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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 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.
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.
Cards are read and punched one column at a time and binary cards are permitted. Cards are read using photocells, [8] illuminated by fiber optics, unlike the IBM 1402, which uses wire brushes to read cards. It is even possible to create (but not read, except in Binary Mode [9]) "IBM Doilies," cards with every possible hole punched. Few other ...
A punched card sorter is a machine for sorting decks of punched cards. Sorting was a major activity in most facilities that processed data on punched cards using unit record equipment. The work flow of many processes required decks of cards to be put into some specific order as determined by the data punched in the cards.
In computing, a signed overpunch is a coding scheme which stores the sign of a number by changing (usually) the last digit. It is used in character data on IBM mainframes by languages such as COBOL, PL/I, and RPG. [1]
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 ...
Cards with a particular punch could be treated as master cards causing different behavior. For example, customer master cards could be merged with sorted cards recording individual items purchased. When read by the tabulating machine to create invoices, the billing address and customer number would be printed from the master card, and then ...