<P> A punched card or punch card is a piece of stiff paper that can be used to contain digital information represented by the presence or absence of holes in predefined positions . The information might be data for data processing applications or, in earlier examples, used to directly control automated machinery . </P> <P> Punched cards were widely used through much of the 20th century in what became known as the data processing industry, where specialized and increasingly complex unit record machines, organized into semiautomatic data processing systems, used punched cards for data input, output, and storage . Many early digital computers used punched cards, often prepared using keypunch machines, as the primary medium for input of both computer programs and data . </P>

Who introduced famous 20 point input output program