Random reset in Nios II

A cpu reset probably only changes the program counter and disables any mmu! The other registers might be reset, M9K memory is unlikely to be affected and the contents of external memory are extremely unlikely to change.

Of course, once the processor is executing code again, it will change registers and memory.

So any data in the old stack will remain until overwriten, but the stack pointer will be unknown (written to by the reset code).

One thing I've not looked at is whether %r0 is actually writable! It is assumed to read zero - but is a real memory location.