History effect of ferrite cores as analog storage elements

Studies on 2-and 3-mm ferrite cores for use as storage elements in an analog core memory are presented. The information is stored as the flux level of the magnetic core. The partial fluxswitching is performed by voltage pulses with constant amplitude but varying length. Between writing and reading an error appears which is caused by the reversible portion of the flux and whose value depends upon the switched flux level. It is shown that there exists a relation between the magnitude of the error and the characteristic properties of the cores. The measured character of the error depends on how often a particular write-read cycle is repeated before changing the amplitude of the switched flux. A history effect was found to be the reason for this. A special method has been developed to drive the cores in a matrix array [1]. In this mode the history effect did not occur.