Clarence Ellis (computer scientist)

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Clarence (Skip) Ellis
Born Clarence Arthur Ellis
(1943-05-11)11 May 1943
Chicago, Illinois, USA
Died 17 May 2014(2014-05-17) (aged 71)
Boulder, Colorado, USA
Residence Boulder, Colorado, USA
Nationality American
Fields Computer Science, Groupware, Computer-supported cooperative work, Workflow
Institutions Ashesi University College
University of Colorado, Boulder
University of Texas, Austin
Xerox PARC
Stanford University
Massachusetts Institute of Technology
Microelectronics and Computer Technology Corporation
Alma mater Beloit College
University of Illinois, Urbana-Champaign
Thesis Probabilistic Languages and Automata (1969)
Doctoral advisor David E. Muller[1]
Doctoral students Kwang-Hoon Kim
Karim Keddara
Paulo Barthelmess
Aubrey J. Rembert
Carlos Maltzahn

Clarence (Skip) Ellis was an American computer scientist, and Emeritus Professor of computer science and cognitive science at the University of Colorado Boulder. While at the University of Colorado Boulder, he was the director of the Collaboration Technology Research Group and a member of the Institute of Cognitive Science. Ellis was the first African-American to earn a Ph.D. in computer science (1969), and the first African-American to be elected a Fellow of the ACM (1997). Ellis was a pioneer in computer supported cooperative work and groupware. He and his team at Xerox PARC created one of the first Groupware systems, OfficeTalk. Ellis also pioneered operational transformation, which is a set of techniques that enables real-time collaborative editing of documents. [2]


Clarence Ellis was born in 1943 in Chicago, Illinois. In 1958, at age 15, Ellis applied for a job as a graveyard shift computer operator at Dover to earn money to help his family. He was offered the job because he was the only applicant for the position. Although his job title was computer operator, his main duties were to walk around all night and be visible to prevent break-ins, and to watch over, but not touch, the company's new computer, which was based on vacuum tube technology (2,400 vacuum tubes), used punch cards as input and output, and filled an extremely large room. [3] In Ellis' free time on the job at Dover, he read and re-read the dozens of computer manuals that came with the machine. He taught himself as much as possible about the machine without touching it. Two months after he started the job, Ellis helped the company through an emergency. They had run out of unused punch cards, and needed to process payroll on the computer by the morning. Because of his late night computer manual reading, Ellis knew how to recycle the used punch cards. He lifted the hood of the computer and disabled the parity check circuitry. The used punch cards were recycled and the company processed the payroll by the morning. After this, the company began to seek him out whenever they computer had problems, and asked him to operate and program the computer for them. Ellis states that this experience helped ignite his passion for computing.

High school and college[edit]

Throughout high school, Ellis' teachers recommended that he attend summer school programs at the local universities in Chicago. This was his first encounter with college-level students and university life. Though poor, Ellis was able to obtain a scholarship from his church to attend Beloit College in the fall of 1960. In Ellis' junior year, an IBM 1620 computer was donated to Beloit College. He and his chemistry professor were asked to set it up. This computer was the start of the campus's computer lab, of which Ellis was the director. At Beloit College, during that time, there was no degree in computer science, however Ellis was able to substitute some of his science laboratory work with computer projects. In 1964, Ellis received a B.S. degree from Beloit College, double majoring in math and physics.

After graduating from Beloit College, Ellis enrolled in MIT for graduate school, but only stayed a short time because of his civil rights activism. He eventually attended graduate school at the University of Illinois Urbana-Champaign, where he worked on hardware, software, and applications of the ILLIAC IV supercomputer. In 1969, Clarence Ellis earned a Ph.D. in computer science, becoming the first African-American to do so. His Ph.D. advisor was David E. Muller.


After completing his Ph.D., Ellis worked at Bell Labs from 1969 to 1972 on probability theory applied to the theory of computing. He left Bell Labs in 1972 to become an assistant professor, and a founding member of the computer science department at the University of Colorado Boulder to work on operating systems research. Ellis left the University of Colorado Boulder after three years to accept a position as an assistant professor in EECS at MIT to work on research related to ARPANET. He left MIT after one year to start work at Xerox PARC and Stanford University. Ellis remained at Xerox PARC and Stanford University for nearly a decade. During his time there, he worked on the icon-based GUI, object-oriented programming languages, and groupware systems. He left Xerox PARC and Stanford University in the mid-1980s to lead the Groupware Research Group at the Microelectronics and Computer Technology Corporation (MCC). While at MCC, he led efforts in Real-time Collaborative Editing, and pioneered the field of Operational transformation. In the early 1990s, Ellis left MCC to become the Chief Architect of the FlowPath workflow product of Bull S.A. in France. In 1992, Ellis returned to the University of Colorado Boulder as full professor with tenure in the computer science department. There he continued his work on groupware, in particular next-generation, large-scale Workflow systems, and agent-mediated meeting support systems. In 2009, he became an emeritus professor at the University of Colorado Boulder. In 2013, Ellis won a Fulbright Scholarship to teach and perform research in the computer science department at Ashesi University. At Ashesi, his research interests were developing computer systems to simulate alternative forms of government for developing countries. At various points during his career, Ellis worked as a visiting scientist, or a lecturer at IBM Research, Argonne National Laboratory, Los Alamos National Laboratory, Stevens Institute of Technology, the University of Texas, and internationally in Taiwan, Paris, and Accra. He died at the age of 71 in 2014.[4]


  1. ^ Clarence Ellis (computer scientist) at the Mathematics Genealogy Project
  2. ^ Ellis, Clarence (2002), "Affective Computing", in Jones, Lee, Making it on Broken Promises: Leading African American Male Scholars Confront the Culture of Higher Education, Stylus Publishing, pp. 149–159 
  3. ^ Barber, John T. (2006). The Black Digital Elite: African American Leaders of the Information Revolution. 
  4. ^ "Clarence Ellis's Obituary by The Boulder Daily Camera". Retrieved 2014-05-23.