Over at Hoff’s Blog, he recently discussed some thoughts he had about text editors. However, it was in the comments where I learned why TECO is so unstable on OpenVMS for Itanium. You wouldn’t think that anything in a shipping product would regularly do the equivalent of dump core – not to mention something as old and tested as TECO – but it’s true. Apparently TECO (being the old and unkillable beast that it is) wasn’t rewritten or debugged for Itanium, but rather was put on top of an emulation layer and translation layer, which seems to cause stability issues.
Thus, if you want a stable TECO (and who doesn’t want a stable editor?) you are better off getting a version of TECO-C and compiling it or installing it onto OpenVMS rather then using EDIT/TECO.
Believe it or not – I learned more about TECO before I learned about OpenVMS. And even among OpenVMS people, the TECO users must seem to be antiquarians or eccentrics! I just like the idea of programming my text editor…. (so I’m a little strange…)
Of course, vim and other more current editors are also available – and there are EDT clones for other machines if your inclination leans that way.
PS: Talking of editors – do any of you remember a text editor called NEAT? I seem to remember liking it, but I haven’t seen it since the Univac 1100/80 was decommissioned at the local university (a long time ago). And have you tried googling for a NEAT editor? (ouch!)
UNIX Administratosphere 
TECO was available on TOPS-10 and TOPS-20 and RSX so I guess you first found it then.
I first discovered teco on TOPS-10 at University. I did ‘cheat” a bit by using vt52.tec initially but did get the hang of it eventually,
I still have a printout of the TECO-11 manual on line printer paper.
Not I. Believe it or not, I think the first TECO I interacted with was on UNIX. It might have been the idea that EMACS could be written in TECO that caught my interest.
I’ve no idea. I’ve never used TOPS-10 or TOPS-20 or RSX – though I’ve used RSTS/E but I don’t remember TECO being on there.