The term core memory originates from the early days of memory technology, when the smallest ferrite beads of only 0.5 mm diameter were built up into memory matrices.
The remanence offerrite has two stable magnetic states, representing the two binary states. Thus, one ferrite core can store one bit. Write and read wires were pulled through the ferrite beads, which interrogated or changed the magnetic state. A ferrite bead-based core memory was a non-volatile memory whose access time was in the range of 800 ns. When the core memory cell was read out, however, the remanence could be impaired to such an extent that the core memory cell lost its information. This was referred to as destructive readout( DRO).
The term core memory is often used synonymously with random access memory( RAM), although it is a semiconductor memory.