TomOS is a simple 16 bit operating system for x86. It is based on MikeOS version 2.0.0. It is entirely written in the assembly language. TomOS is an educational project.
A FOSS operating system that aims to meet NSA's TPEP TCB A1 evaluation standard while retaining application compatibility at minimal performance overhead.
Story OS is a small microkernel system with object-oriented service interface.