Jack B. Dennis

A pioneer of time-sharing and hacker culture, Dennis is a computer scientist whose research group owned the PDP-1 at MIT — the machine that later became famous in computer science history as the birthplace of hacker culture.

Jack B. Dennis entered the Massachusetts Institute of Technology (MIT) in 1949 as an electrical engineering major. He received his MS degree in 1954, continued doctoral research, and received his ScD in 1958. Dennis became a full professor at MIT in 1969.

He also sponsored the MIT student-run Tech Model Railroad Club in its early years, where the hacker culture is said to have taken root before spreading to the MIT Artificial Intelligence Lab.

Later, Dennis was one of the founding members of the Multics project, to which he contributed one of its most important concepts, the single-level memory. Multics, though not particularly commercially successful in itself, was an inspiration for Ken Thompson to develop Unix. The latter part of his career was devoted to non-von Neumann models of computation, architecture, and languages.

He wanted to free programs from the concept of a program counter. Adopting the concept of "single-assignment," Dennis along with his students and others developed data flow concepts which executed instructions as soon as data became available. This specific model came to be called "static" in contrast to Arvind's later "dynamic." He also developed the VAL static data-flow language, which in turn inspired the compiler for the SISAL programming language.

Dennis retired from MIT in 1987 to pursue independent projects and consulting. He has served as a visiting scientist at NASA's Research Institute for Advanced Computer Science (RIACS). In 1994 he was inducted as a Fellow of the Association for Computing Machinery, and he was elected to the National Academy of Engineering in 2009.