Patent GB-1046548-A (GB)
Title: Improvements in or relating to intelligence storage equipment
Inventor: EMERSON JOHN CHRISTOPHER
IPC: G11C7/00
Filed: 1964-03-17
Abstract: 1,046,548. Magnetic storage apparatus. STANDARD TELEPHONES & CABLES Ltd. March 12, 1965 [March 17, 1964], No. 11190/64. Heading H3B. A magnetic element provides a closed flux path around slot 2 subdivided at a plurality of storage locations 4 into first and second flux paths, the minimum cross-sectional area of the first path being equal to the minimum crosssectional area of the undivided portion 3 of the flux path, and the cross-sectional area of the second path being equal to or greater than this minimum cross-sectional area. Bias windings 5 and sense windings 6 thread each hole 4 and a drive winding 7 is provided on limb 3. To write information, drive winding 7 is energized to generate a clockwise flux, and bias windings 5 for the locations required to store a " 0 "' are energized to tend to generate clockwise fluxes around the corresponding apertures 4, the bias currents having a value about half that required to cause a permanent flux change around the aperture. As a result clockwise fluxes are produced around " 0 " storing apertures and flux also passes in a clockwise direction along limb 3, over " 0 " storing apertures and under " 1 " storing apertures. For read-out a bias current of the same value and direction is passed through all the bias windings at the same time as a read current is supplied to drive winding 7 to generate an anticlockwise flux. As a result an anticlockwise flux is produced which flows beneath apertures 4 and through limb 3, the flux directions beneath the " 1 " storing apertures only having been reversed to generate outputs. In a modification (Fig. 6, not shown) the storage locations are made triangular, the bases of the triangles having the same cross-sectional area as the lower limb, and the other sides of the triangles having twice the area. The bias windings are omitted and the sense windings are wound on the large area sides of each triangle. For writing the digit stored is determined by the presence or absence of a current supplied to the sense windings or additionally parallel windings. During read-out, flux generated in the drive winding preferentially takes the shorter path along the base of each triangle unless this path is already saturated by a stored " 1." In a further modification (Fig. 7a, not shown) the uppermost sides of the triangles are equal in cross-sectional area to the bases and to the lower limb. Operation is similar except that the information is stored by a continuous flux along the lower limb and along the bases or the uppermost sides of the triangles, with no circulating fluxes around the triangles. The corresponding arrangement with circular apertures is also described (Fig. 8, not shown). Elements as shown in Fig. 1a may be stacked to form a three-dimensional array, corresponding apertures in each plane having common sense and bias windings, and the planes having a common write drive winding, but separate read drive windings, on the lower limbs. Alternatively several separate read drive windings may be provided for each plane so that reading is only achieved when currents are supplied to all the drive windings. In order that the wires between the planes may be kept straight the lower limb may be shaped as in Fig. 5. Each plane initially consists of a plate having a slot and a row of apertures at each side of the slot. One set of apertures forms storage apertures 13, but material adjacent the other apertures is removed on one side or the other of the lower limb, leaving triangular notches. In Fig. 5, two selection wires are associated with each slot, both passing down in the centre of the limb and one passing up through slot 12 and the other passing up outside the core. The wires are connected to current sources A, A B, B, C, C, D and D, one wire from each pair being energized to select a plane. In Fig. 5, plane 25a is selected by currents ABCD since these windings all link the lower limb. The selection windings may be opposed by a common auxiliary drive winding providing two units of flux in the opposite direction to the main drive windings. The auxiliary drive current may be the return currents from the main drive windings. The device shown in Fig. 9 is produced by'removing triangular portions 54 from a square plate having four storage apertures 52 and four additional apertures. This differs from the other devices in that each storage location is separated from the next by a region having the same crosssectional area as the storage region between the aperture and the central slot 53. The storage region on the other side of each aperture may be of equal area and equal length, equal area and greater length, unequal area and equal length, or unequal area and unequal length to the region between the aperture and the slot. A stack corresponding to that in Fig. 5 may be formed using four similar elements of the type shown in Fig. 9, each being rotated through 90 degrees from the adjacent one. Larger stacks may be formed from pentagonal or hexagonal elements. The sense windings on one half of a stack may be reversed relative to those on the other half so that currents induced by the write currents cancel.