The politics of development

XVII.5 September + October 2010
Page: 53
Digital Citation

Project SAGE, a half-century on

John King

In 1959 a Project SAGE Sector Direction Center went live in Syracuse, NY. It was the first of more than two dozen such centers built in the U.S. and Canada. They were part of NORAD, the North American Air Defense Command, headquartered in the bowels of Cheyenne Mountain in the Colorado Rockies. Project SAGE cost more than the Manhattan Project (between $20 billion and $60 billion in today’s dollars, depending on how one counts), yet few people have heard of it. It never saw a single instance of what it was built to detect—an attack by Cold War adversary the Soviet Union—but deterrence would have been its greatest victory. Yet it launched the modern computer age in the U.S. As its peculiar name suggests, SAGE (Semi-Automatic Ground Environment) was by design a human-computer system.

In 1945 the U.S. tested the first atomic bomb in New Mexico, dropped atomic bombs on Hiroshima and Nagasaki in Japan, and ended World War II in the Pacific. The Yalta Conference that year raised British and American fears about Soviet ambitions following the war; the Berlin crisis of 1948 confirmed those fears. In 1949 the Soviet Union tested its first atomic bomb and unveiled the TU-4, its first long-range bomber capable of carrying nuclear weapons. That same year, the Western allies created NATO to counter Soviet expansion: a Soviet attack on any NATO member would be an attack on all. The Cold War was on.

NATO leaders anticipated Soviet attacks on the ground from the east into Western Europe, by sea from the west into the Pacific, and by air from the north over Canada to the U.S. Project SAGE was a response to the third scenario. In 1947 Canada began erecting the Pine Tree Line, a set of radar stations just north of major Canadian population centers, connected by telephone to Canadian air-defense centers. The risk rose as jet aircraft flying low and fast could use the curvature of the Earth to mask an attack until it was too late for air defenses to respond. The answer? Move the radar stations closer to the enemy. The Mid-Canada Line, begun in 1952, moved detection several hundred miles north. The U.S. joined the Canadian effort in 1955, helping to build the Distant Early Warning (DEW) Line across Alaska and the Northwest Territories near the Arctic Ocean in 1958.

In 1948 two MIT researchers, Robert Valley and Jay Forrester, noted that air defense was actually an air-traffic-control problem, and that computers, such as the Whirlwind built at MIT under Forrester’s direction, could help monitor airspace. The U.S. Air Force bought the idea in 1949, launching Project SAGE in 1950 with Jay Forrester as its director. Project SAGE offered the solution to a vexing problem facing the systems being built in Canada: to determine whether the enemy was attacking with a surgical strike or in force across a wide frontier. By linking radar to computers via human operators, Project SAGE enabled rapid calculation of the situation and appropriate provisioning of air-defense response using interceptor aircraft and/or anti-aircraft missiles. The entire set of assets—radar stations, command centers, and air-defense positions—would be connected through a data-communication network and modern computers operating 24/7.

Project SAGE protected North American airspace by detecting incoming enemy aircraft from the north, integrating that information with other incoming information and known conditions, calculating the appropriate air-defense response, and launching counter-measures. Nothing like this had ever been tried before. Cooperation between the Canadian and American governments had to be established within NATO parameters, and a mix of military, public, and private organizations had to be brought together to work as a collaborative whole. MIT’s Lincoln Laboratories spun the Whirlwind computer off to the IBM Corporation as the IBM A/N FSQ7. The computer had 32-bit word length, four index registers, a real-time clock, magnetic (ferrite) core memory, and 60,000 vacuum tubes. It weighed half a million pounds and consumed three megawatts of power. Two A/N FSQ7s were built for each center, one of which would be in operation and the other of which would be in hot standby mode at any given time. MIT also spun off a new nonprofit organization called the MITRE Corporation to do systems integration. Other partners included the strategic-defense think tank RAND Corporation, which, with IBM, set up the Systems Development Corporation to do programming. AT&T Long Lines built the long-distance communications; AT&T Western Electric built the control centers; and Burroughs Corporation solved analog/digital conversion by building modems.

The cost of Project SAGE was enormous. In addition to the expense of R&D and the deployment of infrastructure, each Sector Direction Center operated four shifts per day of more than 100 people per shift. Additional thousands were employed in the command centers, the radar stations, the interceptor aircraft wings, and the missile batteries.

Was Project SAGE worth what it cost from a defense perspective? It is difficult to know. The ideal outcome was not air defense but deterrence: making the risk of defeat in an attack so high that the enemy would never attack. It is impossible to know what role Project SAGE played in the Cold War, but there never was an attack from the north. Project SAGE ran for two decades and never saw a bogie, much less a bandit. Moreover, the intercontinental ballistic missile (ICBM) introduced in the late 1950s made traditional air defense moot: ICBMs flew so fast there was little warning time before they struck, and they were almost impossible to shoot down. Project SAGE was kept in operation to protect against attack by manned bombers. It was surely targeted by Soviet ICBMs, but nuclear war was avoided and Project SAGE never faced the ultimate test.

