AN / FSQ - 7 Combat Direction Central 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 tube s ( 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 automated the " Whiz Wheel " ( Felsenthal CPU - 73 A / P Air Navigation Attack Computer ) method used in manual command post operations . The Q7 fire button launched the Bomarc , and an additional Q7 algorithm automatically directed the missile during climb and cruise to the beginning of " its supersonic dive on the target " when guidance transferred to " the missile seeker system " for the " homing dive " . Later improvements allowed transmission of Q7 guidance to autopilots of manned fighters for vectoring to targets via the SAGE Ground to Air Data Link Subsystem ( cf . bomber vectoring to a Bomb Release Point in 1965 - 73 Vietnam via vacuum - tube " analog " computers . ) History . The first US radar network used voice reporting to the 1939 Twin Lights Station in New Jersey , and the post - WWII experimental Cape Cod System used a Whirlwind I computer at Cambridge to network long - range and several short - range radar s . The key Whirlwind modification for radar netting was the development of magnetic core memory that vastly improved reliability , operating speed ( ×2 ) , and input speed ( ×4 ) over the original Williams tube memory of the Whirlwind I . The AN / FSQ - 7 was based on the larger and faster Whirlwind II design , which was not completed and was too much for MIT ' s resources ( Lincoln Laboratory Division 6 still participated in AN / FSQ - 7 development ) . Similar to the Q7 , the smaller IBM AN / FSQ - 8 Combat Control Central was produced without an Automatic Initiation Area Discriminator and other equipment . " " The experimental SAGE subsector , located in Lexington , Mass . , was completed in 1955 … equipped with a prototype AN / FSQ - 7 … known as XD - 1 " " in Building F . The third evaluation run with the XD - 1 was in August and the prototype was complete in October 1955 except for displays . By 1959 , the 2000th simulated BOMARC intercept had been completed by the Q7 , while the Cape Canaveral BOMARC 624 - XY1 ' s intercept of a target drone in August 1958 used the Kingston , New York , Q7 " 1500 miles away " . DC - 1 at McGuire AFB was the first operational site of the AN / FSQ - 7 with consoles scheduled for delivery Aug - Oct 1956 . Groundbreaking at McChord Air Force Base was in 1957 where the " electronic brain " began arriving in November 1958 . The " SAGE / Missile Master test program " conducted large - scale field testing of the ATABE " mathematical model " using radar tracks of actual Strategic Air Command and Air Defense Command aircraft conducting mock penetrations into defense sectors ( cf . Operation Skyshield ) . The vacuum - tube SAGE network was completed ( and obsolete ) in 1963 , and a system ergonomic test at Luke Air Force Base in 1964 " " showed conclusively that the wrong timing of human and technical operations was leading to frequent truncation of the flight path tracking system " " ( Harold Sackman ) . Backup Interceptor Control System s ( BUIC ) were used to replace the AN / FSQ - 7s : two remained at SAGE sites until 1983 including McChord AFB , and the Q7 at Luke AFB was demolished in February 1984 . The SABRE airline reservation system used AN / FSQ - 7 technology . Q7 components were used in numerous films TV series and TV series needing futuristic looking computers , despite the fact they were built in the 1950s . Q7 components were used in " The Time Tunnel " , " The Towering Inferno " , " Logan ' s Run " , " WarGames " and " Independence Day " amongst many others . The Computer History Museum displays several AN / FSQ - 7 components . Equipment . The Central Computer System of the AN / FSQ - 7 had two computers for redundancy each with Arithmetic , Core Memory , Instruction Control , Maintenance Control , Selection & IO Control , and Program elements . The Q7 had input / output devices such as : Punched card data was transferred to and from the core memory as binary image s . Only the right 64 columns were transferred , with each row containing two 32 - bit words . ( The left columns could be punched using a special instruction . ) Data was transferred to the line printer as a card image as well . Core Memory Element . The FSQ - 7 and - 8 used core memory with 32 - bit words plus a parity bit , operating at a 6 - microsecond cycle time . Both machines had two banks of memory , memory 1 and memory 2 . On the FSQ 7 memory 1 had 65 , 536 words and memory 2 had 4096 words . On the FSQ - 8 , each bank had 4096 words . For data storage , each word was divided into two halves , each half was a 15 - bit number with a sign bit . Arithmetic operations were performed on both halves simultaneously . Each number was treated as a fraction between - 1 and 1 . " This restriction is placed on data primarily so that the multiplication of two numbers will always result in a product smaller than either of the numbers , thus positively avoiding overflow . " Properly scaling calculations was the responsibility of the programmer . Instructions used the right half word plus the left sign bit to form addresses , yielding a 17 - bit address space . The remainder of the left half word specified the operation . The first three bits after the sign specified an index register . The following bits specified an instruction class , class variation and instruction - dependent auxiliary information . Addresses were written in octal notation , with the two sign bits forming a prefix , so 2 . 07777 would be the highest word in memory 2 . Arithmetic registers were provided for both halves of the data word and included an accumulator , an A register that held the data value retrieved from memory , and a B register that held the least significant bits of a multiplication , the magnitude of a division , as well as shifted bits . There was also a program counter , four index registers , and a 16 - bit real time clock register which was incremented 32 times a second . Trigonometric sine and cosine functions used 1 . 4 degree precision ( 256 values ) via look - up tables .