Punched card facts for kids
A punched card is a stiff piece of paper that stores information using holes punched in it. Imagine a secret code where the holes tell a machine what to do! These cards were super important in the 20th century, especially for handling lots of information and controlling machines automatically.
Many of the first digital computers used punched cards to feed in both their instructions (programs) and the information they needed to work with. You could put data onto a punched card using a special machine called a keypunch.
Even though we don't use punched cards much for storing data anymore, some voting machines still used them to count votes as recently as 2012! These cards also had a big impact on how people thought about technology in the 1900s.
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History of Punched Cards
The idea of using holes to control machines or store data popped up several times throughout history. It's interesting because many inventors came up with similar ideas without knowing about the others' work!
Early Ideas and Inventions
In 1725, a person named Basile Bouchon figured out how to control a loom (a machine for weaving fabric) using holes punched in paper tape. His assistant, Jean-Baptiste Falcon, and later Jacques Vaucanson, made this idea even better. These improvements helped control the patterns woven into the fabric, but someone still had to operate the machine.
Then, in 1804, Joseph Marie Jacquard showed off a way to make loom operation fully automatic. He linked many punched cards together to form a long chain. Each card held instructions for one step of the weaving process, like raising or lowering threads and choosing the right shuttle. This was a huge step forward!
A Russian inventor named Semyon Korsakov was one of the first to suggest using punched cards for storing and searching for information in 1832.
Even the famous inventor Charles Babbage thought about using "Number Cards" with holes to help his calculating machines store numbers. However, he never actually built a working version of this part.
In 1881, Jules Carpentier created a system called the Mélographe Répétiteur. It used punched cards to record and play back music played on a harmonium! It basically "wrote down" the music as holes on cards, like Jacquard's loom. Later, he split it into two machines: one to record the music (the Melograph) and one to play it back (the Melotrope).
Punched Cards in the 20th Century
Towards the end of the 1800s, Herman Hollerith invented a way to record data on a medium that a machine could read. He developed punched card technology for the 1890 United States Census. His machines could read and summarize the data stored on these cards. This was a big deal for government and business data processing!
At first, these machines just counted holes. But by the 1920s, they could also do basic math. Hollerith started a company called the Tabulating Machine Company in 1896. This company later became part of what we now know as IBM in 1924. Many other companies also started making punched cards and machines to create, sort, and count them. These machines were used even after electronic computers started to appear in the 1950s.
By 1937, IBM was making millions of punched cards every day! Punched cards were even used for important legal documents, like U.S. government checks and savings bonds.
During World War II, punched card machines helped the Allies try to decode secret messages from the Axis powers. For example, at Bletchley Park in England, about 2 million punched cards were made each week to help with this huge effort. In Nazi Germany, punched cards were used for censuses (counting people) in different areas and for other purposes.
Punched card technology became a very powerful tool for businesses to process their information. By 1950, punched cards were used almost everywhere in businesses and government offices.
In the 1950s, magnetic tape started to be used for data entry. During the 1960s, magnetic tape slowly replaced punched cards as the main way to store computer data. This happened as computers became better and more powerful. By the mid-1980s, magnetic disk storage became much cheaper, and computer terminals allowed people to interact directly with computers. This made punched cards mostly obsolete for storing data and programs.
Punched Card Designs
The very first Hollerith punched cards for the 1890 U.S. census were plain. But after that, cards usually had printing on them. This printing helped people easily see where the rows and columns for holes were. Sometimes, the cards even had names for different sections, lines to mark fields, or company logos.
There were also "general purpose" cards. For special uses, like separating main cards from detail cards, the cards might have different diagonal cuts on their top corners. This allowed machines to sort them easily. Most cards had one corner cut off so you could tell if a card was upside down or if it was the wrong type.
Machines That Used Punched Cards
Many different machines were used to handle punched cards:
- Keypunches: These machines had a keyboard. Operators would type data, and the machine would punch the corresponding holes into the cards.
- Unit record equipment: These were machines that processed data on punched cards before computers were widely used. They included card sorters (to put cards in order), tabulating machines (to count and summarize data), and many other types of machines.
- Computer punched card readers: These were computer input devices. They read computer programs and data from punched cards and sent it to the computer. Early card readers could read about 100 cards per minute, while faster ones could read around 1,000 cards per minute!
- Computer card punches: These were computer output devices. They would punch holes into cards based on information from the computer.
- Voting machines: As mentioned, some voting machines used punched cards to record votes well into the 21st century.
Images for kids
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A 12-row/80-column IBM punched card from the mid-twentieth century.
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A stack of punched cards that make up a computer program. The red line helps keep them in the right order.
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A Hollerith card from 1895, with 12 rows and 24 columns.
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A punched card from a Fortran computer program. It shows "Z(1) = Y + W(1)" and sorting info.
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A binary punched card.
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An invalid "lace card" like this could cause problems for card readers.
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An IBM 5081 card made by a different company.
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An IBM 96-column punched card.
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A blank Remington Rand UNIVAC format card.
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A punched Remington Rand card next to an IBM card for comparison.
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An HP Educational Basic optical mark-reader card.
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An Aperture card.
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Universities often printed their logos on general purpose cards. Many forms and documents, like checks, were printed on punched cards without affecting how the machines worked.
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A printing plate used to make punched cards.
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A $75 U.S. Savings Bond, Series EE, issued as a punched card. Eight holes record the bond's serial number.
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Boxes of punched cards stored at a U.S. National Archives facility in 1959. Each box held 2,000 cards.
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A U.S. Census Bureau clerk (left) uses a pantograph, like the one Herman Hollerith developed, to prepare punch cards. Another clerk (right) uses a faster 1930s key punch.
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A large display sample of a punch card for the 1954 U.S. Census of Agriculture.
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An IBM Port-A-Punch device.
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A FORTRAN Port-A-Punch card.
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Another view of a Port-a-punch.
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See also
In Spanish: Tarjeta perforada para niños
