Punched Cards

Punch cards, also known as punched cards or perforated cards, were a dominant medium for data storage and processing from the late 19th century well into the mid-20th century.

Their origins trace back to early textile automation, with Joseph-Marie Jacquard’s loom (1801) using punched cards to control weaving patterns. However, it was Herman Hollerith who revolutionized their use for data processing. In 1890, Hollerith developed an electromechanical tabulating system for the U.S. Census that employed punched cards to encode demographic data.

His early cards were 3-1/4 inches by 7-3/8 inches, with 12 rows and 24 columns, each hole representing data bits. This system significantly expedited census processing and laid the groundwork for modern data handling.

Hollerith’s cards evolved, especially after his company merged to form the Computing-Tabulating-Recording Company, which later became IBM. IBM standardized the 80-column format in the 1920s, a design that became synonymous with computing. These cards, measuring 7-3/8 inches by 3-1/4 inches, featured rectangular holes arranged in 80 columns and 12 rows.

Each column held one character, which could be interpreted using IBM’s proprietary codes. The most common character set, the IBM BCD (Binary-Coded Decimal), was later extended into the IBM EBCDIC

(Extended Binary-Coded Decimal Interchange Code), used by mainframes¹. Other variations of the card emerged for specific uses. IBM’s 40-column Port-A-Punch card was a manually punchable card intended for field use, where clerks could encode data without a machine. IBM also introduced stub cards and short cards, truncated versions designed for routing or partial data entry. With increased data density needs, IBM developed a 96-column card format in the 1960s, using smaller, circular holes.

These were often used with optical mark and high-speed reading equipment. Concurrently, Powers/Remington Rand/UNIVAC systems used 90-column cards, which stored alphanumeric data using three rows of round holes. Powers-Samas in the UK used yet other card formats with unique hole arrangements, often tailored to European business machines.

A notable adaptation of the punch card was the “mark sense” format, which allowed users to make pencil marks instead of punching holes. These cards were optically or electrically read and often used in educational testing and surveys.

Despite the variety in formats, manufacturing punch cards remained a precise operation. Special cardstock, typically 0.007 inches thick, ensured consistency for mechanical handling. Cards were die-cut or drilled with exacting standards to maintain alignment and integrity during high-speed reading or punching. Culturally, punch cards left a deep impression.

The phrase “Do Not Fold, Spindle, or Mutilate” became a widely recognized warning, originally intended to preserve cards’ readability. Over time, it became a metaphor for the depersonalization inherent in bureaucratic systems, especially during the 1960s and 70s counterculture movement. Punch cards also found ironic use in art and protest, representing mechanized conformity.