Also, remember that for the early DEC PDPs 1/6/10 machines, there were Stopgap, SonOfStopgap (a.k.a. SOS - which became DEC's EDIT), Teco, and eventually EMACS [remember UNIX emacs is a clone of the original TOPS-10/ITS EMACS]; and probably others that I am forgetting - those the ones I used in PDP-10 days.
TECO (Text Editor and COrrector) was interesting in a couple of ways. All of its commands were a single character. It was also programmable in a very powerful way. EMACS was first implemented as a set of TECO macros (the name EMACS is an acronym for Editor MACroS).
-Paul W.