A punched card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions.
Now almost an obsolete recording medium, punched cards were widely used throughout the 19th century for controlling textile looms and in the late 19th and early 20th century for operating fairground organs and related instruments. They were used through the 20th century in unit record machines for input, processing, and data storage. Early digital computers used punched cards, often prepared using keypunch machines, as the primary medium for input of both computer programs and data.
Relation to Computing:
Punch cards provided a more robust way of storing programs than punch bands (which used paper tape), but easier to create and cheaper to replicate than other possibilities such as pegs attached to a rotating barrel. It wasn’t until the mid 19th century that punch cards were used for storing data as well as instructions, and although initially these were once more fixed function machines they pointed the way towards the development of computers that could be both reprogrammed to perform different tasks, and operate on different sets of data.
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