Editing Teleprinter (section)

==Teleprinters in computing==<!-- This section is linked from [[Line printer]] -->
[[File:ASR-33 Teletype terminal IMG 1658.jpg|thumb|A Teletype Model 33 ASR with paper tape reader and punch, as used for early [[modem]]-based computing]]
Computers used teleprinters for input and output from the early days of computing. [[Punched card]] readers and fast printers replaced teleprinters for most purposes, but teleprinters continued to be used as interactive [[time-sharing]] [[computer terminal|terminals]] until video [[computer display|displays]] became widely available in the late 1970s.

Users typed commands after a [[Command-line interface#Command prompt|prompt]] character was printed. Printing was unidirectional; if the user wanted to delete what had been typed, further characters were printed to indicate that previous text had been cancelled. When video displays first became available the user interface was initially exactly the same as for an electromechanical printer; expensive and scarce video terminals could be used interchangeably with teleprinters. This was the origin of the [[text terminal]] and the [[command-line interface]].

[[Punched tape|Paper tape]] was sometimes used to prepare input for the computer session off line and to capture computer output. The popular [[Teletype Model 33]] used 7-bit [[ASCII]] code (with an eighth [[parity bit]]) instead of Baudot. The common [[modem]] communications settings, ''Start/Stop Bits'' and ''Parity,'' stem from the Teletype era.

In early operating systems such as [[Digital Equipment Corporation|Digital's]] [[RT-11]], serial communication lines were often connected to teleprinters and were given device names starting with {{mono|tt}}. This and similar conventions were adopted by many other operating systems. [[Unix]] and [[Unix-like]] [[operating system]]s use the [[prefix]] {{mono|tty}}, for example {{mono|/dev/tty13}}, or {{mono|pty}} (for pseudo-tty), such as {{mono|/dev/ptya0}}, but some of them (e.g. Solaris & recent Linux) have replaced pty files by a pts folder (where "pt" stands for "pseudoterminal" instead). In many computing contexts, "TTY" has become the name for any text terminal, such as an external [[system console|console]] device, a user dialing into the system on a [[modem]] on a [[serial port]] device, a printing or graphical [[computer terminal]] on a computer's serial port or the [[RS-232]] port on a [[USB]]-to-RS-232 converter attached to a computer's USB port, or even a [[terminal emulator]] application in the window system using a [[pseudoterminal]] device.

Teleprinters were also used to record fault printout and other information in some [[TXE]] telephone exchanges.