GB490164A - Improvements in or relating to coding and decoding machines - Google Patents

Abstract

490,164. Ciphering-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 20, 1937, No. 22885. Convention date, Aug. 27, 1936. [Class 146 (ii)] Ciphering and deciphering apparatus comprises a primary machine such as a typewriter connected through a number of coding-elements to a secondary machine, the coding- elements comprising circuit-changing devices which are set individually under the control of mechanisms adapted to be operated singly or in selected combinations. Each coding- element 6, Fig. 1, comprises a series of brushes 7 carried by a fixed insulating-ring and adapted to engage conducting-segments on a ring rotatable with a shaft 14. The segments are connected to slip-rings rotatable on the shaft 14 and engaged by brushes 8. Depression of a key in the keyboard T<1> of the primary typewriter closes a circuit from the battery 15 through the normally-closed switch 16 and the elements 6, leads 19, 20, 21, normally-closed switches 22, and leads 23, 24 to the solenoids 3 operating the keys of the secondary typewriter T<2>. Depression of the keys of the primary typewriter also actuates one or more permutation bars similar to those of a Baudot transmitter to close corresponding contacts 5 whereby magnets 10 are energized to step forward the corresponding element 6. For deciphering, the ciphered message may be typed on the primary typewriter, and the plain message received by the secondary typewriter, but since the closing of the contacts 5 depends on the letters of the plain message, the switch 28 is operated, so that the switches 5a actuated by the keys of the secondary typewriter control the energization of the magnets 10 ; alternatively, the ciphered message may be typed on the secondary typewriter, the switch 28 being in the original position, but the switch 31 closed to energize magnet 17, thus closing switches 25, 26 and opening switches 16, 22. To reset the machine to original position at the commencement of a ciphering or deciphering operation, switches 33, 34 are closed. Each element 6 carries a brush 38 moving over a ring 37 having a single conducting segment 39. If any element is not in home position, closing of switch 34 connects battery 36 to magnet 10a through switches 43, 41, thus opening switch 43, and moving the element forward one step. The de-energization of the magnet again closes the switch 43, so that the element is moved forward step by step until the brush 38 engages the segment 39, when the battery 35 energizes magnet 40 and opens switch 41 to prevent any further energization of magnet 10a. In order further to complicate the code, the elements 6 may carry discs 50, Fig. 2, having movable plugs 52 which may be set arbitrarily to close switches 60, whereby when any of the contacts 5 are closed on operation of a key, a magnet 10 other than the one directly connected to the contact is energized.