NOT Mac OS9, OS-9 as in one of the first Unix clones. Without going out to find a tandy or an MSX 2 I don't really know much about it. I know there was support on the TRS-80 machines and some about Nitro-9 (OS-9 built for the Hitachi\Motorola 6304 processor) but other than what is in a podcast I listen to and on the wikipedia page theres nothing about user experience, doing stuff in terminal, if anyone made DE's for it, nothing like that. Just about it being on machines and what people have done to it.
This probably isn't the best crowd to ask but its the only one I have :\
Its still around to. I hate to wonder what it even is anymore.
Some links are dead. TRS-80 oriented. http://pages.cs.wisc.edu/~pruyne/os9faq.html From 1995, the net glory days. Hope this helps. no idea why the first link took up so much space.
Never got into macs much. My first thought Plan 9 but that was 486 stuff. CP/M kinda dominated the 8080 segment except for TRS-DOS. Not sure but is the last link and the first link relevant?
I can't even find it on the list of obscure posix compliant OS's and there are a bunch of em.