OS6--An Experimental Operating System for a Small Computer. Part 1: General Principles and Structure

This paper is a description of a simple operating system, which runs in a virtual machine (implemented on a real machine by an interpreter). OS6 copes with only one user at a time, and is not a multi-programming system: many major problems associated with large operating systems have therefore been avoided or considerably simplified. It nevertheless has several features of interest, including the fact that it is written almost entirely in the high-level language BCPL. The most important single feature, however, is the hierarchical nature of its control structure, which avoids the need for a special job-control language.