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by Dinesh Thakur

The principle form of electronic MEMORY used in computers prior to the invention of semiconductor memory chips. It consisted of thousands of tiny rings called cores, made from a magnetic FERRITE material and each threaded onto three fine copper wires: the whole formed a two-dimensional mesh much like a knitted textile.

By passing current down the two appropriate vertical and horizontal wires, a particular core could be addressed and its direction of magnetization either read or altered using the third wire, so it behaved as a RANDOM ACCESS memory. The size of its components restricted the amount of core memory that could fit into a computer to thousands rather than millions of bytes.