In addition to being vital for national security, SAGE was a proving ground for the US Department of Defense. It demonstrated the government’s ability to coordinate large-scale, diversified and highly sophisticated computer research and development.

From his earliest conversations with MIT, IBM vice president of engineering John McPherson, who would become the company’s point person on SAGE, quickly recognized the magnitude of the data processing opportunity — the largest for IBM since it was contracted to develop the accounting and tracking system for the Social Security Administration in the mid-1930s. Thomas Watson Jr., IBM’s president at the time, agreed. “I worked harder to win that contract than I worked for any other sale in my life,” he would recall in his memoir.

IBM won the rights to build the computer at the heart of the digital system, known as the AN/FSQ-7, because of the company’s “much higher degree of purposefulness, integration and esprit de corps,” according to MIT project leader Jay W. Forrester, and closer ties among research, factory and field maintenance. About 300 full-time IBMers were assigned to SAGE by the end of 1953, primarily in the company’s Poughkeepsie and Kingston, New York, facilities, and in MIT’s hometown of Cambridge, Massachusetts.

When the AN/FSQ-7 prototype was unveiled in 1956, it provided military commanders a view of an air battle and demonstrated the ability to automatically calculate the most effective use of missiles and aircraft to fend off attack. By 1958, more than 7,000 IBMers were involved in the project, including engineers, sales staff and senior management, as well as the technical liaisons who collaborated with academics and military personnel on installation, operation and maintenance.

When fully deployed in 1963, SAGE included multiple redundancies to allow downtime-free maintenance. The system was deployed across 27 North American centers, each with its own AN/FSQ-7 system that comprised two fully functional machines, one of which served as a backup. The total cost of SAGE is commonly estimated to have been around USD 8 billion, including 56 IBM computers at USD 30 million each. The AN/FSQ-7 system weighed 250 tons and occupied an acre of floor space.