I believe the author is referring to how many logical threads/hyperthreads can a core run (for AMD and Intel, two. I believe POWER can do 8, Sparc 4). The extr

I believe the author is referring to how many logical threads/hyperthreads can a core run (for AMD and Intel, two. I believe POWER can do 8, Sparc 4). The extra physical registers are there for superscalar execution, not for SMT/hyperthreading.