Patent GB-705504-A (GB)
Title: Improvements in and relating to the electronic storage of information
Inventor: WILLIAMS FREDERIC CALLAND
IPC: H04Q3/52
Filed: 1950-09-25
Abstract: 705,504. Digital electric calculating. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Aug. 21, 1951 [Sept. 25. 1950], No. 23489/50. Class 106 (1). [Also in Group XL(c)] In a store of the type in which a charge pattern is set up on the insulating screen of a cathode ray tube and regenerated, a characteristic state of charge is set up at a selected distance from a reference point to represent a digit. The system is particularly applicable to notations of higher order than binary, e.g. decimal, bi-quinary &c. A number in decimal notation is allocated a length of trace, Fig. 1 (a), the cathode ray beam being operative during clock pulses, Fig. 1 (d), fed from a generator 24 through a gate 34 to the grid of C.R.T.20. The clock pulses also control the digit time base 36, the output from which is combined with the sawtooth from X-scan generator 38 to produce the stepped waveform, Fig. 1 (c), the steps having sufficient duration that the charge on each spot is neutralized by the electrons leaving the succeeding spot as described in Specification 657,591. In the initial scan, the beam is switched off at the desired digit 6, leaving the charge pattern, Fig. 1 (b). Subsequent step-by-step scanning produces a signal, Fig. 1 (e), on plate 21 which, after passage through the amplifier 22 appears smoothed as at Fig. 1 (f). Generator 24 controls a strobe pulse generator 23, Fig. 1 (g) to select the large pulse P2 which passes through a network 33 to give a delay of one clock pulse and then operates the trigger circuit 35, Fig. 1 (h) to close the gate 34. The fly-back of the digit time base 36 resets the trigger circuit, and a blackout wave, Fig. 1 (i), is used to suppress the beam between scans. New information is written in by the use of a paralyzing bias applied at 40 to prevent the amplifier passing a signal. Clock pulses are fed to a divider 41 to produce pulses at one-twelfth the recurrence frequency and these are fed to a delay line 42. An electronic switch 43 selects a suitably delayed pulse and feeds it to the trigger circuit 35 to cut off the beam and leave the desired charge pattern on the screen. Two spot positions A, B are provided to enable 0 and 1 to be properly recorded, and the O position may be placed after the 9 so that the extinction of the beam by the black-out wave automatically records 0. Modifications.-A digit may be indicated by a gap in the trace, Fig. 2 (a), to give a charge pattern, Fig. 2 (b), the circuit being modified to the form shown in Fig. 10. A trigger circuit 35' maintains the beam operative until the strobed amplifier output opens the gate 34' to cause the next clock pulse to operate the trigger circuit and cut off the beam, Fig. 2 (h), circuit 35' being reset by the flyback of the digit time base. A dot-dash technique, Fig. 3 (not shown), may be employed of the type described in Specification 657,591 a dash indicating the required digit, the time-base being linear or with steps of dot duration. An economy of space may be obtained by arranging a series of dots, Fig. 4 (not shown), followed by a further vertically displaced dot arranged under the desired digit, the trace being flashed-back after the normal time base and displaced by a transverse shift voltage so that the charge on the spot representing the desired digit is neutralized and an output occurs from the amplifier during a succeeding sweep. The strobed output pulse operates a gate to release a clock pulse which is fed to a counter circuit which determine the position of the flashed-back dot. The dot may be drawn into a line to indicate the desired digit, Fig. 5 (a), the output from amplifier 22, Fig. 5 (f), being gated in valve V1, Fig. 6, by strobing pulses, Fig. 5 (g), from generator 23 controlled by clock pulse generator 24. The strobed pulse Fig. 5 (h), triggers dash and square wave generators 25, 26 the wave, Fig. 5 (i), maintaining the C.R.T. beam operative through the dash period due to diode D3 conducting. The clock pulses are fed to the C.R.T. grid during the positive going portion of the square wave, Fig. 5 (j), since diode D2 is held cut off and diodes D1 and D4 conduct the resulting grid waveform being Fig. 5 (e). The clock pulses are gated by the dash pulse in valves V41, V5 to produce the output, Fig. 5 (l), fed to the cathode of diode D5, the dash pulse being fed to the cathode of diode D8. As a result, during the clock pulses outside the dash pulse, diodes D6, D7 are held non-conducting and the time base executes the level parts a. Between clock pulses diode D5 cuts off and D6 conducts so that rundown occurs at a rate determined by resistor R1 to produce slope b. During the dash pulse diode D8 cuts off and the run-down b<SP>1</SP> is determined by resistor R2. The cathode follower V8 provides rapid recharging of Miller capacitor C during the fly-back, and the time base duration is determined by pulse, Fig. 5 (m), from generator 27. In a modification, Fig. 8, the trace is progressed so rapidly that the charge behind the moving spot is not filled so that a charge pattern, Fig. 7 (c), is produced. The delayed strobed output from the amplifier, Fig. 8, is fed to a trigger circuit 35" which closes the gate valve V9 to prevent further charging of time base capacitator Cl. At the termination of the time base interval diode D10 is rendered conducting to discharge the capacitor C1 and the trigger circuit is reset. Bi-quinary notation.-One part of the trace is used to indicate 0 or 5 while a second part records 0 to 4. A time-base waveform sweeps over the binary record and then the quinary the latter following the former directly if an "0" is recorded but being delayed by the time of sweep over the quinary if a " 5 " is recorded. Alternatively, the beam may sweep once over the binary followed by twice over the quinary, the beam being blacked out in the first or second sweep according to whether a "5" or "0" is recorded in the binary section. Display.-The digits may be arranged vertically the beam being moved horizontally to commence each fresh digit. Specifications 645,691, 705,474, 705,498 and 705,502 also are referred to.