Difference between revisions of "Punched card"
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| − | '''Punched cards''' were a very popular medium for [[input/output]] and [[secondary storage|data storage]] in the early period of computer usage. | + | '''Punched cards''' were a very popular medium for [[input/output]] and [[secondary storage|data storage]] in the early period of computer usage. Data was stored in them by the presence, or absence, of holes punched in pre-determined locations. |
They were actually a hangover from a pre-[[electronic]] stage of [[data processing]]; Herman Hollerith pioneered the use of cards for data storage for the 1890 U.S. census, and [[International Business Machines|IBM]] became a world-wide colossus before World War II on its dominance of card processing. | They were actually a hangover from a pre-[[electronic]] stage of [[data processing]]; Herman Hollerith pioneered the use of cards for data storage for the 1890 U.S. census, and [[International Business Machines|IBM]] became a world-wide colossus before World War II on its dominance of card processing. | ||
| − | A number of different formats were used over time. but the most popular by far was IBM's format, introduced in 1928: they were 7-3⁄8 by 3-1⁄4 inches in size, with rectangular holes in 80 columns of 12 rows. | + | Physically, they were stiff, thin cardboard, typically slightly less than .01 inches thick. A number of different formats were used over time. but the most popular by far was IBM's format, introduced in 1928: they were 7-3⁄8 by 3-1⁄4 inches in size, with rectangular holes in 80 columns of 12 rows. |
In the pre-electronic era brushes were used to sense the presence or absence of a hole; later on, optical sensors were common. | In the pre-electronic era brushes were used to sense the presence or absence of a hole; later on, optical sensors were common. | ||
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Revision as of 22:26, 29 April 2018
Punched cards were a very popular medium for input/output and data storage in the early period of computer usage. Data was stored in them by the presence, or absence, of holes punched in pre-determined locations.
They were actually a hangover from a pre-electronic stage of data processing; Herman Hollerith pioneered the use of cards for data storage for the 1890 U.S. census, and IBM became a world-wide colossus before World War II on its dominance of card processing.
Physically, they were stiff, thin cardboard, typically slightly less than .01 inches thick. A number of different formats were used over time. but the most popular by far was IBM's format, introduced in 1928: they were 7-3⁄8 by 3-1⁄4 inches in size, with rectangular holes in 80 columns of 12 rows.
In the pre-electronic era brushes were used to sense the presence or absence of a hole; later on, optical sensors were common.
