A punched card reader or just card reader is a computer input device used to read data from punched cards. A card punch is a output device that punches holes in cards under computer control. Sometimes card readers were combined with card punches and, later, other devices to form multifunction machines.
The earliest computers, such as ENIAC were programmed and fed data using switches, patch cords and punched paper tape or film. When IBM entered and began to dominate the computer industry starting in the early 1950s, it used the punched card for programming, data input and often for data output. IBM had been selling punched card based unit record equipment for over half a century by then and its technology was mature and reliable. Business were familiar with storing data on punched cards and keypunch machines and their operators were widely employed. Punched cards were a good fit with the new art of computer programming, as having individual machine instructions or programming language statements entered on separate punched cards allowed programs to be edited relatively easily. See computer programming in the punched card era.
IBM adapted electromechanical card reading and punching mechanisms for use on early computing experiments, such as the IBM Selective Sequence Electronic Calculator and the IBM Card Programmed Calculator and used them on its electronic computers starting with the IBM 701.[1] Card readers and and punches were ubiquitous on computers supplied by IBM, and most of its competitors, through the mid-1970s.
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Documation Inc., of Melbourne, Florida, made card readers for minicomputers in the 1970s: