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HoloDust on 08 February 2013
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Aielyn said:
HoloDust said:
I this case, they are the same, there most likely isn't actually any difference between them - Xenos' shaders are based on R600 architecture, for WiiU it is believed it is based on R700, but Markan said it's registers are R6xx, so it might be also based on R600. Even if it's R700 (or even Evergreen) they are all VLIW5, which means 4 "simple" + 1 "special" in group (let's call them like that, to not overcomplicate things). VLIW5 was pretty inefficient, using mostly 3-4 out of 5 ALUs, so later they dropped to VLIW4, and finally to GCN in 77xx and up cards.

So... if they found that VLIW5 was inefficient, and VLIW4 increases efficiency, why is it then assumed that VLIW5 is being used in the Wii U? And what impact would that change have on the Wii U GPU interpretation, if possible?

Keep in mind, I'm not arguing for VLIW4 - I'm just trying to understand the reasoning behind each of the claims being made, because at this time, I'm getting somewhat confused by terminology and the details of GPU design.

VLIW4 is found in very few GPUs - 69xx and current APUs - AMD moved to GCN after 69xx series for their cards, and new APUs will also have GCN inside. HD 2xxx/3xxx (R600), HD4xxx (R700), HD5xxx (Evergreen) and HD6xxx (Northern Islands) minus HD69xx are all VLIW5. Since Nintendo decided to use older desings (R700 is usually believed to serve as base, though there is everything, even R600 as of lately, as speculation), it is most likely that it is VLIW5 inside.

I can't really pretend to understand Nintendo's design philosophy, but as BlueFalcon mentioned several times, it is really unfortunate they haven't opted for some AMD APU instead of this design - they would get both better CPU and GPU component, and Dolphin is excellent example they could've made software Wii emulator for backward compatibility.