If you’ve ever wanted to play around with the patriarch of the Emacs family, now you can. The TECO editor was developed in 1962 to work with paper tapes. In fact, TECO originally stood for “Tape Editor and Corrector” but the acronym’s meaning was changed to “Text Editor and Corrector” as it was adapted for other media. The other salient fact about TECO is that the original Emacs—the literal Editing MACroS—was implemented as TECO macros.
Every once in a while I see someone proudly announce that they still use, or at least prefer, TECO but until Mike Zamansky’s Emacs vs. Vi rant I had never seen it in action. I assumed that those still using it were one of the people who collect old computers such as the PDP-1 on which it was originally implemented. It turns out, though, that it was ported to C and is available in a GitHub repository maintained by Blake McBride.
Of course, if you think line editors such as ed are a pain, you should know that TECO is a character editor—presumably from its heritage as a paper tape editor. The README for the repository and the manual have more details on how it works. If you feel like having a retro moment, now you know where to get it.