Patent GB-782368-A (GB)
Title: Electronic digital data storage device
IPC: G11C11/56
Filed: 1954-11-19
Abstract: 782,368. Electric digital-data-storage apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 19, 1954 [Nov. 24, 1953], No. 33544/54. Class 106 (1). In a cyclically-operated electronic digital data store each storage element includes a capacitor adapted to be charged (or discharged) at a constant rate through a first electronic tube to a predetermined value and then suddenly discharged (or recharged) through a second electronic tube to its initial value, means for applying an input signal to initiate the charge (or discharge) of the capacitor at a selected instant in a cycle corresponding to the data to be stored, means for detecting when the capacitor is fully charged (or discharged), and means responsive to the detecting means for providing an output signal, the rate of charge (or discharge) being adjusted so that the output signal is produced at an instant in the following cycle corresponding to the data stored. In the described embodiment the storage capacitor 19 is initially uncharged and remains so as long as both halves of a tube 6 are non-conducting. A decimal digit is entered in the form of a positive pulse at terminal c at a time in the machine cycle indicative of its numerical value and this starts conduction in the L.H. triode charging the capacitor 19 at a constant rate until the zero point in the cycle is reached. At this point a thyratron (Fig. 3, not shown) is fired by a control pulse, and delivers an increase in voltage via terminal d to the cathodes of tube 6 sufficient to render the tube non-conductive and therefore to stop the charging of capacitor 19. During the remaining portion of the machine cycle, which allows time for carry-over and control pulses, the charge on capacitor 19 remains unchanged. At the commencement of the digit period of the following cycle the absence of an " entry " control pulse allows the terminal b to rise to a higher voltage which permits conduction in the R.H. triode of tube 6 whereby the charging of the capacitor 19 is resumed and continues until the point is reached corresponding with the original entry time when the capacitor 19 will have been charged to 300 volts. At this point, in synchronism with a clock pulse, the voltage obtained from terminal a will fire a thyratron (Fig. 10, not shown) which rapidly discharges the capacitor 19 and brings terminal a back to + 300 volts. A pulse obtained from this action provides a time-representation of the stored digit which may be used to control a recording device. The R.H. triode of tube 6 still being conductive, the capacitor 19 starts to charge up again at a constant rate and the cycle described above is repeated. The store is zeroized when the entry control pulse reappears; the thyratron (Fig. 10, not shown) is fired to discharge the capacitor 19 at the beginning of the digit period and the tube 6 remains non-conductive until the digit pulse appears at terminal c as described above. To counter the effect of possible variations in the supply voltage the multivibrator (Fig. 4, not shown) which produces the various control. pulses is fed with sync. pulses from a capacitorcharging arrangement, including a double triode and a thyratron, similar to the storage circuit described above, but adjusted to send out control pulses at.digit frequency. Throughout the circuits hard-valve trigger circuits could be used instead of thyratrons. Moreover, the read-out pulses may be arranged to represent the nines or tens complements of the stored digits. Specifications 642,927, 673,759 and 781,295 are referred to.