Punch Card

What Does Punch Card Mean?

A punch card is a simple piece of paper stock that can hold data in the form of small punched holes, which are strategically positioned to be read by computers or machines. It is an early computer programming relic that was used before the many data storage advances relied upon today.

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A punch card is also known as a punched card, IBM card or Hollerith card.

Techopedia Explains Punch Card

In the earliest, most primitive computing setups, punch cards were fed into large computers that held very little memory or data. These large computers were sometimes called big iron machines. One example of the use of punch card technology is in the renowned Turing machine invented by Alan Turing, a leader at the time in the information technology movement.

Obvious design weaknesses led punch card technology to become quickly obsolete, as newer forms of data storage were invented. Interestingly, the unit of data used by a punch card does not typically correlate to the smallest units of data held in today’s storage media. Rather than using binary data, as they do today, punch cards used individual characters – mostly letters and numbers – wherein each punch in the card represented the selection of one particular character.

Punch cards, like mainframe and supercomputers of the late 20th century, are now mostly historical items of curiosity.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…