1.0 INTRODUCTION

1.1 Specification objectives

The purpose of this document is to serve as an introduction to and detailed description of an operating system known informally as the New System. The document is intended as preliminary general information for all purposes and thus is addressed to a number of different audiences. Many readers will wish to skim over various sections.

The document contains overview information, philosophy of operating system structure, actual design specifications and implementation details. The organization is intended to be open ended as much more detail remains to be added, both in breadth and depth. When rate of change of fundamental concepts slows somewhat, the document will be maintained on a computer to achieve rapid updates and fast publication turn-around.

The current specification deals only with the design of an operative system. Details of subsystems and other user level software are not covered here. Hence, the document may make rather dry reading for the non-technical reader. This approach is intentional, for several reasons: operating system design must come first, before anything but external specifications can be written for user software; a somewhat different audience is concerned about user software than operating systems; and the process of system design must be kept to a manageable size before it can make any progress.

1.2 Acknowledgments

The sources of ideas for a system design are not generally easy to classify. The text of this document is mostly mine but no such claim can be made for the-ideas. Post of the concepts appearing in the design were those appearing in Norm Hardy’s original notes on new ideas in operating systems. They have-been thrashed out and refined in extensive and productive discussions among Norm, Bill Weiher and myself.

We do not, however, claim much in the way of original invention; the system design developed here is mainly a synthesis of-our experience with the individual ideas of many other people. Certainly the development of such a design is heavily dependent on being able to interact with the many Tymshare people whose interest somewhere bears on the requirements of operating systems.

We wish to emphasize our dependence on the rest of the Tymshare people because of the nature of the design process. A coherent design must of necessity be done by a small group of people. That design, however, must satisfy the needs of a great number. It is hoped that this extensive document can help to reconcile these opposing demands.