Patent GB-957514-A (GB)
Title: Improvements in magnetic core storage devices
IPC: G11C11/06
Filed: 1960-06-03
Abstract: 957,514. Magnetic storage devices. BURROUGHS CORPORATION. June 3, 1960 [June 5, 1959; May 17, 1960], No. 19755/60. Heading H1T. [Also in Division H3] A magnetic device comprises an apertured core 10 (Fig. 3A), of material, capable of assuming different states of magnetic remanence, having a winding 42 linking both sides of the core without passing through the aperture to produce, when energized, opposing magnetic forces round the core and a second winding 48 linking the core in such a way as to produce, when energized, a magnetic force around the core. The device is designed to give non- destructive read-out of information stored therein, the core 10, which may be of ceramic ferrite or thin alloy tape, being saturated in one direction to record a " 1 " (clockwise) and in the other direction to record a " 0 " (anticlockwise), the information being written in by a signal applied either to winding (or windings), 48 only or coincidentally also to winding 42. A pulse or current in 48 coincident a burst of high frequency A.C. or D.C. pulses in 42 may be used. Read-out is by application of a pulse to winding 42 which produces opposing fields (marked " H field ") on the opposite sides of the core. The field on one side is in the same direction as the saturating flux in the core and so has little effect while the field on the other side opposes the saturating flux and produces temporary changes in flux in the parts of the core surrounded by sense winding(s) 48 resulting in an output in 48, the polarity of which depends on the direction of the saturating flux in the core and is independent of the polarity of the read-out pulse. With the decay of the read pulse the flux in the core returns to its previous state an oppositely directed output being produced in winding(s) 48. The core can be switched by a D.C. pulse in write winding 48, which is insufficient to produce switching by itself, and a coincident burst of pulses in read winding 42. Pieces of low reluctance magnetic material 108, 110 (Fig. 7), may be positioned adjacent winding 42 to increase the output in the sense winding when an interrogating pulse is passed through 42. Alternatively, the signal to ratio may be increased using a biasing magnetic field in the direction of the field produced by the read winding. This may be produced by a biasing D.C. current in the read windings, a bar magnet, an electromagnet, a solid sheet of permanently magnetized material or a thin permanently magnetized high coercive nickel cobalt film 238 deposited on a copper-coated substrate 240 arranged as shown in Fig. 12. The thin film acts as a permanent magnet producing a field in the same direction as the read current so that the effect of the former is to cause change of the remanent flux density Br (Fig. 13), in the part(s) of the core linked by the output winding to that represented by B 1 . The read pulse then causes a further change to B 2  and is said to give an output voltage five times that obtained without the biasing arrangement. Any high coercivity magnetic material may be used including impregnated rubber or plastic rubber magnetic material or metallic sheets. The cords are cemented in holes in a flat phenolic card. Specifications 957,515 and 957,516 are referred to.