Patent GB-970062-A (GB)
Title: Binary transfer device
IPC: G06F7/38
Filed: 1961-02-08
Abstract: 970,062. Shift registers and half adders. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb.9, 1961 [Feb.9, 1960], No. 4881/61. Headings G4A and G4C. [Also in Division H3] Thin magnetic films 2, 3, Fig. 1, each having an easy axis of magnetisation E2, E3 displaced by a small angle e from the axis of respective driving conductors 7, 8 are linked by a coupling conductor 4 arranged at an angle of between 15 degrees and 75 degrees with respect to each driving conductor. The coupling conductor need not be cranked as shown. The films 2, 3 are deposited on an insulating layer of evaporated silicium oxide, which overlays a metal film 1 of silver, copper or aluminium on a glass substrate. The ends of the coupling conductor are connected to the metal film 1. The film 2 is a controlling element and stores a binary value according to its remanent magnetisation direction along the easy axis. When switched to the hard direction by a pulse in driving conductor 7, the film 2 induces an output in the coupling conductor consisting either of two sequential pulses of small magnitude and opposite sense or a large unidirectional pulse, depending on the direction of remanent magnetisation and the polarity of the driving pulse. Immediately prior to this operation the controlled film 3 is magnetised in the hard direction by a pulse in driving conductor 8. This pulse terminates before the induced voltage in the coupling conductor, and the controlled film 3 takes up a remanent state the direction of which is determined by the polarity and magnitude (large or insignificant) of the coupling conductor pulse, the polarity of the driving conductor pulse, and the positive or negative sense of the small angle e between the easy axis of magnetisation and the axis of the associated driving conductor. The sense of the easy axis angle e and the polarity of the driving pulse in conductor 7 also determine the direction of remanent magnetisation which film 2 takes up when the driving pulse terminates. By way of example, if the remanent magnetisations of films 2 and 3 are both directed to the right (binary one), and the easy axis angle e is zero, then a positive driving current in conductor 7 will cause negligible current to be induced in the coupling conductor. If the driving conductor is negatively pulsed, the absence of coupling current will cause the controlled film 3 to revert to the right when the coupling current terminates. If the film 2 is directed to the left initially (binary zero), the polarity and magnitude of the coupling current causes film 3 to take up a remanent direction to the left along the easy axis. Converse effects are obtained if the coupling conductor is positioned orthogonally to that shown. By having a positive easy axis angle + e, the remanent magnetisation of a film will establish to the right if a positive driving pulse is applied and no coupling current is present, or to the left if the driving pulse is negative. The reverse is obtained in the absence of a coupling pulse for a negative easy axis angle-#. Instead of providing the small angle e between the easy and driving conductor axes, the bias effect may be obtained from a permanent field such as the earth's magnetic field. Logical circuits. These principles are used to form a variety of logical circuits performing such functions as AND, AND-OR, OR-AND, inclusive OR and exclusive OR, numerous examples being given. An AND circuit is shown in Fig. 15 in which films 135, 136 are controlling elements, and film 137 is the controlled element, the easy axis angle e being positive. The driving conductors A and B are pulsed by the positive and negative pulses respectively, each pulse terminating as the other begins. As the coupling conductors 138, 139 are orthogonal, the conditions for induced currents of effective magnitude from the films 136, 137 differ. Thus if films 135, 136 are both magnetised in the binary zero sense-(left), a large current-I is induced in conductor 138 only and element 137 takes up a zero state. If only one or other of films 135, 136 are magnetised in the binary sense one (right), both coupling conductors will have the same induced currents, either large or small depending on which film is in the binary one sense, but of opposite polarities. As film 137 is pulsed by negative driving current it will revert to the zero state. When both films are magnetised in the binary one sense, a large current + I is induced in conductor 139 which switches film 137 to the binary one state. In a modification the pulses in the driving conductors A and B are of negative and positive polarities respectively and the circuit then performs the logical OR operation. Half adder. Magnetic films 161 to 166 Fig. 42 are arranged in three stages controlled by two overlapping driving conductors 170, 171. Alternatively three separate driving conductors (not shown) may be used. Several switching programmes are possible depending on the senses of the various easy axis angles e. With two overlapping driving conductors, the switching programme for pulses S, T shown in Fig. 43 may be used, for example. This programme corresponds to energization of three separate driving conductors by respective pulses A, B and C, Fig. 37. In this example elements 163 to 166 have positive easy axis angles + e, while the angle of inclination e of elements 161 or 162 may be of either sense. The two binary values X1 and X2 to be added are stored in films 161 and 162 respectively, and after the application of pulse S which mutually cancels with T in the second stage, the magnetic state of film 163 represents X 1  . X 2  and that of film 164 represents X 1  . X 2 . When pulse T terminates, the second stage is acted up by pulse S and the content is transferred to the third stage to establish the binary sum (X 1 #X 2 ) + (#X 1  . X 2 ) in film 166 and the carry X 1  . X 2  in film 165. Shifting registers. Thin films 101 to 106, Fig. 11 are associated in groups of three with respective driving conductors to which pulses A, B and C are applied according to the programme shown in Fig. 12. Automatic, reset to binary zero in the absence of a one-switching pulse in an associated coupling conductor is effected by negatively inclining the easy axes. A similar shifting register is also described with reference to Fig. 14 (not shown). The shifting register of Fig. 11 may be modified by using overlapping coupling conductors 188-195, Fig. 45, so that a complete cycle of driving pulses, U, V .W applies to groups of six films. Suppressing spurious outputs. Directly induced voltages in the coupling conductors from the driving conductors may be suppressed by the arrangements shown in Figs. 10a to 10d. In Fig. 10a the coupling conductor 61 is looped back over the driving conductor 62 before connecting with the conductive base plate. The same principle of inducing an equal and opposite spurious voltage to effect suppression is used in Fig. 10b in which the coupling conductor 66 is cranked and the film 70 is associated with one only of the cranked portions 71, 72. An alternative method is to use two driving conductors 73, 74, Fig. 10c which are pulsed in opposite directions, either or both conductors being associated with magnetic thin films 76, 77. Also the Figs. 10b and 10c methods may be combined as shown in Fig. 10d