Diff — Punched card

A **punched card** is a stiff paper card in which data is stored as the presence or absence of holes at fixed positions. For nearly two centuries it was *the* standard medium for feeding instructions and data into machines — from silk looms to mainframes — and it is the direct physical ancestor of the stored program.

# From music to weaving

The idea of controlling a mechanism by holes in a moving medium is older than computing. Pinned barrels and perforated paper ran **barrel organs** and music boxes in the 1700s. Weavers adopted it early: **Basile Bouchon** used perforated paper tape for pattern control in 1725, **Jean-Baptiste Falcon** chained cards in 1728, and **Jacques de Vaucanson** refined the approach in 1745 — but all three mechanisms were fragile and saw little use.

[[Joseph-Marie Jacquard]] made it work. His **1801–1804** loom read a loop of chained cards, one card per row of cloth, each hole deciding a single thread: the first high-volume, reliable use of a stored instruction sequence in industry.

# Into computing

- **1830s** — [[Charles Babbage]] adopted Jacquard-style cards for the [[Analytical Engine]]: *operation cards* held the program, *variable cards* the data. [[Ada Lovelace]]'s notes — including the [[Bernoulli numbers]] program — were written to be punched on cards.

- **1890** — [[Herman Hollerith]]'s tabulating machine processed the US census on punched cards, cutting years off the count. His company eventually became **[[IBM]]**.

- **1900–1970s** — cards became the universal input/output medium: the IBM **80-column card** (1928) fixed the standard, and generations of programmers wrote code by punching one statement per card — FORTRAN's fixed-column layout is a direct fossil of card fields.

# What the card actually was

A card is storage you can see: each position is binary — hole or no hole — so a card is literally a row of bits a machine can sense with pins, brushes, or light. Because decks were physical, they developed their own culture: decks were labeled, numbered, rubber-banded, and dreaded-dropped (a dropped deck was an unsorted disaster; diagonal marker lines across the top edge existed so you could reorder one by eye).

When interactive terminals arrived in the 1970s the card vanished almost overnight — but its DNA survives: fixed-width fields, batch processing, the 80-column text line, and the word "**program**" applied to a prepared sequence of operations all trace back to paper with holes in it.

# See also

- [[Jacquard Loom]]

- [[Herman Hollerith]]

- [[Analytical Engine]]

- [[History of Programming]]

# References

3. Truesdell, Leon E. *The Development of Punch Card Tabulation in the Bureau of the Census* (GPO, 1965).

[[Category:History]]

[[Category:Hardware]]