Magnetic core Whirlwind computer IBM 704 semiconductor memory patent 702 Ferranti memory IBM computer
Magnetic core memory patented in 1949 with its first usage demonstrated for the Whirlwind computer in August 1953. Commercialization followed quickly. Magnetic core was used in peripherals of the IBM 702 delivered in July 1955, and later in the 702 itself. The IBM 704 (1955) and the Ferranti Mercury (1957) used magnetic-core memory. It went on to dominate the field into the 1970s, when it was replaced with semiconductor memory.  Magnetic core peaked in volume about 1975 and declined in usage and market share thereafter.
