elks VS gcc-ia16

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.

Mainstream GCC has never supported 16-bit code on x86, only 32-bit

However, there is (at least one) fork which adds 16-bit code support, see https://github.com/tkchia/gcc-ia16

I don't think the GCC maintainers have ever or will ever want to support 16-bit x86, because it is so limited, and adds a lot of messy corner cases, and nowadays is really only of hobbyist/retrocomputing interest.

Maybe there is some 16-bit x86 embedded system still being maintained–there were military spec versions of the 8086, and possibly some weapons system, aircraft, satellite, etc, still in use contains one. But I doubt they'd have any interest in adopting a 16-bit GCC – they'd already have some proprietary compiler they'd been using for decades, switching now would add a lot of risk, very late in the life of a legacy system, for no tangible benefit

These days there is also a 16-bit GCC port to DOS (https://github.com/tkchia/gcc-ia16). I never encountered one of those back in the day? I think the compiler itself does not run in 16-bit DOS though.

Anyone interested in compiling for DOS (32-bit or 16-bit) should also check out Free Pascal.

My advice is, when you feel you need that challenge, install DOSBox or DOSBox-X and Open Watcom C/C++, DJGPP, or gcc-ia16 and do some retro-programming. You'll also get the fun of being able to do low-level hardware twiddling and rely on DOS being so simple that it's effectively an RTOS.

Looking at part 1 and some of the videos, it looks like this doesn't actually use OpenWatcom, but i16gcc from the FreeDOS distribution, which looks to be a port of gcc that targets 16-bit x86.

And, if that surprises you, gcc-ia16 is a thing that has come into existence not only over a decade after DJGPP but also after Open Watcom already existed.

or GCC IA 16 (https://github.com/tkchia/gcc-ia16) gets someday mainlined (also a multi month/years project) and then gccrs can maybe use it as backend

There is a 16-bit port of GCC these days as well included together with DJGPP if you install FreeDOS, but available separately as well (I think it can cross-compile from other systems like DJGPP can too?) https://github.com/tkchia/gcc-ia16

TK Chia and others have been working on adding DOS C/C++ compiler-isms to GCC as well as improving the the codegen to make it more hospitable for DOS apps. So far, the FreeDOS kernel compilable by gcc-ia16.

https://github.com/tkchia/gcc-ia16

There is a more recent fork of gcc/DJGPP to make 16-bit DOS applications that I also never tried, but that might be worth using (and I think it is bundled in the latest FreeDOS, so it might be very easy to set up by just installing that in a virtual machine?): https://github.com/tkchia/gcc-ia16