Patent GB-899366-A (GB)
Title: Improvements in or relating to magnetic core shift registers
IPC: G11C19/06
Filed: 1960-11-11
Abstract: 899,366. Circuits employing bi-stable magnetic elements. AMP Inc. Nov. 11, 1960 [Nov. 25, 1959], No. 38753/60. Class 40 (9). [Also in Group XIX] In a shifting register in which each stage comprises a magnetic core 40, Fig. 2, formed of bi-stable remanent material and having a transmit aperture T, an optional receive aperture R, and a larger main aperture M, a clockwise flux, Fig. 2A, is established around the main aperture of a cleared or zero state core, clockwise and anticlockwise fluxes, Fig. 2B, are established around the transmit and optional receive apertures in the binary one storage state, the flux around the transmit aperture is reversed to the anticlockwise sense, Fig. 2C, by a priming operation preparatory to read-out, and the flux around the transmit aperture is restored to the binary one clockwise sense to establish a like registration in the next register stage. The object of the priming phase is to permit the use of less critical switching currents. One embodiment using cores 11-14 each with three apertures is shown in Fig. 3, the advance and priming windings through the transmit apertures being shown only on cores 11 and 14 respectively to simplify the diagram. In operation core 11 is initially in the cleared state, and is switched to the binary one condition if a pulse is applied to a receive aperture winding 19 by a data source 16. To advance registrations from the odd cores, 11, 13 to the even cores 12, 14, a pulse is applied from a prime-0 source to a priming winding 52, and the flux about the respective transmit apertures is reversed if a binary one is stored. The amplitude of the pulse is insufficient to influence the flux about the main aperture. A pulse is next applied by an advance winding 47 to cores 11 and 13 from an advance O to E source to restore the flux about the transmit apertures. Each odd core, if in a binary one state, induces a pulse in its associated transfer winding 1L21, 1L23 which establishes a corresponding state in the adjacent even core 12, 14. The odd cores are then set to zero by a clear pulse in winding 54 which also acts through hold windings in the transmit apertures of the even cores to prevent an output from an odd core from incorrectly influencing the even core immediately preceding. The next phase of operation is the transfer of registrations from the even to the odd cores, and this is effected by prime-0, advance E to O and clear E pulses applied in turn to windings 50, 49 and 56. A modified circuit is described, Fig. 4, in which a prime winding 70 is common to all the cores and is pulse or D.C. energized, and the cores are optionally biased by a winding 66. Also the separate advance and clear stages of operation are combined by connecting a common advance and hold winding 64, which passes through all the transmit apertures, in series with the clear O and clear E windings 60, 62. In a further modification, Fig. 5, the priming winding 70 is arranged so as to pass through the transmit apertures instead of the main apertures. The use of receive apertures is avoided in the circuits shown in Figs. 6 and 7. Fig. 6 is not shown since it is otherwise the same as Fig. 4. In Fig. 7 the priming winding 114 is connected in series with the clear odd and clear even windings 98, 102 and with the advance and hold winding 112. Specification 896,657 is referred to.