1. A device for parallel multithreaded blending in graphics systems comprising: means to receive a plurality of color components and alpha information from multiple source and multiple destination image fragment streams; means to receive configuration information prior to executing a batch of graphics operations; a blender processing unit capable of combing in parallel the color and alpha channels from a plurality of pixels in the source and destination images in order to produce a plurality of fragment pixels of a target image; the blender processing unit capable of executing at least two parallel threads of operation, wherein said blender processing unit multiplexes in time a plurality of blending functions and memory operations on different fragments; the blender processing unit supporting concurrent multithreaded processing of the plurality of fragments with different blending functions applied to each fragment; the blender processing unit capable of executing programmable concurrent multithreaded vertex shading on vertex primitives using the said configuration information; the blender processing unit capable of executing programmable concurrent multithreaded fragment shading on fragment primitives using the said configuration information; the blender processing unit processes each of the multiple concurrent threads in a round robin fashion; and the blender processing unit comprising multiple register files, multiple execution units, and multiple instruction pointers wherein each parallel thread is associated with a specific and predetermined instruction memory and instruction pointer; and the blender processing unit comprising multiple instruction memories, wherein each instruction memory is associated with one thread and each instruction memory contains instruction code formatted as a very long instruction word and includes multiple op-codes, multiple destination descriptors, and multiple source descriptors.