TECO (text editor)
TECO (/ˈtiːkoʊ/; originally an acronym for [paper] Tape Editor and COrrector, but later Text Editor and COrrector, then Text Editor Character Oriented) is a text editor originally developed at the Massachusetts Institute of Technology (MIT) in the 1960s, after which it was modified by "just about everybody". TECO was a direct ancestor of Emacs, which was originally implemented in TECO macros.