A punched card (also punch card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 19th to 20th centuries, punched cards were widely used for data processing, the control of automated machines, and computing. Early applications included controlling weaving looms and recording census data. Punched cards were widely used in the 20th century, where unit record machines, organized into data processing systems, used punched cards for data input, data output, and data storage. The IBM 12-row/80-column punched card format came to dominate the industry. Many early digital computers used punched cards as the primary medium for input of both computer programs and data. Punched cards were used for decades before being replaced by magnetic-tape data storage. While punched cards are now obsolete as a storage medium, as of 2012, some voting machines still used punched cards to record votes. Punched cards had a significant cultural impact in the 20th century. Their legacy persists in modern computing, influencing the 80-character line standard still present in some command-line interfaces and programming environments.
History The idea of control and data storage via punched holes was developed independently on several occasions in the modern period. In most cases there is no evidence that each of the inventors was aware of any other earlier work.
Precursors
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. Multiple 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. 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[ing] 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. There is no evidence that he built a practical example. 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 described that "it writes down ordinary music played on the keyboard 'dans le 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.
20th century At the end of the 1800s Herman Hollerith created a method for recording data on a medium that could then be read by a machine, developing punched-card data-processing technology for the 1890 U.S. census. This was inspired in part by Jacquard loom weaving technology and by railway punch photographs. Punch photographs were quick ways for conductors to mark a ticket with a description of the ticket buyer (e.g., short or tall, dark or light hair). They were used to reduce ticket fraud, as conductors could "read" the punched holes to get a basic description of the person to whom the ticket was sold. Hollerith's 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. Hollerith founded the Tabulating Machine Company (1896), which was one of four companies that were amalgamated via stock acquisition to form a fifth company, Computing-Tabulating-Recording Company (CTR) in 1911, later renamed International Business Machines Corporation (IBM) in 1924. Other companies entering the punched-card business included The Tabulator Limited (Britain, 1902), Deutsche Hollerith-Maschinen Gesellschaft mbH (Dehomag) (Germany, 1911), Powers Accounting Machine Company (US, 1911), Remington Rand (US, 1927), and H.W. Egli Bull (France, 1931). These companies, and others, manufactured and marketed a variety of punched cards and unit record machines for creating, sorting, and tabulating punched cards, even after the development of electronic computers in the 1950s.
Both IBM and Remington Rand tied punched-card purchases to machine leases, a violation of the US 1914 Clayton Antitrust Act. In 1932, the US government took both to court on this issue. Remington Rand settled quickly. IBM viewed its business as providing a service and that the cards were part of the machine. IBM fought all the way to the Supreme Court and lost in 1936; the court ruled that IBM could only set card specifications. "By 1937 ... IBM had 32 presses at work in Endicott, N.Y., printing, cutting and stacking 5 to 10 million punched cards every day." Punched cards were even used as legal documents, such as U.S. Government checks and savings bonds. During World War II punched card equipment was used by the Allies in some of their efforts to decrypt Axis communications. See, for example, Central Bureau in Australia. At Bletchley Park in England, "some 2 million punched cards a week were being produced, indicating the sheer scale of this part of the operation". In Nazi Germany, punched cards were used for the censuses of various regions and other purposes (see IBM and the Holocaust).
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