Editing PL/C (section)

== Origins and rationale ==
[[Image:Cornell Engineering Quad in rain 1998.jpg|thumb|right|PL/C came from Cornell University's Department of Computer Science, located in Upson Hall on the Engineering Quadrangle<ref name="cw-mar76"/> (building on center-left with yellow bands, here seen in the 1990s)]]

Work on this project was based on a prior Cornell compiler for the programming language [[Cornell University Programming Language|CUPL]], which in turn was influenced by the earlier Cornell language implementation [[CORC]].<ref name="afips-plc"/>  Both of these were small, very restricted languages intended for the teaching of beginning programming.<ref name="PLCConwayWilcox"/>  CORC had been used at Cornell from 1962 to 1966 and CUPL from 1965 to 1969.<ref name="cornell-history-computing"/>  Conway's group had been involved in the development of both of those efforts,<ref name="pom-bio"/><ref name="cornell_cs_timeline"/> each of which attempted automatic repair of source code errors.<ref name="PLCConwayWilcox"/>
 
As the 1970s began, Cornell was attempting to find a teaching language that had general commercial acceptance but also contained modern language features.<ref name="plcs"/>  As another Cornell computer science professor, [[David Gries]], wrote at the time, the first criterion effectively eliminated the [[ALGOL family]] of languages and the second criteria argued against [[FORTRAN]] and [[BASIC]] (with [[COBOL]] not even being considered); thus, they chose PL/I.<ref name="gries-what">{{cite conference | author-first=David |author-last=Gries | author-link=David Gries | title=SIGCSE '74: Proceedings of the fourth SIGCSE technical symposium on Computer science education | date=January 1974 | pages=81–89 | doi=10.1145/800183.810447 | contribution=What should we teach in an introductory programming course? | publisher=Association for Computing Machinery }}</ref> While PL/I did have a foothold in educational use,<ref name="nmsu-review"/> the decision went against the grain of most universities, where one survey found that some 70&nbsp;percent of American college students were being taught with FORTRAN.<ref name="gries-what"/>  However, Cornell was intent on having a language useful for showing computer science principles and best engineering practices and through which methods such as [[structured programming]] and [[stepwise refinement]] could be taught, and PL/I was a more expressive vehicle for that than FORTRAN.<ref name="conway-gries"/>

For educational institutions that did choose to use the language, the production [[PL/I#IBM PL/I F and D compilers|IBM PL/I F compiler]] then available was much too slow, in both compile time and execution time, for its use to be practical for student programs.<ref name="nmsu-review"/>  A similar situation existed for FORTRAN, where the [[Fortran#FORTRAN IV|IBM FORTRAN IV G compiler]] was too slow and the [[University of Waterloo]]'s [[WATFOR]] implementation had become a very popular alternate solution.<ref name="nmsu-review"/>  So there was an opening for a student compiler for PL/I; indeed, IBM recognized this and contacted Cornell and suggested they make a 'WATFOR for PL/I'.<ref name=CUPL.Conway>{{cite interview |last=Conway |first=Richard W. |subject-link= |interviewer=David Gries |title=A Conversation with Richard W. Conway |work=An Oral History of Computer Science  |date=July 31, 2015 |publisher= Cornell University Library |location= |url=https://ecommons.cornell.edu/handle/1813/40564?show=full }} See segments at 35:00 and 40:30.</ref> Indeed, this simile would be made explicit; as one university would explain to their computer center users, "PL/C is to PL/I what WATFOR is to FORTRAN IV, a fast compile-and-go system with some batching capabilities intended primarily for student use."<ref name="mts-jan71">{{cite news | url=https://books.google.com/books?id=aBxVAAAAMAAJ&pg=PA7 | title=Availability of PL/C in MTS | work=Computing Center Newsletter | publisher=University of Michigan | date=January 21, 1971 | page=5 }}</ref>
  
IBM supplied some of the funding for the initial PL/C development effort, which took place during 1968 and 1969,<ref name="cornell-history-computing">{{cite book | url=http://cac.cornell.edu/about/pubs/History_Computing_Cornell_Rudan.pdf | title=The History of Computing at Cornell University | author-first=John W. | author-last=Rudan | publisher=The Internet-First University Press | location=Ithaca, New York | year=2005 | pages=48, 57, 62, 65–66, 86–87 }}</ref> with the "C" in the name standing for Cornell.<ref name="pom-bio">{{cite journal | title=Richard Conway | journal= Production and Operations Management | volume=19 | number= 3 | date=May 2010 | pages= 2-ix, x | url= https://www.proquest.com/docview/356759223 | id= {{ProQuest|356759223}} | via=ProQuest }}</ref>  PL/C began being used on a regular basis in September 1970.<ref name="cornell-history-computing"/>