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Ten years and more of micro-programming

Published:01 December 1977Publication History
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Abstract

Micro-programming was not a bright idea that came in a flash, but a solution slowly arrived at to a consciously posed problem, namely, that of finding a systematic way of designing the control unit of an electronic digital computer. As such it had to meet criticisms of inefficiency in rather the same way that high-level languages did at a later date. In both instances, a shift in emphasis has since taken the edge off such criticisms, but at the time the whole argument turned on them. In the case of micro-programming, therefore, stress was originally put on ways of realising the concept that would lead to efficient operation. One thought in terms of a long micro-instruction word, with no decoding of fields, and of the entire micro-operation being encompassed in one pulse time. This is what is now referred to as pure horizontal micro-programming. It imposed no restriction on the number of register transfers that could take place simultaneously. The long word gave a very large number of possible micro-instructions of which relatively few were usable. In these circumstances it was more natural to think of constructing a micro-instruction to do a certain job than to think of choosing one from a micro-instruction set.

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  • Published in

    cover image ACM SIGMICRO Newsletter
    ACM SIGMICRO Newsletter  Volume 8, Issue 4
    December 1977
    25 pages
    ISSN:1050-916X
    DOI:10.1145/1096518
    Issue’s Table of Contents

    Copyright © 1977 Author

    Publisher

    Association for Computing Machinery

    New York, NY, United States

    Publication History

    • Published: 1 December 1977

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