Comment by Rochus

Interesting. Never heard of this system before. It's apparently a monolithic kernel, developed almost exclusively by originally Canadian programmer Andy McLaughlin since 1997. The system has a graphical user interface, preemptive multitasking, and virtual memory. It is implemented in C and IA-32 assembly language. Here is a 2012 interview with the author: https://www.pingdom.com/blog/visopsys-operating-system/.