This is an interesting comment but I’m not sure it stands up to closer examination. For example, ISA’s change very slowly - more so than aspects of fabrication.

This is an interesting comment but I’m not sure it stands up to closer examination. For example, ISA’s change very slowly - more so than aspects of fabrication. I’d argue that the parts of the stack that connect with other levels move more slowly than those that don’t. They need to be stable so that the whole stack continues to work together.