A lot of the problems encountered here seem to be due to bit rot, unavailable archives and these were, from my experience, not too uncommon for relatively rare Linux platforms like the RISC PC even more than 20 years ago.
RISC PC systems are still a supported (tier 2) platform in NetBSD. You should be able to cross-compile the whole system including X11 from any Linux or NetBSD host (I did this last week for the next68k port) and the developers would certainly be happy
about feedback before the 11.0 release is published. So this might be worth giving a try.
Not everything is working in NetBSD all the time. When testing the “previous” NeXT emulator, we faced some nasty regressions last year that prevented NetBSD 10 (and, as we found out, every release after 5.2.3!) to run on next68k, but things were fixed eventually thanks to the nice and friendly next 68k platform maintainer!
I just tested the build. It seems that the NetBSD build tries to compile for armv4 (which, as on Linux, means StrongARM only).
When trying to specify -a earm (which should imply ARM v3) instead of the default -a earmv4 to build.sh (./build.sh list-arch gives the supported architectures), the script complains that "MACHINE_ARCH 'earm' does not support MACHINE 'acorn32'".
So it seems there's more work to be done for the armv3 machines, sorry...
Update: Early Acorn machines with ARM2 and ARM3 processors were supported by NetBSD/acorn26 (see https://www.netbsd.org/ports/acorn32/faq.html). This is a bit strange, since IIRC ARMv3 got rid of the 26 bit PC mode.
Unfortunately, support for this port ended back in 2018 with NetBSD 8.0 and the acorn26 supported platform list doesn't include the ARM710 RiscPC, so it might also be significantly more difficult to get NetBSD to work on your machine...
A lot of the problems encountered here seem to be due to bit rot, unavailable archives and these were, from my experience, not too uncommon for relatively rare Linux platforms like the RISC PC even more than 20 years ago.
RISC PC systems are still a supported (tier 2) platform in NetBSD. You should be able to cross-compile the whole system including X11 from any Linux or NetBSD host (I did this last week for the next68k port) and the developers would certainly be happy about feedback before the 11.0 release is published. So this might be worth giving a try.
https://wiki.netbsd.org/ports/acorn32/
https://www.netbsd.org/docs/guide/en/chap-build.html
Not everything is working in NetBSD all the time. When testing the “previous” NeXT emulator, we faced some nasty regressions last year that prevented NetBSD 10 (and, as we found out, every release after 5.2.3!) to run on next68k, but things were fixed eventually thanks to the nice and friendly next 68k platform maintainer!
I just tested the build. It seems that the NetBSD build tries to compile for armv4 (which, as on Linux, means StrongARM only).
When trying to specify -a earm (which should imply ARM v3) instead of the default -a earmv4 to build.sh (./build.sh list-arch gives the supported architectures), the script complains that "MACHINE_ARCH 'earm' does not support MACHINE 'acorn32'".
So it seems there's more work to be done for the armv3 machines, sorry...
Update: Early Acorn machines with ARM2 and ARM3 processors were supported by NetBSD/acorn26 (see https://www.netbsd.org/ports/acorn32/faq.html). This is a bit strange, since IIRC ARMv3 got rid of the 26 bit PC mode.
Unfortunately, support for this port ended back in 2018 with NetBSD 8.0 and the acorn26 supported platform list doesn't include the ARM710 RiscPC, so it might also be significantly more difficult to get NetBSD to work on your machine...