For questions regarding the OS-9 Operating System released in 1979 for the Motorola 6809 processor.

OS-9 is a UNIX-like OS intended to make full use of the features incorporated in the 6809 processor that represented an advance over earlier processors.

Later versions ran on later processors (e.g. OS-9/68k on the 68000 series and OS-9000 on 80386 and PowerPC.