Patent GB-717104-A (GB)
Title: Improvements in or relating to data storage circuits and memory elements therefor
IPC: G11C19/00
Filed: 1952-10-24
Abstract: 717,104. Electric digital data storage apparatus. WESTERN ELECTRIC CO., Inc. Oct. 24, 1952 [Nov. 1, 1951], No, 26741./52. Class 106 (1) A data storage circuit comprises a condenser having a dielectric of a ferroelectric material in an initial polarization, means for applying storage spulses to the condenser, the storage pulses reversing the polarization: of the material, means, for applying a read-out pulse to the condenser to cause the material to traverse a portion of the hysteresis loop, and means for receiving an output pulse from the condenser upon application of the read-out` pulse, the magnitude of the output pulse depending on the slope of the portion of the hysteresis loop traversed. In a first embodiment a barium titanate crystal 10, Fig. 2A, with. silver spots 11 and 12 affixed on opposite sides, is first subjected to a pulse of positive, potential from a source 16. By virtue of the' ferroelectric nature of the crystal, the. polarization is only partially removed when the positive pulse is ended, being left in state A, Fig. 2B. Binary digit " 1 " can now be recorded in the crystal by application of a negative pulse from source 17. This causes a change of polarization represented by following the curve AD and returning to B when the negative potential is removed. Binary digit "0" is represented when the polarization is left in state A. Read-out of the stored digit is.performed by applying a positive pulse to the crystal. If the crystal is in state " 1 " and a change from B to A via C takes place, a relatively large output pulse appears at terminal 15 ; if, on the other hand, digit "0" is recorded, a smaller pulse of the same polarity appears at 15. Similar results can be obtained by urging pulses all of opposite polarity from those stated above and reversing the diode 14. In a second, embodiment, the use of a diode having a much greater back resistance, and very short read-out pulses, enables many read-outs to be taken after one recording. An extra-long pulse is used to erase the record. In a third embodiment aplurality of pairs of silver spots are arranged on a single elongated crystal and further diodes or rectifiers are used as buffer devices. This leads to a compact form of construction in which rectifiers 14, Fig. 9C, and 34 are combined with the crystal 10: Other con structions enclosed in a glass or plastic envelope are also described. A fourth embodiment, Fig. 10, comprises a shifting register in which each stage includes two crystals. Negative data pulses enter at terminal 40 in synchronism with negative stepping pulses (-E) applied to line 60. Intermediate positive stepping pulses (+E) are applied to line 50. Negative-going outut pulses appear in succession at a terminal 70. In a fifth embodiment data from crystal storage devices are read into an electric delay line to obtain the result in series-mode form. In a sixth embodiment (Fig. 13, not shown) ten crystal storage devices are arranged to form a decade counter unit. Initially, the odd-numbered crystals are in one state of polarization, and the even-numbered crystals are in the opposite state. Positive and negative input pulses are supplied alternately and cause a change of state as follows : Pulse 1+ Stages 1, 2 positive Pulse 2- Stages 1, 2, 3 negative Pulse 3+ Stages 1, 2, 3, 4 positive &c. In general, the highest numbered crystal which is polarized opposite from its initial state represents the magnitude of the count, and arrangements for read-out on this basis are provided. In a seventh embodiment a pair of crystals are employed for the storage of a binary digit and arranged so that the stored digit can be read out repeatedly with no loss of amplitude.