During the course of his work on the difference engine, he conceived of a more sophisticated
machine he called the analytical engine. The analytical engine was meant to be programmed using punched
cards, and would employ features such as sequential control, branching, and looping. Although Babbage
never built a complete working model of either machine, his work became the basis on which many modern
computers are built. (One of Babbage??™s earlier difference engines was eventually constructed from drawings
by a team at London??™s Science Museum in the 1990s. The machine weighs 3 tons and is 10 feet wide
by 6 1/2 feet tall.)
In his work on the analytical engine, Babbage made an important intellectual leap regarding the punched
cards. In the Jacquard loom, the presence or absence of each hole in the card physically allows a colored thread
to pass or stops that thread. Babbage realized that the pattern of holes could be used to represent an abstract
idea such as a problem statement or the raw data required for that problem??™s solution.
Because of the connection to the Jacquard loom, Babbage called the two main parts of his Analytic Engine
the ???Store??? and the ???Mill???, as both terms are used in the weaving industry.
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