3 ms·

You only need a renamer for out-of-order issue - I guess you could execute a backward compatible ISA using only in-order issue. Still, it doesn't strike me as v

by ajb 3y ago

You only need a renamer for out-of-order issue - I guess you could execute a backward compatible ISA using only in-order issue. Still, it doesn't strike me as very likely to be implemented in that way.

rbanffy 3y ago
> I guess you could execute a backward compatible ISA using only in-order issue. We did that for a very long time.
- ajb 3y ago
  Do you mean, there were CPUs with 2 ISAs, one in-order and one out of order? Which ones, if you can say?
  - rbanffy 3y ago
    A modern x86 runs machine code out of order while an older Atom runs it jn order.
    - ajb 3y ago
      I think we are talking at cross purposes. I assumed that everyone who has followed the discussion so far knew about in order implementations of a single ISA, which they all were, originally.