GCN at 25
Around the time GCN was beginning its own era, in the last month of 1982, the Air Force was about to bring another era to an end by shutting down the Semi-Automatic Ground Environment.
SAGE was conceived of in the late 1940s as a means of tracking Soviet and other enemy aircraft and came into being during the next decade. The system consisted of about 30 computers housed at separate centers, and the last SAGE, deployed in 1963, was the largest computer ever built. It had more than 50,000 vacuum tubes, took up 20,000 square feet and weighed more than 250 tons. It consumed more than a million watts, generating so much heat that, if the air conditioning (the centers had large cooling towers) failed, SAGE would melt within a minute.
But SAGE was a lot more than just the largest and last of the old vacuum-tube dinosaurs. It was one of the first large wide-area networks, using modems for communications among the various centers and more than 100 radar stations nationwide. It employed the first CRT monitors ' about 150 per center ' and operators could use light guns to highlight images on screen. The system also had built-in redundancy ' each center had an extra CPU in stand-by mode.
SAGE, built by IBM with software integration by the Massachusetts Institute of Technology's Lincoln Laboratory, had a further influence on people who worked on the program, including J.C.R. Licklider, who later led the research toward creating ARPAnet.
By the time SAGE was put to rest in 1983, it had paved some of the paths government information technology managers would follow in the decades to come.