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Simula is a name for two programming languages, Simula I and Simula 67, developed in the 1960s at the Norwegian Computing Center in Oslo, by Ole-Johan Dahl and Kristen Nygaard. Syntactically, it is a fairly faithful superset of Algol 60. Simula 67 introduced objects, classes, subclasses, virtual methods, coroutines, discrete event simulation, and features garbage collection. Simula is considered the first Object Oriented Programming (OOP) language. As its name implies, Simula was designed for doing simulations, and the needs of that domain provided the framework for many of the features of object-oriented languages today. Simula has been used in a wide range of applications such as simulating VLSI designs, processes, protocols, algorithms, and other applications such as typesetting, computer graphics, and education. Since Simula-type objects are reimplemented in C++, Java and C# the influence of Simula is often understated. The creator of C++, Bjarne Stroustrup, has acknowledged that Simula 67 was the greatest influence on him to develop C++, to bring the kind of productivity enhancements offered by Simula to the raw computational speed offered by lower level languages like BCPL. HistoryKristen Nygaard started writing computer simulation programs in 1957. Nygaard saw a need for a better way of describing the heterogeneity and the operation of a system. To go further with his ideas on a formal computer language for describing a system, Nygaard realized that he needed someone with more programming skills than he had. Ole-Johan Dahl joined him on his work in January 1962. The decision of linking the language up to Algol 60 was made shortly after. By May 1962 the main concepts for a simulation language were set. "SIMULA I" was born, a special purpose programming language for simulating discrete event systems. Kristen Nygaard was invited to Univac late May 1962 in connection with the marketing of their new UNIVAC 1107 computer. At that visit Nygaard presented the ideas of Simula to Robert Bemer, the director of systems programming at Univac. Bemer was a sworn Algol fan and found the Simula project compelling. Bemer was also chairing a session at the second international conference on information processing hosted by IFIP. He invited Nygaard, who presented the paper "SIMULA -- An Extension of ALGOL to the Description of Discrete-Event Networks". Norwegian Computing Center got a UNIVAC 1107 in August 1963 at a considerable discount, on which Dahl implemented the SIMULA I under contract with Univac. The implementation was based on the UNIVAC Algol 60 compiler. SIMULA I was fully operational on UNIVAC 1107 January 1965. In the following couple of years Dahl and Nygaard spent a lot of time teaching Simula. Simula spread to several countries around the world and SIMULA I was later implemented on Burroughs B5500 computers and the Russian URAL-16 computer. In 1966 C. A. R. Hoare introduced the concept of record class construct, which Dahl and Nygaard extended with the concept of prefixing and other features to meet their requirements for a generalized process concept. Dahl and Nygaard presented their paper on Class and Subclass Declarations at the IFIP Working Conference on simulation languages in Oslo, May 1967. This paper became the first formal definition of Simula 67. In June 1967 a conference was held to standardize the language and initiate a number of implementations. Dahl proposed to unify the Type and the Class concept. This led to serious discussions, and the proposal was rejected by the board. SIMULA 67 was formally standardized on the first meeting of the SIMULA Standards Group (SSG) in February 1968. Simula was influential in the development of Smalltalk and later Object Oriented Programming (OOP) languages. It also helped inspire the Actor model of concurrent computation although Simula only supports co-routines and not true concurrency. In November 2001, Dahl and Nygaard were awarded the IEEE John von Neumann Medal by the Institute of Electrical and Electronic Engineers "For the introduction of the concepts underlying object-oriented programming through the design and implementation of SIMULA 67". In February 2002 they received the 2001 A. M. Turing Award by the Association for Computing Machinery (ACM), with the citation: "For ideas fundamental to the emergence of object oriented programming, through their design of the programming languages Simula I and Simula 67." Unfortunately neither Dahl, nor Nygaard could make it to the ACM Turing Award Lecture, scheduled to be delivered at the OOPSLA 2002 conference in Seattle, as they both passed away within two months of each other in June and August, respectively. Simula Research Laboratory is a research institute named after the Simula language, and Nygaard held a part time position there from the opening in 2001. Article source: http://en.wikipedia.org/wiki/Simula Go back to Programming Articles home page
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