The branch prediction logic was redesigned completely. It followed a 2-level scheme: with a local history table of 1024 records 10-bit each, and a local predictor of 1024 records 3-bit each, also with a global predictor of 4096 records 3-bit each, and a history path of 12 bits. Both algorithms worked independently, and if the local traced every branch detected, so the global traced sequences of branches. The branch predictor analyzed results of both algorithms, and made conclusions to a separate choice predictor of 4096 records 2-bit each, which was the source of a preferred decision if the predictions were different. Such a cooperative approach allowed achieving better results than any of them both if used individually.

During EV6 development the clock frequency generator subsystem was redesigned entirely because the functional units were numerous and interacted with one another in a very complex manner. More efficient signal flow allowed the core to work at the frequencies of a much simpler EV56 core, while the same technical process was involved. Overall, power consumed by the EV6 clock subsystem made about 32% of the total core power. To give you a better idea let me make a few comparisons: for EV56 it was about 25% of the total core power, for EV5 - about 37%, for EV4 - about 40%.

EV6 was manufactured using the same 6-layer 0.35µ CMOS6 process, like EV56, and consisted of 15.2 mln transistors (including about 9 mln for I-cache, D-cache, and branch predictors). Its die was 314mm² big, and required 2.1V-2.3V power voltage. The core frequencies ranged from 466MHz to 600MHz (TDP approx. from 80W to 110W). The processor was designed in PGA-587 (Pin Grid Array) form-factor.

21264A (EV67) entered the market in the end of 1999. It was produced by Samsung with 0.25µ CMOS7 process, and featured a 210mm² die. It required lower power voltage of 2.0V. This solution boasted no architectural differences compared to EV6. The core frequencies ranged between 600MHz and 833MHz (TDP approx. from 70W to 100W), that allowed Alpha to bring back the leadership on integer tasks, which was lost not so long ago to Intel and AMD processors.