Editing PL/I (section)

===IBM PL/I F and D compilers===
PL/I was first implemented by IBM, at its [[Hursley Laboratories]] in the United Kingdom, as part of the development of [[System/360]]. The first production PL/I [[compiler]] was the PL/I F compiler for the [[OS/360]] Operating System, built by John Nash's team at Hursley in the UK: the runtime library team was managed by I.M. (Nobby) Clarke. The PL/I F compiler was written entirely in System/360 assembly language.<ref name=Krasun>{{cite web|last1=Krasun|first1=Andy|title=The first 35+ years of Hursley software 1958-1993 with some hardware asides, a personal account|url=https://apsg.bcs.org/materials/presentations/20061026krasun.pdf|access-date=May 5, 2020}}</ref>   Release 1 shipped in 1966. OS/360 is a real-memory environment and the compiler was designed for systems with as little as 64 kilobytes of real storage – F being 64 kB in S/360 parlance. To fit a large compiler into the 44 kilobytes of memory available on a 64-kilobyte machine, the compiler consists of a control phase and a large number of compiler phases (approaching 100). The phases are brought into memory from disk, one at a time, to handle particular language features and aspects of compilation. Each phase makes a single pass over the partially-compiled program, usually held in memory.<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/pli/Y28-6800-1_PL1(F)_PLM_Sep66.pdf|title=IBM System/360 Operating System PL/I (F) Compiler Program Logic Manual|id=Y28-6800-1|date=December 1966|publisher=IBM|at=Section 2: Compiler Phases}}</ref>

Aspects of the language were still being designed as PL/I F was implemented, so some were omitted until later releases. PL/I RECORD I/O was shipped with PL/I F Release 2. The [[list processing]] functions<ref>These were designed in 1966 for an early Optimizing compiler, written in PL/I and to be bootstrapped starting with the PL/I F compiler</ref>{{snd}} Based Variables, Pointers, Areas and Offsets and [[LOCATE-mode I/O]]{{snd}} were first shipped in Release 4. In a major attempt to speed up PL/I code to compete with Fortran object code, PL/I F Release 5 does substantial [[program optimization]] of DO-loops facilitated by the REORDER option on procedures.

A version of PL/I F was released on the [[TSS/360]] timesharing operating system for the [[System/360 Model 67]], adapted at the IBM Mohansic Lab. The IBM La Gaude Lab in France developed "Language Conversion Programs"<ref>There were many delays in shipping these, so a common PL/I joke at the time was that [[Charles de Gaulle|Gen de Gaulle]] forbade La Gaude from shipping them until the [[Concorde]] had its first flight</ref> to convert Fortran, Cobol, and Algol programs to the PL/I F level of PL/I.

The PL/I D compiler, using 16 kilobytes of memory, was developed by IBM Germany for the [[DOS/360]] low end operating system. It implements a subset of the PL/I language requiring all strings and arrays to have fixed extents, thus simplifying the run-time environment. Reflecting the underlying operating system, it lacks dynamic storage allocation and the ''controlled'' storage class.<ref>{{cite book|url=http://www.bitsavers.org/pdf/ibm/360/pli/C28-8202-0_PLIsubsetRM_1967.pdf|title=IBM System/360 PL/I Subset Reference Manual|id=C28-8202-0|date=1967|publisher=IBM}}</ref>  It was shipped within a year of PL/I F.