Magnetic core memory was the most widely used form of digital computer memory from its birth in the early 1950s until the era of integrated-circuit memory began in the early 1970s. Aside from being extremely reliable, magnetic core memory is an appealing technology because it is based on a very simple idea.
A core, a ring of magnetic material, stores one bit by the direction of its magnetization.
A magnetic core is a ring of ferrite material. It can be permanently magnetized either clockwise or anti-clockwise about its axis just as a vertical bar magnet can be magnetized up or down. We can then turn a magnetic core into a bit of digital memory by letting these two magnetization states correspond to 0 and 1.
It provides non-volatile storage.
The core needs no power to retain its data. In other words, core memory is a form of non-volatile storage like modern hard disk drives, although in its day it fulfilled the ‘high-speed’ role of modern RAM.
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