Patent GB-722509-A (GB)
Title: Electrical calculating apparatus
IPC: G06F11/10
Filed: 1951-06-11
Abstract: 722,509. Digital electric calculating-apparatus; counting-apparatus. COMPAGNIE DES MACHINES BULL. June 11, 1951 [June 15, 1950], No. 13850/51. Class 106 (1). Electric apparatus for calculating from a number a checking symbol whose value is the remainder when dividing by a base value N the difference between the sums of the digits of odd and even denominations of the number, or the complement of this remainder with respect to N, comprises entering organs one for each digit value and each controlling N switching members, two storage devices each comprising N storage organs each to represent one symbol value when operated, a control device adapted automatically to cause the storage devices to operate separately and alternately when digits are entered, and electric conductors interconnecting the switching members and storage organs, whereby a newly entered digit is added to or subtracted from a stored symbol value (without carry-over) according to whether the value is stored in one or the other of the storage devices. In a modified apparatus, only one storage device is used and has delayed operating switches and holding means associated therewith. In the arrangement shown in Figs. 6a and 6b for computing the checking symbol to base 11 of a number, for the purpose described in Specification 702,214, digits are entered one by one by closing Eo-Ex (x representing 10) which may be key-operated contacts or recordcard-sensing contact brushes, and which energize relays Ro-Rx; which close corresponding rows of contacts connecting upper terminals Ao-Ax to lower terminals Bo-Bx. The connections are such that if a potential is applied, to a terminal Ay or Bz and a relay Rs is energized then the potential will appear on terminal Bz or Ay, where s - y - z=11K, K being an integer that may be 0. Initially, relay MSO is energized through a circuit comprising reset contacts CD, relay contacts CRD, terminal Ao, coil PTI of transformer TI and relay RD which opens CRD, the relay MSO being held through contacts CSO and CMS. If, e.g., digit 3 is entered and relay R3 is energized, the positive potential applied to Ao will be sent through contacts 33 to terminal B3 and relay MI3, the circuit to this relay being completed through coil PTS of transformer TS and relay RD. A pulse is then applied through secondary STS and rectifier AS to relay RMS which opens contacts CMS to de-energize relay MSO, and relay MI3 is held through contacts CI3 and CMI. Similarly, if, e.g., the next entered digit is an 8, the potential now applied to B3 will be sent through contacts 85 and terminal A5 to relay MS5 (8 - 3=5) which will then be energized in series with PTI, a pulse being applied to relay RMI to open CMI and break the circuit of MI3. Thus as successive digits are entered selected relays MI, MS are energized alternately under control of the trigger circuit including transformers TS, TI. The positive potential on the corresponding terminal A or B is applied through rectifiers such as ASO, ABO, Fig. 6a, to a lamp O-X and recording (e.g. punching or printing) magnet Fo-Fx, Fig. 6b. When the whole number has been entered the corresponding checking digit may be registered. The entry of this digit should cause a return to zero; if it does not, an error detecting magnet EB is not energized. It is stated that the relay- and-transformer trigger circuit could be used to form binary counting chains. In a modification, the trigger circuit is replaced by an electro-magnetically-operated alternate-make- and-break contact arrangement, and the base value is 10 in place of 11. In the modified arrangement employing only one set of storage relays MI, Fig. 9 (not shown), operations are timed by slow-acting contacts of these relays.