Punched card

A punched card or punch card is a piece of stiff paper that can be used to contain digital data represented by the presence or absence of holes in predefined positions. Digital data can be used for data processing applications or, in earlier examples, used to directly control automated machinery. Punched cards were widely used through much of the 20th century in the data processing industry, where specialized and increasingly complex unit record machines, organized into semiautomatic data processing systems, used punched cards for data input, output, and storage. Many early digital computers used punched cards, often prepared using keypunch machines, as the primary medium for input of both computer programs and data. While punched cards are now obsolete as a storage medium, as of 2012, some voting machines still use punched cards to record votes. Basile Bouchon developed the control of a loom by punched holes in paper tape in 1725. The design was improved by his assistant Jean-Baptiste Falcon and by Jacques Vaucanson. Although these improvements controlled the patterns woven, they still required an assistant to operate the mechanism. In 1804 Joseph Marie Jacquard demonstrated a mechanism to automate loom operation. A number of punched cards were linked into a chain of any length. Each card held the instructions for shedding (raising and lowering the warp) and selecting the shuttle for a single pass. It is considered an important step in the history of computing hardware. Semyon Korsakov was reputedly the first to propose punched cards in informatics for information store and search. Korsakov announced his new method and machines in September 1832. Charles Babbage proposed the use of 'Number Cards', 'pierced with certain holes and stand opposite levers connected with a set of figure wheels ... advanced they push in those levers opposite to which there are no holes on the cards and thus transfer that number together with its sign' in his description of the Calculating Engine's Store. In 1881 Jules Carpentier developed a method of recording and playing back performances on a harmonium using punched cards. The system was called the Mélographe Répétiteur and “writes down ordinary music played on the keyboard dans la langage de Jacquard”, that is as holes punched in a series of cards. By 1887 Carpentier had separated the mechanism into the Melograph which recorded the player's key presses and the Melotrope which played the music. At the end of the 1800s Herman Hollerith invented the recording of data on a medium that could then be read by a machine. 'After some initial trials with paper tape, he settled on punched cards...', developing punched card data processing technology for the 1890 US census. His tabulating machines read and summarized data stored on punched cards and they began use for government and commercial data processing. Initially, these electromechanical machines only counted holes, but by the 1920s they had units for carrying out basic arithmetic operations.