX Time-Sharing System: A Minicomputer Satellite Processor System

The satellite processor system (SPS) and the concept of a satellite processor have evolved over the years at Bell Laboratories to provide software support for the ever-increasing number of mini- and microcomputer systems being used for dedicated applications. The satellite processor concept allows the advantages of a large computing system to be extended to many attached miniprocessors, giving each satellite processor (SP) access to the central processor's (CP) 2103 file system, software tools, and peripherals while retaining the realtime response and flexibility of a dedicated minicomputer. Since the cost of the peripherals for a minicomputer often far exceeds the cost of its CPU and memory, the CP provides a pool of peripherals for the support of many SP's. Although each SP requires a hardware link to a CP, the idea of a satellite processor is basically a software concept. It allows a user program, which might normally run in the CP using its operating system, to run in an SP with no resident operating system. This paper describes the hardware and software required for SPS, the concepts involved in SPS, and how these concepts can be extended to provide even more powerful tools for the SP. Several examples of the use of the SPS in Bell Laboratories projects are described.