DEC's VT100 made ANSI escape codes the terminal standard that every emulator still speaks

In 1978 Digital Equipment Corporation introduced the VT100, a video terminal whose keyboard and screen replaced the teletype. Its user guide states the design explicitly: the terminal follows two programming standards — ANSI and VT52 — and in ANSI mode "will generate and respond to coded sequences per ANSI standards X3.41-1974 and X3.64-1977." That decision — implement the public standard instead of inventing a private code language — is what made the VT100's control sequences universal.

The escape sequences — the "ESC[" forms that move the cursor, clear the screen, set attributes and scroll — became the de facto way programs talked to any terminal. As The TTY Demystified describes it, solid-state video terminals such as the VT-100 in the late 1970s made "fancy cursor movements, colour output and other advanced features" possible; today, in a world where physical terminals are extinct, the software everyone runs is "emulated video terminals — software simulations of the real thing."

Rivals and successors kept the same ANSI dialect rather than introducing another private language, and Unix applications assumed it. The VT100 itself was succeeded by later DEC terminals, but its control sequences remained the baseline: every modern terminal emulator — xterm, iTerm2, Windows Terminal — still interprets VT100-style escape codes.