Patent GB-734903-A (GB)
Title: Gaseous electric discharge storage or counting tube
IPC: H03K29/00
Filed: 1953-07-27
Abstract: 734,903. Digital electric calculating-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. July 27, 1953 [July 30, 1952], No. 20760/53. Class 106 (1). [Also in Group XL (a)] An accumulator for effecting both addition and subtraction comprises units, tens, hundreds and thousands orders, each order including a selfcomplementing gas - discharge tube GC (see Group XL (a)) having ten transfer cathodes T, ten complement cathodes C, and ten digit representing cathodes of which nine are designated as D and the tenth as D-9. Cathode D-9 is connected through a resistor 30 to the terminal 31 of a supply source and the cathodes D are connected through a resistor 32 and switch 33 to the terminal 31. Thus, if a glow discharge exists at any of the cathodes D in the tube and the switch 33 is opened, the discharge will thereafter exist between the anode A and the cathode D-9 and closing the switch 33 will not disturb-this condition. The cathodes are so arranged that the discharge is stepped to the various digit representing cathodes D by applying negative pulses to the transfer cathodes T, and by applying a negative pulse to the complement cathodes C a discharge existing at a digit representing cathode is transferred to the cathode representing the nines complement of that digit. This selfcomplementing feature of the tube is utilized just prior to and after an addition but is not utilized for subtraction. The other circuit elements are shown in block diagram form. Each square with four terminals is a conventional Eccles-Jordan trigger circuit, an X near the right of the square indicating that the circuit is initially in the RIGHT condition, so that the voltage at terminal PR is low as compared with that at terminal PL. The trigger will switch from the RIGHT to LEFT condition only if a negative pulse is applied to terminal GR, and similarly will switch from the LEFT to RIGHT condition only if a negative pulse is applied to the terminal GL. The trigger circuits shown are the add-subtract trigger AS; input triggers ITTh, ITH, ITT and ITU; the positive-negative trigger TS for determining the sign of the result; and carry storage triggers CSTh, CSH, CST and CSU. The rectangles having three terminals therein are electronic gates which conduct when a positive voltage is applied to both grids G1 and G2. The rectangles having two terminals are electronic inverters. The accumulator is operated by pulses as shown in Fig. 5 which relate to the solution of the example problem problem 23-39+3, and are produced by a read card controlled mechanism comprising a commutator having output terminals which are connected to the terminals A, B, C, D, F, SUBTRACT and ADD respectively. The card is fed between a feed roll, to which a negative voltage is applied, and card brushes which are connected to the INPUT terminals of the accumulator, so that when a brush encounters a hole in the card, a negative pulse is passed to the accumulator. Addition is indicated by an 11 hole in the card and subtracted by a 12 hole. Whether addition or subtraction is being effected, the switch 54s is placed in the ACCUMULATE position. The switches 33 are first operated to place 9999 in the accumulator. At 11 time an A pulse switches triggers ITU, ITT, ITH and ITTh to the LEFT condition to apply a positive voltage to the terminal G2 of gates GTH, GH, GT and GU. Also at 11 time a pulse is applied to the ADD terminal of trigger AS to switch the trigger to the LEFT condition and apply a positive voltage to the terminal G2 of the gate GAS. Also at 11 time a positive pulse is applied to terminal D which causes the terminal G1 of gate GAS to go positive. Gate GAS therefore conducts and passes a negative pulse to inverter IAS which transfers a positive pulse to inverter IC. A negative pulse is thus passed to the complement cathodes C of all the tubes GC to complement the value stored and thus place the value 0000 therein. An F pulse is then applied between 11 and 0 time to switch triggers CSU, CST, CSH and CSTh to the RIGHT condition and thus apply a negative or low voltage to the terminal G2 of gates GT2, GH2, GTh2, GTS and GU2. At 0 time a pulse is applied to the INPUT terminals of triggers ITH and ITh to switch them to the RIGHT condition to place a low voltage on the terminal G2 of gates GH and GTh and thus prevent the subsequent entry of B or input pulses to the hundreds and thousands orders of the accumulator. The first two positive B pulses, occurring just prior to 1 and 2 time, render the gates GU and GT conductive and accordingly two pulses are applied to the tubes GC of the units and tens orders to effect storage of the digit 2 in each. At 2 time a pulse is applied to trigger ITT to prevent subsequent conduction of the gate GT in response to B pulses. Similarly the next B pulse occurring just prior to 3 time effects storage of a digit in the units order and at 3 time a pulse is applied to trigger ITU to render the gate GU non-responsive. The accumulator now indicates 0023. Finally, the carry pulse C is applied to the terminal G 1 of gates GU2, GT2, GH2, GTh2 and GTS, but the gates are not rendered conductive because the terminal G2 of each has a low voltage applied from the carry storage trigger connected thereto. The next D pulse causes the amount stored to be again complemented, so the value becomes 9976. The sign trigger TS has not been switched and remains in the RIGHT condition, thus indicating that the amount stored is positive. The accumulator is now ready to effect storage of - 39. At 12 time a negative pulse is applied to the SUBTRACT terminal of trigger AS to switch it to the RIGHT condition. A low voltage is applied to terminal G2 of gate GAS so that the next D pulse (11 time) does not render gate GAS conductive, and the amount in the accumulator is not complemented in response to that D pulse. The digits 39 are then stored in the same way as for the adding operation, except that between 2 and 3 time when the glow discharge is transferred from cathode D-9 of the tens tube, the resulting decreased voltage is applied to the terminal GR of trigger CST to switch it to the LEFT condition and thus place a positive voltage on the terminal G2 of gate GH2. In the same way, between 3 and 4 time when the discharge is transferred from the cathode D-9 of the units tube, a positive voltage is placed on terminal G2 of gate GT2. Consequently when the carry pulse C is applied to the terminal G1 of gates GT2 and GH2 the gates conduct and an additional digit is stored in the tens and hundreds tubes. The storage of this digit in the hundreds tube results in the storage of an additional digit in the thousands tube, which in turn results in the storage of an additional digit in the units tube and the switching of the sign trigger TS to the LEFT condition. Thus at the termination of the C pulse the accumulator has 0016 stored therein and the trigger TS is in the LEFT condition, indicating that the quantity is negative. The next D pulse has no effect and the quantity is not complemented. Addition of the digit 3 is then effected by complementing the stored number to give 9983, adding 3 to give 9986, and again complementing to give 0013, the trigger TS indicating that the sign is negative. To effect read out, the value stored is complemented, ten pulses are applied to each order of the accumulator and the value again complemented to return the accumulator to its initial condition just prior to read out. The read out pulses are applied to terminal B beginning at 0 time and ending at 9 time, and the time at which the glow discharge leaves cathode D-9 of each of the tubes GC, thus passing a negative pulse to the output terminal, indicates the digit stored in each tube. B and C pulses are not applied to the accumulator, but the D pulses are applied through switch 54s to the terminal G1 of gate GRO. During the read out cycle a hole indicating add or subtract is not provided in the 'card and therefore no add or subtract pulses are present, but if the quantity in the accumulator is negative, trigger TS is in the LEFT condition and a positive voltage is applied to terminal G2 of gate GRO. Hence the D pulse causes the gate to conduct and a pulse is passed through inverter IAC and gate IC to complement the value stored in the accumulator. Any or all of the cathodes of the tubes BC may be used to provide an output and the tube may be modified to provide the tens complement of the value stored. Specification 720,179 is referred to.