25th Anniversary of the Personal Computer" 4205
One of the things that made OS-9 "Big", was Radio Shack's decision to use the 6809 in their Color Computer", and then added OS-9 to the catalog. The CoCo version (which wasn't a limited version, just with some mods for the hardware) was significantly cheaper than OS-9 for the 6809 "mainframes".
I'm not saying it was insignificant, just that without the CoCo version it never would have propogated as well. The other 6809 systems were too expensive for it to gain that much popularity.
But when the 16-bit home computers came along, like the Atari ST and the Amiga, the price of the OS never reached the same low cost. I remember looking at it for the ST, and the basic version was about on par with the CoCo version, but it came with no programming language. The version with the Basic09 (and maybe an buttembler) was significantly more costly.
25th Anniversary of the Personal Computer
When dial-up BBSes were still all the rage, I used to have an elaborate set of self-made ARexx (and other) scripts to facilitate offline messaging. We had metered calls...
I remember thinking, circa 1990, that Minix seemed like the way to go rather than OS-9 for the Atari ST.
If Radio Shack had come out with a 68000-based system, well a cheap one like a 16-bit version of the CoCo, and added a 68000-based OS-9 to the catalog at a similar price, I think the 16 bit version would have propagated as well as the 6809 version.