SegyOS is just a protected mode application rather than standalone operating system because it lacks of many features that OS must have (mm, paging, multithreading...). The motivation was to make self-sufficient application that runs from DOS/FREE-DOS and creates linear frame buffer for beautiful demos made in pure assembly!
Use NASM to compile with:
nasm -o segy_os.com segy_os.asm
You can use either VM with DOS or download Rufus and flash FREE-DOS on your portable device, then just run:
segy_os.com