Rhys Adams

Vintage computing, cyber security and other interesting stuff.


16-bit kernel inspired by DOS

This is my kernel/OS, written in mainly C with some assembler.

It is 16-bit to ensure compatability with my 286 machines, all the way up to modern machines with BIOS emulation.


  • 2-stage bootloader
  • Monolithic kernel
  • Userspace programs
  • I/O redirection
  • Serial I/O
  • Fat12 filesystem

The boot process:

RhysOS Boot Process

Directory listing:

RhysOS Directory Listing

Reading from the RTC:

RhysOS RTC Read

Filesystem reading a file:

RhysOS FS Read