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75-455: Any software is source-available in the broad sense as long as its source code is distributed along with it, even if the user has no legal rights to use, share, modify or even compile it. It is possible for a software to be both source-available software and proprietary software (e.g. id Software 's Doom ). In contrast, the definitions of free software and open-source software are much narrower. Free software and/or open-source software

150-533: A basic block , to whole procedures, or even the whole program. There is a trade-off between the granularity of the optimizations and the cost of compilation. For example, peephole optimizations are fast to perform during compilation but only affect a small local fragment of the code, and can be performed independently of the context in which the code fragment appears. In contrast, interprocedural optimization requires more compilation time and memory space, but enable optimizations that are only possible by considering

225-412: A concrete syntax tree (CST, parse tree) and then transforming it into an abstract syntax tree (AST, syntax tree). In some cases additional phases are used, notably line reconstruction and preprocessing, but these are rare. The main phases of the front end include the following: The middle end, also known as optimizer, performs optimizations on the intermediate representation in order to improve

300-422: A PDP-7 in B. Unics eventually became spelled Unix. Bell Labs started the development and expansion of C based on B and BCPL. The BCPL compiler had been transported to Multics by Bell Labs and BCPL was a preferred language at Bell Labs. Initially, a front-end program to Bell Labs' B compiler was used while a C compiler was developed. In 1971, a new PDP-11 provided the resource to define extensions to B and rewrite

375-437: A Production Quality Compiler (PQC) from formal definitions of source language and the target. PQCC tried to extend the term compiler-compiler beyond the traditional meaning as a parser generator (e.g., Yacc ) without much success. PQCC might more properly be referred to as a compiler generator. PQCC research into code generation process sought to build a truly automatic compiler-writing system. The effort discovered and designed

450-401: A commercial status. Without these licenses, such systems could not have been built and used, and protected legally against various international patent claims. Due to the huge cost of these French strategic systems, a very strong licensing scheme was absolutely necessary to help protecting these investments against illegitimate claims by other commercial third parties, and one of the first needs

525-405: A compiler up into small programs is a technique used by researchers interested in producing provably correct compilers. Proving the correctness of a set of small programs often requires less effort than proving the correctness of a larger, single, equivalent program. Regardless of the exact number of phases in the compiler design, the phases can be assigned to one of three stages. The stages include

600-432: A component of an IDE (VADS, Eclipse, Ada Pro). The interrelationship and interdependence of technologies grew. The advent of web services promoted growth of web languages and scripting languages. Scripts trace back to the early days of Command Line Interfaces (CLI) where the user could enter commands to be executed by the system. User Shell concepts developed with languages to write shell programs. Early Windows designs offered

675-520: A different CPU or operating system than the one on which the cross-compiler itself runs. A bootstrap compiler is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software include decompilers , programs that translate from low-level languages to higher level ones; programs that translate between high-level languages, usually called source-to-source compilers or transpilers ; language rewriters , usually programs that translate

750-628: A front end, a middle end, and a back end. This front/middle/back-end approach makes it possible to combine front ends for different languages with back ends for different CPUs while sharing the optimizations of the middle end. Practical examples of this approach are the GNU Compiler Collection , Clang ( LLVM -based C/C++ compiler), and the Amsterdam Compiler Kit , which have multiple front-ends, shared optimizations and multiple back-ends. The front end analyzes

825-527: A grammar for the language, though in more complex cases these require manual modification. The lexical grammar and phrase grammar are usually context-free grammars , which simplifies analysis significantly, with context-sensitivity handled at the semantic analysis phase. The semantic analysis phase is generally more complex and written by hand, but can be partially or fully automated using attribute grammars . These phases themselves can be further broken down: lexing as scanning and evaluating, and parsing as building

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900-432: A result, compilers were split up into smaller programs which each made a pass over the source (or some representation of it) performing some of the required analysis and translations. The ability to compile in a single pass has classically been seen as a benefit because it simplifies the job of writing a compiler and one-pass compilers generally perform compilations faster than multi-pass compilers . Thus, partly driven by

975-478: A separate agreement. The license is compatible with the GPL through an explicit relicensing clause. Article 13's explicit reference to French law and a French court does not limit users, who can still choose a jurisdiction of their choice by mutual agreement to solve any litigation they may experience. The explicit reference to a French court will be used only if mutual agreement is not possible; this immediately solves

