Patent GB-776864-A (GB)
Title: Improvements in or relating to record card checking devices
Inventor: KEEN HAROLD HALL
Filed: 1954-03-09
Abstract: 776,864. Statistical apparatus. BRITISH TABULATING MACHINE CO., Ltd. March 9, 1954, No. 6829/54. Class 106 (1). Apparatus for checking the accuracy of a value, including a check symbol, to be recorded on a statistical record card, comprises a keyboard for entering the value together with the check digit, (symbol), which, in the embodiment described, is calculated by adding unity to the remainder derived by dividing the value by eleven. The value and the check digit are registered in a storage device which controls the column-by-column feed of the record card through a punching mechanism where the stored digits of the value and the check digit are recorded successively. The check digit is calculated as the value digits are recorded stepby-step, under joint control of the storage device and timing means operated synchronously therewith, and switching means synchronized with the card movement control the particular group of card columns for which the check digit calculating circuit is operable and also test the calculated check digit against the corresponding entered check digit as the latter is recorded in the card. The invention is described as applied to the punch disclosed in Specification 621,697, [Group VIII], and uses latched relays as described in Specification 675,844, [Group XXXVII]. The check digit calculating unit is rendered operative by a control card so that checking may be performed on any desired field or fields of card columns. The control card sensing arrangement of Specification 621,697 is modified by the addition of strips 188<SP>1</SP>, Fig. 1, to allow holes in the 5 and 6 index point positions to be sensed to initiate and terminate checking, respectively. As checking is initiated a relay R6 is energized and in turn energizes the coil R8P of a differential relay which locks for the duration of a check and prepares the calculating circuit. As each digit is punched the remainder digit (i.e. the remainder plus-one) is calculated and stored on latched relays R5(2), R5(3) ... until the next digit to be punched is read out from the storage device. Normally all these relays R5(2), ... &c. are latched representing a remainder digit of one. Contacts of these relays are wired in a coding circuit, Fig. 2, which determines the remainder digit at each step. These contacts are wired in eleven groups, one of ten of these groups being selected by a digit-set-up relay R1(1), R1(2), ..., Fig. 1, operated in parallel with the respective punch selector magnet 154<SP>1</SP>. Assuming now, for example, that the number 13905 has been entered into the operative field of the storage device of the punch, i.e. the value 1390 followed by the check digit 5, and that the storage device is initiating punching as described in Specification 621,697; then, when the first digit 1 is read out, a circuit is made over contacts 244<SP>1</SP> of the " one " position of the storage device index point one to energize digit set up relay R1(1) in parallel with the punch selector magnet 154<SP>1</SP>(1) which punches a hole at the one position in the appropriate column of the card and then steps the card. Relay R1(1) selects, at its contacts R1(1)a, Fig. 2, a group of coding contacts over which (all being in their normal latched positions), is energized, a relay R2(2) of a series of relays R2(2), R2(3), R2(4), ... which when operated unlatch the respective relays R5(2), R5(3), ..., Fig. 1, via their unlatching coils R5(2)u, R5(3)u ... , Fig. 2, as soon as cam contacts c6 open. Thus, after the digit 1 has been read out from the storage device all relays R5(2), R5(3) ... &c. are latched except R5(2) corresponding to the remainder digit 2, i.e. the remainder plus one after dividing the recorded digit 1 by eleven. The next digit 3 to be read out, energizes relay R1(3), Fig. 1, which over its contacts R1(3)a, Fig. 2, and unlatched contacts of relay R5(2), energizes-over line 23- the relay R2(3) which in due course unlatches relay R5(3) immediately after which cam concontacts c5 close to relatch R5(2). The only R5 relay now unlatched, i.e. R5(3), corresponds to the remainder digit 3 derived from dividing the number recorded so far, i.e. 13 by eleven. In a similar manner, as the following digits 9, 0, 5 are read out from the storage device, the relays R2(8), R2(5), R2(2) will be energized, respectively, the energizing of R2(2) at the final step of the check digit calculation indicating in all cases that the punched check digit is correct. As the check digit 5 is being punched the hole in the control card at index position 6 is sensed to energize a relay R7 which, if R2(2) is not energized, at this stage, operates error indication relays R9, R3<SP>1</SP> in turn and also energizes the coil R8R of the differential relay to cancel the effect of coil R8P and render the checking circuit ineffective for the next field. Checking may be effected for further fields of the card being punched by appropriate punching of the control card. Specification 747,870 also is referred to.