teleprinters

Teleprinters, also known as teletypewriters, are electromechanical devices that can both receive and print typed text over telecommunication networks. They were designed to convert between keyboard input, electrical signals, and printed output, enabling long-distance text communication before digital computers became common.

Most early teleprinters used a five-bit Baudot code (ITA2) that encoded letters and figures with a character shift. Transmission was typically asynchronous, and messages could be sent over telephone lines, radio circuits, or dedicated private networks. Input could be supplied by a keyboard or by punched paper tapes. Output was a continuous strip of paper on a typewriter-like printer, printing at speeds from tens to a few hundred words per minute depending on model.

Teleprinters were widely adopted by newspapers, government agencies, banks, and military organizations. During the mid-20th century, teletype networks such as Telex linked remote offices and enabled automatic dispatch of news, stock quotes, and messages. The technology evolved through devices produced by Teletype Corporation and other manufacturers, with popular models introducing asynchronous serial operation and improved reliability. In computing, teletype units often served as character-based terminals or input/output devices for early computers.

By the 1980s and 1990s, digital networks, fax, email, and computer terminals largely supplanted teleprinters. Some systems persisted in specialized or archival contexts, and the term survives in telecommunications as teletypes (TTY) and in computing as terminal devices. Modern message exchange usually uses fully digital text protocols and display interfaces, but teleprinters played a crucial role in the transition to networked digital communication.