Computer terminal

Typical parts and operation

Traditional terminals were character-oriented devices optimized for text: a keyboard for input, a screen designed for rows and columns of characters, firmware that processed control codes, and a communications interface to a host. Terminals commonly used serial links (for example RS-232) or networked connections and understood escape sequences to position the cursor, clear the screen, or change attributes such as color or intensity.

Types

• Dumb terminals: minimal local processing; display and transmit characters to a host which does most of the work.
• Smart terminals: include local editing, function keys, character attributes, and limited local processing.
• Block-mode and forms terminals: send and receive whole blocks of data for form-oriented applications, common in mainframe environments.
• Terminal emulators: software windows or apps that emulate terminal behavior and connect to local shells or remote hosts via protocols such as Telnet or SSH.

History and standards

Terminals evolved from electromechanical teleprinters and teletypewriters to electronic glass displays. De facto standards and conventions such as ANSI escape codes and DEC-compatible control sequences shaped how software controlled cursor movement and text attributes. As personal computers and networks emerged, many terminal functions moved into software, while serial console ports and virtual terminals remained important for system access and recovery.

Uses and continued relevance

Terminals remain central to system administration, programming, embedded device consoles, and network equipment management. Concepts from terminal design persist in operating system primitives named for them (for example TTY and pty), in terminal multiplexers, and in text-based user interfaces. Even where graphical interfaces dominate, text terminals are valued for low bandwidth, scriptability, and direct control of remote systems.