An operating system written from scratch: boot sector, FAT filesystem, DOS-compatible interrupts, sound, a 32-bit runtime and a graphical desktop - Made-In-Basement/ember
Aero is a new modern, experimental, UNIX-like operating system following the monolithic kernel design. Supporting modern PC features such as long mode, 5-level paging, and SMP (multicore), to name ...
AtheOS is an GPL'ed alternative OS running on Intel based PC's. Featuring an object oriented GUI interface, multi threading SMP, journaling filesystem, TCP/IP network stack and various other components expected in a modern desktop OS