rust_dos VS DOjS

You do not need segment registers much if you stick to the tiny model. Here is someone compiling Rust to a 16-bit DOS COM executable:

https://github.com/o8vm/rust_dos

Not sure what the approach would be for them to expand that to support segments.

In DJGPP there are macros to allow your protected mode application access physical real-mode addresses (like when you want to write to video RAM). I don't know if IA-16 also does something like that, or if they added far/near keywords to the language like old 16-bit C compilers did (at least the ones I used).

Free Pascal has helper-functions to work with segment+offset pointer pairs, also without having to modify the language itself. I think that would work well enough in C, but I guess the old method of adding non-standard keywords was seen as slightly more convenient.

Demo: https://github.com/o8vm/rust_dos

It is probably possible for almost any old platform with some cross-compilation magic, but not anything that will be officially supported as the compiler-makers focus on modern systems. There is for instance an unofficial 16-bit DOS backend for GCC and at least one or two projects to compile Rust to DOS-executables (that I assume use Clang?) (in addition to 32-bit DJGPP(gcc) for MSDOS that I linked to above). Probably are similar projects to target 68k somewhere?

I did not know of a Java port, but this reminds me there is some kind of JavaScript-based environment for DOS that I see linked now and then (think it is bundled with FreeDOS?). Probably this one:

https://github.com/SuperIlu/DOjS

"DOjS is a JavaScript programming environment for systems running MS-DOS, FreeDOS or any DOS based Windows (like 95, 98, ME). It features an integrated editor, graphics & sound output, mouse/keyboard/joystick input and more"

Never tried it.

A guy I know is working on a DOS compatible JS OS. It's out at least 10 years and runs on the original hardware if the time. https://github.com/SuperIlu/DOjS