| AN/FSQ-7 Combat Direction Central | |
|---|---|
| Part ofSemi-Automatic Ground Environment | |
| AL:Gunter Annex(DC-09) AZ:Luke Air Force Base(DC-21)[1] CA:Beale Air Force Base(DC-18) CA:Norton Air Force Base (DC-17) ME:Bangor Air National Guard Base(DC-15) MI:Custer Air Force Station(DC-06) MI:K.I. Sawyer AFB(DC-14) MN:Duluth AFB(DC-10) MO:Richards-Gebaur Air Force Base (DC-08) MT:Malmstrom Air Force Base (DC-20) ME:Topsham Air Force Station (BaADS)(DC-05) ND:Grand Forks Air Force Base(DC-11) ND:Minot Air Force Base(DC-19) NJ:McGuire Air Force Base (DC-01) NV:Stead AFB (DC-16) NY:Hancock Field (Syracuse AFS) (DC-03) NY:Stewart Air Force Base(DC-02) ON:CFB North Bay,Ontario (DC-31) OR:Adair Air Force Station(DC-13) VA:Fort Lee Air Force Station (DC-04) WA:McChord Air Force Base(DC-12) WI:Truax Field(DC-07) in United States | |
 The AN/FSQ-7 included a MaintenanceIntercom System (the phone on end of cabinet). | |
| Site information | |
| Type | Militarycommand, control and coordination system |
| Also known as | Q7 |
|---|---|
| Manufacturer | IBM |
| Generation | 1 |
| Release date | 1955; 70 years ago (1955) |
| CPU | 49,000vacuum tubes @ 75,000instructions per second |
| Power | up to 3megawatts of electricity |
| Weight | 250 tons |
TheAN/FSQ-7 Combat Direction Central, referred to as theQ7 for short, was acomputerizedair defensecommand and control system. It was used by theUnited States Air Force forground-controlled interception as part of theSemi-Automatic Ground Environment network during theCold War.[2]
The name “AN/FSQ” derives fromArmy-Navy / Fixed Special eQuipment.[3]
An advancement of the pioneeringMITWhirlwind IIdigital computer design, and manufactured byIBM as prime contractor, the AN/FSQ-7 was the largest discrete computer system ever built. Each of the 24 installed machines[4]: 9 weighed 250tons.[5] The AN/FSQ-7 used a total of 60,000vacuum tubes[5] (49,000 in the computers)[4]: 9 and up to 3megawatts of electricity, performing about 75,000instructions per second for networking regional radars.
Installations in theUSAFSemi-Automatic Ground Environment (SAGE)air defense network were configured as duplex systems, using a pair of AN/FSQ-7 computers to providefault tolerance. One was active at any time, the other on standby. The standby system copied data from the active system to minimize switchover time if needed. A scheduled switchover took place every day.[6]: 179–181
The AN/FSQ-7 calculated one or more[2] predicted interception points[7] for assigning manned aircraft orCIM-10 Bomarc missiles to intercept an intruder using the Automatic Target and Battery Evaluation (ATABE) algorithm.[8] Also used in theNike AN/FSG-1 system, ATABE automated the Whiz Wheel (Felsenthal CPU-73 A/P Air Navigation Attack Computer)[9] method used in manual command post operations.[10]
The Q7 fire button launched the Bomarc,[11] 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.[7]: 30–3 Later improvements allowed transmission of Q7 guidance to autopilots of manned fighters for vectoring to targets[12] via the SAGEGround to Air Data Link Subsystem (cf. bomber vectoring to a Bomb Release Pointin 1965–1973 Vietnam viavacuum-tubeanalog computers.)
The first United States radar network used voice reporting to the 1939Twin Lights Station in New Jersey, and the post-World War II experimentalCape Cod System used aWhirlwind I computer atCambridge, Massachusetts to network long-range and several short-rangeradars. The key Whirlwind modification for radar netting was the development ofmagnetic-core memory that vastly improved reliability, doubled operating speed, and quadrupled input speed relative to the originalWilliams tube memory of the Whirlwind I.[citation needed]
The AN/FSQ-7 was based on the larger and faster (but uncompleted) Whirlwind II design.[2] It proved too much for MIT's resources, resulting inIBM being retained asprime contractor – though theMIT Lincoln Laboratory Division 6 still participated in AN/FSQ-7 development.[13]
Similar to the Q7, the smallerAN/FSQ-8 Combat Control Central was produced without an 'Automatic Initiation Area Discriminator'[14][15]: 151
A simplex version of the AN/FSQ-7 was located at the premises of theSystem Development Corporation in Santa Monica, California from 1957 until the premises were vacated some time after 1981.
