reikäkorttien

Reikäkorttien, often translated as punch cards, were a form of data storage used from the mid-19th century to the late 20th century. They consisted of a piece of stiff paper or cardstock that could be encoded with data by punching holes in specific positions. The presence or absence of a hole in a particular location represented a binary digit, either a one or a zero. These holes were designed to be read by machines, either mechanically or optically.

The earliest applications of punch cards were in the textile industry, notably by Joseph Marie Jacquard for controlling looms in 1801, allowing for the automated weaving of complex patterns. Later, Herman Hollerith developed a punch card system for the 1890 U.S. Census, significantly speeding up data tabulation. This invention led to the formation of the Tabulating Machine Company, a precursor to IBM.

Punch cards were widely used in early computing as a primary method for inputting both programs and data. Programmers would punch instructions onto cards, and these would be fed into computers for processing. While revolutionary for their time, punch cards were cumbersome, prone to errors if damaged or mispunched, and had a limited storage capacity. Their use gradually declined with the advent of magnetic tape, floppy disks, and eventually solid-state memory, becoming largely obsolete by the 1980s and 1990s.