IBM Electronic Keypunch Machine

Keypunch machines are devices for transferring data by means of punched holes or notches on a series of cards or paper tape.

The first practical use of punched cards for data processing is credited to the American inventor Herman Hollerith, who used punched cards to represent the data gathered for the American census of 1890, and to read and collate this data using an automatic machine. In consequence of his success Hollerith founded a company (which became International Business Machines IBM in 1924) that eventually standardized these cards and held an effective monopoly on them for many years.

Punch cards were a piece of cardboard, about the thickness of a 3 x 5 index card and cut into a rectangle about 3" by 7 1/2". On each card (of 80 columns and 12 rows), 80 alpha-numeric characters of data could be punched. The cards were punched with keypunch machines, typewriter-like devices handled by operators. At the top centre of each machine was a removable drum onto which a punch card was clamped to direct the key punch. Punches in the drum card determined how to treat the corresponding column of the cards being punched. At the same time as holes were punched into a card, key punch machines printed the data on the top line of each card.

From the 1920s through the 1950s punched cards and keypunch machines were the mainstay of business data processing. Up until the 1950s almost all input to computers was stored on punched cards (data as well as programs).