The Early History and Characteristics of PL/I

Abstract

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. © 1978, ACM. All rights reserved.