The AN/FSQ-7 Combat Direction Central, referred to as the Q7 for short, was a
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
ized
command and control
Command and control (abbr. C2) is a "set of organizational and technical attributes and processes ... hatemploys human, physical, and information resources to solve problems and accomplish missions" to achieve the goals of an organization or en ...
system for
Cold War
The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because the ...
ground-controlled interception Ground-controlled interception (GCI) is an air defence tactic whereby one or more radar stations or other observational stations are linked to a command communications centre which guides interceptor aircraft to an airborne target. This tactic was p ...
used in the
USAF
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
Semi-Automatic Ground Environment
The Semi-Automatic Ground Environment (SAGE) was a system of mainframe computer, large computers and associated computer network, networking equipment that coordinated data from many radar sites and processed it to produce a single unified image ...
(SAGE)
air defense
Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...
network.
[
The name “AN/FSQ” derives from ''Army-Navy / Fixed Special eQuipment''.]
An advancement of the pioneering MIT
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
Whirlwind II digital computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These pro ...
design, and manufactured by IBM as prime contractor, the AN/FSQ-7 was the largest discrete computer system ever built. Each of the 24 installed machines[ weighed 250 tons.][ The AN/FSQ-7 used a total of 60,000 ]vacuum tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied.
The type kn ...
s (49,000 in the computers)[ and up to 3 ]megawatt
The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...
s of electricity, performing about 75,000 instructions per second
Instructions per second (IPS) is a measure of a computer's processor speed. For complex instruction set computers (CISCs), different instructions take different amounts of time, so the value measured depends on the instruction mix; even for compa ...
for networking regional radars.
Primary functions
Installations in the USAF
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
Semi-Automatic Ground Environment
The Semi-Automatic Ground Environment (SAGE) was a system of mainframe computer, large computers and associated computer network, networking equipment that coordinated data from many radar sites and processed it to produce a single unified image ...
(SAGE) air defense
Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...
network were configured as duplex systems, using a pair of AN/FSQ-7 computers to provide fault tolerance
Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the ...
. 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.
The AN/FSQ-7 calculated one or more[ predicted interception points][ for assigning manned aircraft or ]CIM-10 Bomarc
The Boeing CIM-10 BOMARC (Boeing Michigan Aeronautical Research Center) (IM-99 Weapon System prior to September 1962) was a supersonic ramjet powered long-range surface-to-air missile (SAM) used during the Cold War for the air defense of North ...
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][compiled by ] via the SAGE Ground to Air Data Link Subsystem (cf. bomber vectoring to a Bomb Release Point in 1965–1973 Vietnam via vacuum-tube ''analog'' computers.)
History
The first United States radar network used voice reporting to the 1939 Twin Lights Station in New Jersey, and the post-World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
experimental Cape Cod System The Cape Cod System was a computer system designed to simulate an air defense system covering southern New England. It was named after Cape Cod, the location of many of the radars.
History
The Cape Cod System was designed to demonstrate a computeri ...
used a Whirlwind I
Whirlwind I was a Cold War-era vacuum tube computer developed by the MIT Servomechanisms Laboratory for the U.S. Navy. Operational in 1951, it was among the first digital electronic computers that operated in real-time for output, and the first t ...
computer at Cambridge, Massachusetts
Cambridge ( ) is a city in Middlesex County, Massachusetts, United States. As part of the Boston metropolitan area, the cities population of the 2020 U.S. census was 118,403, making it the fourth most populous city in the state, behind Boston, ...
to network long-range and several short-range radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
s. The key Whirlwind modification for radar netting was the development of magnetic-core memory
Magnetic-core memory was the predominant form of random access, random-access computer memory for 20 years between about 1955 and 1975.
Such memory is often just called core memory, or, informally, core.
Core memory uses toroids (rings) of a ...
that vastly improved reliability, doubled operating speed, and quadrupled input speed relative to the original Williams tube
The Williams tube, or the Williams–Kilburn tube named after inventors Freddie Williams and Tom Kilburn, is an early form of computer memory. It was the first random-access digital storage device, and was used successfully in several early co ...
memory of the Whirlwind I.
The AN/FSQ-7 was based on the larger and faster (but uncompleted) Whirlwind II design.[ It proved too much for MIT's resources, resulting in IBM being retained as ]prime contractor
A general contractor, main contractor or prime contractor is responsible for the day-to-day oversight of a construction site, management of vendors and trades, and the communication of information to all involved parties throughout the course of ...
– though the MIT Lincoln Laboratory
The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and dev ...
