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The Evolution of Babbage's Calculating Engines

IP.com Disclosure Number: IPCOM000129535D
Original Publication Date: 1987-Mar-31
Included in the Prior Art Database: 2005-Oct-06
Document File: 24 page(s) / 85K

Publishing Venue

Software Patent Institute

Related People

ALLAN G. BROMLEY: AUTHOR [+2]

Abstract

This paper traces the evolution of Charles Babbage's design ideas for automatic computing machines from Difference Engine No. 1 (1822-1833), through the Analytical Engine (1834-1846), to Difference Engine No. 2 (1846-1847). The design evolution is discussed from four essentially hierarchically related points of view: (1) mechanism -- the basic mechanical apparatus for storing, transferring, and adding numbers; (2) architecture -- the arrangement and interconnection of the basic mechanisms in the complete design. (3) algorithms -- the functional utilization of the basic mechanism in carrying out such operations as multiplication, division, and signed addition (the microprogram or register-transfer level of description); (4) programs -- the user- level application of the machine in solving such problems as tabulating series or solving simultaneous equations. The paper examines how developments at each level interacted in the design of the Analytical Engine. It also discusses the ways Babbage's designs anticipated, or failed to anticipate, modern computer designs.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Copyright ©; 1987 by the American Federation of Information Processing Societies, Inc. Used with permission.

The Evolution of Babbage's Calculating Engines*1

ALLAN G. BROMLEY

(Image Omitted: Author's Address: Basser Department of Computer Science, University of Sydney N S W. 2006. Australia.)

This paper traces the evolution of Charles Babbage's design ideas for automatic computing machines from Difference Engine No. 1 (1822-1833), through the Analytical Engine (1834- 1846), to Difference Engine No. 2 (1846-1847). The design evolution is discussed from four essentially hierarchically related points of view: (1) mechanism -- the basic mechanical apparatus for storing, transferring, and adding numbers; (2) architecture -- the arrangement and interconnection of the basic mechanisms in the complete design. (3) algorithms -- the functional utilization of the basic mechanism in carrying out such operations as multiplication, division, and signed addition (the microprogram or register-transfer level of description); (4) programs -- the user- level application of the machine in solving such problems as tabulating series or solving simultaneous equations. The paper examines how developments at each level interacted in the design of the Analytical Engine. It also discusses the ways Babbage's designs anticipated, or failed to anticipate, modern computer designs.

Categories and Subject Descriptors: K.2 [computing Milieux]: History of Computing -- Babbage, hardware, people, software General Terms: Algorithms, Design Additional Key Words and Phrases: Analytical Engine, Difference Engine, Microprogramming

Introduction

Figure 1 is a time line of Charles Babbage's life and his interests related to calculating machinery. Babbage was born in London in 1791; he studied mathematics at Cambridge University and worked as a mathematician during his twenties.

The first idea of an automatic calculating machine occurred to Babbage around 1820, and by 1822 the idea of a difference engine was well established. He worked on this first machine, Difference Engine No. 1, from 1822 until 1833. In this period Babbage made a serious attempt to build the machine. The project was financed by the British government but failed for reasons associated with the arrangement of the financial support and the failure of relationships between Babbage and the engineer Joseph Clement (Collier, 1970).

In 1833, when work on the Difference Engine stopped, Babbage's ideas broadened to a much more elaborate automatic machine, the Analytical Engine, which was capable of calculating essentially any function and can be seen as a precursor of modern computers. Babbage worked intensively on the design of the Analytical Engine from 1834 to 1846, but did not attempt to build the machine at that time (he was, I suspect, in that practical field somewhat disillusioned by his experiences with Difference Engine No. 1).

1 *© 1987 by A...