[SIGCIS-Members] whirlwind, radar and real-time tracking

Paul N. Edwards pedwards at stanford.edu
Sat Apr 24 12:01:45 PDT 2021

Guy, seconding Pierre’s good response and adding that in 1951, analog computers were still far faster than digital for most complex calculations, because they are inherently parallel processors. Digital machines were also prone to *very* frequent failure. Most sensors were analog, too, providing no numerical readouts. Few control engineers would have even considered a digital computer for any real-time application until the second half of that decade, and even then they were not the natural choice for most applications.

The early chapters of my book The Closed World: Computers and the Politics of Discourse in Cold War America (Cambridge, MA: MIT Press, 1996) cover SAGE and the surrounding computing landscape of the 1940s-1950s.

Other resources on SAGE:

Everett, Robert R., Charles A. Zraket, and Herbert D. Benington. “Sage: A Data-Processing System for Air Defense.” Proceedings of the Eastern Joint Computer Conference (1957): 339–45.

Redmond, Kent C. and Thomas M. Smith. Project Whirlwind: The History of a Pioneer Computer. Boston: Digital Press, 1980.

Valley, George E., Jr. “How the Sage Development Began.” Annals of the History of Computing 7, no. 3 (1985): 196–226.

Redmond, Kent C. and Thomas M. Smith. From Whirlwind to Mitre: The R&d Story of the Sage Air Defense Computer. Cambridge: MIT Press, 2000.


Paul Edwards

On Apr 23, 2021, at 16:41, Guy Fedorkow <guy.fedorkow at gmail.com<mailto:guy.fedorkow at gmail.com>> wrote:

Greetings Colleagues,
  I've been working on restoring a 1951 Whirlwind program, written at MIT, used to demonstrate real-time tracking of aircraft with radar for the purposes of guiding an interception (the Cold War was in full flight in the 1950's).  This work ultimately led to the massive SAGE air defense network in the US.
  You can see some rather informal preliminary notes on the work at
  The program does work in simulation; you can see a four-minute video of the simulator running an intercept at
  Spoiler alerts: The original really did display moving dots on a CRT, but the graphics are "spartan" to say the least.  And nothing in particular happens when the intercept actually happens.

  Would anyone know of contemporaneous work involving digital computers for either radar tracking or real-time computing around 1951?  I think all the familiar digital computers from those years were used in applications where batch operation was perfectly acceptable, e.g., computing ballistics tables.
  Innovations like this rarely occur in a complete vacuum, but I don't see references to any similar digital computing projects.
  If anyone has pointers, do let me know!
Guy Fedorkow

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Paul N. Edwards<https://profiles.stanford.edu/paul-edwards>

Director, Program on Science, Technology & Society<http://sts.stanford.edu>
William J. Perry Fellow in International Security and Senior Research Scholar
Center for International Security and Cooperation<http://cisac.fsi.stanford.edu/>
Co-Director, Stanford Existential Risks Initiative<https://cisac.fsi.stanford.edu/stanford-existential-risks-initiative>
Stanford University

Professor of Information<http://www.si.umich.edu/> and History<http://www.lsa.umich.edu/history/> (Emeritus)
University of Michigan

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