Citation
"For ideas fundamental to the emergence of object oriented programming, through their design of the programming languages Simula I and Simula 67."

Object-oriented programming is a dominant programming paradigm of this age. Fundamental to the emergence of this paradigm were core concepts such as objects, classes, and inheritance with virtual quantities, all clearly established in Ole Johan Dahl's and Kristen Nygaard's discrete event simulation language Simula I and general programming language Simula 67. The objects integrate the data, procedural and (cooperating) action sequence aspects into one very general and powerful unifying entity.

By embodying these core concepts in a language designed both for system description and programming, Dahl and Nygaard provided not just a logical, but a notational basis for the ideas. Software could be built in layers of abstraction, each one relying on a description and conceptual platform implemented by the previous layers. By defining Simula 67 to be an extension of an international standard language, Algol-60, this medium of expression was accessible and available to the entire research community. Simula shaped and sped the emergence of object-oriented programming and the management discipline that accompanies it by many years.

Professor emeritus Ole-Johan Dahl (October 12, 1931 - June 29, 2002) was a Norwegian computer scientist and is considered to be one of the fathers of Simula and object-oriented programming along with Kristen Nygaard.

He was born in Mandal, Norway. He received the 2001 Turing Award for his work.

• Multiple index countings on the Ferranti Mercury computer / by O.-J. Dahl. Oslo: Norwegian Defence Research Establishment, 1957.
• Programmer's handbook for the Ferranti Mercury Computer, Frederic at the Norwegian Defense Research Establishment / By O.-J. Dahl, and Jan V. Garwick. - 2nd ed., Kjeller : Norwegian Defence Research Establishment, 1958.
• Automatisk kodning : et prosjekt ved Forsvarets forskningsinstitutt.
• Simscript implementation / by Vic Bell and Ole-Johan Dahl. Oslo : Norwegian Computing Center, 1963.
• Basic concepts of SIMULA : an ALGOL based simulation language / by Ole-Johan Dahl and Kristen Nygaard. Oslo: Norsk regnesentral, [1965?].
• SIMULA : a language for programming and description of discrete event systems : introduction and user's manual. Oslo : Norsk regnesentral, 1965.
• Discrete event simulation languages : lectures delivered at the NATO summer school, Villard-de-Lans, September 1966 / by Ole-Johan Dahl. Oslo : Norsk regnesentral/Norwegian Computing Center, 1966.
• SIMULA : an ALGOL based simulation language / by Ole-Johan Dahl and Kristen Nygaard. Oslo : Norsk regnesentral, 1966.
• Simula : an ALGOL-based simulation language / Ole-Johan Dahl and Kristen Nygaard. New York : Association for Computing Machinery, 1966. I: Communications of the ACM ; 9(1966).
• Class and subclass declarations / Ole-Johan Dahl and Kristen Nygaard. Amsterdam : North-Holland, c1968. I:Simulation programming languages : proceedings of the IFIP working conference on simulation programming languages, Oslo, May 1967 / O.-J. Dahl, conference chairman; organized by IFIP Technical Committee 2, programming languages ; edited by J.N. Buxton.
• Discrete event simulation languages / Ole-Johan Dahl. London : Academic Press, 1968. (Programming languages : NATO Advanced Study Institute / edited by G. Genuys.)
• SIMULA 67 : common base language / by Ole-Johan Dahl, Bjørn Myhrhaug and Kristen Nygaard. Oslo : Norsk regnesentral, 1968. (Publication S / Norwegian Computing Center ; 2) Rev. 1970: Common base language (Publ. ; 22).