ArcaneOS:
It's a protected mode kernel with paging and all the usual stuff. Among other things, it has:
- A working VESA interface
- The ability to run code in real mode and allocate low memory
- Pool based memory manager for kernel memory (the kernel tends to allocate many objects of the same size, so it seemed a good idea)
- A device and driver manager. Drivers register themselves with the driver manager, then the kernel/drivers add devices to the device manager. The device and driver manager work together to find suitable drivers for each device added.
- Standard interfaces for certain types of driver
- A virtual file system (including mount points for a device folder, using the device manager, and the initrd)
- A floppy disk driver