A form of core memory for data storage. The core is made of tiny ferrite rings threaded with wires that are magnetized by electrical current. The two possible polarities of magnetization were used to represent the binary values zero and one. Data are stored by magnetizing an array of cores in a particular combination of zeros and ones. Data are retrieved by sending electrical pulses to the specific array of cores holding the desired information. The pulses reverse the direction of magnetization in the cores, including output signals corresponding to the stored data.
This form of memory storage began in the 1950s and was widely used up through the 1970s. Core memory, which made forms of memory such as the magnetic drum obsolete, was rendered obsolete by semiconductor memory.