Need an Introduction to Tiny Core? Or peruse Core Concepts.
https://stackoverflow.com/questions/72694268/can-you-make-an-os-only-using-assembly-languagehttps://en.wikipedia.org/wiki/BareMetalhttps://github.com/ReturnInfinity/BareMetal-OShttps://en.wikipedia.org/wiki/KolibriOShttps://www.kolibrios.org/en/index.htm