elks VS FUZIX

ELKS supported MMU-less operation on 8088 and 80286 machines, but I don't think an ARM port exists: https://github.com/ghaerr/elks

Roughly in the mid-90s I bought at a local surplus store a "Carry 1" industrial 8088 computer which to my surprise I later discovered it could run Linux (ELKS: https://github.com/ghaerr/elks). I ultimately sold it on Ebay because although it was a beautiful piece of old tech, I was struggling to find more space for other things.

Here's one. I had only the central unit, mine had two floppy drives.

I don't think you can replace the OS on these. Unless there is a way to boot them from DOS, but you are looking at 8c086 machine so the choice is limited. Linux or BSD won't work. But ELKS might if it can be made to boot from DOS. Minix 2.02 seems to work.

Yet ELKS works on 16 bit computers with 640k of RAM.

Some small size Linux-like OSes do exist though: one commenter suggested Lunix (which I didn't know, thanks for the link), and a slightly bigger one is ELKS which runs on old MMU-less x86 CPUs. I managed to run it on a 8088 industrial PC ages ago.

https://github.com/jbruchon/elks

I should have a Furby buried somewhere; now that I think of it, it may be the right platform to stick a bigger brain into, make it wireless so that it could be connected to the home IoT network then signal events or alerts.

Alan Cox has a "Fuzix" repo, that puts together Uzix variants for the Z80.

https://github.com/EtchedPixels/FUZIX

Fuzix does appear to have CPU support for 6800 and is probably your best starting location. Although based on what I've seen of the ET-3400 you could be in for quite the uphill struggle.

Software complexity also helps to establish or maintain the predominance of large corporations on the market. In contrast, a simple software system can be reimplemented by a small team or even a single person, so there is more competition. This is not only demonstrated by Wirth's systems, but also by several 7th edition Unix clones of the 80's [1-4] as well as current ones [5] and also reimplementations of the classic MacOS [6].

Back in the 1980s, operating systems and compilers were often seen as the most complex pieces of software. Nowadays, web browsers include (and reimplement) large parts of an OS and compiler and are probably even more complex than a current OS such as Linux or a current compiler such as clang/LLVM. Only rich (or well funded) companies such as Google, Apple and the Mozilla foundation can afford to build a browser today that can be used to access current web pages.

So a central question is if we can turn back times and make software more simple again. Maybe this ship has already sailed - but it can't hurt to try. From experience with my students, it is extremely satisfying for them to build a complete system from scratch instead of mostly copying and pasting library calls or StackOverflow code snippets. Thus, I try to enable my students to experience this sense of achievement. They will probably never get the chance to do something similar in their later career in industry.

[1] One Man Unix for 68k - http://www.pix.net/mirrored/discordia.org.uk/~steve/omu.html

[2] Uzix for Z80 (link to the MSX port) - http://uzix.sourceforge.net

[3] Coherent Unix - https://en.wikipedia.org/wiki/Coherent_(operating_system)

[4] Minix - https://www.minix3.org

[5] Alan Cox' Fuzix - https://github.com/EtchedPixels/FUZIX

[6] Ardi Executor - https://en.wikipedia.org/wiki/Executor_(software)

How about FUZIX? It might be a better fit for vintage computers?

https://github.com/EtchedPixels/FUZIX

Also fuzix: https://github.com/EtchedPixels/FUZIX