Patent GB-949038-A (GB)
Title: Logical circuit
IPC: G06F7/38
Filed: 1959-12-21
Abstract: 949,038. Shifting registers; full adders. KOKUSAI DENSHIN DENWA KABUSHIKI KAISHA. Dec. 21, 1959 [Dec. 30, 1958; Feb. 28 195], No. 43356/59. Headings G4A and G4C. [Also in Division H3] In an arrangement of two or four magnetic cores having rectangular hysteresis loops which are switchable between remanent states by alternately applied writing and reading pulses, the reading pulses are applied to output windings connected with rectifiers so as to form a bridge circuit, output pulses being obtained across the bridge the polarity of which are dependent on the polarity of input pulses applied simultaneously with the writing pulses. As shown in Fig. 1, two cores M1, M2 have their output windings C1, C2 connected in a bridge circuit with rectifiers D1, D2, the input bridge terminals being connected to a readout source R and the output bridge terminals being connected to a load such as the input windings I N  of the next stage. A write winding W is pulsed at the same time as an input pulse is applied to the core input winding I N , with the result that both cores are brought to the same magnetic polarity in one or the other sense depending on the input pulse direction. A reading pulse I R  then brings the two cores into opposite polarity states, and since the state of one core only is changed the bridge becomes unbalanced and a major portion of the reading pulse passes to the output circuit with appropriate polarity. A four core arrangement the operation of which is not so dependent on the output load impedance is shown in Fig. 5. Three pulse periods are used in each cycle of operation of this embodiment, the cores M1-M4 being reset by a pulse Is applied to a resetting winding S between the reading and writing pulse periods. Thus, after resetting, the magnetic polarities of the cores M1-M4 are respectively (-), (+), (+), (-). When the writing and input pulses are coincidently applied these polarities change to wholly (+) if the input pulse is positive and wholly (-) if the input pulse is negative. The reading pulse causes cores M2, M4 to change from (+) to (-) in the former case or causes M1,M3 to change from (-) to (+) if a negative input is stored, thereby unbalancing the bridge circuit comprising output windings 01-04 and rectifiers D1-D4. As a result a major portion of the reading pulse passes to the output with appropriate polarity. The cycle is recommenced by I s  resetting the core polarities to their initial state. Several groups of cores I-1,I-2,II-1,II-2, Fig. 10 may be connected in series to form a shifting register, alternate core groups I, II being subjected to respective resetting Is, writing I w  and reading I r  pulses in different phase positions as shown in Fig. 6. Binary input signals are represented by positive and negative pulses in the windings I N . In a modification, Fig. 11 (not shown), the output connections between alternate stages are reversed to effect the logical "NOT" operation at these points. Fig. 17 shows a binary full adder in which four groups of cores E1-E4 each perform a logical operation in response to coincident input signals x, y and z which can be either negative or positive, the respective directions of energization of the input windings I nx , I ny , I nz  being indicated by (+) and (-) symbols. Following the writing pulse I W  phase which is effected simultaneously in all four core groups, read-out pulses from separate sources are applied coincidently to respective terminal pairs R2, Ra1 and R4, Ra3. As a result a positive or negative current I 0  passes through Z L  in accordance with the core states set up by the input signals. The various polarity combinations of the inputs x, y, z, the resultant output polarities from each of the core groups E1-E4 and the direction of output current I 0  are as follows:- Arrangements for performing various logical operations are also described (see Division H3).