Baudot code

Baudot code

The Baudot code, named after its inventor Emile Baudot, is a character set predating EBCDIC and ASCII and used originally and primarily on teleprinters.

Baudot's original code is known as International Telegraph Alphabet No 1, and is no longer used.

Baudot code was then improved by Donald Murray by adding extra characters and shift codes. This code is what is generally known as the 'Baudot code', also known as the International Telegraph Alphabet No 2 (ITA2). ITA2 is still used in TDDss and some ham radio applications, such as RTTY.

Table of ITA2 codepoints (hexadecimal)

In ITA2, characters are expressed using five bits. ITA2 uses two code sub-sets, the "letter shift" (LTRS), and the "figure shift" (FIGS). The FIGS character (11011) signals that the following code is to be interpreted as being in the FIGS set, until this is reset by the LTRS (11111) character. "ENQuiry" will trigger the other machine's answerback. It means "Who are you?" Code points 0D, 14 and 1A are not used in telex communication.

CR is carriage return, LF is linefeed, BELL is the bell, SP is space, and STOP is the stop character.

Note: the binary conversions of the codepoints are often shown in reverse order, depending on (presumably) which side you are viewing the papertape from.

US American implementations of Baudot code may differ in the use of ENQ, +, and f,g,h on the FIGS layer. The above table represents the official ITA2 code.

External references:

Adapted from FOLDOC, with permission.