MAGNETIC CORE MEMORY:

This type of memory is used extensively in airborne digital systems, although integrated circuits are being developed with most modern aircraft systems.  This system works by a Ferro-magnetic material will become magnetized if placed in the proximity to an electric current.  Each bit in the magnetic core memory is a ferrite ring in which a magnetic field can be induced by a current flowing in a wire.  Figure 9 shows typical ferrite ring for storing a single bit.

Ferrite Ring Memory

Although the wire carrying the current is wound round the ring, the same effect is obtained if the wire passes through the ring.  This is a more convenient way to set the magnetic state of each ring when a plane of cores is built.  The advantage of this type of memory is that when the power is removed it holds its state, i.e. it is a non-volatile memory.  A matrix of cores containing 16 bits of information is shown in Figure. 

16 Bit Ferrite Memory