Jacquard

The Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, which used the holes punched in pasteboard punch cards to control the weaving of patterns in fabric. The loom enabled even amateur weavers to weave complex designs. more...

Each punch card corresponded to one row of the design and the cards were strung together in order. It was based on an earlier invention by the French mechanic Falcon in 1728.

Each hole in the card corresponds to a "Bolus" hook, which can either be up or down. The hook raises or lowers the harness which carries and guides the warp thread so that the weft will either lay above or below it. The sequence of raised and lowered threads is what creates the pattern. Each hook can be connected via the harness to a number of threads, allowing more than one repeat of a pattern. A loom with a 400 hook head might have 4 threads connected to each hook, giving you a fabric that is 1600 warp ends wide with four repeats of the weave going across.

It was the first machine to use punch cards to control a sequence of operations. Although it did no computation based on them, it is considered an important step in the history of computing hardware. The ability to change the pattern of the loom's weave by simply changing cards was an important conceptual precursor to the development of computer programming. Specifically, Charles Babbage planned to use cards to store programs in his Analytical engine. At first sight this may seem unremarkable but it was a clear turning point in the ability to store and re-use machine instructions. Whilst Babbage did not live to see that his ideas were viable they have since been proved to work reliably.

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