1050-431: A simple batch programming capability. The conventional transformation of these language used an interpreter. While not widely used, Bash and Batch compilers have been written. More recently sophisticated interpreted languages became part of the developers tool kit. Modern scripting languages include PHP, Python, Ruby and Lua. (Lua is widely used in game development.) All of these have interpreter and compiler support. "When

1125-492: Is Open64 , which is used by many organizations for research and commercial purposes. Due to the extra time and space needed for compiler analysis and optimizations, some compilers skip them by default. Users have to use compilation options to explicitly tell the compiler which optimizations should be enabled. The back end is responsible for the CPU architecture specific optimizations and for code generation . The main phases of

1200-557: Is a computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language , object code , or machine code ) to create an executable program. There are many different types of compilers which produce output in different useful forms. A cross-compiler produces code for

1275-561: Is a source-available license. In the narrow sense, the term source-available specifically excludes FOSS software. The following source-available software licenses are considered non-free licenses because they have limitations that prevent them from being open-source according to the Open Source Initiative and free to the Free Software Foundation . The Commons Clause, created by Fossa, Inc.,

1350-564: Is a modification of the GNU Affero General Public License created by the MongoDB project. It modifies a clause relating to usage of the licensed work over a network, stating that if SSPL-licensed software is incorporated into a "service" offered to other users, the source code for the entirety of the service (including without limitation all software and APIs that would be required for a user to run an instance of

1425-425: Is also always source-available software , but not all source-available software is also free software and/or open-source software. This is because the official definitions of those terms require considerable additional rights as to what the user can do with the available source (including, typically, the right to use said software, with attribution, in derived commercial products). In the broad sense, any FOSS license

1500-613: Is also commercial support, for example, AdaCore, was founded in 1994 to provide commercial software solutions for Ada. GNAT Pro includes the GNU GCC based GNAT with a tool suite to provide an integrated development environment . High-level languages continued to drive compiler research and development. Focus areas included optimization and automatic code generation. Trends in programming languages and development environments influenced compiler technology. More compilers became included in language distributions (PERL, Java Development Kit) and as

1575-622: Is an addendum to an open-source software license that restricts users from selling the software. Under the combined license, the software is source-available, but not open-source. On August 22, 2018, Redis Labs shifted some Redis Modules from the GNU Affero General Public License to a combination of the Apache License 2.0 and the Commons Clause. In September 2018, Matthew Garrett criticized Commons Clause calling it an "older way of doing things" and said it "doesn't help

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1650-446: Is favored due to its modularity and separation of concerns . Most commonly, the frontend is broken into three phases: lexical analysis (also known as lexing or scanning), syntax analysis (also known as scanning or parsing), and semantic analysis . Lexing and parsing comprise the syntactic analysis (word syntax and phrase syntax, respectively), and in simple cases, these modules (the lexer and parser) can be automatically generated from

1725-554: Is protected by reputed public research centers (in France the INRIA, a founding member of the international W3 consortium, and the CEA working on atomic energy) which use them to publish their own open-source and free software, and by critical governmental organizations (which are also working in domains like military and defense systems) also gives much more security than using the GPL alone, as

1800-748: The Centre National de la recherche scientifique (National Centre for Scientific Research) and the Institut national de recherche en informatique et en automatique (National Institute for Research in Computer Science and Control). It was announced on 5 July 2004 in a joint press communication of the CEA, CNRS and INRIA. It has gained support of the main French Linux User Group and the Minister of Public Function, and

1875-543: The Apache License , but retained the TrueCrypt License for code inherited from TrueCrypt. The Open Source Initiative rejects the TrueCrypt License, as "it has elements incompatible with the OSD ." The Free Software Foundation criticizes the license for restricting who can execute the program, and for enforcing a trademark condition. BeeGFS EULA is the license of the distributed parallel file system BeeGFS, except

1950-857: The MIT License . This makes GitLab an example of an open core company. In 2016, Mega Ltd. released the source code of their Mega clients under the Mega Limited Code Review Licence, which only permits usage of the code "for the purposes of review and commentary". The source code was released after former director Kim Dotcom stated that he would "create a Mega competitor that is completely open source and non-profit" following his departure from Mega Ltd. Microsoft's Shared Source Initiative , launched in May 2001, comprises 5 licenses, 2 of which are open-source and 3 of which are restricted. The restricted licenses under this scheme are

