OS/2 on hardware other than '286 or '386 processors

Not having seen the PPC source, but the 86/286/386 monster of OS/2-kernel source (3.x), I can only agree. I consider it almost impossible, without a complete rewrite and then only - as in the PPC implementation - with largely different APIs to port this thing to anything else, including PDP-11. Given the 386 ring architecture, it would be more likely to transfer a look-alike to a VAX, but not to a PDP with MMU. But even then; the question is: what benefit would there be? DEC systems were already a dying platform at the time of OS/2, and lack of any compatibility to the original x86-based system would gain nothing. Even the PPC was not a success, not only because of the obscure CHRP architecture no other vendor used, but also because of the lack of killer application or migration path. Apple those days did it better in providing an emulator to run older 68K apps on the PPC.