Edge-notched cards or edge-punched cards are a system used to store a small amount of binary or logical data on paper index cards, encoded via the presence or absence of notches in the edges of the cards.[1] The notches allow efficient sorting of a large number of cards in a paper-based database, as well as the selection of specific cards matching multiple desired criteria.
Unlike machine-readable punched cards, edge-notched cards were designed to be manually sorted by human operators. They are also informally called needle cards since they can be sorted with the help of long knitting needles. In the mid-20th century they were sold under names such as Cope-Chat cards, E-Z Sort cards, McBee Keysort cards,[2] and Indecks cards.[3]
- ^ Casey 1958.
- ^ Casey 1958, p. v.
- ^ Kelly 2008.