History of Punch Cards

Punch holes in a paper tape was used to control a loom in 1725 by Basile Bouchon.  Eventually a number of punch cards were linked to form a paper chain of any length.   Herman Hollerith invented the recording of data on punch cards that could be read by a machine, which was first widely used in the 1890 U.S. census.  The holes on the punch cards were punched by a key punch machine.  The company Hollerith founded, with 3 other companies, combined to form IBM.    Starting 1929, punch cards had 80 columns of data with 12 rows available for punching and were about the size of a dollar bill.  In the early 20th century, punch cards were the primary means of data storage with 10 million printed daily in the 1930s.

When computers were developed after World War II, punch cards were used to read the programs and data into the computer. With the introduction of computers, new formats were developed for the cards.  Letters, and later symbols like $ could be represented on the cards using punches in 2 rows with the code known as EBCDIC.  Other formats included Column Binary and Chinese binary.  The punch cards were printed for various uses such as data or program.  A sample card used in Fortran programing is shown below with the English equivalence printed on the top line.  About 2000 cards would be stored within a box.  Many programs were not serialized so one can imagine the difficulty in putting the cards in order after a deck was dropped and most programmers would experience such an incident.  Dropping of several boxes at the same time would be remembered for years, such as occurred on an escalator when an elevator was not working at a Hartford company in the 1990s.

Magnetic tape gradually replaced cards starting in the 1960s.  Terminals started being used in the 1980s for direct entry of programs and data, particularly with the introduction of Personal Computers.  The last key punch machine was made in 2012.  A 16GB thumb drive will hold the contents from about 200 million punch cards.

Leave a Reply

Your email address will not be published. Required fields are marked *