| bdbdbd said: @WereKitten: Cache coeherence? You mean what was specifically patented to Gekko and is gone around in 360 by detailing in the patent L1 to be used instead of L2. G5 and G3 aren't that different, atleast on the part that counts here, which is the cost. I also didn't the part of the number of processors, unless you're specifically saying that Xenon doesn't consist of 3 PPC CPU:s. So, Xenon is PPC-ISA because it's made by IBM, but Broadway isn't because it's made by IBM. Ok, i stand corrected. |
The Xenon using the PPC ISA - because that's what IBM chips use - exactly as Broadway doesn't make it 3 Wii CPUs any more than an Intel Core 2 Quad is 4 Pentiums 4 CPUs. This is what my sentence meant.
Gekko and Broadway are G3 models, but Xenon's cores are derived from the Cell's PPE. Again using the PPC ISA doesn't mean anything about its architecture. For one the Xenon's cores and PPE are in-order processors.
And the cache issue was exactly about this: multicore chips are more than sticking together N old cpus with magic glue because new problems arising with cache contention and memory access require new solutions. In the case of the Xenon and the Cell, they're quite different from all previous IBM designs.
To reiterate my point: saying that "the 360 has 3 Wii CPUs clocked at 3.2GHz" is rubbish.
