Patent GB-762225-A (GB)
Title: Comparing device
IPC: G06F7/02
Filed: 1954-04-27
Abstract: 762,225. Comparing digital data. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 27, 1954 [April 29, 1953], No. 12130/54. Class 106 (1). In a device for comparing numbers registered in devices of the type in which a digit is registered in a corresponding denominational section by making an electrical connection from a common contact element to a digit-representing contact point, the corresponding contact points of the several sections of co-operating devices being electrically connected, corresponding common contact elements of the registration devices also are connected, switching means connect together the contact points representing selected digits into one group and all other contact points to form another group, further switching means progressively vary the composition of the groups, and a discrepancy detection circuit connected to the contact point groups indicates whenever a connection is found therebetween. As shown, two 4-digit decimal numbers to be compared are registered by differentially positioned brushes 4 which connect contact points 5 to common contact elements 2u, 2d, 2c, 2m and 3u, 3d, 3c, 3m of counters or storage devices. The points 5 for equi-valued digits are all connected to a common line, these lines 10-19 being connected to contacts 22a-22j of a relay 22. The comparison is effected in four stages initiated by closing switch 1 which causes relays 22, 23, 24 and 25 to operate in succession. During the first stage, when 22 only is operated, lines 10-15 are connected to line 27 and lines 16-19 at line 28. Thus if any of the digits 0-5 in one number corresponds to a digit 6-9 in the other, a circuit will be completed'from line 20 through switch, 1, contacts 21a, 22k, line 27 contacts of relay 22 and possibly 23-25, one of lines 10-'15, brushes 4 and an appropriate pair of elements 2, 3 linked by contacts 37 (closed for read-out) and a pair of hubs, such as 30, 34, one of lines 16-19, relay contacts, line 28 and resistor 38 to line 26. The resultant voltage rise applied to the grids of tube 41 causes the latter to conduct and produce a positive error-indicating pulse at terminal 42 which may stop a machine or control a punching or printing operation. The other three stages operate similarly contacts of relays 23-26 connecting different sets of the lines 10-19 to lines 27, 28 respectively. For example, during the fourth stage when all relays 22-25 are operated, lines 27, 28 are connected to the sets of lines for even and odd digits, thus enabling the discrepancy indicated between the " 7 " and " 6 " registered in 2d, 3d respectively, to be detected. Contacts 25f complete a circuit to reset relay 21 which opens contacts 21a and 21c to end operation of relays 22-25 and tube 41, if rendered conductive, and closes hold contacts 21b. The amounts registered may be compared also with the amount (8,371) represented by connections 43-46 between the pairs of hubs, such as 30, 34, and the appropriate lines 10 ... 19. A read-out emitter comprises contact element 47 and brush 6. The tube 41 may be replaced by a relay (Fig. 2, not shown). Reference is made to bases of notation other than decimal, e.g. quinary or duodecimal.