[exikyut]

I'm having a hard time understanding how this would actually work in practice.

CPUs act on data coming from eg the disk, memory, the network, etc. The results of instructions influences what the CPU will do next, especially so in the case of self-modifying code.

So, with a system that has a "chaser" CPU following a master CPU one instruction behind... how do you also impose a one-instruction delay on the CPU's view of the real world?!

Unless this is done, the chaser CPU is going to see real-world data and I/O that is out of sync with the instruction stream, isn't it?

I'm quite sure this problem was very elegantly solved, and I'm very curious+interested to find out what that solution was.