Editing PL/I (section)

==Early history==
In the 1950s and early 1960s, business and scientific users programmed for different computer hardware using different programming languages. Business users were moving from [[Autocoder]]s via [[COMTRAN]] to [[COBOL]], while scientific users programmed in [[Fortran]], [[ALGOL]], [[GEORGE (programming language)|GEORGE]], and others. The [[IBM System/360]]<ref name="AndEarly">{{cite book|last1=Pugh|first1=Emerson W.|last2=Johnson|first2=Lyle R.|last3=Palmer|first3=John H.|year=1991|title=IBM's 360 and early 370 systems|url=https://archive.org/details/ibms360early370s0000pugh|url-access=registration|publisher=[[MIT Press]]|location=Cambridge, Mass.|isbn=978-0-262-16123-7}}</ref> (announced in 1964 and delivered in 1966) was designed as a common machine architecture for both groups of users, superseding all existing IBM architectures. Similarly, IBM wanted a single programming language for all users. It hoped that Fortran could be extended to include the features needed by commercial programmers. In October 1963 a committee was formed<ref>The committee actually had 8 members at the time the report was released. They were:{{citation needed|date=February 2020}}

* Hans Berg, [[Lockheed Corporation|Lockheed]] Burbank
* [[George Radin]], IBM
* James Cox, [[Union Carbide]]
* Bruce Rosenblatt, [[Standard Oil of California]], Chair.
* [[Douglas McIlroy]], Bell Laboratories
* Robert Sheppard, [[Procter & Gamble]]. From the GUIDE organization
* C.W. Medlock, IBM
* Bernice Weitzenhoffer, IBM.
</ref> composed originally of three IBMers from New York and three members of [[SHARE (computing)|SHARE]], the IBM
scientific users group, to propose these extensions to Fortran. Given the constraints of Fortran, they were unable to do this and embarked on the design of a new programming language based loosely on [[ALGOL]] labeled '''NPL'''. This acronym conflicted with that of the UK's National Physical Laboratory and was replaced<ref>{{cite magazine
 |author=<!--Unstated staff writer(s)-->
 |date=April 1965
 |department=Business & Science
 |title=MPPL in for NPL
 |volume=11
 |issue=4
 |page=17
 |url=http://bitsavers.org/magazines/Datamation/196504.pdf
 |magazine=Datamation
 |publisher=Frank D. Thompson
}}
</ref> briefly by '''MPPL''' (MultiPurpose Programming Language) and, in 1965, with<ref>{{cite magazine
 |author=<!--Unstated staff writer(s)-->
 |date=June 1965
 |url=http://bitsavers.org/magazines/Datamation/196506.pdf
 |department=Business & Science
 |title=Another New Name, More Compilers for NPL
 |volume=11
 |issue=6
 |page=17
 |magazine=Datamation
 |publisher=Frank D. Thompson
}}
</ref> '''PL/I''' (with a [[Roman numeral]] "I"). The first definition appeared in April 1964.<ref>Report II of the SHARE Advanced Language Development Committee, June 25, 1964</ref><ref>{{cite journal|title=Highlights of a New Programming Language|first1=G.|last1=Radin|author-link=George Radin|author2=H. Paul Rogoway|journal=[[Communications of the ACM]]|volume=8|issue=1|pages=9–17|date=January 1965|doi=10.1145/363707.363708|s2cid=17133703|doi-access=free}}</ref>

IBM took NPL as a starting point and completed the design to a level that the first compiler could be written: the NPL definition was incomplete in scope and in detail.<ref name="characteristics1978">{{cite journal|last1=Radin|first1=G.|title=The Early History and Characteristics of PL/I|date=August 1978|journal=[[SIGPLAN Notices|ACM SIGPLAN Notices]]|volume=13|issue=8|pages=227–241|doi=10.1145/960118.808389|s2cid=13925251|doi-access=free}}</ref> Control of the PL/I language<ref>Control of the language was vested in a dedicated Language Control group and a Language Control Board that included representatives of the compiler groups (6 by 1973) in three countries. Daily
communication was by [[telex]]. Changes and extensions were made through a Language Log that reached several thousand detailed points. A management level Language Review Board resolved issues escalated to it by the Control Board.</ref> was vested initially in the New York Programming Center and later at the IBM UK Laboratory at [[IBM Hursley|Hursley]]. The SHARE and [[GUIDE International|GUIDE]] user groups were involved in extending the language and had a role in IBM's process for controlling the language through their PL/I Projects. The experience of defining such a large language showed the need for a formal definition of PL/I. A project was set up in 1967 in [[IBM Laboratory Vienna]] to make an unambiguous and complete specification.<ref>The Universal Language Document (ULD). Technical reports TR25.081, TR25.082, TR25.083, TR25.0S4, TR25.085, TR25.086 and TR25.087, IBM Corp Vienna Austria June 1968</ref> This led in turn to one of the first large scale [[Formal Methods]] for development, [[Vienna Development Method|VDM]].

[[Fred Brooks]] is credited with ensuring PL/I had the CHARACTER data type.<ref>{{cite web|url=https://www.computer.org/web/awards/goode-frederick-brooks|title=Frederick P. Brooks Jr. - IEEE Computer Society|year=1989|publisher=[[IEEE Computer Society]]}}</ref>

The language was first specified in detail in the manual "PL/I Language Specifications. C28-6571", written in New York in 1965, and superseded by "PL/I Language Specifications. GY33-6003", written by Hursley in 1967. IBM continued to develop PL/I in the late sixties and early seventies, publishing it in the GY33-6003 manual. These manuals were used by the [[Multics]] group and other early implementers.

The first compiler was delivered in 1966. The Standard for PL/I was approved in 1976.