2025-487: The commons ". Business Source License has been introduced by MariaDB Corporation in 2016 and rapidly became one of the most adopted "delayed open source" licenses. It prohibits use of the code in production environments, where a commercial license is required. Functional Source License has been introduced in November 2023 by Sentry, as a simpler alternative to Business Source License. It prohibits any "competing" use of

2100-599: The (since 1995, object-oriented) programming language Ada . The Ada STONEMAN document formalized the program support environment (APSE) along with the kernel (KAPSE) and minimal (MAPSE). An Ada interpreter NYU/ED supported development and standardization efforts with the American National Standards Institute (ANSI) and the International Standards Organization (ISO). Initial Ada compiler development by

2175-630: The CeCILL FAQ there are no major differences in spirit, though there are in terms. The most notable difference in CeCILL v2 is the fact that the English text was approved not as a draft translation (as in CeCILL v1) but as an authentic text, in addition to the equally authentic French version. This makes the CeCILL license much easier to enforce internationally, as the cost of producing an authentic translation in any international court will be lower with

2250-587: The Early PL/I (EPL) compiler by Doug McIlory and Bob Morris from Bell Labs. EPL supported the project until a boot-strapping compiler for the full PL/I could be developed. Bell Labs left the Multics project in 1969, and developed a system programming language B based on BCPL concepts, written by Dennis Ritchie and Ken Thompson . Ritchie created a boot-strapping compiler for B and wrote Unics (Uniplexed Information and Computing Service) operating system for

2325-677: The French government will make a future version of the CeCILL unfree and restricted. The CeCILL license is approved as a "Free Software" license by the FSF with which the CeCILL project founders have worked. Since version 2.1, CeCILL is also approved by the Open Source Initiative as an "Open Source" license. The CeCILL project also adds two other licenses: These two licenses are also defined to make BSD-like and FSF's LGPL licenses enforceable internationally under WIPO rules. Although

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2400-771: The Microsoft Limited Public License (Ms-LPL), the Microsoft Limited Reciprocal License (Ms-LRL), and the Microsoft Reference Source License (Ms-RSL). Prior to version 5, Scilab described itself as "the open source platform for numerical computation " but had a license that forbade commercial redistribution of modified versions. Versions 5 and later are distributed under the GPL -compatible CeCILL license. The Server Side Public License

2475-528: The Sun 3/60 Solaris targeted to Motorola 68020 in an Army CECOM evaluation. There were soon many Ada compilers available that passed the Ada Validation tests. The Free Software Foundation GNU project developed the GNU Compiler Collection (GCC) which provides a core capability to support multiple languages and targets. The Ada version GNAT is one of the most widely used Ada compilers. GNAT is free but there

2550-670: The U.S. Military Services included the compilers in a complete integrated design environment along the lines of the STONEMAN document. Army and Navy worked on the Ada Language System (ALS) project targeted to DEC/VAX architecture while the Air Force started on the Ada Integrated Environment (AIE) targeted to IBM 370 series. While the projects did not provide the desired results, they did contribute to

2625-471: The University of Cambridge was originally developed as a compiler writing tool. Several compilers have been implemented, Richards' book provides insights to the language and its compiler. BCPL was not only an influential systems programming language that is still used in research but also provided a basis for the design of B and C languages. BLISS (Basic Language for Implementation of System Software)

2700-550: The back end include the following: CeCILL CeCILL (from CEA CNRS INRIA Logiciel Libre ) is a free software license adapted to both international and French legal matters, in the spirit of and retaining compatibility with the GNU General Public License (GPL). It was jointly developed by a number of French agencies: the Commissariat à l'Énergie Atomique (Atomic Energy Commission),

2775-435: The basis of digital modern computing development during World War II. Primitive binary languages evolved because digital devices only understand ones and zeros and the circuit patterns in the underlying machine architecture. In the late 1940s, assembly languages were created to offer a more workable abstraction of the computer architectures. Limited memory capacity of early computers led to substantial technical challenges when

2850-433: The behavior of multiple functions simultaneously. Interprocedural analysis and optimizations are common in modern commercial compilers from HP , IBM , SGI , Intel , Microsoft , and Sun Microsystems . The free software GCC was criticized for a long time for lacking powerful interprocedural optimizations, but it is changing in this respect. Another open source compiler with full analysis and optimization infrastructure

