Legends of Technology - Babbage, Charles | HackTHatCORE

Babbage, Charles

1791 - 1871

British, Mathematician, Inventor

Charles Babbage made wide-ranging applications of math- ematics to a variety of fields including economics, social statistics, and the operation of railroads and lighthouses. Babbage is best known, however, for having conceptualized the key elements of the general-purpose computer about a century before the dawn of electronic digital computing. As a student at Trinity College, Cambridge, Babbage was already making contributions to the reform of calcu- lus, championing new European methods over the New- tonian approach still clung to by British mathematicians. But Babbage’s interests were shifting from the theoretical to the practical. Britain’s growing industrialization as well as its worldwide interests increasingly demanded accurate numeric tables for navigation, actuarial statistics, inter- est rates, and engineering parameters. All tables had to be hand-calculated, a long process that inevitably introduced numerous errors. Babbage began to consider the possibil- ity that the same mechanization that was revolutionizing industries such as weaving could be turned to the auto- matic calculation of numeric tables. Starting in 1820, Babbage began to build a mechani- cal calculator called the difference engine. This machine used series of gears to accumulate additions and sub- tractions (using the “method of differences”) to gener- ate tables. His small demonstration model worked well, so Babbage undertook the full-scale “Difference Engine Number One,” a machine that would have about 25,000 moving parts and would be able to calculate up to 20 dec- imal places. Unfortunately, Babbage was unable, despite financial support from the British government, to over- come the difficulties inherent in creating a mechanical device of such complexity with the available machining technology. Undaunted, Babbage turned in the 1830s to a new design that he called the Analytical Engine. Unlike the Difference Engine, the new machine was to be programmable using instructions read in from a series of punch cards (as in the Jacquard loom). A second set of cards would contain the variables, which would be loaded into the “store”—a series of wheels corresponding to memory in a modern computer. Under control of the instruction cards, numbers could be moved between the store and the “mill” (corresponding to a modern CPU) and the results of calculations could be sent to a printing device. Collaborating with Ada Lovelace (who translated his lec- ture transcripts by L. F. Menebrea) Babbage wrote a series of papers and notes that explained the workings of the pro- posed machine, including a series of “diagrams” (programs) for performing various sorts of calculations. Building the Analytical Engine would have been a far more ambitious task than the special-purpose Difference Engine, and Babbage made little progress in the actual con- struction of the device. Although Babbage’s ideas would remain obscure for nearly a century, he would then be rec- ognized as having designed most of the key elements of the modern computer: the central processor, memory, instruc- tions, and data organization. Only in the lack of a capability to manipulate memory addresses did the design fall short of a modern computer.

References:

• “The Analytical Engine: the First Computer.” Available online. URL: http://www.fourmilab.ch/babbage/. Accessed April 20, 2007.
• Babbage, Henry Prevost, ed. Babbage’s Calculating Engines: A Col- lection of Papers. With a new introduction by Allan G. Brom- ley. Los Angeles: Tomash, 1982.
• Campbell-Kelly, M., ed. The Works of Charles Babbage. 11 vols. London: Picerking and Chatto, 1989.
• “Who Was Charles Babbage?” Charles Babbage Institute. Avail- able online. URL: http://www.cbi.umn.edu/exhibits/cb.html. Accessed April 20, 2007.
• Swade, Doron D. “Redeeming Charles Babbage’s Mechanical Com- puter.” Scientific American, February 1993.