Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A card punch such as the IBM 3525 (not to be confused with keypunch), is an electronically mechanized output device used to punch data into punched cards. Sometimes combined with card readers and other functions to form multifunction machines, such as the IBM 2540 card reader-punch, such devices were attached to a computer. A punched card (or punch card or Hollerith card or IBM card) is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions. Now almost an obsolete recording medium, punched cards were widely used throughout the 19th century for controlling textile looms and in the late 19th and early 20th century for operating fairground organs and related instruments.

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