Improvements in or relating to counters and number accumulators

Abstract

Abstract 609,502. Calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd. Dec. 14, 1945, No. 33968. Convention date, Dec. 27, 1944. [Class 106 (i)] [Also in Group XL (c)] An electronic counter comprises a series of stages each including a trigger circuit having two stable conditions between which it alternates in response to electrical impulses, each stage, except the highest in the series, on changing to one of its stable conditions, transmitting an operating impulse to the next higher stage, and control means operated by a higher stage, which prevents response of an intermediate stage to certain impulses. In the described embodiment, a record card crossfooting punch is hand operated to reproduce two multi-denominational numbers in first and second fields of a card. As the second number is being entered, each digit is added to the corresponding digit of the first number and, after the units have been entered, the machine operates automatically to reproduce the sum in a third field of the card. Impulse emitter. The depression of each punch key closes associated contacts to energize a corresponding relay R1 . . . R9, Fig. 7. Each relay is arranged to complete a circuit and supply a positive impulse to the grid of a corresponding valve J1 . . . J9 raising the potential of the grid and so causing that valve to fire. The flow of current through the valve, however, energizes a relay R21 ... R29 which operates to close its " a " contacts, shortcircuiting the valve. The rise in potential on the cathode of each J valve when it is fired is communicated to the grid of the next (lowernumbered) valve in the series, and also to a related triode K1 . . . K9 from the anode of which a negative impulse is passed to the output wire 230. Thus, starting from the valves corresponding in value to a depressed punch key, J and K valves are fired and extinguished, in descending order, supplying a corresponding number of impulses to the output wire. Brushes on the carriage of the machine, sliding over contacts, control the circuits to direct the impulses to the appropriate order of the accumulator. Accumulator. Each order of the accumulator comprises four stages, A, B, C, D, Fig. 6, each of which includes a trigger circuit comprising two triodes, one of which (marked " 0 ") is normally conducting. A negative impulse received from the emitter at the input terminal 95 causes the potentials on both grids 89 to be so lowered that the current through valve A2 is cut off. Consequently, the potential on the anode of this valve rises rapidly and, since it is connected with the grid of valve A1, this valve is fired and remains so until the next impulse is received. The fall in potential on the anode of the fired valve causes a corresponding drop on the grid of the opposite valve and so prevents the latter from firing. With the arrival of a second impulse, the stage A is restored to its initial state in which the valve A2 is conducting. The firing of this valve, however, causes a negative impulse on the line 85 due to the fall in potential on the anode of the valve. This negative impulse is passed on to stage B and also to the grid of valve D2 in stage D. The provision of a normally fired valve B3 prevents the reversal of valves B1, B2 by the second impulse, its anode being connected with the grid of valve B1 and so preventing a rise in potential above the firing point. The valves D1, D2, however, are reversed by this impulse, and a connection 114 to the grid of the valve B3 causes this valve subsequently to be extinguished. Thus, the next impulse arriving from stage A (corresponding with the fourth impulse at the input 95) causes valves B1, B2 to be reversed. They are restored after the sixth impulse at input 95 and pass an impulse to stage C causing the valves C1, C2 to reverse. The tenth impulse is passed through, restoring all the valves to their-initial states and sending out a " carry " impulse on the output wire 117. Carry circuit. The carry impulse reverses a trigger circuit E, Figs. 8c, 8d, associated with that order of the accumulator, and the consequent rise in potential on the anode of the extinguished E valve raises the potential on the grid 121 of an associated valve F to just below the firing point. When the entry of the second number has been completed, a " carry operate " trigger circuit G, Fig. 8d, is reversed, the conducting valve G1 being extinguished and the valve G2 being fired, the fall in potential of the anode of the valve causing a valve H to be extinguished. The rise in potential on the anode of the H valve is communicated to the grids of all the F valves and is sufficient to cause those which have been " primed " by carry impulses to fire and thus send negative impulses to the next order of the accumulator. Subtraction is provided for by reversing contacts R44b ... R44j, Fig. 7, and controlling the emitter circuit to send out impulses equivalent to the complement of the number entered, arrangements being made to enter the " fugitive one " during the carry operation. Fig. 6a shows diagrammatically an alternative arrangement of the circuit shown in Fig. 6 in which the valve B3 is initially non-conducting. Other arrangements for adapting the circuit to duodecimal and other systems are also referred to.

Inventors

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