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Punched card

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A punched card is a stiff, paper-based medium used to store digital information. It functions through the presence or absence of holes in very specific, predefined positions. These holes act as a code that machines can read to process data or follow instructions.

Punched card program deck.agr
Punched card program deck.agr

For much of the 20th century, these cards were essential for data processing and controlling automated machines. They served as the primary method for inputting both computer programs and raw data into early digital computers. Even though they are now obsolete, their influence remains in modern computing standards.

The mechanism of a punched card relies on physical patterns. When a machine reads a card, it detects the holes to determine the information stored there. In some electromechanical systems, holes might allow levers to move or electrical signals to pass through.

Hollerith punched card
Hollerith punched card

A collection of these cards is known as a card deck. Within a deck, certain cards serve specific roles. A master card contains fixed or indicative information for a group. Other cards, called detail cards, provide the specific data points. These cards are often organized into fields, which are sequential columns allocated for specific uses like names or numbers. The small bits of paper removed during the punching process are called chad or chips.

Different formats and types of cards were developed to suit various needs. The IBM 12-row/80-column format became the dominant industry standard. This specific layout provided 80 character positions per line. Some cards featured unique physical markings to help with organization. For example, master cards might have different diagonal corner cuts than detail cards. This allowed machines to separate them automatically during sorting.

Punch-card-5081
Punch-card-5081

Other cards were printed with vertical lines, logos, or field names to make the rows and columns easier for humans to see. Some cards were even used as legal documents, such as U.S. Government checks and savings bonds.

US Savings Bond EE $75
US Savings Bond EE $75

The history of punched card technology spans several centuries and multiple independent inventions. In 1725, Basile Bouchon used paper tape with holes to control a weaving loom. This was later improved by Jean-Baptiste Falcon and Jacques Vaucanson. In 1804, Joseph Marie Jacquard automated loom operation using a chain of linked punched cards.

These cards controlled the shedding process, which involves raising and lowering the warp threads. Later, in 1881, Jules Carpentier used a system called the Mélographe Répétiteur to record and play music on a harmonium. He used the Jacquard method to translate musical performances into holes punched in a series of cards.

In the late 19th century, Herman Hollerith revolutionized data processing. He developed a method to record data on cards for the 1890 U.S. census.

Hollerith punched card
Hollerith punched card

His idea was partly inspired by railway punch photographs, where conductors used punches to mark ticket descriptions. Hollerith's tabulating machines could count and summarize data stored on these cards. He founded the Tabulating Machine Company, which eventually became part of IBM in 1924. By 1937, IBM's production was massive, with 32 presses in Endicott, New York, printing between five and 10 million cards every day. During World War II, these machines were used by the Allies to help decrypt Axis communications. At Bletchley Park in England, workers produced approximately 2 million punched cards every week.

The rise of the punched card had significant economic and legal impacts. Large companies like IBM and Remington Rand often tied card purchases to machine leases. This practice led to legal battles, including a 1936 Supreme Court case where the court ruled that IBM could only set card specifications.

Remington Rand punched card.mw
Remington Rand punched card.mw

By 1950, punched cards were ubiquitous in both government and industry. However, the technology began to change as more capable computers arrived. In the 1950s, the Univac UNITYPER introduced magnetic tape for data entry. Throughout the 1960s, magnetic tape gradually replaced punched cards as the primary storage medium. By the mid-1980s, the combination of affordable magnetic disk storage and interactive terminals made punched cards obsolete for most computing tasks.

Despite being replaced, the legacy of the punched card persists in modern digital environments. One major connection is the 80-character line standard. Many modern command-line interfaces and programming environments still use this convention. This is because early terminals, such as the IBM 3270, displayed 80 columns of text to remain compatible with existing software.

Tambor para Punch Card - Photo 3165102
Tambor para Punch Card - Photo 3165102

While newer systems use graphical interfaces with variable-width fonts, the structural influence of the 80-column format can still be seen in how data is organized and displayed today.

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🖼️ Images & Media (25)
File:Used Punchcard (5151286161).jpg
Used Punchcard (5151286161).jpg
File:Tambor_para_Punch_Card_-_Photo_3165102.JPG
Tambor_para_Punch_Card_-_Photo_3165102.JPG
File:DMM 29263ab Jacquardwebstuhl.jpg
DMM 29263ab Jacquardwebstuhl.jpg
File:This is a card puncher, an integral part of the tabulation system used by the United States Census Bureau to compile... - NARA - 513295.jpg
This is a card puncher, an integral part...
File:Keypunch operator 1950 census IBM 016.jpg
Keypunch operator 1950 census IBM 016.jpg
File:Punched card program deck.agr.jpg
Punched card program deck.agr.jpg
File:Hollerith punched card.jpg
Hollerith punched card.jpg
File:FortranCardPROJ039.agr.jpg
FortranCardPROJ039.agr.jpg
File:Blue-punch-card-front-horiz.png
Blue-punch-card-front-horiz.png
File:IBM1130CopyCard.agr.jpg
IBM1130CopyCard.agr.jpg
File:IBM lace card.jpg
IBM lace card.jpg
File:Punch-card-5081.jpg
Punch-card-5081.jpg

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