alt. 'punch card' [techspeak] n.obs. The signature medium of computing's Stone Age, now obsolescent outside of some IBM shops. The punched card actually predated computers considerably, originating in 1801 as a control device for mechanical looms. The version patented by Hollerith and used with mechanical tabulating machines in the 1890 U.S. Census was a piece of cardboard about 90 mm by 215 mm, designed to fit exactly in the currency trays used for that era's larger dollar bills.
IBM (which originated as a tabulating-machine manufacturer) married the punched card to computers, encoding binary information as patterns of small rectangular holes; one character per column, 80 columns per card. Other coding schemes, sizes of card, and hole shapes were tried at various times.
The 80-column width of most character terminals is a legacy of the IBM punched card; so is the size of the quick-reference cards distributed with many varieties of computers even today.