Originally Posted by DeusGear
How the hell does xbox 360 support dx11 tessellation when the hd4xxx line does not (and the 360 gpu chip is a much older architecture).
A large part of the idea is to unify the interface to simplify cross platform development. The reality is the Xbox GPU lacks some DX10/11 features and has some extra features not in the PC DX spec. If 90% of the code is the same there is less platform specific code to write.