Per Brinch Hansen

His father, Jørgen Brinch Hansen, worked as a civil engineer, becoming a leading expert in soil mechanics, and later accepting a professorship at Technical University of Denmark.

Jørgens Gymnasium and then studied electrical engineering at Technical University of Denmark where he sought an area to pursue that "was still in its pioneering phase" on the belief that "If a subject was being taught, it was probably already too late to make fundamental contributions.

However, in the mid 1960s, the dividing line between language implementation and operating systems was still not clearly understood.In 1966, Brinch Hansen moved to Henning Isaksson's hardware group at Regnecentralen, by then a company with shareholders.

[1] In late 1970, Brinch Hansen moved to Pittsburgh, accepting an invitation from Alan Perlis to visit the department of computer science at Carnegie Mellon University as a research associate, while he wrote the first systematic textbook on operating system principles.

[1][2] During this time, at the 1971 Summer School in Marktoberdorf and a symposium in Belfast, Brinch Hansen, Tony Hoare and Dijkstra began to discuss ideas that evolved into the monitor concept.

[7] In July 1972, Brinch Hansen joined the faculty of the California Institute of Technology (Caltech) as an Associate Professor of computer science, where he began work on defining a programming language with concurrent processes and monitors.

[1][2] A Concurrent Pascal compiler for the PDP 11/45, written by Brinch Hansen's doctoral student, Al Hartmann, was released in January 1975.

[8] Subsequently, Brinch Hansen began writing model operating systems in Concurrent Pascal, to evaluate the language.

Next, he rewrote the original RC 4000 real-time scheduler in Concurrent Pascal, taking three days to write it, and three hours of machine time to systematically test it.

[1] In 1976, Brinch Hansen chose University of Southern California (USC) for his next post, so that his family could remain in their Altadena home.

[9] In 1978, Brinch Hansen became the first computer scientist awarded the Doctor Technices degree, the highest academic distinction within engineering and technological science in Denmark,[10] for the work documented in The Architecture of Concurrent Programs.

[11] Also in 1978, L. J. Sevins and Steve Goings from Mostek visited Brinch Hansen at USC, where he outlined a low-cost multiprocessor architecture.

[1] In 1984, feeling homesick for Denmark after 14 years abroad, Brinch Hansen left USC and joined the faculty of the University of Copenhagen as a Professor of datalogy.

[16] While designing a multicomputer operating system for Danish company GN Elmi, Brinch Hansen concluded he needed a new language, this time leveraging the message passing paradigm of Hoare's CSP.

[1] After finding that neither he nor his family felt at home in Denmark, Brinch Hansen decided to return to the US, but discovered that their immigration status required them to do so very quickly.

[1] Working with his student Rangachari Anand, Joyce was moved to an Encore Multimax 320 multiprocessor at SU's Northeast Parallel Architectures Center.

Eventually published in six languages (English, Japanese, German, Czech, Polish and Serbo-Croatian),[1] it remained in print for decades, and years after the RC 4000 system it described had become outdated.

Using Concurrent Pascal, Brinch Hansen demonstrated that it was feasible to fully implement operating systems in high level languages, and that doing so reduced the development effort by one to two orders of magnitude.

Brinch Hansen did precisely that in The Architecture of Concurrent Programs, leading Roy Maddux and Harlan Mills to declare: Part two of the book is indeed remarkable.

"[33] Source and portable code for Concurrent Pascal and the Solo operating system were distributed to at least 75 companies and 100 universities in 21 countries, resulting in its widespread adoption, porting and adaptation in both industry and academia.

[25]In 2005, ACM members voted The Architecture of Concurrent Programs a top 25 classic book, ranking it 18th in the survey, and appearing on 8% of ballots.

[36] Later, Brinch Hansen developed two languages extending Hoare's CSP message-passing paradigm with parallel recursion,[17][19] and showed how to efficiently implement such.

Per Brinch Hansen as a student in 1959
Age 21 in 1959
Per Brinch Hansen at age 29, in the RC 4000 computer lab (1967)
At age 29, in the RC 4000 computer lab (1967)
Per Brinch Hansen at the Taj Mahal, after attending a conference in Bombay (1975)
At the Taj Mahal, after attending a conference in Bombay (1975)
Per Brinch Hansen on vacation in Washington, D.C. (1990)
On vacation in Washington, D.C. (1990)