Dagnar on Nostr: Computer punch cards worked by using patterns of punched holes to represent data and ...

Computer punch cards worked by using patterns of punched holes to represent data and instructions, which were then read by a machine that converted the holes into digital information. To create a card, a keypunch machine was used to punch holes in a pre-defined coding scheme. For reading, the card was passed through a card reader, which used mechanical probes, or more commonly, a light-based system to detect the presence or absence of a hole in each position, thereby translating the physical holes into electronic signals that the computer could understand.