Patent GB-846107-A (GB)
Title: Improvements in or relating to electric calculating equipment
Inventor: TAYLOR ALAN HEATLEY
IPC: G06F7/52
Filed: 1955-11-23
Abstract: 846,107. Digital electric calculating-apparatus. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. Nov. 23, 1956 [Nov. 23, 1955], No. 33608/55. Class 106 (1). In electrical calculating equipment employing registers each comprising a plurality of denominational multi-cathode counting tubes, the addition of two numbers set up in transmitting and receiving registers respectively is effected by sending a continuous train of pulses to the transmitting register to cycle each tube thereof in turn and sending groups of nine impulses separated by one impulse space to the corresponding tube in the receiving register under the control of a gate which for each group of impulses is opened when the corresponding tube of the transmitting register passes through the zero position. As shown in Fig. 1, in an array of ten-cathode counting tubes arranged in horizontal registers, all the first guide electrodes GD1 of the tubes in a column are connected together and all the second guide electrodes GD2 of the tubes in a row or register, are connected together. Nine of the cathodes of each tube are multipled together and an output is taken from the zero cathode, the zero cathodes in a row being connected together. The discharge is normally to a first guide electrode and thus an output is obtained for a predetermined time during cycling of the tube. Y drive pulses are applied through gates G1 to the first guides GD1 and X drive pulses of half the length of the Y pulses are applied through gates G2 to the second guide electrodes. Addition.-A first number set up in one register called the transmitter, Fig. 3, is added into another register called the receiver which contains the second number. The first ten transmitter X drive pulses, Fig. 2, are arranged to cycle the units tube of the transmitter register. When this tube passes through the zero position an output TS, Fig. 2, is obtained which sets an electronic relay H called the arithmetic store to provide an output which opens the gate G4 to permit the receiver gate pulses, Fig. 2, to step the units tube of the receiver. If this tube passes through the zero position, an output RS, Fig. 2, is obtained which sets an electronic relay J called the carry store to provide an output which opens a gate G5 to pass a carry pulse to the tens receiver tube when the tens denominational cycle begins. Strobe pulses TE are provided, the arithmetic store H being reset at the end of each denominational cycle by the strobe pulse following the last transmitter drive pulse of the cycle and the carry store J being reset by the strobe pulse which follows the carry pulse unless a further output is obtained from the receiver indicative of a new carry digit, in which case the carry store remains set. Subtraction.-This is effected by adding the nines complement of the number in the transmitter into the receiver and also a further unit. A switch CO, Fig. 3, is changed over so that the gate G4 is controlled by the reverse output of the relay H instead of by the normal output. Thus pulses pass through the receiver gate G4 from the beginning of each pulse cycle until the tube being cycled in the transmitter passes through the zero position when the pulse supply ceases. Other operations.-By cutting off the transmitter drive pulses when the transmitter tubes pass through the zero position the operations of " transfer " and " complements transfer " are effected, wherein the transmitter is left clear at the end of the operation of addition or subtraction. Multiplication.-This is effected by repeated addition of the multiplicand a number of times corresponding to the respective digits of the multiplier commencing with the units digit. A separate 4-digit register is provided to hold the multiplier and an additional register tube is arranged to hold successively the complements of the operative multiplier digits and to be stepped on by one until position 0 is reached for each addition of the multiplicand. Control circuits for the various operations are described (Figs. 4, 5, not shown). The transmitter and receiver registers are each controlled by a further counting tube.