[batman-farts]

> You can probably take the same set of execution units, forwarding paths, branch predictors, etc. and slap several different ISAs over it - I've seen CPU architects show experiments where (for x86 and ARM at least) two chips with the same number and type of these internal features will perform the same regardless of the instruction set.

Isn’t this what Transmeta was trying to do back in the day? I remember they famously employed Linus Torvalds for a while, but I never learned anything about the technical details of their ISA front-ends.

[batman-farts]

Forgive me, it looks like I had mis-remembered, and Transmeta’s translation layers were mainly software?

[FullyFunctional]

It was purely software, but future developments of the idea (like NVIDIA Denver) wasn't purely software. However, the backend is necessarily tried to the ISA you are emulating (true for all of them, including SoftMachine). You need the data types to match (eg. Transmeta supported x87-style FP) to have any hope of performance. The universal machine is neither possible nor desirable (it would be inefficient).

These days the IMO most interesting ISA from a JIT point of view is WASM as it's the one that offers the most information (context) and the fewest constraints on the implementation.

[AnotherGoodName]

The AM29000 is probably what you're thinking of. AMD turned it into the more well known x86 processor the K5 among other things.