Patent GB-1062235-A (GB)
Title: Information storage apparatus
IPC: G11C11/06
Filed: 1964-06-18
Abstract: 1,062,235. Circuits employing bi-stable magnetic elements. WESTERN ELECTRIC CO. Inc. June 18, 1964 [June 21, 1963], No. 25208/64. Heading H3B. In an arrangement for non-destructive readout of information from a magnetic core storage element 11 11 , an associated access core 10 11  is switched from a predetermined remanent state to its other remanent state, thereby inducing in a winding 12 11  a voltage sufficient to switch the storage core. The access core 10 11  is subsequently reset at a rapid rate if core 11 11  has been switched, thereby resetting it to its original state, or is reset at a slow rate if core 11 11  has not been switched, leaving core 11 11  unchanged. A two-by-two memory matrix 18 is shown, having column conductors 20, 21 and row conductors 25, 26, each provided with a switch 23 at one end and a switch 28 at the other end. The row and column conductors are coupled to access cores 10 so as to generate clockwise fluxes when energized. Each access core also has a bias winding 56 tending to reset it in the anticlockwise remanent state. X- and Y-selection sources 65, 66 normally provide a high D.C. voltage to all switches 23 and 28, causing saturation of transistors 30 and consequent non-conduction of transistors 31. When a core is selected for read-out a pair of x-conductors and a pair of y-conductors are each supplied with a low voltage pulse to render transistors 30 non-conductive and transistors 31 conductive in the selected row and column. The pulses in the y-conductors are normally of longer duration than those in the x-conductors. Conduction of transistors 31 allows current to flow from source 33 to earth through windings 20 and 25 so that access core 10 11  is switched. If storage core 11 11  is in its clockwise (zero) remanent state the current 100 induced in winding 12 11  by switching of core 10 11  merely drives core 11 11  further into saturation, and negligible output is produced in output winding 15. When the x-select pulses terminate switches 23 are rendered non-conductive, whereas the y-select pulses maintain switches 28 conductive. The current in bias winding 56 then resets core 10 11 ,which induces voltages in windings 20, 25. The base-emitter junction of transistor 31 in each switch 23 now acts as a forward-biased diode and is effectively a constant voltage source of low voltage. Since the voltages induced in windings 20, 25 by resetting of core 10 11  are held to a low magnitude, resetting is relatively slow, and the voltage induced in winding 12 11  is insufficient to switch core 111 11 . If, on the other hand core 11 11  had originally been in the anticlockwise (ONE) remanent state switching of core 10 11  would have switched core 11 11  inducing an output in winding 15. Winding 15 is connected to the Y-selection source 66 and the presence of an output voltage causes the y-select pulses to terminate at the same time as the x-select pulses. As a result, when core 10 11  is reset windings 20, 25 are at a floating potential and resetting occurs at a maximum rate. The voltage induced in winding 12 11  thereby restores core 11 11  to its original anticlockwise remanent state. New information is written-in by energization of winding 15 by source 60 and coincident selection by sources 65, 66.