# Niklaus Wirth

Niklaus Emil Wirth (IPA: /vɛrt/) (15 February 1934 – 1 January 2024) was a Swiss computer scientist. He designed several programming languages, including Pascal, and pioneered several classic topics in software engineering. In 1984, he won the Turing Award, generally recognized as the highest distinction in computer science, "for developing a sequence of innovative computer languages".

## Early life and education

Niklaus Emil Wirth was born in Winterthur, Switzerland, on 15 February 1934. He was the son of Hedwig (née Keller) and Walter Wirth, a high school teacher. Wirth studied electronic engineering at the Federal Institute of Technology, Zürich (ETH Zürich) from 1954 to 1958, graduating with a Bachelor of Science (B.S.) degree. In 1960, he earned a Master of Science (M.Sc.) from Université Laval in Quebec. Then in 1963, he was awarded a PhD in electrical engineering and computer science (EECS) from the University of California, Berkeley, supervised by computer design pioneer Harry Huskey.

## Career

From 1963 to 1967, Wirth served as assistant professor of computer science at Stanford University and again at the University of Zürich. In 1968, he became a professor of informatics at ETH Zürich, taking two one-year sabbaticals at Xerox PARC in California (1976–1977 and 1984–1985). He retired in 1999.
Although Wirth was involved with developing international standards in programming and informatics, as a member of the International Federation for Information Processing (IFIP) Working Group 2.1 on Algorithmic Languages and Calculi, which specified, maintains, and supports the programming languages ALGOL 60 and ALGOL 68, he got frustrated by the discussions in the standards groups and published his languages later on as personal work, mainly Pascal, Modula-2 and Oberon.
In 2004, he was made a Fellow of the Computer History Museum "for seminal work in programming languages and algorithms, including Euler, Algol-W, Pascal, Modula, and Oberon."

## Programming languages

Wirth was the chief designer of the programming languages Euler (1965), PL360 (1966), ALGOL W (1966), Pascal (1970), Modula (1975), Modula-2 (1978), Oberon (1987), Oberon-2 (1991), and Oberon-07 (2007). He was also a major part of the design and implementation team for the operating systems Medos-2 (1983, for the Lilith workstation), and Oberon (1987, for the Ceres workstation), and for the Lola (1995) digital hardware design and simulation system.
In 1984, Wirth received the Association for Computing Machinery (ACM) Turing Award for the development of these languages. In 1994, he was inducted as a Fellow of the ACM.
In 1999, he received the ACM SIGSOFT Outstanding Research Award

## Wirth's law

In 1995, he popularized the adage now named Wirth's law. In his 1995 paper "A Plea for Lean Software" he attributed the following to Martin Reiser phrasing it as, "Software is getting slower more rapidly than hardware becomes faster."

## Publications

The April 1971 Communications of the ACM article "Program Development by Stepwise Refinement", concerning the teaching of programming, is considered to be a classic text in software engineering. The paper is considered to be the earliest work to formally outline the top-down method for designing programs. The article was discussed by Fred Brooks in his influential book The Mythical Man-Month and was described as "seminal" in the ACM's brief biography of Wirth published in connection to his Turing Award.
The 1973 textbook, Systematic Programming: An Introduction, was described as a quality source for mathematicians desiring to understand the nature of programming in a 1974 review. The cover flap, of the 1973 edition, stated the book "... is tailored to the needs of people who view a course on systematic construction of algorithms as part of their basic mathematical training, rather than to the immediate needs of those who wish to be able to occasionally encode a problem and hand it over to their computer for instant solution." Described in the review as a challenging text to work through, it was nevertheless recommended as useful reading for those interested in numerical mathematics.
In 1974, The Pascal User Manual and Report, jointly written with Kathleen Jensen, served as the basis of many language implementation efforts in the 1970s (BSD Pascal), and 1980s in the United States and across Europe.
In 1975, he wrote the book Algorithms + Data Structures = Programs, which gained wide recognition. Major revisions of this book with the new title Algorithms & Data Structures were published in 1986 and 2004. The examples in the first edition were written in Pascal. These were replaced in the later editions with examples written in Modula-2 and Oberon, respectively.
In 1992, Wirth and Jürg Gutknecht published the full documentation of the Oberon operating system. A second book, with Martin Reiser, was intended as a programming guide.

## Death

Wirth died in Zürich on New Year's Day 2024, at age 89.