Speaking of emulators... I have a userland Venix/86 executive...

[Warner Losh]

I've written a Venix/86 userland emulator. It uses FreeBSD's vm86 to run
binaries natively and intercepts traps for things like system calls. I
finally have it to the point where it can run the compiler via cc (which
forks and execs c0, copt, cpp, as, ld, etc). My plans to try to recreate
the sources for the binaries for Venix/86 from V7 and other extant sources
have taken a step forward. Don't know if I'll ever get there, but at least
I don't need a working Rainbow and can run the compiler at ~4GHz rather
than ~4MHz....

http://bsdimp.blogspot.com/2021/08/a-new-path-vm86-based-venix-emulator.html
has my latest blog entry on it. The code lives in tools/vm86venix in my
https://github.com/bsdimp/venix repo for those that want to take a look. It
uses vm86 mode of 32-bit intel processors and traps all INT xx and other
privileged instructions and provides appropriate emulation... And the
compiled binary is smaller than the venix kernel (but it does less).

Warner