Patent GB-674326-A (GB)
Title: Improvements in or relating to electronic counters
IPC: H03K23/82
Filed: 1949-04-14
Abstract: 674,326. Digital electric calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd., and CARTWRIGHT, J. R. April 12, 1950 [April 14, 1949], No. 10170/49. Class 106 (i). In an electronic counter comprising one or more denominations, adapted to have numbers entered therein in the same form irrespective of sign, means responsive to an indication that a number to be entered is of opposite sign to that last entered convert the value registered by the counter to the complementary value. Operation. Fig. 3 shows a counter, forming one denomination E of the accumulator illustrated in Fig. 4, and comprising four series - connected trigger stages A, B, C, D and a locking valve L which count in the decimal scale as described in Specification 609,502. Isolating valves T1, T2, T3 separate the stages and the carry pulse, emitted for every tenth input pulse on line 15, is sent through a gate valve C. Inversion of the value in the counter is effected in four steps: (1) a negative potential on line 24 renders valve L ineffective so that the counter capacity is increased to 16; (2) three positive pulses on line 25 are applied to valve T1, thus entering the value 6; (3) a negative potential on line 26 renders valves T1, T2, T3 and C ineffective thus isolating the triggers; (4) a negative inverting pulse on line 27 applied to the suppressor grids of all the trigger valves switches over the triggers to register the complementary value; the potential on lines 24, 26 is then returned to normal. This inversion is initiated by a negative pulse on "subtract" line 1, Fig. 4, which switches over two " flip-flop " circuits which remain in their unstable state for the whole inversion cycle. One circuit controls a multivibrator so that it emits pulses alternately over lines 5 and 9. The other lowers the potential on line 2 (24, Fig. 3) and applies a pulse over line 3 to switch over a " 6 Add" flip-flop which remains in its unstable state for sufficient time to allow three pulses on line 5 to pass through a gate valve, controlled over line 4, to the valves T1 of the denominations E1-E5, and, when it returns to normal, applies a pulse over line 7 to switch over an " Invert Lock" flip-flop which then lowers the potential on line 8 (26, Fig. 3), and remains " on for a sufficient time to allow one inverting pulse from line 9 to pass through a gate valve controlled over line 11. Each pulse on line 1 also switches over a " True Sense " trigger stage which thus registers whether the number of inversions is even or odd. The sign is registered by a "Sign Sense" trigger which is switched over whenever a " fugitive one " pulse is sent over line 12 from the highest to the lowest denomination. Entering and reading out values. Values may be entered in the accumulator from punched record cards. When a hole is sensed in a particular card column a differentially timed positive impulse is sent over line 165, Fig. 6, and switches over a trigger circuit 137, 138, thus raising the control grid potential of a valve 139. The brush of a commutator 148 is driven in synchronism with the card-sensing mechanism to supply pulses to the valve suppressor grid so that if, e.g. a " 6 " hole is sensed, pulses from segments 147 (6) to (1) will produce negative pulses at the anode on line 154 which is connected to the input line 15, Fig. 3, of a counter. The trigger 137, 138 is subsequently reset by a pulse on line 152 To read out from the counter, the trigger is first switched over by a positive pulse on line 156. Thus the commutator will produce pulses on line 154 which are added in the counter until a carry pulse is produced on line 149 connected to the anode of valve D1 (line not shown in Fig. 3). This pulse will switch over trigger 140, 141, thus raising the grid potential of a valve 142 so that it conducts and energizes a relay 155 which closes contacts (not shown) e.g. to operate a punch magnet. During the read-out operation, carry valve C, Fig. 3, is rendered inoperative but valves T1, T2, T3 are not affected, the counter circuit being modified accordingly. Other modifications. The counter, Fig. 3, may be modified to count in the duo-decimal scale by altering the connection between the triggers and to the lock valve L and adding " 4 " instead of " 6 " during inversion. The lock valve may be omitted and a decimal or duo-decimal count obtained by making an initial entry of " 4 " or " 6," this entry also being made when a carry occurs. A modified pulse emitter and associated inversion-control circuits are described, Fig. 5A (not shown), comprising series-connected trigger stages which are successively switched " on " by the preceding stage and switched " off " by pulses from a multivibrator.