The nice thing about more recent architectures is that no one (including the original authors) can rely on cycle-exactness because of the basically unpredictabl

The nice thing about more recent architectures is that no one (including the original authors) can rely on cycle-exactness because of the basically unpredictable effects of caches and speculative execution and bus contention and (...). Most of these, as a big exception, do not apply to the Cell running code on data in its local memory, but fortunately, it's different as seen from other system components, as you say.