fllowing up: in case people don’t know type C-x C-c (the same as GNU/Emacs) to quit emacs and :LOGOUT
to logout (obviously) and finally C-] and quit
telnet.
TECO Emacs is also avaliable in www.twenex.org (unfortunately it’s down today)
And an archived manual in HTML is here: https://web.archive.org/web/20110723033542/http://www.burlingtontelecom.net/~ashawley/gnu/emacs/doc/emacs-1978.html