Editing APL (programming language) (section)

=== Development into a computer programming language ===
As early as 1962, the first attempt to use the notation to describe a complete computer system happened after Falkoff discussed with William C. Carter his work to standardize the instruction set for the machines that later became the [[IBM System/360]] family.

In 1963, Herbert Hellerman, working at the IBM Systems Research Institute, implemented a part of the notation on an [[IBM 1620]] computer, and it was used by students in a special high school course on calculating transcendental functions by series summation. Students tested their code in Hellerman's lab. This implementation of a part of the notation was called Personalized Array Translator (PAT).<ref>{{cite journal |last1=Hellerman |first1=H. |title=Experimental Personalized Array Translator System |journal=Communications of the ACM |volume=7 |issue=7 |pages=433–438 |date=July 1964 |doi=10.1145/364520.364573 |s2cid=2181070 |doi-access=free}}</ref>

In 1963, Falkoff, Iverson, and [[Edward H. Sussenguth Jr.]], all working at IBM, used the notation for a formal description of the [[IBM System/360]] series machine architecture and functionality, which resulted in a paper published in ''[[IBM Systems Journal]]'' in 1964. After this was published, the team turned their attention to an implementation of the notation on a computer system. One of the motivations for this focus of implementation was the interest of John L. Lawrence who had new duties with [[Science Research Associates]], an educational company bought by IBM in 1964. Lawrence asked Iverson and his group to help use the language as a tool to develop and use computers in education.<ref>{{cite journal |last1=Falkoff |first1=Adin D. |author1-link=Adin Falkoff |last2=Iverson |first2=Kenneth E. |author2-link=Kenneth E Iverson |date=August 1978 |url=http://www.jsoftware.com/papers/APLEvol.htm |title=The Evolution of APL |journal=ACM SIGPLAN Notices |volume=13|issue=8 |pages=47–57 |doi=10.1145/960118.808372 }}</ref>

After [[Lawrence M. Breed]] and [[Philip S. Abrams]] of Stanford University joined the team at IBM Research, they continued their prior work on an implementation programmed in [[FORTRAN IV]] for a part of the notation which had been done for the [[IBM 7090]] computer running on the [[IBM 7090/94 IBSYS|IBSYS]] operating system. This work was finished in late 1965 and later named IVSYS (for Iverson system). The basis of this implementation was described in detail by Abrams in a Stanford University Technical Report, "An Interpreter for Iverson Notation" in 1966. The academic aspect of this was formally supervised by [[Niklaus Wirth]].<ref>Abrams, Philip S., [http://infolab.stanford.edu/TR/CS-TR-66-47.html ''An interpreter for "Iverson notation"''], Technical Report: CS-TR-66-47, Department of Computer Science, Stanford University, August 1966;</ref> Like Hellerman's PAT system earlier, this implementation omitted the APL character set, but used special English reserved words for functions and operators. The system was later adapted for a [[time-sharing]] system and, by November 1966, it had been reprogrammed for the [[IBM System/360 Model 50]] computer running in a time-sharing mode and was used internally at IBM.<ref>{{cite journal |last1=Haigh |first1=Thomas |year=2005 |title=Biographies: Kenneth E. Iverson |journal=IEEE Annals of the History of Computing |doi=10.1109/MAHC.2005.4}}</ref>