R740 is more than capable of emulating Wii/GC without edram. It's already doing it on the PC via Dolphin and Nintendo's implementation would be far better optimised.
But you can't emulate in real-time a physical advantage like memory bandwidth.
The Wii's eDRAM is supposedly in the ~27GB/s (GC's ~18GB/s x 1.5), add the ~4GB/s from the 1T-SRAM and probably another ~3GB/s (?) from the GDDR3 and you'll have a peak of ~34GB/s of combined memory bandwidth.
If you're using a single memory pool, you have these options:
- Have no BC at all
- APU with >3MB L3 cache shared between GPU and CPU, and let the GPU use the L3 cache for texture and frame buffer.
- Limit the BC to some games who won't reach a certain bandwidth threshold (don't even know how
doable that would be).
- Get some eDRAM in the GPU to compensate for the 27GB/s eDRAM.
- UMA 128-bit GDDR3 @2200MHz+ (35GB/s)
- UMA 192-bit DDR3 @1600MHz+ (38,4 GB/s)
- UMA 256-bit DDR3 @1066MHz+ (34.1GB/s)
- UMA 128-bit GDDR5 @3.2GHz+ (51.2GB/s)
- UMA of some MoSys 1T-SRAM combination, like 128-bit 2GHz? I wouldn't know..
The benefit of using it to avoid split-screen in multiplayer games or to substitute for an unavailable television set is marginal at best. It makes little sense for Nintendo to spec the controller for such purposes. A controller is an input device first and foremost. The screen will mainly provide visual feedback in game situations involving touch or motion controls, I think.
If that was true, I doubt Nintendo would invest in a 6" screen, as a ~3" would suffice for that purpose.
Being able to play the games away from the TV+console will most definitely be one of the main selling points. To play the "full-fledged" games without having to isolate yourself or the whole living room is definitely interesting from a social point of view.
But this brings another factor in the discussion:
sound.
Will the controller have stereo speakers (if so, what quality? how loud?) and\or a headphone jack? Or maybe even a special digital output for custom 5.1 headphones?
Or analog jack output capable of doing either stereo or Dolby Prologic IIx, with 3rd parties being able to launch custom 7.1\5.1 headphones with a built-in DPIIx decoder?