Division 6 still participated in AN/FSQ-7 development.[
Similar to the Q7, the smaller ]AN/FSQ-8 Combat Control Central
The AN/FSQ-8 Combat Control Central was a United States Air Force computerized command and control system. Several of the centrals were used in the Semi-Automatic Ground Environment (SAGE) air defense network for Cold War ground-controlled inte ...
was produced without a
Automatic Initiation Area Discriminator
and other equipment.[
A simplex version of the AN/FSQ-7 was located at the premises of the System Development Corporation in Santa Monica, California from 1957 until the premises were vacated some time after 1981.
]
Uses
SAGE
The experimental SAGE subsector
The Experimental Semi-Automatic Ground Environment (SAGE) Sector (ESS, Experimental SAGE Subsector until planned Sectors/Subsectors were renamed NORAD Regions, Divisions, and Sectors) was a prototype Cold War Air Defense Sector for developing the ...
, located in Lexington, Massachusetts
Lexington is a suburban town in Middlesex County, Massachusetts, United States. It is 10 miles (16 km) from Downtown Boston. The population was 34,454 as of the 2020 census. The area was originally inhabited by Native Americans, and was firs ...
, 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.
DC-1 at ]McGuire Air Force Base
McGuire AFB/McGuire, the common name of the McGuire unit of Joint Base McGuire-Dix-Lakehurst, is a United States Air Force base in Burlington County, New Jersey, United States, approximately south-southeast of Trenton. McGuire is under the j ...
was the first operational site of the AN/FSQ-7[ with consoles scheduled for delivery Aug–Oct 1956.][ Groundbreaking at ]McChord Air Force Base
McChord Field is a United States Air Force base in the northwest United States, in Pierce County, Washington. South of Tacoma, McChord Field is the home of the 62d Airlift Wing, Air Mobility Command, the field's primary mission being world ...
was in 1957 where the "electronic brain" began arriving in November 1958. The Cape Canaveral BOMARC 624-XY1's intercept of a target drone in August 1958 used the Kingston, New York
Kingston is a Administrative divisions of New York#City, city in and the county seat of Ulster County, New York, United States. It is north of New York City and south of Albany, New York, Albany. The city's metropolitan area is grouped with t ...
, Q7[ 1500 miles away. By 1959, the 2000th simulated BOMARC intercept had been completed by the Q7.
The SAGE/]Missile Master
Missile Master was a type of United States Army, US Army United States Army Space and Missile Defense Command, Missile Command military installation for the Cold War Project Nike, each which were a System of systems, complex of systems and facil ...
test program conducted large-scale field testing of the ATABE mathematical model using radar tracks of actual Strategic Air Command
Strategic Air Command (SAC) was both a United States Department of Defense Specified Command and a United States Air Force (USAF) Major Command responsible for command and control of the strategic bomber and intercontinental ballistic missile ...
and Air Defense Command
Aerospace Defense Command was a major command (military formation), command of the United States Air Force, responsible for continental air defense. It was activated in 1968 and disbanded in 1980. Its predecessor, Air Defense Command, was est ...
aircraft conducting mock penetrations into defense sectors[ (cites Miller 1961)] (cf. Operation Skyshield
Operation Sky Shield, sometimes known as Exercise Skyshield, was a series of three large-scale military exercises conducted in the United States in 1960, 1961, and 1962 by the North American Aerospace Defense Command (NORAD) and the Strategic Ai ...
). The vacuum-tube SAGE network was completed (and obsolete) in 1963, and a system ergonomic test was performed at Luke Air Force Base
Luke Air Force Base is a United States Air Force base in Maricopa County, Arizona, United States., effective 20 December 2007 It is located west of the central business district of Glendale, and west of Phoenix.
Luke AFB is a major training ...
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."[ Back-Up Interceptor Control Systems (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.
Sabre
The SABRE
A sabre ( French: sabʁ or saber in American English) is a type of backsword with a curved blade associated with the light cavalry of the early modern and Napoleonic periods. Originally associated with Central European cavalry such as th ...
airline reservation system used AN/FSQ-7 technology.
In popular media
Q7 components were used as prop
A prop, formally known as (theatrical) property, is an object used on stage or screen by actors during a performance or screen production. In practical terms, a prop is considered to be anything movable or portable on a stage or a set, distinc ...
s in numerous films and television series needing futuristic-looking computers, despite the fact they were built in the 1950s. Q7 components were used in ''The Time Tunnel
''The Time Tunnel'' is an American color science fiction TV series written around a theme of time travel adventure starring James Darren and Robert Colbert. The show was creator-producer Irwin Allen's third science-fiction television series and ...
'', ''The Towering Inferno
''The Towering Inferno'' is a 1974 American disaster film directed by John Guillermin and produced by Irwin Allen, featuring an ensemble cast led by Paul Newman and Steve McQueen. It was adapted by Stirling Silliphant from the novels '' The Towe ...
