Punched card facts for kids
A punched card (also punch card or punched-card) is a piece of card stock that stores digital data using punched holes. Punched cards were once common in data processing and the control of automated machines.
Punched cards were widely used in the 20th century. Many early digital computers used punched cards as the primary medium for input of both computer programs and data.
Data can be entered onto a punched card using a keypunch.
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 also had a significant cultural impact in the 20th century.
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 the 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. 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.
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 "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 invented the recording of data on a medium that could then be read by a machine, developing punched card data processing technology for the 1890 U.S. 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. 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 five 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).
Punched card technology developed into a powerful tool for business data-processing. By 1950 punched cards had become ubiquitous in industry and government. The Univac UNITYPER introduced magnetic tape for data entry in the 1950s. During the 1960s, the punched card was gradually replaced as the primary means for data storage by magnetic tape, as better, more capable computers became available. Mohawk Data Sciences introduced a magnetic tape encoder in 1965, a system marketed as a keypunch replacement which was somewhat successful. Punched cards were still commonly used for entering both data and computer programs until the mid-1980s when the combination of lower cost magnetic disk storage, and affordable interactive terminals on less expensive minicomputers made punched cards obsolete for these roles as well.
Formats
The Hollerith punched cards used for the 1890 U.S. census were blank. Following that, cards commonly had printing such that the row and column position of a hole could be easily seen. Printing could include having fields named and marked by vertical lines, logos, and more. "General purpose" layouts (see, for example, the IBM 5081 below) were also available. For applications requiring master cards to be separated from following detail cards, the respective cards had different upper corner diagonal cuts and thus could be separated by a sorter. Other cards typically had one upper corner diagonal cut so that cards not oriented correctly, or cards with different corner cuts, could be identified.
Punched card devices
Processing of punched cards was handled by a variety of machines, including:
- Keypunches—machines with a keyboard that punched cards from operator entered data.
- Unit record equipment—machines that process data on punched cards. Employed prior to the widespread use of digital computers. Includes card sorters, tabulating machines and a variety of other machines
- Computer punched card reader—a computer input device used to read executable computer programs and data from punched cards under computer control. Card readers, found in early computers, could read up to 100 cards per minute, while traditional "high-speed" card readers could read about 1,000 cards per minute.
- Computer card punch—a computer output device that punches holes in cards under computer control.
- Voting machines—used into the 21st century
Images for kids
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A 12-row/80-column IBM punched card from the mid-twentieth century
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A deck of punched cards comprising a computer program. The red diagonal line is a visual aid to keep the deck sorted.
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Hollerith card as shown in the Railroad Gazette in 1895, with 12 rows and 24 columns.
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Punched card from a Fortran program: Z(1) = Y + W(1), plus sorting information in the last 8 columns.
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Binary punched card.
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Invalid "lace cards" such as this pose mechanical problems for card readers.
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A 5081 card from a non-IBM manufacturer.
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IBM 96-column punched card
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A blank Remington Rand UNIVAC format card. Card courtesy of MIT Museum.
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A punched Remington Rand card with an IBM card for comparison
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HP Educational Basic optical mark-reader card.
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Aperture card
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Institutions, such as universities, often had their general purpose cards printed with a logo. A wide variety of forms and documents were printed on punched cards, including checks. Such printing did not interfere with the operation of the machinery.
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A punched card printing plate.
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A $75 U.S. Savings Bond, Series EE issued as a punched card. Eight of the holes record the bond serial number.
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Cartons of punched cards stored in a United States National Archives Records Service facility in 1959. Each carton could hold 2,000 cards.
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A U.S. Census Bureau clerk (left) prepares punch cards using a pantograph similar to that developed by Herman Hollerith for the 1890 Census, while a second clerk (right) uses a 1930s key punch to perform the same task more quickly.
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A wall-sized display sample of a punch card for the 1954 U.S. Census of Agriculture
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IBM Port-A-Punch
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FORTRAN Port-A-Punch card. Compiler directive "SQUEEZE" removed the alternating blank columns from the input.
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Port-a-punch
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See also
In Spanish: Tarjeta perforada para niños
