> A4000 is hardly an advance over A3000 if A3000 had AGA.

But the A3000 doesn't have AGA, right? So what's the logical conclusion as per your own statement?

> all PA Semis were 2Ghz

No, the PA6T was not. It was and is a 1.8 GHz part which is possibly overclockable to 2.0 GHz.