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A 12-row/80-column IBM punched card from the mid-twentieth century. A punched card (also punch card [1] or punched-card [2]) is a piece of card stock that stores digital data using punched holes. Punched cards were once common in data processing and the control of automated machines.
An 80-column punched card. Rows 0 to 9 are labeled. The 12 row, on top, has one punch in column 7. The 11 row, below it is not punched on this card. As cards passed through a read station, usually 9-edge (bottom edge) first, wire brushes, one for each column, would make contact through the holes.
Columns on different punch cards vary from 5 to 12 punch positions. The method used to store data on punched cards is vendor specific. In general each column represents a single digit, letter or special character. Sequential card columns allocated for a specific use, such as names, addresses, multi-digit numbers, etc., are known as a field.
Punch cards were stepped across the punch one column at a time, and the appropriate punches were activated to create the holes, resulting in a distinctive "chunk, chunk" sound as columns were punched. Both machines could process 51-, 60-, 66-, and 80-column cards. [20] The 026 could print the punched character above each column.
Edge-notched cards were used for course scheduling in some high schools and colleges. [11] Keysort cards were also used in World War II codebreaking. The Stasi used edge-notched cards (German: Kerblochkarteikarten) from 1965 to index information including details of staff, crimes, people under surveillance, and vehicles. Cards often stored ...
Numeric columns have one punch in rows 0-9, possibly a sign overpunch in rows 11-12, and can be sorted in a single pass through the sorter. Alphabetic columns have a zone punch in rows 12, 11, or 0 and a digit punch in one of the rows 1-9, and can be sorted by passing some or all of the cards through the sorter twice on that column.
An IBM 80-column punched card of the type most widely used in the 20th century IBM 1442 card reader/punch for 80 column cards. A computer punched card reader or just computer card reader is a computer input device used to read computer programs in either source or executable form and data from punched cards.
A single program deck, with individual subroutines marked. The markings show the effects of editing, as cards are replaced or reordered. Many early programming languages, including FORTRAN, COBOL and the various IBM assembler languages, used only the first 72 columns of a card – a tradition that traces back to the IBM 711 card reader used on the IBM 704/709/7090/7094 series (especially the ...