Punch-Card Technology
Punch-card (or "punched card") technology involves an essentially outdated computer input and output storage medium consisting of stiff, thin paper that stores data as a series of punched holes arranged in columns. The method for creating the punch-card patterns is called Hollerith coding, where the punch-card was sometimes called the "Hollerith card." From 1890 until the 1970s--at the apex of its popularity--punch-card technology was synonymous with data processing. During this time it was the most popular storage control system for the input and output of data and programs for computers or other data processing machines. Traditionally, a punch-card was a manila card about 3 inches high by 7 inches long, on which 80 columns of data could be entered in the form of holes punched with a keypunch machine or card-punch device. The punched holes corresponded to letters, numbers, and other characters that could be read by a computer connected to a punched-card reader.
Some of the early mechanical information storage devices, the precursors to modern day data processing, were 18th century music boxes that encoded sequences of musical notes as pins on such mechanisms as a revolving drum. The use of punched cards is considered to have originated with the Jacquard loom that was invented in 1801 by French silk-weaver and inventor Joseph-Marie Jacquard (1752-1834). Jacquard used paper cards with information recorded as holes punched in them to control weaving looms. The Jacquard loom was the first automatic loom able to weave complex patterns with the use of punched cards that controlled its operation (however, it did no computations based on the cards). As a result of using punched cards, the Jacquard loom transformed the 19th century textile industry and became the idea for using punched cards in future calculating and tabulating machines.
British mathematician and inventor Charles Babbage (1791-1871) later used Jacquard's idea of punched-card storage in his mechanical calculating machine, the Analytical Engine. The holes on each card allowed an arm to pass through and activate a mechanism on the other side. In the United States census of 1890, American inventor Herman Hollerith (1860-1929) used punched cards to hold data within his statistical Hollerith's tabulator. Intrigued with the idea of tabulating large amounts of data, Hollerith developed over the next several years a number of machines for punching and tabulating cards. These punch-cards were later read by various machines in which rows of electrical contacts sensed when a hole was present. In the 1940s the first electronic computers used punched cards and rolls of paper tape with punched holes for storing both programs and data.
In 1896 Hollerith founded the Tabulating Machine Company that later expanded into the International Business Machines (IBM) Corporation. IBM, originally a producer of punch-card tabulating-machines in 1911, eventually combined the punch-card technology with computers by encoding binary information as patterns of small rectangular holes, one character per column, 80 columns per card. Other coding schemes, card sizes, and hole shapes were tried at different times, but the 80-column width of most character terminals became the foundation of the IBM punched card. Even today the size of quick-reference cards distributed with many computers follows the size of the 80-column punched cards. The punched card is all but obsolete today, being replaced with such input devices as the keyboard and mouse used in conjunction with the computer monitor.
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