2925-398: The client for Linux, which is licensed under GPLv2 . BeeGFS source code is publicly available from their website, and because of this they claiming BeeGFS as "Open-Source" software; it is in fact not because this license prohibits distributing modified versions of the software, or using certain features of the software without authorization. Compile In computing , a compiler

3000-542: The code, to preserve the rights of the author to economically exploit it, but applies for a limited time, after which the code itself is considered to be available under Apache License or MIT License . The GitLab Enterprise Edition License is used exclusively by GitLab 's commercial offering. GitLab Inc. openly discloses that the EE License makes their Enterprise Edition product "proprietary, closed source code." GitLab also releases an open-source Community Edition under

3075-591: The compiler. By 1973 the design of C language was essentially complete and the Unix kernel for a PDP-11 was rewritten in C. Steve Johnson started development of Portable C Compiler (PCC) to support retargeting of C compilers to new machines. Object-oriented programming (OOP) offered some interesting possibilities for application development and maintenance. OOP concepts go further back but were part of LISP and Simula language science. Bell Labs became interested in OOP with

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3150-407: The development of C++ . C++ was first used in 1980 for systems programming. The initial design leveraged C language systems programming capabilities with Simula concepts. Object-oriented facilities were added in 1983. The Cfront program implemented a C++ front-end for C84 language compiler. In subsequent years several C++ compilers were developed as C++ popularity grew. In many application domains,

3225-551: The development of compiler technology: Early operating systems and software were written in assembly language. In the 1960s and early 1970s, the use of high-level languages for system programming was still controversial due to resource limitations. However, several research and industry efforts began the shift toward high-level systems programming languages, for example, BCPL , BLISS , B , and C . BCPL (Basic Combined Programming Language) designed in 1966 by Martin Richards at

3300-424: The development of high-level languages followed naturally from the capabilities offered by digital computers. High-level languages are formal languages that are strictly defined by their syntax and semantics which form the high-level language architecture. Elements of these formal languages include: The sentences in a language may be defined by a set of rules called a grammar. Backus–Naur form (BNF) describes

3375-424: The early days, the approach taken to compiler design was directly affected by the complexity of the computer language to be processed, the experience of the person(s) designing it, and the resources available. Resource limitations led to the need to pass through the source code more than once. A compiler for a relatively simple language written by one person might be a single, monolithic piece of software. However, as

3450-491: The field of compiling began in the late 50s, its focus was limited to the translation of high-level language programs into machine code ... The compiler field is increasingly intertwined with other disciplines including computer architecture, programming languages, formal methods, software engineering, and computer security." The "Compiler Research: The Next 50 Years" article noted the importance of object-oriented languages and Java. Security and parallel computing were cited among

3525-464: The first (algorithmic) programming language for computers called Plankalkül ("Plan Calculus"). Zuse also envisioned a Planfertigungsgerät ("Plan assembly device") to automatically translate the mathematical formulation of a program into machine-readable punched film stock . While no actual implementation occurred until the 1970s, it presented concepts later seen in APL designed by Ken Iverson in

3600-423: The first compilers were designed. Therefore, the compilation process needed to be divided into several small programs. The front end programs produce the analysis products used by the back end programs to generate target code. As computer technology provided more resources, compiler designs could align better with the compilation process. It is usually more productive for a programmer to use a high-level language, so

3675-559: The first pass needs to gather information about declarations appearing after statements that they affect, with the actual translation happening during a subsequent pass. The disadvantage of compiling in a single pass is that it is not possible to perform many of the sophisticated optimizations needed to generate high quality code. It can be difficult to count exactly how many passes an optimizing compiler makes. For instance, different phases of optimization may analyse one expression many times but only analyse another expression once. Splitting

3750-933: The form of expressions without a change of language; and compiler-compilers , compilers that produce compilers (or parts of them), often in a generic and reusable way so as to be able to produce many differing compilers. A compiler is likely to perform some or all of the following operations, often called phases: preprocessing , lexical analysis , parsing , semantic analysis ( syntax-directed translation ), conversion of input programs to an intermediate representation , code optimization and machine specific code generation . Compilers generally implement these phases as modular components, promoting efficient design and correctness of transformations of source input to target output. Program faults caused by incorrect compiler behavior can be very difficult to track down and work around; therefore, compiler implementers invest significant effort to ensure compiler correctness . Compilers are not

