Patent GB-693723-A (GB)
Title: Improvements in or relating to devices for facilitating the detections of errors in symbol groups
IPC: G06Q40/00
Filed: 1951-03-09
Abstract: 693,723. Ciphering-apparatus. REUMERMAN, T., and HELMIG, W. H. T. March 9, 1951. [March 10, 1950; Aug. 21, 1950] No. 5790/51. Class 146 (ii). [Also in Group XIX] A device for determining for a symbol group (e.g. a number, word or sentence), composed from a given series of symbols numbered in a predetermined manner, a corresponding check symbol, comprises a scale member bearing rows of symbols of the series, and a second relatively movable "dialling" member having corresponding rows of holes through which the symbols are visible, the check symbol being visible through a further hole in the second member when the symbols have been "dialled" one after the other in successive rows, a fixed stop member limiting each dialling movement. The check symbol associated with the group can be used for detecting errors, e.g. in copying or transmitting. It defines the remainder R N  (G) obtained by dividing by a given number N a number G = #a i k i  when ai is the number of the symbol in position i, the coefficients or "factors" ki are different for adjacent positions, and N>n and has on factors in common with k i  or (ki +1 - ki ). The symbols with consecutive numbers in a row are shifted over a number Q of positions, the numbers Q for successive rows corresponding with the successive coefficients k 2 . In the device shown in Figs. 1 and 2, the symbols arc the digits 0-9, numbered accordingly, N = 11, and ki = R N (10<SP>i</SP>-<SP>1</SP>). Thus k 1  = k 3  = ..... = 1 and k 2  = k 4  = ......... = 10 (or -1). Therefore two concentric rows of digits are provided on the scale 67, 'Fig. 2, which cooperate with rows of holes 64 in the rotatable disc or dial 63. To find the check symbol (in this case also a digit) of a given number M the dial is first rotated until the digit O appears in the further hole 65. An operating pin or a finger is then inserted in the hole 64 of the outer row displaying the right-most or units digit of the number, and the dial rotated clockwise until -the pin or finger abuts the edge of the semi-circular aperture 62 in the casing 61. The next digit is similarly dialled in the inner row of holes 64 and the dial rotated in the same direction, the two rows being used alternately until the whole number has been entered. The dial has then moved through a number of steps such that the check digit R 11  (G) = R 11  (M) appears in hole 65. In another form of device, the digits may be entered from left to right, the scale having two staggered concentric rows of check digits which are alternately displayed through one of two check holes. Also the dial has ratchet teeth which are engaged by the pawl of a pivoted operating member. Figs. 7 and 8 show a device comprising a rectilinear scale 117 over which moves a dialling member in the form of an endless belt 112 carried by rollers 116. In this case N = 13, and k 1  = R 13  (10<SP>i</SP>-<SP>1</SP>) which gives six different values viz., ki to k. equal to 1, 10, 9, 12, 3 and 4 respectively. Therefore there are six rows of digits on the left of the scale and, in order that the digits may be entered from left to right whatever the highest denomination of the number, six rows of checking symbols (A to L representing remainders 0 to 12) are provided on the right. The rows of digit display holes 113 and the check holes 114 are appropriately staggered, the distance from the first hole 113 displaying a digit (0) to the stop member 115 being 13/6 times the spacing of the holes and digits. The belt may be returned to the zero position (one of the check symbols A displayed) at any time by "dialling" the displayed check symbol by means of the hole 114. A cylindrical drum may be used instead of the belt 112.