Shortly after the Soviet Union detonated their first atomic bomb, on August 29, 1949, the United States government decided that it needed some technology that didn't exist yet.The result, completed less than a decade later, was SAGE, short for Semi Automatic Ground Environment, a system that foretold operating systems and the Internet, gave birth to the largest computer ever built, and came in at an estimated total price between $8 and $12 billion, four times the cost of the Manhattan Project.
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SAGE was, like many of our most expensive things, top secret. It featured a network of AN/FSQ-7 computers, a precursor to modern air traffic control systems that was capable of observing, evaluating and communicating incoming airborne threats. To generals, the computer looked like high-tech security. To IBM, then the lion of computing, the project looked like money. While RCA was awarded an original contract, IBM quickly became the top candidate for building the thing.After consulting with scientists at what would become MIT's defense-focused Lincoln Labs, IBM executives realized they were looking at one of the largest data processing opportunities since the company won the Social Security bid in the mid-1930s. Winning the contract would prove crucial for cementing IBM's domination of the computer industry. But some at the top doubted the wisdom of getting involved in such a complex project. Thomas Watson, Jr., who was then lobbying his father and others at the company to move into the computer market, recalled in his memoirs that he wanted to "pull out all the stops" to be a central player in SAGE. "I worked harder to win that contract than I worked for any other sale in my life."The dividends would be enormous. Between 1952 and 1955, the computer system generated 80 percent of IBM's revenues from computers, and relied on more than 7000 IBMers. The total cost of the project to the American taxpayer remains unknown, but estimates place it between 8 and 12 billion 1964 dollars, around 55 billion 2000 dollars, which was four times more than the Manhattan Project that developed the bomb which SAGE was intended to stop.
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To build the world's most advanced computer, IBM quickly assigned about 300 full-time employees to the project, mainly at IBM's Poughkeepsie and Kingston, NY facilities and in Cambridge, Massachusetts, home of MIT. While they developed brand new memory systems, MITRE and the Systems Development Corporation (part of RAND Corporation) wrote software; other vendors supplied components.

A SAGE operator at his terminal used a light pen, which was shaped like a handheld power drill or gun, to pinpoint threats on the CRT. The terminal's desk contains a built-in ash tray and cigarette lighter.

A radar station on Cape Cod, Massachusetts
A promotional film for SAGE
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With its facade covered in hundreds of neon lamps, dozens of incandescent lamps and hundreds of switches, the computer was the epitome of the giant "blinkenlights" mainframe computers of the 1950s and '60s. The lights weren't for show: they allowed engineers to monitor the flow of data through the system, and in maintenance mode, to literally follow the progress of a program through the computer by watching the neon lights.

A section of the building-sized AN/FSQ-7, which featured built-in telephones for maintenance calls.
Robert Duvall and the SAGE computer in "The Time Tunnel" (1967).
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After the network detected an incoming "blip" from the radar data, a human controller would see the threat as an icon on his CRT radar monitor. Using a "light pen," he would point at the blip, manually feeding back to the computer the information it needed to dispatch interceptors, like missiles and aircraft. Impressively, the system was also designed to connect to a fighter plane's autopilot, allowing the ground operator at the radar scope to use his light pen to actually control the interceptor's speed, heading, and altitude, leaving the pilot to operate the aircraft's radar and weapons system. This silent means of control was called "data link." Today we refer to it as "Internet."

SAGE terminal screen.

A diagram of the SAGE system.
A map of SAGE's radar sites
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A replacement had been a long time coming. From the start of the project, questions lingered about SAGE's usefulness in an actual "hot war" situation. On one occasion, the Strategic Air Command was able to penetrate the system's defenses, and on other occasions huge flocks of seabirds were tracked as a potential bomber attack. By the time the system became fully operational, the USSR had already started deploying ICBMs, which made SAGE largely useless. As an added safety measure, the Air Force also developed the Back Up Interceptor Control System (BUIC), a kind of mini-SAGE located at some of the radar sites that normally fed the SAGE system.Even if SAGE wasn't fast enough to protect against the more formidable threat of massive bomber and long-range missile attacks, its legacy extends far across computer history. Its most direct legacy however may be the systems IBM began developing near the end of the SAGE project: the national air traffic control system and SABRE system, which is still the world's central travel reservations network.Keep that in mind the next time you contemplate the trajectory of technology, or fly: the computer systems that puts airplanes in the sky now grew out of one intended to take them down.

