Magnetic-film logic. A theoretical and experimental study of a system using magnetic films and conducting loops

The general principles of a proposed logic system using magnetic films are described. Groups of binary storage cells are coupled by means of short planar conducting loops close to the film on a conducting substrate. A theoretical analysis is made of the current induced in the loop when a storage cell on it is read. Currents of 250mA, decaying to 50mA in the first 10ns, are expected. Experiments on the properties of a short loop coupling the cells are described, the measured currents being in general agreement with those predicted over the possible range of measurement, provided that the effects of the substrate in setting film cells are separated from the effects of the loops. It is concluded that, although a complete logic system could be made using the proposed technique, the rapid decay of the currents used to set the cells would require the use of very fast pulse generators, and the system could not complete economically with conventional transistor logic of the same speed. The experiments show the practical possibility of two forms of nondestructive-readout store.