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Unit record equipment
Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using electromechanical devices called unit record〔In the late 1800s, early 1900s ''unit record'' was a reference to the recording of all information about a transaction or object on one document. At that time the library index card was pointed out as an early example of a ''unit record''. Even ''unit record'' desks were manufactured, a desk that included what later, for punched cards, would be called a tub file. This quote ''We had records of every car and locomotive on the railroad on a key-punched card or other unit record, either generated in the Car Accountant's Office or through other means'', from shows that in 1888 1) users were applying the term ''unit record'' to punched cards and 2) the term's use was more general than just punched cards. Markus Krajewski in ''Paper Machines: About Cards & Catalogs, 1548-1929'', 2011, MIT, credits Conrad Gessner with developing the unit record concept.〕 equipment, electric accounting machines (EAM) or tabulating machines. Unit record machines came to be as ubiquitous in industry and government in the first two-thirds of the twentieth century as computers became in the last third. They allowed large volume, sophisticated data-processing tasks to be accomplished before electronic computers were invented and while they were still in their infancy. This data processing was accomplished by processing punched cards through various unit record machines in a carefully choreographed progression. This progression, or flow, from machine to machine was often planned and documented with detailed flowcharts that used standardized symbols for documents and the various machine functions. All but the earliest machines had high-speed mechanical feeders to process cards at rates from around 100 per minute to 2,000 per minute, sensing punched holes with mechanical, electrical, or, later, optical sensors. The operation of many machines was directed by the use of a removable plugboard or control panel. Initially all machines were manual or electromechanical. The first use of an electronic component was in 1940 when a gas triode vacuum tube replaced a relay in an IBM card sorter.〔Phelps, B.E. "Early Computers at IBM", Annals of the History of Computing v.2.3, July 1980〕 Electronic components were used on other machines beginning in the late 1940s.
The largest supplier of unit record equipment was IBM and this article largely reflects IBM practice and terminology.
==History==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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