Patent GB-847376-A (GB)
Title: Improvements in or relating to accumulators using multi-cathode counting tubes
Inventor: CAMM KENNETH
IPC: G06F7/52
Filed: 1956-02-22
Abstract: 847,376. Electronic accumulators. INTERNATIONAL COMPUTERS & TABULATORS Ltd., Dec. 21, 1956 [Feb. 22, 1956], No. 5475/56. Class 106 (1). Through carry arrangements.-A multidenominational accumulator has at least three multi-cathode gas discharge counting tubes 3, Fig. 2, forming first, second and third denominational stages of increasing significance, means for entering values into each stage, means for generating a carry signal under control of the first stage, means operable under control of the carry signal to enter a carry into the second stage and gating means C operable by the carry signal if the value registered in the second stage is one less than the radix of that stage to enter a carry in the third stage. The carry transfer arrangements for three stages are shown in Fig. 2, the carry input being applied in each stage to an And gate A the other input of which is connected to a line CL on which is applied a carry test pulse occurring after the value entry time. When the discharge stands on the zero cathode the signal is applied to the control grid of a gas discharge trigger tube 15 which is thereby set indicating a carry. This carry trigger holds until the end of the entry cycle. The carry trigger 15 is connected via an Or gate B to a " Carry out " line. For stages two and three the other input to the gate B is from another And gate C which is controlled jointly by a signal on the carry out line of the previous stage and a discharge on the " nine " cathode. In the case of the lowest stage the carry line signal comes from the " end around carry " from the highest stage. Fig. 1 shows one stage. Negative driving pulses in trains of ten are applied through diode gates to the guides 1 and 2 of counting tube 3 but these are only effective to cause stepping if a negative voltage is applied to line 9 connected to the grid of cathode follower 8. At points in the major cycle of the machine corresponding to the complement of the number to be entered, the line 9 is made negative so that the remaining pulses in the train of ten are applied to the guides 1, 2 and cause stepping of the counting tube. Subtractive entries are made in the usual way by applying from the trains of the pulses, the complement of the number is applied to the guides. The carry trigger 15, set by the stepping of the discharge on to the zero cathode, has an output applied through cathode follower 19 to a diode 20 forming part of a diode OR gate 20, 22. The carry-in signal from the next lower stage is applied to the junction between resistors 27 and 29 and to the grid of a cathode follower 23. If the discharge is on the " nine " cathode the valve 26 conducts. The junction of resistors 27, 29 is normally held positive by the carry-in line through diode 24 but a negative carry-in signal combined with conduction of valve 26 gives an output on cathode follower 23. Resistors 27, 29 and diode 24 form an And gate corresponding to gate C of Fig. 2. An output from cathode follower 23 passes via diode 22 to the grid of cathode follower 21 to give a carry out signal. This can only happen if the trigger 15 is not set since diodes 20, 22 and resistor 65 form an Or gate, corresponding to gate B of Fig. 2. The output of cathode follower 21 passes via the carry-out line to the carry-in line of next higher stage. The carry being applied to diodes 31, 33 of diode gates 31, 32 and 33, 34 is also entered into the counting tube when carry pulses are applied to the lines 37, 38 after the value entry time. Read-out.-The value registered by tube 3 is read out by applying trains of ten shift pulses to lines 41, 42 so that the discharge is stepped right round the tube. When it passes to the zero cathode the trigger 15 is set as before and the output signal is gated by diodes 47, 48 with a simultaneous train of ten pulses applied on line 50. When the trigger is set the remaining pulses pass to the grid of read-out valve 39 which is a cathode follower using the valve 40 as a cathode load. Multiplication and division by ten.-These calculations may be made during read out by applying the read-out pulse train to lines 60 or 59. The output from the trigger 15 through valve 19 is connected to the read-out circuits of the next higher and the next lower stages, and these stages are connected in the same manner to the read-out valves 39, 40 of the stage shown, connections being made on lines 54, 53 to gates 55, 56 and 57, 58. When the pulse train is applied to line 59 the read out is in fact from the next higher stage but is read out in the present denomination, i.e. effectively divided by ten. Likewise the pulse train on line 60 gated with the read-out signal on line 53 from the stage below and the value therein is effectively multiplied by ten. The read-out leaves the value standing in the tube but the accumulator may be cleared by applying a negative pulse to the zero cathode through diode 61. Specification 806,042 is referred to.