The IBM AN/FSQ-31 SAC Data Processing System (FSQ-31, Q-31, colloq.) was a USAF command, control, and coordination system for the Cold War Strategic Air Command (SAC). IBM's Federal Systems Division was the prime contractor for the AN/FSQ-31s, which were part of the TBD 465L SAC Automated Command and Control System (SACCS), a "Big L" system of systems (cf. 416L SAGE & 474L BMEWS( which had numerous sites throughout the Continental United States: "all SAC command posts and missile LCC's" (e.g., The Notch), a communication network, etc.; and the several FSQ-31 sites including: