1. A graphics processing unit (GPU), comprising: a first internal memory comprising a memory controller and memory cells; an execution unit coupled to the first internal memory, wherein the execution unit and the first internal memory are on a same die; and an interface configured to provide high bandwidth dedicated internal memory access to a second internal memory of an additional processing unit, and further configured to provide high bandwidth dedicated internal memory access to the first internal memory by the additional processing unit, the first internal memory being combinable with the second internal memory for general-purpose use by the additional processing unit.