= P =
punched card n.obs.
[techspeak] (alt. `punch card') 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. There is a widespread myth
that it was designed to fit in the currency trays used for that
era's larger dollar bills, but recent investigations have falsified
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. See
chad, chad box, eighty-column mind, green card,
dusty deck, lace card, card walloper.
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.