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Title:A Hardware Tutorial
Author(s):Divilbiss, J.L.
Subject(s):Libraries --Automation
Minicomputers --Library applications
Abstract:In a practical sense, the minicomputer age began in 1964 with the Digital Equipment Corporation's introduction of the PDF 8. Potential com- puter users who had been unable to afford a $500,000 machine found that for the then remarkably low price of $27,000 they could purchase a general purpose computer, limited in power, to be sure, but nonetheless a real computer. The price was achieved by a combination of several factors: a simple, classical, no-frills, logical design; a superior packaging technique for the electronic circuits; and, most important, use of a short word length. Most of the large computers of that era were using word lengths ranging from about 30 to 50 bits, the length being influenced by considerations of accuracy and instruction format. By cutting the word length to 12 bits, DEC was able to greatly reduce the hardware needed in the arithmetic unit. A short word length limits neither accuracy nor type of operations performed, but it often means that computation proceeds more slowly. For example, numerical com- putations may require cumbersome multiple precision routines in order to secure adequate accuracy. In simple terms, short word machines achieve low hardware costs at the expense of execution efficiency. Since there are many applications in which the slowest computer is still much faster than the application requires (e.g., a computer controlling a lathe) the loss of execution efficiency may not be important.
Issue Date:1974
Publisher:Graduate School of Library Science. University of Illinois at Urbana-Champaign
Citation Info:In Applications of minicomputers to library and related problems : papers presented at the 1974 Clinic on Library Applications of Data Processing, April 28-May 1, 1974, ed. F.W. Lancaster. Urbana, Il: Graduate School of Library Science: 3-10.
Series/Report:Clinic on Library Applications of Data Processing (11th : 1974)
Genre:Conference Paper / Presentation
Publication Status:published or submitted for publication
Rights Information:Copyright owned by Board of Trustees of the University of Illinois 1974.
Date Available in IDEALS:2007-06-12

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