A Difference Engine is an automatic mechanical calculator designed in 1837. The size of this calculator is about as big as your living room. It is devised but never actually built by English mathematician Charles Babbage, this massive contraption relied on metal tumblers and cranks rather than electricity and transistors, yet it had all the components of a modern computer: a memory for storing numbers, a central processing unit for calculating math problems, an input device (punched cards) for entering information, and an output device in the form of a printer and a bell.
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