Shader intrinsic functions stand as a partial solution for granting developers more control over existing computational resources and how they are leveraged. This capability (much touted by AMD as a performance-enhancing feature on their GCN-based products) essentially exposes features and capabilities that exist on the hardware developers are programming for, but wouldn't generally be able to access. This can happen either because they're being abstracted by a high-level API (Application Programming Interface, like DX11), or because the API isn't functionally able to access them. To understand why high-level APIs such as DX11 don't usually offer support for a piece of hardware's full feature list, or full processing capabilities, we must first look at the basic architecture of a given computer system.