| | The **Analytical Engine** was [[Charles Babbage]]'s design for a general-purpose programmable computer, worked out through the 1830s–1860s and never completed. Had it been built, it would have been the first Turing-complete machine — a century before Turing. |
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| | ## The design |
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| | Where the Difference Engine could only grind out tables, the Analytical Engine was meant to compute *anything*. Its architecture reads like a modern machine in Victorian brass: |
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| | - **The store** — memory holding roughly 1,000 numbers of 50 digits each. |
| | - **The mill** — the arithmetic unit: today's CPU. |
| | - **Punched cards** — borrowed directly from the [[Jacquard Loom|Jacquard loom]]: operation cards carried instructions, variable cards carried data. |
| | - **Conditional branching and loops** — the machine could change its course based on results, the feature that makes a calculator into a computer. |
| | - **A printer and plotter** — output cast in type, ready to publish. |
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| | In modern terms: memory, processor, program, conditionals, I/O. Every computer since — including the one serving this page — follows that plan. |
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| | ## Lovelace's program |
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| - | In 1843 [[Ada Lovelace]] published her translation of Luigi Menabrea's account of the engine, with notes three times longer than the paper itself. **Note G** contained a worked method for computing Bernoulli numbers on the machine — widely called the first published computer program. More than the algorithm, she grasped what the cards meant: if numbers could stand for things, the engine could manipulate *symbols* — it might compose music, process language, work with ideas. Babbage designed a number machine; Lovelace described a general-purpose thinking machine. |
| + | In 1843 [[Ada Lovelace]] published her translation of Luigi Menabrea's account of the engine, with notes three times longer than the paper itself. **Note G** contained a worked method for computing [[Bernoulli numbers]] on the machine — widely called the first published computer program. More than the algorithm, she grasped what the cards meant: if numbers could stand for things, the engine could manipulate *symbols* — it might compose music, process language, work with ideas. Babbage designed a number machine; Lovelace described a general-purpose thinking machine. |
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| | ## Never built |
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| | The engine defeated Victorian machining: tens of thousands of precision parts were beyond any workshop, and after the Difference Engine's collapse no government would fund another Babbage machine. His son Henry demonstrated a fragment of the mill in 1888 — it computed, correctly, a sliver of the design. |
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| | Modern verdicts have settled the question. The 1991 reconstruction of Difference Engine No. 2 proved Babbage's engineering was sound, and the ongoing **Plan 28** project continues to study building the Analytical Engine from his surviving plans. It was not a fantasy; it was a machine built too early, waiting for its century. |
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| | ## See also |
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| | - [[Charles Babbage]] |
| | - [[Ada Lovelace]] |
| | - [[Jacquard Loom]] |
| | - [[History of Programming]] |
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| | [[Category:History]] |
| | [[Category:Hardware]] |
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