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1 definition found
 for ''punched card''
From The Free On-line Dictionary of Computing (18 March 2015) :

  punched card
  punch card
  
      (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
     formulæ, 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)
  

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