The EMACS package for TECO on ITS isn't an ancestor of modern GNU emacs, which began as a rewrite (based on Gosling's Unix emacs) in 1984. They are both "emacs" in the sense that they are modeless screen editors that share the same default keystrokes.
Really GNU emacs is related to ITS emacs in the same way that vim is to BSD vi: it's a cleaner and much more powerful reimagining of the original that shares some interface details but no implementation.
Really GNU emacs is related to ITS emacs in the same way that vim is to BSD vi: it's a cleaner and much more powerful reimagining of the original that shares some interface details but no implementation.