Punched card - Revision history

Jnc: /* Further reading */ +Punched-Card Systems and the Early Information Explosion

2025-07-02T16:40:36Z

‎Further reading: +Punched-Card Systems and the Early Information Explosion

Jnc: /* External links */ +IBM cards used round holes until the early 1930s

2023-12-05T14:45:40Z

‎External links: +IBM cards used round holes until the early 1930s

Jnc: /* External links */ +good site

2022-05-21T20:35:20Z

‎External links: +good site

Jnc: data encoding

2021-01-11T04:36:47Z

data encoding

Jnc: +cat, +links

2018-12-13T15:02:07Z

+cat, +links

Jnc: Proper cat

2018-10-20T16:34:05Z

Proper cat

Jnc: Clarify

2018-04-29T20:26:06Z

Clarify

Jnc: A decent start

2018-04-29T13:55:30Z

A decent start

New page

'''Punched cards''' were a very popular medium for [[input/output]] and [[secondary storage|data storage]] in the early period of computer usage. Physically, they were stiff, thin cards; data was stored by the presence of 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.

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.

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← Older revision		Revision as of 16:40, 2 July 2025
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		+	==Further reading==
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		+	* Lars Heide, ''Punched-Card Systems and the Early Information Explosion, 1880-1945'', Johns Hopkins University, Baltimore, 2009

	==External links==		==External links==

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 In the pre-electronic era, wire brushes were used to sense the presence or absence of a hole; later on, optical sensors were common.
 ==External links==
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 * [https://homepage.divms.uiowa.edu/~jones/cards/ Punched cards]
 ** [https://homepage.divms.uiowa.edu/~jones/cards/history.html A brief illustrated technical history]
+* [https://ibm-1401.info/RoundHolesIBM-Card.html IBM cards used round holes until the early 1930s]
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+* [https://ibm-1401.info/Who80ColumnRectHolePunchedCard.pdf Who Invented the 80 column, Rectangular Hole Punched Card?]
 [[Category: Device Basics]]

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 A card could hold up to 80 alphanumeric characters, one per column: numbers were indicated by a single punch in rows 1-10; letters were indicated by a punch in row 10/11/12, plus a punch in rows 1-9. Cards could also hold [[binary]] data, with more than two holes per column; by convention, a 7 and 9 punch in the first column indicated that the rest of the card held binary data.
-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, wire brushes were used to sense the presence or absence of a hole; later on, optical sensors were common.
 {{semi-stub}}
 [[Category: Device Basics]]

@@ Line 3: / Line 3: @@
 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.
-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.
+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.
+A card could hold up to 80 alphanumeric characters, one per column: numbers were indicated by a single punch in rows 1-10; letters were indicated by a punch in row 10/11/12, plus a punch in rows 1-9. Cards could also hold [[binary]] data, with more than two holes per column; by convention, a 7 and 9 punch in the first column indicated that the rest of the card held binary data.
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-[[Category: Device Basics‎‎]]
+[[Category: Device Basics]]

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 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.
 {{semi-stub}}

← Older revision		Revision as of 16:34, 20 October 2018
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	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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