Do you seriously think virtualisation was a thing in the 1980s when the B-2 was being designed and built? It wasn't even a thing when the F-35 was being designe

Do you seriously think virtualisation was a thing in the 1980s when the B-2 was being designed and built? It wasn't even a thing when the F-35 was being designed and initially built. It will be single-threaded apps running natively and talking directly to various bus adapters. The most advanced processor available to them was a M68020, maybe. Multi-tasking was still hard, Linux and Windows 3.0 were still a decade away when the systems engineers were designing the B-2. And that's assuming they were able to change the hardware platform in the 1980s - the designs would have been drawn up in the 1970s. There is absolutely no way on Earth that anybody would have thought "what we need here is a VM". I'd be amazed if it even had a Hardware Abstraction Layer, and that had a bit of historical form, albeit not in real-time operating systems yet.