While the current crop of mainstream CPUs does not support anything like it, the idea is old. Basically the CPU need to have hardware support for a PCB and be s

While the current crop of mainstream CPUs does not support anything like it, the idea is old. Basically the CPU need to have hardware support for a PCB and be solely responsible for context switching, and the already complex MMU needs to be context aware. I'm pretty sure we've seen specialized CPUs in the past that did exactly that.