Patent GB-860007-A (GB)
Title: Improvements in registers for data
IPC: G11C11/22
Filed: 1957-11-11
Abstract: 860,007. Ferro-electric pulse-storage and gating circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 11, 1957 [Nov. 9, 1956; Dec. 24, 1956], No. 35103/57. Class 40 (9). [Also in Groups XIX, XXXVI and XL (b)] Ferro-electric material (for example barium titanate) has inter alia the following two electrostrictive properties:-a) if a portion of a slab 20, Fig. 6A, of the material is put into one of its two stable-states of remanent polarization and if a voltage pulse is applied across that portion, for example by means of a pair of electrodes 22a, 22b, the voltage pulse being of too small an amplitude to alter the remanent state of polarization of the material, then a compressional wave is caused to spread throughout the material emanating from the region across which the voltage pulse is applied, the compressional wave having a " polarity " determined by the polarity of the applied pulse and by the particular state of remanent polarization of the portion of the material across which the voltage pulse is applied, and (b) if a compressional wave is set up in a slab of the material (for example by the above method) as it spreads through the slab it produces a potential difference between the two surfaces of the slab, the polarity of the potential difference being determined by the " polarity " of the compressional wave and by the particular state of remanent polarization of the portion of the slab across which the potential difference is measured, and the magnitude of the potential difference being determined by the magnitude of the compressional wave. These properties are used to construct logical switching circuits and to permit the repeated non-destructive read-out and/or dynamicization of binary data stored as one of the two stable states of remanent polarization of a slab of ferro-electric material. For example, if four bits of data are stored in the four regions bounded by the four electrode pairs 22a, 22b, Fig. 6A, and if the region bounded by an output pair of electrodes 24 is put into one of its stable states of remanent polarization, then a pulse (of small amplitude) applied simultaneously to all four electrode pairs 22a, 22b, causes four compressional waves to travel along the slab towards electrodes 24 which they reach successively and cause a succession of four output pulses, whose polarities are indicative of the stored data. A further example is shown in Fig. 5B which shows an " exclusive or " gate. Pulses applied simultaneously to electrodes 42a and 42b (which are oppositely poled) cause compression waves which cancel each other when they reach a central electrode 40 producing no output whereas a pulse applied to one only of the two electrodes 42a, 42b does produce an output pulse at the electrode 40. In the main embodiment, Fig. 6, data from a register 32 is transferred simultaneously to the four rows of a 4 Î 4 array of ferro-electric cells, the four cells in each row being contained in the same slab of ferro-electric material 20 which also has a pair of output electrodes 24 at its end (as in Fig. 6A). In operation the data from register 32 is transferred to each row, the portions of ferroelectric material bounded by the electrodes 24 are put into one of their stable states of remanent polarization and a pulse (of small amplitude) is applied to one of four read-out wires 28a, 28b, 28c, 28d connected as shown, which causes the four bits of data to be read out serially cyclically shifted by an amount determined by the particular read-out wire pulse. The output pulses, which pass through gates 64 can either be routed to a further register 74 or back to the original register 32. In an alternative method of operating the circuit of Fig. 6 when it is not desired to actually store the data in the matrix, every cell in the matrix is set to the same stable state of remanent polarization and the register 32 is caused to deliver signals (of small amplitude) simultaneously with the pulsing of a selected read-out wire. In this case if the register 32 produces pulses to represent ones and nothing to represent zeros, and if the readout pulse applied to the selected read-out wire is of the same polarity as the pulses from register 32, each cell being read will receive a pulse of unit amplitude-if it corresponds to a zero-or of two units amplitude-if it corresponds to a one- and the same correspondence will apply to the output pulses which before being passed through gates 64 will be converted into a " pulse, no-pulse " form by discriminators 62. In a further embodiment, Fig. 10, 16 pairs of electrodes 124, 126 are arranged in two concentric circles about a central pair of electrodes 122. With such an arrangement, because compressional waves travel faster along the diagonal directions than the vertical and horizontal directions (referred to Fig. 10), a compressional wave emanating from the central electrodes 122 reaches first the inner pair 126, then the inner pair 124, then the outer pair 126 and lastly the outer pair 124, so that the four bits stored at these four positions will be read-out serially by means of a pulse applied to the central electrodes 122.