Morse or Murray code.

Morse uses a morse key worked by a skilled operator who sends a series of dots and dashes over the wire. Another operator listens to the dots and dashes and writes the message down on paper.

Murray code is a five bit machine code, used by telexes and teleprinters.

Companies primarily engaged in manufacturing computer terminals, teleprinters, and multistation cathode ray tubes (CRTs) make up the computer terminal industry.

The teleprinter evolved through a series of inventions by a number of engineers, including Royal Earl House, David Edward Hughes, Emile Baudot, Donald Murray, Charles L. Krum, Edward Kleinschmidt and Frederick G. Creed. Teleprinters were invented in order to send and receive messages without the need for operators trained in the use of Morse code. A system of two teleprinters, with one operator trained to use a typewriter, replaced two trained Morse code operators. The teleprinter system improved message speed and delivery time, making it possible for messages to be flashed across a country with little manual intervention.

This began in 1846 with Royal Earl House patenting his printing telegraph through 1924 then Creed & Company, founded by Frederick G. Creed, entered the teleprinter field with their Model 1P. Additional minor improvements were invented from then into the 1960s.

The Shift characters in the Baudot character code are used to switch between letter and figure mode. This allows the same keys to represent both letters and numbers, expanding the character set that can be transmitted using the limited number of keys on early teleprinters.

Like to help, but comms has moved on for me too, as I was a WoP (Telegraphist) in the 70's Trained at RAF Cosford, using then Morse up to 20 words a minute, I think it was and typing to work the the teleprinters & TASS. Can vividly remember the relay stations, the Murray tape, the Morse logs, the Bids, chaff. Did from 74 to 80 and Satellite was just starting to come in by then.

Cheers

Hughmac