I’d found more stuff, and re-bundled it all on archive.org:
https://archive.org/details/mach-microkernel-files

le wow und gratulieren!

I’ll have to ask the devs that they know, although all I know is that they added the i860 emulation from MAME to bring it online, although Im unsure of what code its exactly emulating. From the oldest code of Xnu I could find it certainly insinuates that the XNU kernel ran on i860 and of course the m88k.

It’s a shame that missing link between Mach 2.5 and NeXTSTEP is missing, but I still have high hopes it may accidentally surface at one point in time. And maybe fix the annoying 2GB filesystem limits from those old days.

I’m not sure how complete is the Mach kernel that runs in the ND (maybe it’s a reduced version), but it’s certain that an i860 version of the Mach kernel is running in the ND. Take a look at Previous.

The Mach source I found only supports the i386, sun3 (68030), Vax and MIPS platforms. I didn’t know the NextDimension boards downloaded NS to run onto the board, I’d just assumed that the firmware just ran a direct postscript interpreter as only the assembler cross targeted the i860, not the ObjectiveC compiler.