How did punch cards store non-digital computer data?
Punch cards were used to store data for early computers in a form that, while operational within digital systems, represented data in a physical, mechanical manner rather than in a non-digital or analog format. The concept of “non-digital computer data” as it applies to punch cards needs clarification because punch cards inherently store information in a binary manner—presence or absence of holes, which computers interpret as 1s and 0s, or digital data.
What is a Punch Card? Definition and Uses
Punch cards, also called “Hollerith cards,” or “IBM cards,” are stiff paper cards where holes can be punched manually or by a machine to symbolize computer data and commands. These cards were crucial for entering data into early computing systems. A card reader attached to a computer would read the punched holes, translating them into digital data or machine language.
In early days this method was an initial way to store information, like election votes, and, when used collectively, could store entire programs. Imagine an early computer programmer scribbling a program by hand, then punching the instructions onto these cards using a punch card machine. They would then carry this bundle of cards to a computer, feeding them through a card reader to upload the program. These cards were a bridge between the analog and digital worlds, representing a significant leap in data processing and computer programming.