I came across an Allen-Bradley 1771-DMC4 Control Coprocessor. If you are familiar with AB PLC's, it is a 1771-IO chassis module that could be a "sidecar" for a PLC5 PLC or a standalone module.
It runs some version of OS-9/68k on a 68340 processor. It has 4MB static ram and a 10MB ethernet AUI connector. I hooked up a terminal and can get to an OS-9 prompt. It has by default a 64k RAM disk that is empty. The best I can gather is that there was an external IDE (AB 1771-PCB PCbridge) that was used to create programs that were loaded onto the RAM disk. Once configured it would run standalone. Microware is still around in some form so OS-9 is not completely dead and I did find some references to a Microware product called PBbridge. It would be interesting to experiment with. I am curious if anyone has any experience with this hardware, with the IDE or OS-9/68k in general. I've never seen much discussion of OS-9/68k on classicmp.