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The Design of Colossus

IP.com Disclosure Number: IPCOM000129309D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Oct-05
Document File: 13 page(s) / 50K

Publishing Venue

Software Patent Institute

Related People

THOMAS H. FLOWERS: AUTHOR [+2]

Abstract

During World War II the German armed forces used machine-enciphered teleprinter messages for some of their high-level communications. Mathematicians at Bletchley Park, a high-security establishment in Britain, discovered processes by which such messages might be decoded; for the information to be useful, however, processing speeds such as only electronics could attain would be necessary. The first electronic machines made for the purpose did valuable work but were too slow and cumbersome to handle all the traffic being received. They were superseded by faster and more versatile machines called Colossus.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Copyright ©; 1983 by the American Federation of Information Processing Societies, Inc. Used with permission.

The Design of Colossus

THOMAS H. FLOWERS

  (Image Omitted: © 1983 by the American Federation of Information Processing Societies, Inc. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the AFIPS copyright notice and the title of the publication and its date appear, and notice is given that the copying is by permission of the American Federation of Information Processing Societies, Inc. To copy otherwise, or to republish, requires specific permission. Author's Address: 12 Sunnyfield, Mill Hill, London NW7 4RG, England. Illustrations for this article are courtesy of British Telecom Research Laboratories. The article is adapted from a lecture given at the Digital Computer Museum in Marlboro, Mass., on October 15, 1981. Acknowledgment is made to the Director of Research of British Telecom for permission to make use of the information in these articles. © 1983 AFIPS

01 64-1239/83/030239-252

The Design of Colossus

THOMAS H. FLOWERS .00/00)

During World War II the German armed forces used machine-enciphered teleprinter messages for some of their high-level communications. Mathematicians at Bletchley Park, a high-security establishment in Britain, discovered processes by which such messages might be decoded; for the information to be useful, however, processing speeds such as only electronics could attain would be necessary. The first electronic machines made for the purpose did valuable work but were too slow and cumbersome to handle all the traffic being received. They were superseded by faster and more versatile machines called Colossus.

This article describes the construction and operation of the Colossus machines. The machines had most if not all of the essential features of a modern computer, except that variable programming was provided not by memory store but by hard-wired function units selected and interconnected by switches operated by the mathematician-programmers.

Categories and Subject Descriptors: K.2 [History of Computing] -- Colossus, hardware, people General Terms: Design Additional Key Words and Phrases: cryptology, Bletchley Park, "Heath Robinson"

Foreword

My view of Colossus was that of cryptanalyst-programmer. I told the machine to make certain calculations and counts, and after studying the results, told it to do another job. It did not remember the previous result, nor could it have acted upon it if it did. Colossus and I alternated in an interaction that sometimes achieved an analysis of an unusual German cipher system, called "Geheimschreiber" by the Germans, and "Fish" by the cryptanalysts.

For its time Colossus was a notable innovation, different from its predecessors in many dramatic aspects.

IEEE Computer Society, Jul 01, 1983 Page 1 I...