Patent GB-764998-A (GB)
IPC: G06F11/10
Filed: 1955-02-04
Abstract: 764,998. Selective punching machines. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 4, 1955 [Feb. 8, 1954], No. 3340/55. Class 31 (2). [Also in Groups XVI, XIX and XL (c)] In an electrical device for checking the entry of information into a machine, e.g. a punch, comprising a generator for supplying a number of pulses representative in a predetermined code of each information item, the code being different for alternate items, to a counter adapted to register at least the lowest digit of the sum of the pulses, and means for indicating whether or not the counter registration corresponds to the known correct sum, the pulse generator is of predetermined frequency and is rendered operative, for the period necessary for delivering the number of pulses representing each item by a variable length gating pulse. As shown, a decimal number is entered digit by digit on a keyboard (not shown) which controls switches S0-S9. Associated with each number is a key digit such that the sum of odd-numbered digits of the number, plus digits substituted for the even-numbered digits according to a predetermined code, and the key digit, has a zero in the first decimal denomination; when a number has an odd number of digits, a substitute key digit is used. The switches S1 to S9 are associated with R-C circuits R1-C1 to R9-C9 which have time constants such that on receipt of a negative pulse from a switch they cut off normally conducting tube V1 of a Schmitt trigger circuit V1, V2 for 11 (10 + 1), 2 ... 9 ms. respectively. The positive variable length gate pulse thus obtained from the anode of V1 controls 1 kc/s. multivibrator comprising tubes V3, V4 to cause a corresponding number of pulses (11, 2 ... 9) to be generated and applied via amplifier V5 to the intermediate cathodes 18 of a multi-cathode gas-filled decimal counting tube V6, e.g. constructed as described in Specification 720,179, [Group XL (a)], to step on a glow existing between " zero " cathode 20 or one of the " 1 " to " 9 " cathodes 21 (represented by a single cathode) and plate 19. In operation, a re-set key 16 is operated before a number is entered, and energizes relay K3 which operates contacts 22, 23 to return the glow to cathode 20, and contact 17 to de-energize relays K1, K2 of a two-state counting circuit which receives a pulse from contact 15 for every digit entry. For the first digit, switches S1 ... S9 are connected to their corresponding R-C circuits so that a number of pulses corresponding to the digit value are supplied to V6; the first pulse from' contact 15 energizes relay K2 which closes a contact to energize K1 as soon as 15 is re-opened. Relay K1 operates contacts to connect the switches to the R-C circuits according to the predetermined code, so that for the second digit the substitute value is entered, the second pulse from 15 de-energizing K2 through shifted contacts of K1, the latter relay remaining energized only until 15 is reopened. Similar operations occur for entry of successive odd- and even-numbered digits. The key digit is finally entered, after which, if the operator has entered the number correctly, the glow should be on " zero cathode 20 whereby when a " read " key 25 is depressed neon bulb 24 will be lit. Reference is made to checking alphabetical, as well as .numerical, information.