Punch card

The punch card (or "Hollerith" card) is a recording medium for holding information for use by automated data processing machines. Made of stiff cardboard, the punch card represents information by the presence or absence of holes in predefined positions on the card. In the first generation of computing, from the 1920s into the 1950s, punch cards were the primary medium for data storage and processing. Eventually the punch card would be phased out and replaced with huge floppys for media storage, for loading data, in the late 1970's, early 1980's.

Functional details

The method is quite simple:

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On a piece of light-weight cardboard, successive positions either have a hole punched through them

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or are left intact. The rectangular bits of paper punched out are called chads.

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Thus, each punch location on the card represents a single binary digit (or "bit").

Related Topics:
Binary - Bit

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Each column on the card contained several punch positions (multiple bits).

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