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" [24] to convert Fortran, Cobol, and Algol programs to the PL/I F level of PL/I. Peter Crouch (Aston Villa, Southampton, Liverpool, Portsmouth, Tottenham Hotspur & Stoke City; 2001/02 - 2017/18) IBM, OS/2 PL/I Version 2: Programming: Language Reference, 3rd Ed., Form SC26-4308, San Jose. 1994. The PL/I design principles were retained and withstood this major extension, comprising several new data types, new statements and statement options, new exception conditions, and new organisations of program source. The resulting language is a compatible super-set of the PL/I Standard and of the earlier IBM compilers. Major topics added to PL/I were:

R. N. Cuff (May 1972). "A Conversational Compiler for Full PL/I". The Computer Journal. 15 (2): 99–104. doi: 10.1093/comjnl/15.2.99. VAR x , y , z , q , r , n , f ; PROCEDURE multiply ; VAR a , b ; BEGIN a := x ; b := y ; z := 0 ; WHILE b > 0 DO BEGIN IF ODD b THEN z := z + a ; a := 2 * a ; b := b / 2 END END ; PROCEDURE divide ; VAR w ; BEGIN r := x ; q := 0 ; w := y ; WHILE w <= r DO w := 2 * w ; WHILE w > y DO BEGIN q := 2 * q ; w := w / 2 ; IF w <= r THEN BEGIN r := r - w ; q := q + 1 END END END ; PROCEDURE gcd ; VAR f , g ; BEGIN f := x ; g := y ; WHILE f # g DO BEGIN IF f < g THEN g := g - f ; IF g < f THEN f := f - g END ; z := f END ; PROCEDURE fact ; BEGIN IF n > 1 THEN BEGIN f := n * f ; n := n - 1 ; CALL fact END END ; BEGIN ? x ; ? y ; CALL multiply ; ! z ; ? x ; ? y ; CALL divide ; ! q ; ! r ; ? x ; ? y ; CALL gcd ; ! z ; ? n ; f := 1 ; CALL fact ; ! f END . Oberon-0 [ edit ] Sperry-Univac Computer Systems, SPERRY UNIVAC 1100 Series PL/I Programmer Reference, Reference UP-8277, 1976. The DEFINE-statement introduces user-specified names (e.g. INTEGER) for combinations of built-in attributes (e.g. FIXED BINARY(31,0)). Thus DEFINE ALIAS INTEGER FIXED BINARY(31.0) creates the TYPE name INTEGER as an alias for the set of built-in attributes FIXED BINARY(31.0). DEFINE STRUCTURE applies to structures and their members; it provides a TYPE name for a set of structure attributes and corresponding substructure member declarations for use in a structure declaration (a generalisation of the LIKE attribute). Additional data types and attributes corresponding to common PC data types (e.g. UNSIGNED, VARYINGZ).The PL/I optimizing compiler took over from the PL/I F compiler and was IBM's workhorse compiler from the 1970s to the 1990s. Like PL/I F, it is a multiple pass compiler with a 44 kilobyte design point, but it is an entirely new design. Unlike the F compiler, it has to perform compile time evaluation of constant expressions using the run-time library, reducing the maximum memory for a compiler phase to 28 kilobytes. A second-time around design, it succeeded in eliminating the annoyances of PL/I F such as cascading diagnostics. [30] It was written in S/360 Macro Assembler by a team, led by Tony Burbridge, most of whom had worked on PL/I F. Macros were defined to automate common compiler services and to shield the compiler writers from the task of managing real-mode storage, allowing the compiler to be moved easily to other memory models. The gamut of program optimization techniques developed for the contemporary IBM Fortran H compiler were deployed: the Optimizer equaled Fortran execution speeds in the hands of good programmers. Announced with IBM S/370 in 1970, it shipped first for the DOS/360 operating system in August 1971, and shortly afterward for OS/360, [31] and the first virtual memory IBM operating systems OS/VS1, MVS, and VM/CMS. (The developers were unaware that while they were shoehorning the code into 28 kb sections, IBM Poughkeepsie was finally ready to ship virtual memory support in OS/360). It supported the batch programming environments and, under TSO and CMS, it could be run interactively. This compiler went through many versions covering all mainframe operating systems including the operating systems of the Japanese plug-compatible machines (PCMs). Hart, Timothy P. (October 1963). "MACRO Definitions for LISP". Artificial Intelligence Memos. No.57. hdl: 1721.1/6111. The existence of exception handling ON-units can have an effect on optimization, because variables can be inspected or altered in ON-units. Values of variables that might otherwise be kept in registers between statements, may need to be returned to storage between statements. This is discussed in the section on Implementation Issues above. [81] :pp.249–376 GO TO with a non-fixed target [ edit ] Compile time preprocessor extended to offer almost all PL/I string handling features and to interface with the Application Development Environment

An extensive structure of defaults in statements, options, and declarations to hide some complexities and facilitate extending the language while minimizing keystrokes. PL/I did not fulfill its supporters' hopes that it would displace Fortran and COBOL and become the major player on mainframes. It remained a minority but significant player. There cannot be a definitive explanation for this, but some trends in the 1970s and 1980s militated against its success by progressively reducing the territory on which PL/I enjoyed a competitive advantage. The VALUE attribute declares an identifier as a constant (derived from a specific literal value or restricted expression). Paul Abrahams of NYU's Courant Institute of Mathematical Sciences wrote CIMS PL/I in 1972 in PL/I, bootstrapping via PL/I F. It supported "about 70%" of PL/I compiling to the CDC 6600 [52]

ISM PL 1.0 reviews

Proposals to change the base document were voted upon by both committees. In the event that the committees disagreed, the chairs, initially Michael Marcotty of General Motors and C.A.R. Hoare representing ICL had to resolve the disagreement. In addition to IBM, Honeywell, CDC, Data General, Digital Equipment Corporation, Prime Computer, Burroughs, RCA, and Univac served on X3J1 along with major users Eastman Kodak, MITRE, Union Carbide, Bell Laboratories, and various government and university representatives. Further development of the language occurred in the standards bodies, with continuing improvements in structured programming and internal consistency, and with the omission of the more obscure or contentious features. 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 [6] briefly by MPPL (MultiPurpose Programming Language) and, in 1965, with [7] PL/I (with a Roman numeral "I"). The first definition appeared in April 1964. [8] [9] The first IBM Compile time preprocessor was built by the IBM Boston Advanced Programming Center located in Cambridge, Mass, and shipped with the PL/I F compiler. The %INCLUDE statement was in the Standard, but the rest of the features were not. The DEC and Kednos [39] PL/I compilers implemented much the same set of features as IBM, with some additions of their own. IBM has continued to add preprocessor features to its compilers. The preprocessor treats the written source program as a sequence of tokens, copying them to an output source file or acting on them. When a% token is encountered the following compile time statement is executed: when an identifier token is encountered and the identifier has been DECLAREd, ACTIVATEd, and assigned a compile time value, the identifier is replaced by this value. Tokens are added to the output stream if they do not require action (e.g. +), as are the values of ACTIVATEd compile time expressions. Thus a compile time variable PI could be declared, activated, and assigned using %PI='3.14159265'. Subsequent occurrences of PI would be replaced by 3.14159265. The UNION attribute (equivalent to CELL in early PL/I specifications) permits several scalar variables, arrays, or structures to share the same storage in a unit that occupies the amount of storage needed for the largest alternative. The DEFINE-statement (see below) allows additional TYPEs to be declared composed from PL/I's built-in attributes.