A three-coincident-current ferrite core analog memory matrix

Ferrite cores with rectangular hysteresis loops can store analog values if the flux φi, corresponding to the analog input information, is impressed upon the core. All known techniques, however, are applicable only for a single element, but not for a three-dimensional random access matrix because of physical or economical reasons. A new technique for the selection and driving of each core of a matrix for analog storage by three-coincident pulsewidth modulated currents was developed. To achieve the necessary linear relation between the input value and the impressed flux by voltage pulses of constant amplitude, the amplitude of the and write current pulses is controlled by a reference core, while that of the write pulse is regulated. The total error is within ± 1% for all matrix cores. Serial or parallel operation for writing and reading is possible as well as a quasi-nondestructive readout by quantization of the read analog value before rewriting.