Programmable NVIDIA GPUs are very inspiring to hardware geeks, proving that processors with an original, incompatible programming model can become widely used. NVIDIA call their parallel programming model SIMT - "Single Instruction, Multiple Threads". Two other different, but related parallel programming models are SIMD - "Single Instruction, Multiple Data", and SMT - "Simultaneous Multithreading". Each model exploits a different source of parallelism: In SIMD, elements of short vectors are proc...