3825-454: The future research targets. A compiler implements a formal transformation from a high-level source program to a low-level target program. Compiler design can define an end-to-end solution or tackle a defined subset that interfaces with other compilation tools e.g. preprocessors, assemblers, linkers. Design requirements include rigorously defined interfaces both internally between compiler components and externally between supporting toolsets. In

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3900-559: The help of a second authentic reference text. The second difference is that the reference to the GNU General Public License, with which CeCILL v2 is now fully compatible, is explicitly defined precisely using its exact title and the exact name of the Free Software Foundation, to avoid all possible variations of the terms of the GPL v2. Some additional definitions were added to more precisely define

3975-421: The idea of using a higher-level language quickly caught on. Because of the expanding functionality supported by newer programming languages and the increasing complexity of computer architectures, compilers became more complex. DARPA (Defense Advanced Research Projects Agency) sponsored a compiler project with Wulf's CMU research team in 1970. The Production Quality Compiler-Compiler PQCC design would produce

4050-507: The language that requires licensees to give access to the source code (which had previously caused rejection of version 2.0 by the Open Source Initiative). Note that CeCILL v1 already allowed replacing a CeCILL v1 license with CeCILL v2, so all software previously licensed with CeCILL v1 in 2004 can be licensed with CeCILL v2, with legal terms enforceable as authentic not only in French but in English too. The fact that it

4125-434: The late 1950s. APL is a language for mathematical computations. Between 1949 and 1951, Heinz Rutishauser proposed Superplan , a high-level language and automatic translator. His ideas were later refined by Friedrich L. Bauer and Klaus Samelson . High-level language design during the formative years of digital computing provided useful programming tools for a variety of applications: Compiler technology evolved from

4200-414: The license is supported officially by a government which is a full member of WIPO, and by an enforceable law. This also means that all international treaties related to the protection of intellectual rights do apply to CeCILL-licensed products, and so they are enforceable by law in all countries that signed any of the international treaties protected by WIPO. However, this also leaves open the possibility that

4275-408: The need for a strictly defined transformation of the high-level source program into a low-level target program for the digital computer. The compiler could be viewed as a front end to deal with the analysis of the source code and a back end to synthesize the analysis into the target code. Optimization between the front end and back end could produce more efficient target code. Some early milestones in

4350-570: The only language processor used to transform source programs. An interpreter is computer software that transforms and then executes the indicated operations. The translation process influences the design of computer languages, which leads to a preference of compilation or interpretation. In theory, a programming language can have both a compiler and an interpreter. In practice, programming languages tend to be associated with just one (a compiler or an interpreter). Theoretical computing concepts developed by scientists, mathematicians, and engineers formed

4425-667: The overall effort on Ada development. Other Ada compiler efforts got underway in Britain at the University of York and in Germany at the University of Karlsruhe. In the U. S., Verdix (later acquired by Rational) delivered the Verdix Ada Development System (VADS) to the Army. VADS provided a set of development tools including a compiler. Unix/VADS could be hosted on a variety of Unix platforms such as DEC Ultrix and

4500-511: The performance and the quality of the produced machine code. The middle end contains those optimizations that are independent of the CPU architecture being targeted. The main phases of the middle end include the following: Compiler analysis is the prerequisite for any compiler optimization, and they tightly work together. For example, dependence analysis is crucial for loop transformation . The scope of compiler analysis and optimizations vary greatly; their scope may range from operating within

4575-646: The phase structure of the PQC. The BLISS-11 compiler provided the initial structure. The phases included analyses (front end), intermediate translation to virtual machine (middle end), and translation to the target (back end). TCOL was developed for the PQCC research to handle language specific constructs in the intermediate representation. Variations of TCOL supported various languages. The PQCC project investigated techniques of automated compiler construction. The design concepts proved useful in optimizing compilers and compilers for

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4650-588: The problem of competence of laws (something that the GPL does not solve cleanly, except when all parties in litigation are in the USA). Version 2 was developed after consultations with the French-speaking Linux and Free Software Users' Association, the Association pour la Promotion et la Recherche en Informatique Libre , and the Free Software Foundation ; it was released on 21 May 2005. According to

4725-429: The resource limitations of early systems, many early languages were specifically designed so that they could be compiled in a single pass (e.g., Pascal ). In some cases, the design of a language feature may require a compiler to perform more than one pass over the source. For instance, consider a declaration appearing on line 20 of the source which affects the translation of a statement appearing on line 10. In this case,

