A Hardware Tutorial

Divilbiss, J.L.

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https://hdl.handle.net/2142/903 Copy

Description

Title

A Hardware Tutorial

Author(s)

Divilbiss, J.L.

Issue Date

1974

Keyword(s)

• Libraries --Automation
• Minicomputers --Library applications
• tutorial
• hardware

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.

Publisher

Graduate School of Library Science. University of Illinois at Urbana-Champaign

Series/Report Name or Number

Clinic on Library Applications of Data Processing (11th : 1974)

ISSN

0069-4789

Type of Resource

text

Language

en

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http://hdl.handle.net/2142/903

Copyright and License Information

Copyright owned by Board of Trustees of the University of Illinois 1974.

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