JF Ptak Science Books Post 1341
Quality Control of America's Anti-Bomber Defensive "Shield": the SAGE System, 1958
The SAGE (The Semi-Automatic Ground Environment) was an "air traffic control device"1 that was used to detect enemy aircraft, relate their position and speed to interceptors which would destroy the threat. It was basically the air defense shield against attack of North America by Soviet bombers (in the pre-ICBM days of MAD). The MIT/IBM SAGE system was enormously important in the history of computing because of its many real-time, interactive and online aspects--it was an enormously successful and futuristic system, one of the "best" computers ever built. This paper on the computer's ability to self-reference and check itself, by P.K. Luster, was written in 1958 and serves as an interesting insight into quality control for the world's first nation-wide computer communication network.
Luster (who at one time worked for a contractor in Arlington, Virginia, named the John D. Kettelle Corp) was one of hundreds of programmers who worked on the system, and in this case, for this effort of his, he looked at various ways for selecting the proper way for a SAGE to monitor itself in real time and make assessments of its own reliability. This was a very tricky bit, of course. SAGE was the largest computer ever built–it had 23 installations in the U.S. (And one other in Canada) each given the possibility of tracking about 400 aircraft at one time. SAGE would track these developments, coordinate all efforts in response, and then if the flights were determined to be hostile /Soviet forces, would destroy the buggers with responses from “nuclear tipped” BOMARC and Nike missiles. (The Boeing Michigan Aeronautical Research Center and Nike missiles each carried a 1-5 kiloton warhead, enough so that if it was near its target it would be able to destroy it.The BOMARC looked like a jet aircraft; the Nike looked like a multi-finned, very sleek ultimate 1950's imaginatively-styled rocket ship, but real.) Trying to insure that the system was accurate was a major consideration. (This document is available for purchase from our blog bookstore.)
From Luster’s paper:
"It has been necessary to device tests of the quality of the SAGE computer program in order to ensure its acceptability prior to installation and operation...also to run it "live" in order to give an immediate indication of any degradation of the overall system. In effect, allow the SAGE computer itself to decide the quality of the SAGE computer program...The discussion here is limited to examining the nature of the problem to which such techniques are to be applied, and showing how the application may be made most effectively."
The SAGE system was of course functional, highly reliable, and ws used until 1983. IT was a kind of early version of the Star Wars defense system envisioned by President Reqgana nd Edward Teller, among others. Except that SAGE existed and worked.
It is interesting too to think of it in terms of a sort of pre-ARPANET pre-internet, a pre-pre-internet, in that the system has 24 remote nodes which communicated among themselves. It doesn’t bear much resemblance to J.C.R. Licklider’s Memorandum For Members and Affiliates of the Intergalactic Computer Network (1963)–the true first modeling suggestion for a working internet in which all of the main pieces of the internet are present, but it is at least in the neighborhood, as SAGE was the first operational nation-wide real-time computer network. ( It should also be pointed out that Licklider and other of the creators of ARPANET were programmers for SAGE.) SAGE was in-place by 1959 and operating by 1963, but it had severe limitations as a national defense shield and was ill-equipped to counter ICBMs and SLBMs, but it was kept alive until 1983.
1. SAGE did become the template for SABRE as well as for the national air traffic control ssytem.
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