A radio-frequency nondestructive readout for magnetic-core memories

It is possible to read information nondestructively from two- and three-dimensional magnetic-core digital computer memories in several microseconds by exciting selected cores with rf currents. If two co-ordinate lines of a core in a memory array plane are driven at slightly different frequencies, a beat-frequency signal is generated whose phase may take on one of two values which are separated by 180 electrical degrees. These two possible phases correspond to the 0 and 1 information states of the core. The beat-frequency signal, separated from the inevitable noises by tuned linear filters, may be phase detected to yield the desired information.