GB1117896A - Multi-aperture magnetic logic devices - Google Patents

Abstract

1,117,896. Electronic counters. MULLARD Ltd. 19 Aug., 1965 [14 Oct., 1964], No. 41892/64. Heading G4A. [Also in Divisions H1 and H3] A magnetic logic device comprises a magnetic core member 1 (part of a laddie core) of material having a rectangular hysteresis loop provided with main apertures 2, 3 and minor apertures 5, 6, 15, 16, 19 (Figs. 1a, 1b) windings 24, 25 connected to receive A input (bipolar) signals and windings 27, 28 for B input (bipolar) signals being arranged as shown. An output winding 21 provides a signal on the occurrence of an A or B input but not both (Exclusive OR) while an AND output is provided by winding 22. To secure this bipolar drive pulses are provided in a winding 23 and are of the same phase as the input pulses occurring at the same time. The flux pattern produced by a (positive) drive pulse (Fig. 2a, not shown) is changed on the occurrence of a (positive) A or B signal to provide flux in the same direction on both sides of the central minor aperture 19. Following slow reversal of the flux around minor aperture 16 by a small negative prime pulse in winding 29 (which passes through minor aperture 19 in figure of eight manner to eliminate noise in 21), the device is reset by a negative drive pulse in winding 23 when switching of the flux in leg 18 of minor aperture 19 produces an OR output in winding 21. If the A and B signals coincide, the flux pattern is such (Fig. 2e, not shown) that the next drive pulse following a prime pulse produces an AND output from winding 22. A triggered bi-stable divide-by-two device forming one stage of a binary counter is obtained by connecting the output of the Exclusive OR stage as a feed-back loop 30 (Fig. 3, not shown) in series with the A windings 24, 25, the loop passing through aperture 6 for noise cancellation purposes. Another loop 31 connects the B windings through aperture 6 to a previous stage 32 of the device which generates a carry signal for a binary counter. The first pulse from 32 passes through the B windings and sets the flux for an Exclusive OR output in loop 30 and on the appearance of the next drive pulse (the drive and prime windings 23 and 29 of Fig. lb are included but not shown in Fig. 3) this output passes through the A windings in loop 30 and sets a flux pattern for a first input. This persists until the next pulse from 32 provides a second input setting the AND gate to provide an output in the loop (shown dotted) to the next stage on the occurrence of the next drive (clock) pulse which resets the AND gate for the next operation. It is stated that unipolar pulses can be used if extra drive and prime windings and transfluxors &c. are provided.