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VT100
Features from the DEC VT100 terminal (1978), the de facto standard for terminal emulation. The VT100 defined the escape sequence grammar (ESC [ for CSI), cursor addressing (CUP), scrolling regions (DECSTBM), and character sets that virtually every terminal emulates today. When a terminal calls itself "VT100-compatible," it means it supports this baseline. The VT series continued through VT220 (1983, added 8-bit controls), VT320 (1987), VT420 (1990), and VT510 (1993), each adding features — but VT100 remains the foundational compatibility target. DEC shipped roughly 6 million VT-series terminals over the product line's lifetime. The VT100 launched at $1,800 (about $8,700 in 2024 dollars) and became so ubiquitous that its escape sequences became the lingua franca of terminal communication.
The VT100 protocol defines the sequences that form the baseline of terminal communication. Scroll regions (ESC [r for DECSTBM) allow applications to define a portion of the screen that scrolls independently — the foundation of split-pane editors and status bars. Cursor save/restore (ESC 7 / ESC 8) lets applications preserve cursor position during screen updates. Auto-wrap mode (DECAWM) controls whether text wraps at the right margin or is clipped.
Three VT100 features matter most for modern developers: cursor addressing (ESC [row;colH for CUP), which gives applications random access to any screen position; line drawing characters via the DEC Special Graphics character set (activated by ESC (0), used by every box-drawing TUI; and SGR basic colors (the 8 foreground/background colors from SGR 30-37 and 40-47 that predate 256-color and truecolor extensions).
VT100 compatibility is universally supported. Every terminal emulator, every SSH connection, every container runtime assumes VT100 as the minimum. The TERM=vt100 terminfo entry is the fallback when nothing else is known about a terminal's capabilities.
Historical Context
The DEC VT100, released in August 1978, was the first popular terminal to implement the ANSI X3.64 (ECMA-48) escape sequence standard. Running on an Intel 8080 CPU with just 3KB of RAM and 8KB of ROM, it proved that the new standard could be implemented affordably — silencing critics who called it 'beyond the state of the art.'
The VT100's 80×24 display became the universal terminal size (inherited from IBM's 3270, which got it from 80-column punch cards). Its escape sequence grammar — ESC [ for CSI, the parameter syntax, scroll regions (DECSTBM), character sets — defined what 'terminal compatible' means to this day. DEC shipped over 6 million terminals in the VT series.
Every modern terminal emulator is, at its core, a VT100 emulator with extensions. When software claims 'VT100 compatibility,' it's promising support for the specific behaviors this $1,800 box established nearly 50 years ago.
Analysis2026-09-28
Terminal Applications
Headless Backends
Parser correctness tested via Termless. A ✓ means the parser accepts the sequence, not that it renders correctly.