George Radin

The 801 minicomputer

This paper provides an overview of an experimental system developed at the IBM T. J. Watson Research Center. It consists of a running hardware prototype, a control program and an optimizing compiler. The basic concepts underlying the system are discussed as are the performance characteristics of the prototype. In particular, three principles are examined: system orientation towards the pervasive use of high level language programming and a sophisticated compiler, a primitive instruction set which can be completely hard-wired, storage hierarchy and I/O organization to enable the CPU to execute an instruction at almost every cycle.

AD/Cycle strategy and architecture

Over the years, IBM has made progress in resolving many of the issues that deal with improving application development (AD) productivity and quality. Systems Application Architecture™, together with IBMs recently announced AD/Cycle™ direction, provides a platform for even greater progress. This paper addresses the IBM strategy that supports AD/Cycle and gives an overview of the major components of the AD/Cycle architecture. This paper is an introduction to other papers that follow in this issue.

The early history and characteristics of PL/I

Source material for a written history of PL/I has been preserved and is available in dozens of cartons, each packed with memos, evaluations, language control logs, etc. A remembered history of PL/I is retrievable by listening to as many people, each of whom was deeply involved in one aspect of its progress. This paper is an attempt to gather together and evaluate what I and some associates could read and recall in a few months. There is enough material left for several dissertations. The exercise is important, I think, not only because of the importance of PL/I, but because of the breadth of its subject matter. Since PL/I took as its scope of applicability virtually all of programming, the dialogues about its various parts encompass a minor history of computer science in the middle sixties. There are debates among numerical analysts about arithmetic, among language experts about syntax, name scope, block structure, etc., among systems programmers about multi-tasking, exception handling, I/O, and more.

Object technology in perspective

Since its beginnings half a century ago, the technology applied to the development of software has continually evolved. Object technology is the result of a long progression of improvements, from the closed subroutine, through structured development techniques and data abstractions, to object-oriented languages, design patterns, and frameworks. In this essay, the author reflects on this evolution, specifically in the areas of development productivity, software maintainability, and paradigm consistency.

An Evaluation of Several System Protection Strategies

Let me begin by calling your attention to an excellent discussion of the general subject of protection in Computer Systems in a paper by J. Saltzer and M. Schroeder in the September, 1975 IEEE Proceedings (5). My talk will be confined to protection at the low level of machine addressing. I will describe some of the more common current approaches and then discuss some interesting alternatives.