Punch card

Punch cards are pieces of card with columns where holes could be punched each column to represent a character.

The idea of cards for data (their first use), came from the use of cards to control weaving looms. The principle was invented by Joseph Marie Jacquard in the early years of the 19th century.

When punch cards were used to input programs and data, programming was also a mechanical activity involving finding which card contained the line in the program you wished to change, shuffling through the cards to find it, punching a new card, inserting it into the pack of cards and persuading the card reader to accept your modified program without stopping at a card misread.

• why older computers and monitors had an 80 character wide display
• photograph and explanation on the first punch cards