Patent GB-704754-A (GB)
Title: Information storage system
IPC: G11C11/23
Filed: 1950-04-28
Abstract: 704,754. Digital electric calculating-apparatus. ECKERT-MAUCHLY COMPUTER CORPORATION. April 28, 1950 [June 10, 1949], No. 10554/50. Class 106 (1). [Also in Group XL (c) Apparatus for storing information in the form of an electric charge pattern upon a chargereceiving target in a cathode ray tube, e.g. for use in an electronic digital computer, comprises means for producing first and second charge patterns or spots of circular and annular crosssection respectively, the internal diameter of the second charge pattern being greater than the external diameter of the first. General operation.-In the storage system diagrammatically shown in Fig. 5, 32-digit binary numbers are stored on 32 lines (one number per line) of the screen 12 of a shielded cathode ray tube 56, "1" being represented by a dot formed by a focused beam, and "0" by an annulus formed by circularly deflecting the beam by applying 90 degrees-out-of-phase sinusoidal waves to the horizontal and vertical deflecting plates 60, 61 from a generator 98. The plates 60, 61 also have discrete shift voltages applied thereto from a circuit 68 controlled by timed impulses from binary counter or divider stages 77 driven by a clock pulse generator 75. The beam is switched on and off by voltages applied to the control electrode 64 through a buffer stage 70 from two-state trigger circuits 84, 94 and is deflected or not according to the condition of a two-state trigger circuit 72 which applies voltages to the generator 98 through a switch 88. Bombardment of the screen causes secondary emission of more electrons than are in the beam thus producing a positive potential distribution on the screen such as 18, Fig. 2, and developing signals in a pick-up electrode 20. When a focused spot is bombarded by a deflected beam 34, Fig. 2 (i.e. when a "1" is being "read"), the pulse shown in Fig. 2a, which is positive at 42, is picked up by the electrode 20, amplified at 80, Fig. 5, and passed through a normally closed switch 82 to a coincidence or sampling gate circuit 78, a normally open inhibitory gate 79 and a buffer circuit 91 to switch "on" the trigger 94. This causes the beam to remain on after trigger 72 is switched over to stop deflection of the beam, so that the original focused spot is reproduced. When, however, an annulus or "0" is being read a wholly negative pulse which does not affect the trigger 94 is picked up and the beam is switched off earlier under control of trigger 84. These operations relating to one digit are timed by positive impulses from six tappings on a delay line 85 connected to the generator 75, the sequence being as follows : (1) trigger 72 to deflect condition ; (2) beam switched on by trigger 84; (3) sampling pulse over line 89 (broken lines, Fig. 2a) to select appropriate portion of the pick-up signals ; (4) trigger 84 reset; (5) trigger 72 to focus condition ; (6) trigger 94 reset, if necessary. The successive step-by-step scanning of the spots and lines (" regeneration " cycles) alternates with the scanning of a spot selected by switch 69 in the circuit 68 ("select" cycles), while operative potentials are applied respectively to lines 74, 73 from the first stage F of counter 77. A "1" is written into the selected spot during a select cycle by closing switch 93 so that the delayed pulse on line 89 is diverted through inhibitory gate 90 (closed during regeneration cycles by the potential on line 74) to buffer 91 and trigger 94 so that the trigger is switched on whatever the pick-up signal from the C.R.T. A "1" is erased by closing switch 76 thereby closing gate 79 during select cycles by the potential on line 73, and preventing any pick-up signal reaching trigger 94. If switch 113 is also closed, line 73 is connected to inhibitory gate 87 and beam switch-on during select cycles is prevented. The reading of a "1" causes an output pulse to be sent through a gate 109, the gate being open all the time or only during select cycles according to the position of switch 110. The C.R.T. action may be tested by throwing over switch 88, opening switch 82 and connecting amplifier 80 to an oscilloscope. The generator 98 is thus connected to stage 11 of the counter so that the beam is stationary for a complete scan (32X32= 2<SP>10</SP> spots) and is then deflected for the following scan, and the consequential signal output can be observed. Pick-up-signal amplifier and sampling gate.