Thin film magnetic devices

935,704. Magnetic storage apparatus. INTERNATIONAL COMPUTERS & TABULATORS Ltd. Aug. 22, 1961 [Sept. 13, 1960], No. 31489/60. Class 40 (9). [Also in Group XIX] Data is stored in different areas of a thin magnetic film, and a selected area is brought to a magnetic state opposite to that of an immediately adjacent area by first switching it to the hard direction of magnetization, and subsequently allowing the magnetic state to relax to the easy direction under the influence of the adjacent area. A shifting register is shown in Fig. 2 which comprises storage areas 22/1- 22/n of a thin magnetic film 20 supported by a substrate 21. The easy axis of magnetization of the film is perpendicular to its length, and the film areas are switched to the hard direction in turn by overlapping drive pulses, Fig. 4, applied to respective drive conductors 23/1- 23/n. When the drive pulse in conductor 23/1 terminates, the film area 22/1 relaxes to a magnetic state along the easy direction of magnetization determined by a write pulse in a write conductor 24. The write pulse terminates after the drive pulse in conductor 23/1. When the drive pulse in conductor 23/2 ceases, the associated storage area relaxes to a magnetic state in the easy direction opposite to that of the adjacent area 22/1. The drive conductor 23/1 is re-energized from drive generator 29 and a further write pulse is applied from input 30 when the previous input has progressed sufficiently far along the registration areas to avoid magnetic interaction. A read out conductor 25 is provided at the remote end of the register which is connected to an output unit 30, the identity of the output signal being characterized by the polarity order of two spaced output pulses of opposite polarities. As described, the binary input signal is of positive or negative polarity according to the digit value. Alternatively, an input signal may be present only for a binary one value, in which case a permanently magnetized area 20 is provided to establish a binary zero magnetic state in the first area 22/1. It is stated that a circulating register may be formed by a cylindrical construction in which the areas 22/1 and 22/n are adjacent. A number of parallel registers having common drive conductors and each provided with a read and a write conductor may use a common thin film. Transfer conductors perpendicular to the drive conductors may be provided whereby data may be shifted from one register to another. Specification 905,625 is refer