Patent GB-705499-A (GB)
Title: Improvements in or relating to electronic information-storing devices
Inventor: WILLIAMS FREDERIC CALLAND
IPC: G11C11/23
Filed: 1950-02-16
Abstract: 705,499. Digital electric calculating apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Feb. 1, 1951 [Feb. 16, 1950], No. 4050/50. Class 106 (1) In a method of recording and reading digital information employing an electronic device of the kind in which information is stored as different conditions of charge formed by an electron beam on an insulating surface in a cathode-ray tube, a predetermined path is scanned to set up a positive charge thereon and then one or more parts on or near the path, selected according to the information to be stored, are irradiated with the beam in order to reduce by secondary emission the positive charge on the path in the neighbourhood of the selected part or parts, subsequent scanning along the path generating in a signal plate capacitively coupled to the storage surface signals representative of the stored information. In the described embodiment a master oscillator 10, Fig. 3, controls a "Y" time base generator 12, which may be of the type described in Specification 682,156, and an "X" time base 11 which generates a stepped waveform deflecting the beam in steps separated by digit intervals during which the beam is stationary. A further generator 20 produces a sinusoidal deflecting voltage of 20 Mc/sec frequency which is applied to the Y plates under control of a gate or keying modulator 21 which passes bursts of 20 Mc/sec oscillation in response to "dot" pulses from a generator 13 to deflect the beam along a predetermined path 1, Fig. 1. This action leaves a line of positive charge representing " 0 (diagram 2) due to the liberation of secondary electrons. In order to record digit "1", a spot at one end of the line is reirradiated while the beam is held in this position : this results in a charge pattern 4. A similar irradiation at the opposite end of the line would represent digit " 2 (diagram 6) while a further digit may be represented by irradiating the centre of the line to form a charge pattern 8. Instead of scanning a straight line the electron beam may be arranged to explore a loop (e.g. a circle or elipse) and decimal digits may be recorded by irradiating one or more spots spaced round the loop. When each digit line is explored by the electron beam, signals characteristic of the digit represented are picked up by a plate 19 and passed to an amplifier 25. The output of the amplifier is passed through phase-selective gates 26, 27 controlled by generators 28, 29 which allow a positive pulse to pass a rectifier 30 or 31 according to whether a "1" or a "2" is detected. The signal passes on to the "read" unit 32 and also via " erase" voltage-controlled gates 39, 40 to a trigger circuit 23 which is set according to the value of the digit detected and serves to determine the position of the electron beam on the predetermined path during the subsequent re-irradiation period. Thus, the burst of 20 Mc/sec. oscillation passed through the gate 21 during a dot period is followed by grid cut-off if an " 0 " is represented, but if " 1 " is represented the signal received at the read unit 32 causes the write unit 33 to turn on the beam again to re-irradiate the end of the line to represent a "1". Similarly the detection of a "2" causes the opposite end of the line to be reirradiated. New information arriving at the "write" terminal 38 is assumed to comprise a series-mode pulse train with positive and negative pulses representing "1" and "2". These are fed through rectifiers 35, 36 to the write " unit, the positive pulses being inverted by a device 37. The incoming pulse train is also used to set the trigger 23 for the purpose described above. Specifications 693,424, 705,474 and 705,482 also are referred to.