Description
The term "core" comes from conventional transformers whose windings surround a magnetic core. In core memory the wires pass once through any given core—they are single-turn devices. The magnetic material for a core memory requires a high degree of magnetic remanance, the ability to stay highly magnetized, and a low coercitivity so that less energy is required to change the magnetization direction. The core can take two states, encoding one bit, which can be read when "selected" by a "sense wire". The core memory contents are retained even when the memory system is powered down (non-volatile memory). However, when the core is read, it is reset to a "zero" which is known as destructive readout. Circuits in the computer memory system then restore the information in an immediate re-write cycle. The properties of materials used for memory cores are dramatically different from those used in power transformers.
Read more about this topic: Magnetic-core Memory
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