punchcards

Punchcards are a rigid piece of paper or cardstock into which holes are physically punched in predefined positions. These holes represent data, and the cards were an early method of inputting information into computers and other automated machines. The presence or absence of a hole in a specific location, or the pattern of holes, would be interpreted by a card reader as a specific character or instruction.

Invented in the 19th century, punchcards were first used for the Jacquard loom to control weaving patterns. Later, Herman Hollerith adapted the concept for use in tabulation machines for the 1890 United States Census, significantly speeding up data processing. This led to the formation of the Tabulating Machine Company, a precursor to IBM.

Throughout the 20th century, punchcards were a dominant form of data storage and input for early computers. Programs and data were meticulously punched onto decks of cards, and errors often required re-punching entire cards or even decks. Card readers would then process these cards sequentially.

The use of punchcards declined sharply with the advent of magnetic tape, floppy disks, and eventually hard drives, which offered vastly greater storage capacity and easier data manipulation. By the 1980s, punchcards were largely obsolete for mainstream computing, though they saw limited use in specialized applications for a few more years.