The IBM AN/FSQ-7 Combat Direction Central (colloq. "Q7") was a computerized command and control system for Cold War ground-controlled interception used in the USAF Semi-Automatic Ground Environment (SAGE) air defense network. The largest computer system ever built, each of the 24 installed machines weighed 250 tons and had two computers. The AN/FSQ-7 used a total of 60,000 vacuum tubes (49,000 in the computers) and up to 3 megawatts of electricity, performing about 75,000 instructions per second for networking regional radars. The AN/FSQ-7 calculated one or more predicted interception points for assigning manned aircraft or CIM-10 Bomarc missiles to intercept an intruder using the Automatic Target and Battery Evaluation (ATABE) algorithm. Also used in the Nike AN/FSG-1 system, ATABE automa