'', ''Logan's Run
''Logan's Run'' is a science fiction novel by American writers William F. Nolan and George Clayton Johnson. Published in 1967, the novel depicts a dystopic Malthusianism future society in which both population and the consumption of resource ...
'', ''WarGames
''WarGames'' is a 1983 American science fiction techno-thriller film written by Lawrence Lasker and Walter F. Parkes and directed by John Badham. The film, which stars Matthew Broderick, Dabney Coleman, John Wood, and Ally Sheedy, follows Dav ...
'', ''Independence Day
An independence day is an annual event commemorating the anniversary of a nation's independence or statehood, usually after ceasing to be a group or part of another nation or state, or more rarely after the end of a military occupation. Man ...
'', ''Planet of the Apes
''Planet of the Apes'' is an American science fiction media franchise consisting of films, books, television series, comics, and other media about a world in which humans and intelligent apes clash for control. The franchise is based on Frenc ...
'' TV series (Season 1, Episode 5, "The Legacy" aired October 1974), and many others.
Today
The Computer History Museum
The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact on ...
displays several AN/FSQ-7 components.
Equipment
MIT selected IBM as the prime contractor for equipment construction.
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
In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...
devices such as:
* IBM 723 card punch and IBM 713 punched card
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
reader
* IBM 718 line printer
A line printer prints one entire line of text before advancing to another line. Most early line printers were
impact printers.
Line printers are mostly associated with unit record equipment and the early days of digital computing, but the ...
(64 print positions)
* drum auxiliary memory (50 "fields" of 2048 words each) and IBM 728
The IBM 728 magnetic tape drive was used on the SAGE AN/FSQ-7 computer. It was physically similar to the IBM 727, but with significantly different specifications.
This is one of several IBM 7 track
IBM's first magnetic-tape data storage d ...
magnetic tape drives (32-bit words)
* Crosstelling Input (XTL) from other AN/FSQ sites
* Display and Warning Light System with dozens of consoles in various rooms having Situation Display Tubes, Digital Display Tubes, and controls (e.g., push buttons and light gun) including:
** Duplex Maintenance Console (two), each DMC operated one of the Central Computer Systems and allowed diagnostics (a speaker was available)
** Tracker Initiator Consoles for designating a "blip" (radar return) to be tracked (assign a track number and to relay speed, direction, and altitude)
** Command Post Digital Display Desk[
** Senior Director's keyed console with the Bomarc fire button][
** LRI Monitor Console] for monitoring Long Range Radar data
** Large Board Projection Equipment Operator displays were directly copied on 35 mm film 35 mm may refer to:
* 135 film, a type of still photography format commonly referred to as 35 mm film
* 35 mm movie film
35 mm film is a film gauge used in filmmaking, and the film standard. In motion pictures that record on f ...
which were projected on the board.
Punched card data was transferred to and from the core memory as binary image
A binary image is one that consists of pixels that can have one of exactly two colors, usually black and white. Binary images are also called ''bi-level'' or ''two-level'', Pixelart made of two colours is often referred to as ''1-Bit'' or ''1b ...
s. 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.[
]
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 (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. At Luke Air Force Base
Luke Air Force Base is a United States Air Force base in Maricopa County, Arizona, United States., effective 20 December 2007 It is located west of the central business district of Glendale, and west of Phoenix.
Luke AFB is a major training ...
, 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 a sign bit
In computer science, the sign bit is a bit in a signed number representation that indicates the sign of a number. Although only signed numeric data types have a sign bit, it is invariably located in the most significant bit position, so the term ...
. 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
An index register in a computer's CPU is a processor register (or an assigned memory location) used for pointing to operand addresses during the run of a program. It is useful for stepping through strings and arrays. It can also be used for hol ...
. The following bits specified an instruction class, class variation and instruction-dependent auxiliary information. Addresses were written in octal
The octal numeral system, or oct for short, is the radix, base-8 number system, and uses the Numerical digit, digits 0 to 7. This is to say that 10octal represents eight and 100octal represents sixty-four. However, English, like most languages, ...
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.][
]
See also
*List of vacuum-tube computers
Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preceded by systems using electromechanical relays and followed by systems built from discrete transis ...
References
:*
{{DEFAULTSORT:IBM AN FSQ-7 Combat Direction Central
1955 in computing
1955 in military history
1958 in military history
1983 disestablishments
1983 in military history
Cold War military computer systems of the United States
IBM vacuum tube computers
Equipment of the United States Air Force
Missile guidance
AN/FSQ-7
The AN/FSQ-7 Combat Direction Central, referred to as the Q7 for short, 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 ...