I used emacs on a wide variety of systems many years ago. At the time it was the closest to a universal editor for the different systems I was using back then.
Anyone remember TECO, the line editor used on printing terminals? I used that back before the first version of Emacs was implemented as a giant TECO macro. (Which illustrates how powerful TECO was.) Those seeking nostalgia (or pain!) should check this out:
<http://c2.com/cgi/wiki?TecoEditor>
Included are links to modern ports and the TECO Pocket Guide.
