A punched card, also known as a punch card or perforated card, is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were widely used throughout the 20th century in various fields, including data processing, programming, and computing.
History and Development
Early Beginnings
The concept of punched cards dates back to the 18th century when they were used to control textile looms. In 1801, Joseph Marie Jacquard developed the Jacquard loom, which used punched cards to control the weaving patterns of textiles. This innovation laid the groundwork for later developments in data encoding.
Introduction to Computing
Punched cards became integral to computing with the work of Herman Hollerith during the 1890 U.S. Census. Hollerith’s tabulating machine used punched cards to efficiently count and tabulate census data, demonstrating the potential of this medium for data storage and processing.
Evolution in Technology
By the mid-20th century, punched cards were a standard medium for data storage in early computers. Companies like IBM popularized their use with machines such as the IBM 1401. Punched cards served as both input and output devices, storing instructions, and data for computation.
Structure and Encoding
Physical Characteristics
Punched cards typically measure 7 3/8 by 3 1/4 inches, created from stiff cardstock. The card is divided into rows and columns. Each column represents a single character or digit, encoded by the presence or absence of holes.
Data Encoding
Data on punched cards is represented using various encoding schemes, the most common being the Hollerith code and the IBM 80-column punched card format. Each column can encode a single alphanumeric character by the combination of holes punched in a predefined pattern.
Examples of Organizing Data
- Hollerith Code: Utilizes specific punches in each column to represent numbers and alphabet characters.
- Binary Encoding: Holes represent binary (0s and 1s), facilitating digital processing.
Applicability
Computing and Data Processing
Punched cards were essential in early computing for programming languages such as FORTRAN and COBOL, where each line of code or instruction corresponded to an individual punched card.
Historical Significance
Punched cards stand as symbolic artifacts of the early age of computing, contributing significantly to developments in data processing and storage technologies.
Related Terms
- Tabulating Machine: An early mechanical device that uses punched cards to tabulate data.
- IBM 1401: One of the earliest computers that relied heavily on punched cards for data input and output.
- Keypunch Machine: A device used to create punched cards by manually or electronically punching holes.
FAQs
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Conclusion
Punched cards exemplify an essential era in the history of computing and data processing. Although obsolete today, their impact on the development of modern computing techniques and technologies is undeniable, marking a significant stage in the evolution of data storage and encoding methods.
Summary
Punched cards were pivotal in the progression from manual to automated data processing. Their use across various fields, from textile manufacturing to computing, demonstrates their versatility and historic significance. Understanding punched cards’ structure, encoding methods, and historical context provides valuable insights into the early foundations of today’s data storage and processing technologies.
