> How the heck is a diagnostic ROM going to diagnose
a dead CPU? I
> must be missing something here...
Well, if it's a little more than just ROM but fits in a ROM socket, it
could, for example, notice a lack of read cycles. If it's enough more
than ROM it could run a CPU emulator and notice that it isn't obeying
the instructions it's fetching (though that's hard to do right, since
the ROM socket doesn't see things like interrupts or RAM).
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