Theexperimental SAGE subsector, located inLexington, Massachusetts, was completed in 1955, equipped with a prototype AN/FSQ-7 known as XD-1[16] in Building F. The third evaluation run with the XD-1 was in August[13] and the prototype was complete in October 1955, except for displays.[17]
DC-1 atMcGuire Air Force Base was the first operational site of the AN/FSQ-7[2]: 11:10 with consoles scheduled for delivery Aug–Oct 1956.[18] Groundbreaking atMcChord Air Force Base was in 1957[19] where the "electronic brain" began arriving in November 1958.[20] TheCape Canaveral BOMARC 624-XY1's intercept of a target drone in August 1958 used theKingston, New York, Q7[7]: 57 1500 miles away.[21] By 1959, the 2000th simulated BOMARC intercept had been completed by the Q7.
The SAGE/Missile Master test program conducted large-scale field testing of the ATABEmathematical model using radar tracks of actualStrategic Air Command andAir Defense Command aircraft conducting mock penetrations into defense sectors[8] (cf.Operation Skyshield). The vacuum-tube SAGE network was completed (and obsolete) in 1963, and a system ergonomic test was performed atLuke Air Force Base in 1964. According to Harold Sackman, it "showed conclusively that the wrong timing of human and technical operations was leading to frequent truncation of the flight path tracking system."[4]: 9 Back-Up Interceptor Control Systems (BUIC) were used to replace the AN/FSQ-7s:[4]: 10 two remained at SAGE sites until 1983[4]: 9 including McChord AFB,[22] and the Q7 at Luke AFB was demolished in February 1984.[23]
TheSABRE airline reservation system used AN/FSQ-7 technology.[24]
Q7 components were used asprops in numerous films and television series needing futuristic-looking computers, despite the fact they were built in the 1950s. Q7 components were used inThe Time Tunnel,The Towering Inferno,Logan's Run,WarGames,Independence Day,Planet of the Apes TV series (Season 1, Episode 5, "The Legacy" aired October 1974),[25] and many others.[26]
TheComputer History Museum displays several AN/FSQ-7 components.
MIT selected IBM as the prime contractor for equipment construction.[27]TheCentral 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.[28] The Q7 hadinput/output devices such as:
Punched card data was transferred to and from the core memory asbinary images. Only the rightmost 64 columns were transferred, with each row containing two 32-bit words. (The left columns could be punched using a special instruction.) Data were transferred to the line printer as a card image as well.[15]: 125
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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 (Commonly referred to as Big Mem and little Mem). On the FSQ 7 memory 1 had 65,536 words and memory 2 had 4096 words. AtLuke Air Force Base, the FSQ-7 held 65,536 words at each bank and the FSQ-8 4096 words at each bank.
For data storage, each word was divided into two halves, each half was a 15-bit number with asign 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 anindex register. The following bits specified an instruction class, class variation and instruction-dependent auxiliary information. Addresses were written inoctal 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.[15]: 27 Trigonometric sine and cosine functions used 1.4 degree precision (256 values) via look-up tables.[15]: 67
Luke center was unique in the fact that it was the programming center for all other sage sites. This only meant that our computers…had more core memory, 32K total
TheSystem Development Corporation…in the design of massive computer programs … Burroughs…electronic equipment … Western Electric…assist the Air Force in coordinating and managing the entire effort…and design of buildings. …SAGE project office…Air Material CommandNOTE: The film identifies "Direction Center" versus "Data Center".minute 5:15
On August 7, 1958, the IBM/SAGE computer at Kingston[the IBM facility] undertook the first remote-controlled intercept of a drone target by a BOMARC missile. The BOMARC was fired from Cape Canaveral and the intercept was made at sea.: 15
Future experiments and/or tests: Data from the Phase II and Phase IIINORADSAGE/Missile Master test program is to be used to validate the mathematical model. These are large-scale system tests employingSAC andADC aircraft. The field test program is the responsibility of the NORAD Joint Test Force stationed atStewart Air Force Base.(cites Miller 1961)
{{cite report}}: CS1 maint: numeric names: authors list (link){{cite report}}: CS1 maint: numeric names: authors list (link)introduction of the air defense[software] program … from the Drum System when available and needed. … For more information on the subject of programming, refer to PH 45-00002.: 57 (one of various SAGE documents at BitSavers.org)
| External videos | |
|---|---|
 "On Guard! The Story of SAGE" | |
| AN/FSQ-7 used for Bomarc launch | |
| "In Your Defense" (Col. John Morton, narrator) |
| Records | ||
|---|---|---|
| Preceded by | World's most powerful computer 1958–1959 | Succeeded by |
