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The SSEC in Historical Perspective

IP.com Disclosure Number: IPCOM000129400D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Oct-05
Document File: 22 page(s) / 84K

Publishing Venue

Software Patent Institute

Related People

CHARLES J. BASHE: AUTHOR [+2]

Abstract

The Selective Sequence Electronic Calculator (SSEC) was the first machine to combine electronic computation with a stored program, and the first machine capable of operating on its own instructions as data. When placed in operation in 1948, and for some time thereafter, it was the most flexible and powerful computer in existence. IBM published relatively little about it, and the SSEC has been largely overlooked by computer historians. This paper provides a historical setting for the SSEC.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Copyright ©; 1982 by the American Federation of Information Processing Societies, Inc. Used with permission.

The SSEC in Historical Perspective

CHARLES J. BASHE

(Image Omitted: © 1982 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: IBM Corporation, Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598. © 1982 AFIPS 0164-

1239/82/040296-312

The SSEC in Historical Perspective

CHARLES J. BASHE .00/00)

The Selective Sequence Electronic Calculator (SSEC) was the first machine to combine electronic computation with a stored program, and the first machine capable of operating on its own instructions as data. When placed in operation in 1948, and for some time thereafter, it was the most flexible and powerful computer in existence. IBM published relatively little about it, and the SSEC has been largely overlooked by computer historians. This paper provides a historical setting for the SSEC.

Categories and Subject Descriptors: A.0 [General] -- biographies; K.2 [History of Computing] -- hardware, people, SSEC General Terms: Design, Experimentation, Management Additional Key Words and Phrases: relay memory, paper-tape memory, electronic memory, stored program, IBM Corporation

1. Introduction

In January 1948, the IBM Corporation announced and dedicated at its headquarters in New York City a huge machine called the Selective Sequence Electronic Calculator (SSEC). In modern terminology a computer, it possessed at least the following noteworthy characteristics:

1. Sequence control by means of program instructions resident in a large, hierarchic memory involving electronic, relay, and paper-tape storage units. 2. A completely electronic arithmetic section. (The machine contained 12,500 tubes.) 3. The ability to branch at any instruction. 4. The ability to modify any part of an instruction under program control. (Instructions were stored in the same form as data.) 5. A large and flexible table-lookup facility.

Although many of the most prominent people in the field of computing attended the SSEC dedication ceremony and came to know a good deal about its capabilities, the SSEC was not described in technical detail in publications widely read by engineers or experts in computing. It was transitional in its use of both electromechanical and electronic memory components, and did not therefore provide an extensive technological model for subsequent computer

IEEE Computer Society, Oct 01, 1982 Page 1 IEEE Annals...