Semi Automatic Ground Environment (SAGE) was a real-time, computer based command and control system designed in the late 1950's and fully functional and deployed by 1963. The system as designed consisted of 24 directional centers around the United States as well as three combat centers. Data was collected at each of the directional centers from over 100 different sources such as radar, human volunteers and aircraft sightings. This information was collated and forwarded via telephone communication lines to one of the three combat centers.

The information was interpreted by the computer and displayed on something totally revolutionary for that time period: a cathode ray tube display screen. The display, while similar to a radar screen, was extremely versatile. The operator of the terminal could pull up past positions of aircraft or missiles, as well as project future locations. In addition, the system used another feature far in advance of its time: a light gun. The gun was used by the operators to point at an aircraft on the screen, and the computer would respond by displaying related identification information about that aircraft. The system has the dubious distinction of holding the record for the world's largest (physical size) computer ever created.

1. Deployed: 1963 - 1983
2. Computer Used: AN/FSQ-7
3. Employed 55,000 vacuum tubes each
4. Occupied 1/2 acre of floor space
5. Weight: 275 tons per unit
6. Electrical supply required: up to 3 megawatts
7. Each system could support up to 150 terminals
8. Total systems actually deployed: 22
9. First use of magnetic memory - 64 Kb
10. Total Cost: Approximately $61 Billion