How does G80 handle DX9?

[Eva_Unit_0]

In all of the G80 hype I've seen nothing but people touting the amazingness of the new DX10 features, the new restyled "pipeline" design, and so on. However, it has left me wondering one thing: How does G80 process DirectX9 code? Surely DirectX9 doesn't know how to properly use the DX10-class processors onboard the chip. I don't imagine that it could interface directly with the stream processors and unified shaders and such. We've been told time and time again that DX10 is, for the first time, not backwards compatible with existing DirectX versions.

So how did nVidia do it? Does anyone know? Do the drivers emulate DX9 hardware on the DX10 hardware? Does the chip handle DX9 code in hardware via some sort of hardware translation (a la the Itanium or Transmeta Crusoe running x86)?

I've been looking through the reviews trying to figure this out (just for curiosity's sake, really) but I can't find much. Anyone know?

 

[Hyperblau]

Very Very Well.

At the moment, most people are asking how does the G80 handle DX10, as there is really no way to test it right now.

 

[dR.Jester]

Someone needs to post results from Flight Sim X. That game was very very demanding on my 7900GTX. Be interesting to see how it handles a G80.

 

[Arcygenical]

Flight Sim X AND Vista RC2

 

[meatfestival]

I've been looking through the reviews trying to figure this out (just for curiosity's sake, really) but I can't find much. Anyone know?

The G80 doesn't have specific DX10 hardware, it's more like a collection of generic programmable shaders (or stream processors as Nvidia calls them). So the GPU can be programmed to do anything. That is and always has been the job of the drivers, eg to translate the Direct3D/OpenGL calls into something that can be digested by the GPU.