BOS was an idea for a multitasking microkernel operating system for various Commodore computers, including the C128, C64, SuperCPU, and VIC-20.
Here is a C= Hacking article I wrote about a multitasking OS. This will serve as the task switcher for BOS-128, although I will have to change the interprocess communication mechanism to use semaphores. [article]
Here are some random notes about the project.