TTYpäätteitä

TTYpäätteitä, often translated as TTY terminals or teletypewriters, are a type of electro-mechanical teleprinter that was used for transmitting and receiving text messages. They operated by converting electrical signals into printed characters and vice versa. Early TTY devices were used for telegraphy and later became integral to early computer systems.

These devices typically consisted of a keyboard for input and a printer for output, usually on paper tape or rolls. They communicated over serial lines, often at relatively low speeds compared to modern networking. The term "TTY" itself is derived from "Teletypewriter," the name of a prominent manufacturer of these devices.

In the context of computing, TTY devices served as the primary interface for users to interact with mainframe computers. Users would type commands on the keyboard, and the computer's responses would be printed out. This provided a rudimentary form of human-computer interaction before the advent of graphical user interfaces. Even after the widespread adoption of video terminals, the underlying concepts and control sequences associated with TTY devices persisted in many operating systems, influencing how terminal emulators function. The legacy of TTYpäätteitä can still be seen in the standard TTY devices found on Unix-like operating systems.