Sorry to bump this old thread - but the X16 is gaining momentum again, the 100 unit run was a success and the next 1000 unit run is right around the corner.

I came across ASMEDIT here: (sorry referencing a different forum, but it is the "official" X16 forum and place to get software for it so far)
https://cx16forum.com/forum/viewtopic.php?t=6729

A couple of us have tested it out and it does work - but I think it uses an older asm format (from older original CBM textbooks).

Is anyone here involved with that project? Or any new updates on the "on system" assemblers that were mentioned earlier in this thread?