02 What is the CCITT-2 Code?


To facilitate character entry, Donald Murray developed a keyboard around 1901 similar to that of a typewriter, which punched the associated string of five bits into a punched tape by pressing a single key.

Murray retained Baudot’s level switching, but rearranged the order of characters in the code so that frequently used letters, such as “E” and “T” were given code positions that required shorter and less frequent movement of the mechanism in the equipment to send and receive. This reduced wear and tear and the need for maintenance. Murray also added a carriage return character to subdivide telegrams.

Another important change was that spaces and letter/digit switches were separated and became separate characters. To be able to drive sheet recorders (devices that write line by line on a sheet instead of endlessly on a strip), control characters for carriage return and line feed were added. To this was added a code for triggering an automatic name generator on the remote device, to be able to make sure who one was connected to (Who there?) even with unmanned remote stations, as well as the possibility of triggering a bell to attract the attention of the operator.

This modified code was standardized in 1932 by the CCITT as the International Telegraph Alphabet No. 2 (CCITT-2 or ITA2 for short).