4800-510: The service themselves) must be released under the SSPL. The license is considered non-free by the Open Source Initiative , Debian and Red Hat , as it contains conditions that are unduly discriminatory towards commercial use of the software. In 2007 Michael Tiemann , president of OSI, had criticized companies such as SugarCRM for promoting their software as "open source" when in fact it did not have an OSI-approved license. In SugarCRM's case, it

4875-448: The software be distributed under the CeCILL, but it makes no claim to work that executes in "separate address spaces", which may be licensed under terms of the licensee's choice. It does not grant a patent license (as some other common open-source licenses do), but rather includes a promise by the licensor not to enforce any patents it owns. In Article 9.4, the licensor agrees to provide "technical and legal assistance" if litigation regarding

4950-469: The software is brought against the licensee, though the extent of the assistance "shall be decided on a case-by-case basis...pursuant to a memorandum of understanding". The disclaimers of warranty and liability are written in a manner different from other common open-source licenses to comply with French law. The CeCILL does not preclude the licensor from offering a warranty or technical support for its software, but requires that such services be negotiated in

5025-490: The source code to build an internal representation of the program, called the intermediate representation (IR). It also manages the symbol table , a data structure mapping each symbol in the source code to associated information such as location, type and scope. While the frontend can be a single monolithic function or program, as in a scannerless parser , it was traditionally implemented and analyzed as several phases, which may execute sequentially or concurrently. This method

5100-469: The source language grows in complexity the design may be split into a number of interdependent phases. Separate phases provide design improvements that focus development on the functions in the compilation process. Classifying compilers by number of passes has its background in the hardware resource limitations of computers. Compiling involves performing much work and early computers did not have enough memory to contain one program that did all of this work. As

5175-440: The syntax of "sentences" of a language. It was developed by John Backus and used for the syntax of Algol 60 . The ideas derive from the context-free grammar concepts by linguist Noam Chomsky . "BNF and its extensions have become standard tools for describing the syntax of programming notations. In many cases, parts of compilers are generated automatically from a BNF description." Between 1942 and 1945, Konrad Zuse designed

5250-610: The terms with less ambiguity. With these changes, the CeCILL is now fully enforceable according to WIPO rules, and according to French law in courts, without the legal problems remaining in GPL version 2 outside the United States. Version 2.1 was released in June 2013. It allows relicensing to the GNU Affero General Public License and the European Union Public License as well as the GPL, and clarifies

5325-607: The three CeCILL licenses were developed and used for strategic French research systems (in the domain of defense, space launching systems, medical research, meteorology/climatology, and various domains of fundamental or applied physics), they are made to be usable also by the general public or any other commercial or non-profit organization, including from other governments, simply because these software component need and use (or are integrated with) component software or systems which were initially released with an open-source or free license, and they are operated by organizations that also have

5400-580: Was because the software is so-called " badgeware " since it specified a "badge" that must be displayed in the user interface. SugarCRM's open source version was re-licensed under the GPL version 3 in 2007, and later the GNU Affero GPL version 3 in 2010. The TrueCrypt License was used by the TrueCrypt disk encryption utility . When TrueCrypt was discontinued, the VeraCrypt fork switched to

5475-554: Was considered for adoption at the European level before the European Union Public Licence was created. The CeCILL grants users the right to copy, modify, and distribute the licensed software freely. It defines the rights as passing from the copyright holder to a "Licensor", which may be the copyright holder or a further distributor, to the user or "Licensee". Like the GPL, it requires that modifications to

5550-432: Was developed for a Digital Equipment Corporation (DEC) PDP-10 computer by W. A. Wulf's Carnegie Mellon University (CMU) research team. The CMU team went on to develop BLISS-11 compiler one year later in 1970. Multics (Multiplexed Information and Computing Service), a time-sharing operating system project, involved MIT , Bell Labs , General Electric (later Honeywell ) and was led by Fernando Corbató from MIT. Multics

5625-470: Was written in the PL/I language developed by IBM and IBM User Group. IBM's goal was to satisfy business, scientific, and systems programming requirements. There were other languages that could have been considered but PL/I offered the most complete solution even though it had not been implemented. For the first few years of the Multics project, a subset of the language could be compiled to assembly language with

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