punched card
<storage, history> (Or "punch card") The signature medium of computing's
Stone Age, now long obsolete outside of a few legacy systems. The punched card
actually predates computers considerably, originating in 1801 as a control
device for Jacquard looms. Charles Babbage used them as a data and program
storage medium for his Analytical Engine:
"To those who are acquainted with the principles of the Jacquard loom, and who
are also familiar with analytical formulę, a general idea of the means by which
the Engine executes its operations may be obtained without much difficulty. In
the Exhibition of 1862 there were many splendid examples of such looms. [...]
These patterns are then sent to a peculiar artist, who, by means of a certain
machine, punches holes in a set of pasteboard cards in such a manner that when
those cards are placed in a Jacquard loom, it will then weave upon its produce
the exact pattern designed by the artist. [...] The analogy of the Analytical
Engine with this well-known process is nearly perfect. There are therefore two
sets of cards, the first to direct the nature of the operations to be performed
-- these are called operation cards: the other to direct the particular
variables on which those cards are required to operate -- these latter are
called variable cards. Now the symbol of each variable or constant, is placed at
the top of a column capable of containing any required number of digits."
-- from Chapter 8 of Charles Babbage's "Passages from the Life of a
Philosopher", 1864.
The version patented by Herman Hollerith and used with mechanical tabulating
machines in the 1890 US 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 this.
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.
[Jargon File]
(1998-10-19)
Nearby terms:
pumpkineer « pumpking « punch card « punched card
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