Bell Telephone Laboratories

Abstract

The potentialities of telephone equipment for the construction of digital calculation devices were not realised for many years. The first automatic telephone exchange, which used the step-by-step or Strowger switch, was installed in 1892. As early as 1906 Molina devised a system for translating the pulses representing the dialled decimal digits into a more convenient number system. Exchanges based mainly on the use of electromechanical relays started to come into use at the turn of the century, the earliest successful centralized automatic exchanges dating from about 1914. However, from the late 1920’s various different calculating devices were developed using telephone equipment. Perhaps the most spectacular of these was the automatic totalisator.