> I also came across vteco some years back which was a full-screen TECO > with infinite undo:
For those of you who care, this is one of the (very) remote ancestors of Emacs. TECO was originally intended to be a language for the development of editing tools, and vteco was the first step in it's transition to visual editors. Gosling Emacs drew a lot from vteco, and there's still a few bits and pieces in GNU Emacs where the screen handling (particularly in column-editing and box mode) resembles the way vteco did things.
