FDOS/kernel ? reverse-engineered prompt

I want to get this FreeDOS kernel building cleanly from source and make it easier to verify that it still works.

Please look through the current code and build files, fix anything that is broken or outdated, and make sure there is a clear way to compile the kernel and run the basic checks or tests that are already in the repo. If anything depends on older tools or missing setup steps, update the scripts or notes so a normal developer can follow along without guesswork. I’d also like the README to clearly explain what the project does, how to build it, and how to know the build succeeded.

If you need to check current compiler or tooling details online, go ahead and do that. Keep the changes focused on making the project buildable and understandable without changing the actual DOS kernel behavior more than necessary.