Patent GB-702219-A (GB)
Title: Improvements in or relating to means for detecting errors by accounting machines
IPC: G06F11/10
Filed: 1951-02-01
Abstract: 702,219. Statistical apparatus. COMPAGNIE DES MACHINES BULL. Feb. 1, 1951 [Feb. 17, 1950; Oct. 27, 1950], No. 2534/51. Class.106 (1) The invention relates to a modification of the principle described in Specification 702,214 in which a number transposed from one record card to another is checked by means of a checking symbol which renders the complete number formed by the association of the figures of the number and the checking symbol divisible by eleven or some similar constant arithmetical property. The present invention utilizes this basic principle but employs a double checking system in which a checking symbol is employed twice, on two different bases, for example the constant arithmetical properties of the two bases may be divisibility by 3 and 8 separately. In the example of checking apparatus shown in the drawing the usual code for machines of this type is followed as indicated by the numbered brushes 77 and corresponding numbered relays. The double check of figures is done according to the congruences modulo 3 and modulo 8 by counters C3 and C8 each receiving alternately a number of impulses according to the value or position of marks increased by one and a number of impulses equal to the complements to 3 and 8 of the same number of impulses. Impulse emitter 58(E) is designed to send impulses in the same operation on alternative switch 60 for counter C8 and on alternative switch 61 for counter C3. Interference between the two is prevented by uni-directional rectifier elements 51 to 56. The emitter adds one impulse for each mark sensed on a card, when 60 and 61 are in the adding position ; the total number of impulses being reduced modulo 3 and modulo 8. A mark on the card when a column is sensed causes a flow of current to pass through one relay winding RX to R9 and distributer D1 causes voltage to appear on the wiper 66 of emitter 58(E). For decimal figures relay winding 40 is not energized. The energization of relay 40 requires that both relay windings R7-R9 should be energized. When alternative switches 60 of C8 and 61 of C3 are in the adding position, relay blades 26 and 36 break their contacts and wiper 66 of emitter 58(E) has no action on C8, contact a7 sends an impulse to 60 and C8 through relay blades 25, 24, 23, 8, 22, 29, 21, 28 and 20. When alternative switches 60 of C8 and 61 of C3 are in subtracting position and when R6 is excited relay blades 26 and 36 break their contacts and wiper 66 of emitter 58(E) goes over contacts a8 to a1. Contact a8 is the only one to send an impulse to counter C8 and 1 is the complement to 8 or 7. Counter C3 at the same time receives impulses from 58(E) when wiper 66 goes over a 5 and a 1 thus two impulses are sent and 2 is the complement to 3 of 1. The counter C8 is of the conventional binary type in which 1, 2 and 3 are electronic triggers, for example of the Eccles-Jordan type, they have two stable states and are controlled by the negative impulses acting through symmetrical inputs on the control grids of a pair of tubes forming each trigger. Use is also made of an asymmetrical input to the control grid of one tube of each trigger as described in Specification 679,993 to ensure that at the beginning of a checking operation the three triggers are in a state representing zero. The counter C3 is a special relay counter using only three relay windings. A first impulse going from alternative contact 61 to ground M3 through unidirectional element 65 and relay winding 82 sets relay blade 75 on its contact. Relay blade 87 makes contact at the same time with 82 and blocks 75 on its contact, unidirectional element 65 prohibiting any action of the positive terminal on relay winding 81 through 88, 87 and 75. Counters C3 and C8 having respectively reacted to the impulses in numbers of 3 and 8 return to zero state. When the reading of data and checking symbols do not give rise to a number of impulses matching with the check one at least of the counters is not returned to zero state and when wiper 182 of distributer D1 goes over a checking contact such as 89 relay blade 91 directs current to actuate relay 92 which via its contacts 93 supplies current to a locking device or sorter to indicate the presence of an error, and opens the counters.