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Wednesday, 24 May 2017

Punched card

A punched card is a storage medium. It contains information in the form of holes that are at precise locations on the card.

The first use of punched cards was in the Jacquard loom, which was used to make patterns in clothing material. The loom was invented by French technologist Joseph Marie Jacquard (1752-1834) in 1801 and simplified the process of making textiles with complex patterns. Encouraged by its success, Jacquard went on to make his major improvement, which was to use cards with punched holes to control cams that directed pattern weaving. By the 1830s many were in use.

Close-up of the 8 × 26 hole punched cards on a Jaquard loom

Jacquard's method of coding information for manual looms implies that a hole or its absence can correspond to an 'on or off' action - or to 0 and 1 in binary notation.

Jacquard's method became dominant in textile pattern making and the punch cards were soon adopted for use in other fields as well. The English inventor Charles Babbage, for example, adapted the cards as a control mechanism for his calculator.

The American statistician Herman Hollerith was issued US patent #395,791 for the 'Art of Applying Statistics' in 1889 for his punched card calculator. He was inspired by railway conductors using holes punched in different positions on a ticket to record traveler details such as gender and approximate age. Hollerith went on to be awarded a series of patents and is regarded as one of the seminal figures in the development of data processing.

Hollerith card as shown in the Railroad Gazette in 1895, with 12 rows and 24 columns
The principle of using punched cards or tape had to await the replacement of mechanical sensing by electronic computers and magnetic tape or discs before, in this much altered form, it could take a large part in the powered machine tool industry.

Source Europress Family Encyclopedia 1999.

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