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Simple calculating devices had been perfected almost two centuries before Babbage, starting with Pascal’s Pascaline in 1642, which could add numbers, and a multiplying machine developed by Gottfried Wilhelm Leibniz a couple of decades later. But automating the computing of logarithms was far more ambitious than anything that had been previously attempted.
Babbage didn’t get very far—he exhausted his financial resources, got into a dispute with the British government over ownership, had problems getting the unusual precision parts fabricated, and saw his chief engineer fire all of his workmen and then quit himself. He was also beset with personal tragedies, including the death of his father, his wife, and two of his children.
The only obvious thing to do now, Babbage figured, was to abandon his “Difference Engine” and embark on something yet more ambitious: the world’s first fully programmable computer. Babbage’s new conception—the “Analytical Engine”—could be programmed to solve any possible logical or computational problem.
The Analytical Engine had a random-access memory (RAM) consisting of 1,000 “words” of 50 decimal digits each, equivalent to about 175,000 bits. A number could be retrieved from any location, modified, and stored in any other location. It had a punched-card reader and even included a printer, even though it would be another half century before either typesetting machines or typewriters were to be invented. It had a central processing unit (CPU) that could perform the types of logical and arithmetic operations that CPUs do today. Most important, it had a special storage unit for the software with a machine language very similar to those of today’s computers. One decimal field specified the type of operation and another specified the address in memory of the operand. Stan Augarten, Bit by Bit: An Illustrated History of Computers (New York: Ticknor and Fields, 1984): 63-64.
Babbage describes the features of his machine in “On the Mathematical Powers of the Calculating Engine,” written in 1837 and reprinted as appendix B in Anthony Hyman’s Charles Babbage: Pioneer of the Computer (Oxford: Oxford University Press, 1982). For biographical information on Charles Babbage and Ada Lovelace, see Hyman’s biography, and Dorothy Stein’s book Ada: A Life and a Legacy (Cambridge, MA: MIT Press, 1985).