Go to http://204.57.142.148/NEC/RISCServer.html
you'll find the beta2 iso image...

Notice although the site seem's to be only applicable
to RiscServer this image is 'generic'.

The kernel itself isn't from beta2 (everything else is)
but is a modified 1.51U... the reason is to support
a bunch more 'arc' machines.
This kernel should fine for
'pica/olevetti',r2250,RiscServer Express,at least
one series of RiscServer 2200 (according to
NEC three versions ie R96,R96A,R96B).

Hopefully after the rewrite I did to 'raster'
driver I use it will also now support
video on RiscStation r2200 both isa and pica
and mips magnum..

I also built the kernel image with an modified
OpenBSD elf2ecoff so hopefully DeskStation
will now load and maybe run.

Of course we need lot's of tester's to check
how many things I broke/fixed !