The “Baudot” Code

This table presents a programmer’s quick reference to the “Baudot” character set.

IMPORTANT NOTE: The code presented here is with reference to usage in the computer industry. The original, true, baudot code differs from that presented below. The following table presents CCITT Alphabet No 2 which was developed from Murray’s code which was in turn developed from Baudot’s code. Baudot’s code was replaced by Murray’s code in 1901.
And ITA2 replaced both by the early 1930’s, so virtually all “teletype” equipment made in the U.S. uses ITA2 or the U.S. national version of the code.

The ‘baudot’ code has been used extensively in telegraph systems. It is a five bit code invented by the Frenchman Emile Baudot in 1870. Using five bits allowed 32 different characters. To accomodate all the letters of the alphabet and numerals, two of the 32 combinations were used to select alternate character sets. The figures column is valid after a figures shift character has been received. It remains in effect until a letters shift is received, after which the letters column should be referred to (and vice-versa).

Two ‘Baudot codes’ are in common useage. The first as used in America. The second, used in Europe, is also termed the CCITT Alphabet No. 2. In each, the ‘letters’ are identical, but the ‘figures’ differ.

The five-bit words are bracketed by a start bit (space) and a stop bit (mark). Idling is shown by the ‘marking’ state. Words are transmitted LSB first.