STOS is a highly modular monolithic kernel inspired by bits. As such, each feature is not directly integrated into the kernel, but dynamically loaded during execution. The kernel in itself knows how to do one thing and one thing only: load a module and its dependencies.
One of the project objective, besides being completely modular, is to be portable on different architectures. Currently, STOS boots on PowerPC, Sparc64, ARM and x86.
STOS git repository: repository.