Teleprinter
The teleprinter is an apparatus allowing the generation and the reception of messages via electrical signals. It is in general about a telegraphic line, but one can also use a radio contact. In this case, one speaks about Radiotélétype.
The first computers, deprived of screen, used also the teleprinter like single peripheral of input-output.
One also speaks about teleprinter or teleprinter (TTY in notation shortened). Télétype is in the beginning a registered trademark in 1925 by the company Edouard Belin and would have, for this reason, being written with an initial capital .
The apparatus
This apparatus is of appearance similar to a Typewriter. The typed characters could be memorized by perforation of a paper band.A mechanical system prevents that one types more quickly than the transmission speed of characters. The scheduling of the keys is identical to that of the typewriters (QWERTY or AZERTY).
Evolution
The first apparatuses used the Code Baudot. One used the ASCII code later.
Speed, 45,5 bits a second, went up to 200 bits a second.
The apparatuses were made increasingly compact. The noise can be reduced thanks to the impression with needles.
The telex network
An international telecommunication network was created to connect between them these apparatuses: the telex network. See the article Telex.
The exchanges Telex allowing the speed and code conversion as well as intermediate memorizing. The setting in network of apparatuses various standards and speeds became thus possible.
It lost its importance by the invention of the Télécopieur (fax) and of the Email.
History
- 1866, David E Huges: 1000 words per hour
- 1874, the teleprinter of Emile Baudot with 5 keys (one by finger), 4000 words per hour
- 1901, the teleprinter with keyboard of typewriter and it punched tape of Donald Murray
| Random links: | Citroen Jumpy | Joe Girard | Robert Sparks | Country of Brittany | Siddhi | Senussi |