Charles Babbage - Analytical Engine

Analytical Engine

Soon after the attempt at making the difference engine crumbled, Babbage started designing a different, more complex machine called the Analytical Engine. The engine is not a single physical machine but a succession of designs that he tinkered with until his death in 1871. The main difference between the two engines is that the Analytical Engine could be programmed using punched cards. He realised that programs could be put on these cards so the designer had only to create the program initially and then put the cards in the machine and let it run. The analytical engine would have used loops of Jacquard's punched cards to control a mechanical calculator, which could formulate results based on the results of preceding computations. This machine was also intended to employ several features subsequently used in modern computers, including sequential control, branching and looping and would have been the first mechanical device to be Turing-complete.

Ada Lovelace, who corresponded with Babbage during his development of the Analytical Engine, is credited with developing an algorithm for the Analytical Engine to calculate a sequence of Bernoulli numbers. Although there is disagreement over how much of the ideas were Lovelace's own, she is often described as the first computer programmer.

In 2011, researchers in Britain embarked on a multimillion-pound project, "Plan 28", to construct Babbage's Analytical Engine. Since Babbage's plans were continually being refined and were never completed, they will engage the public in the project and crowd-source the analysis of what should be built. It would have the equivalent of 675 bytes of memory, and run at a clock speed of about 7 Hz. They hope to complete it by the 150th anniversary of Babbage's death, in 2021.