In “Floppies: The Disks That Changed the World” thread, @oldben writes:
It seems unlikely. OS-9 had some disadvantages that kept it from becoming popular:
- It required a 6809 CPU. This was never all that popular both becuase it came out several years after the 6502 and the Z80, and because it was more expensive.
- It was expensive: several hundred dollars. For vendors creating new machines without a software base, a much cheaper option was to use an 8080-series or Z80 CPU, license CP/M, and write just the BIOS, which was fairly small and cheap to write. For vendors who already had more extensive software (often licensed Microsoft BASIC supplemented by their own ROM routines), it was cheaper to write their own DOS. (This was the approach taken by Apple, Tandy and Commodore.)
There was a situation perfect for OS-9, if it was going to happen: the Fujitsu FM-7 series in Japan. The FM-7 had diskette drives available on release in 1982, drives were standard equipment from the 1984 FM77 onwards, and OS-9 was ported to it. But Fujitsu already had their own BASIC and DOS, so they probably felt it wasn’t worthwhile to pay yet more money to license another OS, and consumers apparently didn’t feel that the added expense, when they already had a DOS that was free, was worthwhile.