The Evolution of Character Codes, 1874-1968

Émile Baudot’s printing telegraph was the first widely adopted device to encode letters, numbers, and symbols as uniform-length binary sequences. Donald Murray introduced a second successful code of this type, the details of which continued to evolve until versions of Baudot’s and Murray’s codes were standardized as International Telegraph Alphabets No. 1 and No. 2, respectively. These codes were used for decades before the appearance of computers and the changing needs of communications required the design and standardization of a new code. Years of debate and compromise resulted in the ECMA-6 standard in Europe, the ASCII standard in the United States, and the ISO 646 and International Alphabet No. 5 standards internationally.