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The Semi-Automatic Ground Environment (SAGE) was a system of large computers and associated networking equipment that coordinated data from many radar sites and processed it to produce a single unified image of the airspace over a wide area. SAGE directed and controlled the NORAD response to a Soviet air attack, operating in this role from the late 1950s into the 1980s. Its enormous computers and huge displays remain a part of cold war lore, and a common prop in movies such as ''Dr. Strangelove'' and ''Colossus''. Powering SAGE were the largest computers ever built, IBM's AN/FSQ-7. Each SAGE Direction Center (DC) contained two FSQ-7's for redundancy, filling two floors of a large cube-shaped concrete building. The upper two floors contained offices, operator stations, and a single two-story radar display visible to most of the DC's personnel. Information was fed to the DC's from a network of radar stations as well as readiness information from various defence sites. The computers, based on the raw radar data, developed "tracks" for the reported targets, and automatically calculated which defences were within range. Subsets of the data were then sent to the many operator consoles, where the operators used light guns to select targets onscreen for further information, select one of the available defences, and issue commands to attack. These commands would then be automatically sent to the defence site via teleprinter. Later additions to the system allowed SAGE's tracking data to be sent directly to CIM-10 Bomarc missiles and some of the US Air Force's interceptor aircraft in-flight, directly updating their autopilots to maintain an intercept course without operator intervention. Each SAGE DC also forwarded data to a Combat Center (CC) for "supervision of the several sectors within the division"〔 ("each combat center () the capability to coordinate defense for the whole nation").〔 Connecting the various sites was an enormous network of telephones, modems and teleprinters. SAGE became operational in the late 1950s and early 1960s at a combined cost of billions of dollars. It was noted that the deployment cost more than the Manhattan Project, which it was, in a way, defending against. Throughout its development there were continual questions about its real ability to deal with large attacks, and several tests by Strategic Air Command bombers suggested the system was "leaky". Nevertheless, SAGE was the backbone of NORADs air defence system into the 1980s, by which time the tube-based FSQ-7's were increasingly costly to maintain and completely outdated. Today the same command and control task is carried out by microcomputers, based on the same basic underlying data. ==Background== Computerized command and control for United States air defense was conceived in July 1945 during the Signal Corps' Project 414A contracted to Bell Laboratories after "employment of an American version of CDS", the British air defense C2 system, had been identified for air defense command and control on June 12.〔 (cited by Schaffel pdf p. 311)〕 The terms of the National Security Act were formulated during 1947, leading to the creation of the US Air Force out of the former US Army Air Force. During April of the same year, US Air Force staff were identifying specifically the requirement for the creation of automatic equipment for radar-detection which would relay information to an air defence control system, a system which would function without the inclusion of persons for its operation.〔 The December 1949 "Air Defense Systems Engineering Committee" led by Dr. George Valley had recommended computerized networking〔 (cited by Schaffel p. 197)〕 for "radar stations guarding the northern air approaches to the United States" (e.g., in Canada). After a January 1950 meeting, Valley and Jay Forrester proposed using the Whirlwind I (completed 1951) for air defense. On August 18, 1950, when the "1954 Interceptor" requirements were issued, the USAF "noted that manual techniques of aircraft warning and control would impose “intolerable” delays"〔 (cited by Volume I p. 187)〕 (Air Material Command (AMC) published ''Electronic Air Defense Environment for 1954'' in December .) During February–August 1951 at the new Lincoln Laboratory, the USAF conducted Project Claude which concluded an improved air defense system was needed. In a test for the U.S. military at Bedford, during the 20th of April 1951, data produced by radar monitoring was transmitted through telephone lines to a computer for the first time, showing the detection of a mock enemy aircraft. This indicated the likelihood of possible future technology being produced capable of detecting and directing U.S. fighter planes to defend the security of the U.S.A. in the air, through the creation of an air-borne attack defence system. This first test was directed by C. Robert Wieser.〔(''20th of April 1951'' - p.1, ''National Security Act 1947'' - p.12, ''April 1947'' - p.13)〕 The "Summer Study Group" of scientists in 1952 recommended "computerized air direction centers…to be ready by 1954."〔 (citation 29 of Volume I, p. 25)〕 IBM's "Project High" assisted under their October 1952 Whirlwind subcontract with Lincoln Laboratory, and a 1952 USAF Project Lincoln "fullscale study" of "a large scale integrated ground control system" resulted in the SAGE approval "first on a trial basis in 1953". The USAF had decided by April 10, 1953, to cancel the competing ADIS (based on CDS), and the University of Michigan’s Aeronautical Research Center withdrew in the spring. Air Research and Development Command (ARDC) planned to "finalize a production contract for the Lincoln Transition System". Similarly, the July 22, 1953, report by the Bull Committee (NSC 159) identified completing the Mid-Canada Line radars as the top priority and "on a second-priority-basis: the Lincoln automated system"〔quote from Schaffel p. 191; Condit p. 259 footnote 1 cites: "''CCS 381 US (5-23-46) sec 37.''"〕 (the decision to control Bomarc with the automated system was also in 1953.)〔 (cited by Volume I p. 108 footnote 69: "''Before the end of 1953, it was also decided that the Sage system being developed by Lincoln Laboratories would be used to control the Bomarc.69''")〕 The Priority Permanent System with the initial (priority) radar stations was completed in 1952 as a "manual air defense system"〔 (e.g., NORAD/ADC used a "Plexiglas plotting board" at the Ent command center.) The Permanent System radar stations included 3 subsequent phases of deployments and by June 30, 1957, had 119 "Fixed CONUS" radars, 29 "Gap-filler low altitude" radars, and 23 control centers". At "the end of 1957, ADC operated 182 radar stations () 17 control centers … 32 () had been added during the last half of the year as low-altitude, unmanned gap-filler radars. The total consisted of 47 gap-filler stations, 75 Permanent System radars, 39 semimobile radars, 19 Pinetree stations,…1 Lashup -era radar and a single Texas Tower". "On 31 December 1958, USAF ADC had 187 operational land-based radar stations" (74 were "P-sites", 29 "M-sites", 13 "SM-sites", & 68 "ZI Gap Fillers"). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Semi-Automatic Ground Environment」の詳細全文を読む スポンサード リンク
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