In 1970, he received a Ph.D. in computer science from Stanford University, with a dissertation on cellular automata theory jointly supervised by Michael A. Arbib, Edward J. McCluskey, and Bernard Widrow.

[citation needed] While at Xerox PARC in 1974, Smith worked with Richard Shoup on SuperPaint, one of the first computer raster graphics editor, or 'paint', programs.

In 1975, Smith joined the new Computer Graphics Laboratory at New York Institute of Technology (NYIT), where he was given the job title "Information Quanta".

[7] He was also the programmer and collaborator on Ed Emshwiller's animation Sunstone,[citation needed] included in the collection of the Museum of Modern Art in New York.

Smith worked at NYIT until 1979 and then briefly at the Jet Propulsion Laboratory with Jim Blinn on the Carl Sagan Cosmos: A Personal Voyage television series.

From 1988–1992, Smith was a member of the board of regents of the National Library of Medicine in Bethesda, Maryland, where he was instrumental in inaugurating the Visible Human Project.

[16] Smith retired from Microsoft in 1999 to spend his time giving talks, making digital photographs, doing scholarly genealogy, and researching technical history.

[18] In 1990, Smith and Richard Shoup received the ACM SIGGRAPH Computer Graphics Achievement Award for their development of paint programs.

[20] In 2010, Smith was elected a Fellow of the American Society of Genealogists and presented the Washington Award in Chicago for advancing "the welfare of humankind".