You could definitely define pixel shaders on the Xbox using a combiner type struct. See the D3DPIXELSHADERDEF struct in the docs, from memory the equivalent of

You could definitely define pixel shaders on the Xbox using a combiner type struct. See the D3DPIXELSHADERDEF struct in the docs, from memory the equivalent of one of the NV register combiner extensions from OpenGL with additional access to a secret extra stage ordinarily reserved for some fixed function pipeeline stuff.