Comparing device for employment in a record card collator or like machine

783,108. Statistical apparatus; electric digital data-storage apparatus; comparing digital data. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 1, 1955 [Feb. 4, 1954], No. 2927/55. Class 106 (1). A comparing device, e.g. for a record card collator, comprises means for generating a first pulse train representing first information, means for generating a second pulse train representing second information and means for simultaneously receiving and comparing said pulse trains and for indicating the result of the comparison. As described the apparatus compares the numeric or alphabetical data on successive pairs of primary and secondary cards 101P, 101S, Fig. 2. Each card comprises three decks A, B, C each having sixty columns of seven index positions designated " 5 ", " 3 ", " 1 ", " 0 ", " Z ", " Y '', " X " at which holes may be punched to represent information. The primary and secondary cards pass between read, brushes 91P-95P, 91S-95S and contact rolls 110P, 110S respectively. Each brush is connected to a corresponding arm 61PA-65PA, 61SA- 65SA of commutators 61P-65P, 61S-65S each having seven conducting segments which are connected, as shown, to write heads PW1- PW5, SW1-SW5 uniformly disposed about the periphery of primary and secondary magnetic recording drums D1 and D2. The information on the record cards is transferred to the drums D1, D2, each brush 91P-95P, 91S-95S transmitting the data it senses in the associated column via the corresponding writing head PW1-PW5, SW1-SW5 to the drums D1, D2 index position by index position so that in one fifth of a revolution of the drums the information in the five columns being sensed is written upon the primary and secondary tracks of the drums. Within the drums D1, D2 are read heads RP1, RS1 which rotate on the drum axis to transmit the stored information in serial form column by column to inputs 1C, 3C, Fig. 3 (not shown), respectively of a comparer circuit which indicates by energization of one or other of two relays which of the two series of pulses represents information of the higher " order ". Neither relay is energized if the two series of impulses are of equal " order ". The comparer can also distinguish between a series of pulses representing alphabetic information and a series of pulses representing numeric information. The arrangement is such that the result of the comparison is indicated as soon as possible. The primary and secondary read heads then effect erasure of the information from the prim