|
The ASC-15 (Advance System Controller Model 15) was a digital computer developed by International Business Machines (IBM) for use on the Titan II intercontinental ballistic missile (ICBM).〔1958: "IBM develops the ASC-15 guidance computer for the United States Air Force Titan II missile computer. " IBM Archives: Space flight chronology. Web page at http://www- 03.ibm.com/ibm/history/exhibits/space/space_chronology.html. See also Bilstein, Stages to Saturn, p. 243. See also Olsen and Orrange, p. 406〕〔http://ed-thelen.org/comp-hist/BRL61-a.html〕 It was subsequently modified and used on the Titan III and Saturn I Block II launch vehicles. Its principal function on these rockets was to make navigation calculations using data from inertial sensor systems. It also performed readiness checks before launch.〔Larson, p. 7〕 It was a digital serial processor using fixed-point data with 27-bit words. The storage was a drum memory. Electronic circuits were welded encapsulated modules, consisting of discrete resistors, transistors, capacitors, and other components welded together and encapsulated in a foam material. It was manufactured in the IBM plant at Owego, NY.〔Larson, p. 4. See also: Martin H. Weik. "A Third Survey of Domestic Electronic Digital Computing Systems" Ballistic Research Laboratories, Aberdeen Proving Ground, Maryland Report No. 1115, March 1961 http://ed-thelen.org/comp-hist/BRL61-a.html pages 58-59.〕 == ASC-15 for Titan II == The first inertial guidance system for the Titan II was built by AC Spark Plug, and included an inertial measurement unit based in designs from Draper Labs at MIT and the ASC-15 computer designed and built by IBM in Owego, NY. The first Titan II missile carrying this system was launched 16 March 1962. Acquiring spares for this system became difficult, and the Air Force decided to replace it with a new system. The AC Spark Plug system, including the ASC-15, was replaced by the Delco Electronics Universal Space Guidance System (USGS) on operational Titan II missiles starting in January 1978.〔David K. Stumpf. Titan II. A History of a Cold War Missile Program. University of Arkansas Press, Fayetteville, Arkansas, 2000. ISBN 1-55728-601-9. Pages 63-67.〕 The guidance computer in the USGS was the Magic 352, made by Delco.〔A.C. Liang and D.L. Kleinbub."Navigation of the Titan IIIC space launch vehicle using the Carousel VB IMU." AIAA Guidance and Control Conference, Key Biscayne, FL, 20–22 August 1973. AIAA Paper No. 73-905.〕 The ASC-15 was built on an aluminum frame about 1.5x1.5x1 feet.〔Estimate based on mensuration of photographs of the ASC-15 and a volume of reported in "Spaceborne Digital Computer Systems," NASA, SP-8070, March 1971.〕 The sides, top and bottom were covered by pieces of laminated plastic, covered with gold-plated aluminum foil. These covers were slightly convex and ribbed for stiffness. Inside the covers were fifty-two logic sticks, each containing four welded encapsulated modules. These surrounded a bell frame housing a drum memory.〔"Missile Launch/Missile Officer (LGM-25) Missile Systems." USAF, Sheppard Technical Training Center, May 1967. Student Study Guide OBR1821F/3121f-V-1 thru 4, Volume I of II.〕 See Figure 2. The drum was a thin-walled stainless steel cylinder 3 inches long and 4.5 inches in diameter covered with a magnetic nickel-cobalt alloy. It was driven by a synchronous motor at 6,000 rpm. The drum had 70 tracks, of which 58 were used and 12 were spare. These tracks were used as follows: The capacity of a track was 1,728 bits. Instruction words were 9-bits long, and data was stored in 27-bit words.〔A.E. Cooper and W.T. Chow. "Development of On-board Space Computer Systems" IBM Journal of Research and Development, January 1976. Pages 5-18.〕 Coincident with 58 tracks were 67 read heads and 13 write heads. While the drum was spinning at 6,000 rpm, the heads floated above the surface of the drum on a thin layer of air. When the drum was spinning up or slowing down, the heads were raised off the drum by camshafts rotated by a chain that was driven by a motor on top of the drum housing, to avoid scoring the magnetic surface. See Figure 3. 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「ASC-15」の詳細全文を読む スポンサード リンク
|