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.