Leaving aside the defense outcomes of Project SAGE, it is fair to say the enormous investment in the effort paid off in the creation of a unique U.S. computer and communications industry that has generated hundreds of billions of dollars in value over the past half-century. Two SAGE contributions were directly related to HCI: interactive CRT displays and light-pen I/O devices that foreshadowed the creation of the mouse. In addition, SAGE introduced a number of important technical innovations: ferrite core memory used in computers from 1953 until the mid-1970s; analog/digital and digital/analog conversion through the modem; multiprocessing; real-time database management; distributed processing; time-sharing; marginal checking for component failure (arguably the beginning of intelligent devices); memory cycle-stealing (LISP machines subsequently made this popular); buffered I/O; the COMPOOL (shared memory for subroutines that reappeared in COBOL); and large-scale system executives (the SAGE real-time executive had more than 500,000 lines of code). The IBM System 360, the most successful mainframe computer in history, with more than $100 billion in sales, was a major beneficiary of SAGE. So too was the MIT TX2, the precursor to Digital Equipment Corporation’s PDP-10, the first truly successful computer for artificial intelligence research.

Project SAGE led to broader development of the computing field and new applications of information technology. SAGE was the direct precursor to the Ballistic Missile Early Warning System, BMEWS. It also created modern air-traffic control; in fact, for many years ATC terminals looked exactly like SAGE terminals. Tracking for manned space vehicles was built on knowledge gained from SAGE. The Semi-Automatic Business Research Environment, or SABRE, came from SAGE and was used to create one of the first successful computerized airlinereservation systems. The System Development Corporation and IBM Corporation, working on Project SAGE, arguably invented the profession of computer programming. And the entire constellation of high-tech defense programs, including Project SAGE, proved to be an incubator of systems management and the concept of human organizations as systems that profoundly affected engineering and management education for decades.

Project SAGE touched thousands of people who shaped the future of U.S. information technology. One of these was Vinton Cerf, a co-creator of the Internet, whose first experience with computers was in 1958 at a Project SAGE facility at the System Development Corporation in Santa Monica. He was fascinated by the experience, took all the computer science courses he could find in college, and then began his career at IBM. Project SAGE proved beyond doubt that it is possible to build very large, integrated systems linking geographically remote (including offshore) sites with real-time computation to maintain 24/7 engagement with a highly complicated task. This proof was instrumental in many areas of large-scale socio-technical endeavor, not the least of which was the U.S. Space Program that successfully landed a human on the moon within a decade of President John F. Kennedy’s famous challenge of May 1961. Project SAGE never received the fame of the space program. The program was kept quiet, and most citizens living near the Sector Direction Centers never knew what they were. Project SAGE was phased out in 1983, made obsolete by other technologies and strategic strategies. It disappeared without a whimper.

Many lessons can be drawn from Project SAGE, but three stand out. One is that enough smart people and enough resources can make remarkable things happen—the old adage that you cannot solve anything by throwing money at it simply is not true. It is difficult to tell whether the Cold War would have turned out any differently without Project SAGE, but the Computer Age of the U.S. would almost certainly have been different—and less spectacular—without Project SAGE. Another is that bold initiatives draw naysayers who, for reasons that seem perfectly sensible at the time, doubt that anything good will come from such initiatives. In the late 1950s, computers were for calculation. Who better to ask for an opinion than mathematicians? Distinguished mathematicians reviewing the proposal said Valley and Forrester were not sufficiently sophisticated in mathematics to create such a complicated system. Fortunately, risk-takers won the day, but only because confidence in peer review was relaxed in the face of pressing national need. Finally, the “multiplier” effect of Moore’s Law had a profound effect on the consequences of Project SAGE. Gordon Moore described the law in 1965, well after SAGE was launched. Few could imagine in 1950 that a revolution in materials, design, and manufacturing would produce a multidecade era of increasingly powerful and inexpensive computers that were far more versatile and reliable than Whirlwind. Project SAGE advanced technical aspects of computer-building, but perhaps the greatest effect of the project was to show that large-scale, computer-assisted systems could be built and operated successfully as essential infrastructure. When SAGE went live in the early 1960s, this was unknown; when SAGE was finally shut down in the early 1980s, that knowledge was commonplace. Project SAGE constructed a new reality.

* Recommended reading

Edwards, P. N. The Closed World: Computers and the Politics of Discourse in Cold War America. Cambridge: MIT Press 1996.

Green, T. Bright Boys. Natick, Massachusetts: A K Peters Ltd., 2010.

Hughes, T. Rescuing Prometheus: Four Monumental Projects that Changed the Modern World. New York: Pantheon Books, 1998.

MITRE Corporation:

Moore, G. E. “Cramming More Components onto Integrated Circuits.” Electronics, April 19, 1965, 114–117.


YouTube; “SAGE - Semi Automatic Ground Environment; Parts 1 and 2”


John Leslie King is W.W. Warner Bishop Professor of Information and vice provost at the University of Michigan. His research is on the relationship between technical change and social change, particularly focused at this time on higher education. He is currently the liaison between the Advisory Committee for Cyberinfrastructure and the Advisory Committee for Social, Behavioral and Managerial Sciences at the National Science Foundation, and a member of the Council of the Computing Community Consortium.




UF1Figure: A late 1950s SAGE console with “light gun” used to select radar tracks for display on central “summary board” (not shown). The operator accesses information and directs action using sliders, switches, buttons, and dials. Courtesy IBM Archives.

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