Edge-notched card

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Edge-notched card used as a library card. Edges not notched here.

Edge-notched cards, or McBee cards, were a manual data storage and manipulation technology invented in 1896 and used for specialized data storage and cataloging applications through much of the 20th century. While there were many variants, a popular version consisted of 5 inch by 8 inch paperboard cards with holes punched at regular intervals along all four edges, a short distance in from the edges. To record data, the paper stock between a hole and the nearest edge was removed by a special notching tool. The holes were assigned a meaning dependent upon a particular application. For example, one hole might record the answer to a yes/no question on a survey, with the presence a notch meaning yes. More complex data was encoded using a variety of schemes. The center of the card might be blank space for information to be written, or contain a pre-printed form. One corner of each card was beveled, much like Hollerith punched cards, but edge-notched cards were not intended to be read by machines.

Edge-notched cards were manipulated by putting one or more long wire pins through certain holes. As the pins were lifted, the cards that were notched in the hole positions where the pins were inserted would be left behind as rest of the deck was lifted by the pins. Using two or more pins produced a logical and function. Combining the cards from two different selections produced a logical or. Quite complex manipulations, including sorting were possible using these techniques.

Before the widespread use of computers, some public libraries used a system of small edge-notched cards in paper pockets in the back of library books to keep track of them.