Punched card available, e.g. "80-column card". A sequence of cards that is input to or output from some step in an application's processing is called a "card deck" or simply "deck". The rectangular, round, or oval bits of paper punched out were called chad ("chads") or "chips" (in IBM usage). Sequential card columns allocated for a specific use, such as names, addresses, multi-digit numbers, etc., are known as a "field". The first card of a group of cards, containing fixed or indicative information for that group, is known as a "master card". Cards that are not master cards are "detail cards". The
Punched card input/output CPM: The number of cards which can be read or punched in one minute. Card reader models vary from 300 to around 2,000 CPM. If all columns of an 80 column card encode information this translates to approximately 2,500 characters per second (CPS). Cards may be read using mechanical "brushes" that make an electrical contact for a hole, and no contact if no punch, or photoelectric sensors that function similarly. Timing relates the signals to the position on the card. Cards may be read serially, column by column, or in parallel, row by row. Card punches necessarily run more slowly