- The pick-up electrode 20, Figs. 5 and 7, is connected to the control grid 634 of the first of four amplifier stages 636, 648, 654 and 662. The grid circuits are connected to a switch 686 which, in the position shown, permits manual gain control by a potentiometer 687, and in the other position permits automatic gain control by feed-back of the negative portion of the amplifier output through a rectifier 694. The output is also fed to the gate comprising normally conducting rectifiers 702, 712. When a positive sampling pulse on line 714 (89, Fig. 5) coincides with a positive pulse from the amplifier, conduction occurs in rectifier 716 and a positive pulse is sent through polarity-reversing valve 722 and switch 82 to output line 736 leading to the trigger 910, Fig. 8 (94, Fig. 5). The sampling pulse is obtained from a tapping 962 on the delay line 738 (85, Fig. 5), a triangular pulse being applied to the control grid of valve 463 to produce a negative anode pulse applied through a rectifier 475 and polarity-reversing valve 491 to the line 714. The amptitude of pulse necessary to pass through the rectifier, and therefore the sampling pulse width, can be adjusted by potentiometer 483. Beam-control circuits.-The deflection-control trigger circuit 765, Fig. 8 (72, Fig. 5), comprising a pair of cross-coupled valves 762, 764, receives switching and resetting pulses through rectifiers 758, 836 and polarity-reversing valves 750, 832 from tappings 742 and 820 respectively on the delay line 738. The anode potential of valve 762 is applied to the control grid of valve 792 and the resulting potential at the anode 806 is applied through the switch 88, Figs. 5 and 8, to line 632 and the deflection-wave generator, Fig. 9. The trigger circuit 840 (84, Fig. 5) is switched over, to switch on the C.R.T. beam, by an impulse from tapping 846 through valve 852 which cuts off the normal conduction through rectifier 866 thus sending a negative impulse through rectifier 868 to the anode of valve 842. This impulse is inhibited during a select cycle, if switches 76, 113 are closed, by the conduction of rectifier 911 due to the positive anode potential of valve 291 whose control grid is connected to a line 290 to which negative and positive potentials are applied during select and regeneration cycles respectively. The trigger 840 is reset by an impulse from tapping 924 through valve 921 and rectifier 917. The other beam-control trigger 910 is switched over by a negative signal pulse on line 736. Figs. 7 and 8, except when switch 76 is closed during a select cycle, through the inhibitory gate (79, Fig. 5) comprising rectifiers 942, 946,, 948. Also if switch 93 is thrown over to connect capacitor 974 to the control grid of valve 954 the cut-off bias is momentarily removed so that when, during the following select cycle, a positive impulse appears at the tapping 962, a negative triggering impulse at anode 952 is sent through the inhibitory gate (90, Fig. 5) comprising rectifiers 956, 958, 940. During regeneration cycles, the negative potential on line 314 produces a positive potential at the anode of valve 315 so that rectifier 958 conducts and inhibits the triggering impulse. The output potentials from triggers 840, 910 on lines 900, 992 respectively, are applied to the control electrode 64, through a twin-triode buffer 904 and polarity-reversing valve 622. The trigger 910 is reset by an impulse from tapping 980 through valve 976 and rectifier 990. This sends a negative impulse from the anode 918 to an output line 943 through a gate (109, Fig. 5), comprising rectifiers 945, 949, open only during select cycles if the switch 937 is in the position shown. The voltages applied to the horizontal and vertical deflecting plates 60, 61, Fig. 7, are obtained from the anode and cathode circuits of valves 472, 582 respectively, having shift-control voltages applied to their control grids, and from lines 432, 452 connected to the deflection-wave generator. Deflection-wave generator.-The generator 98, Fig. 5, comprises valves 409, 411, Fig. 9, controlled by an oscillator 401 in such manner that when a positive potential exists on line 632, anode output signals are applied to lines 432, 452 of substantially equal amplitude but quadrature phase due to the adjustment of inductors 425, 441 and capacitors 429, 445. Specifications 645,691, 657,591, 682,156 and 688,120 are referred to.