John Leroy Gustafson (born January 19, 1955) is an American computer scientist and businessman, chiefly known for his work in high-performance computing (HPC) such as the invention of Gustafson's law, introducing the first commercial computer cluster,[citation needed] measuring with QUIPS, leading the reconstruction of the Atanasoff–Berry computer, inventing the unum number format and computation system,[1] and several awards for computer speedup. Currently he is the Chief Technology Officer at Ceranovo, Inc.[2] He was the Chief Graphics Product Architect and Senior Fellow at AMD from September 2012 until June 2013,[3][4] and he previously held the positions of Architect of Intel Labs-SC,[5] CEO of Massively Parallel Technologies, Inc.[6] and CTO at ClearSpeed Technology.[7] Gustafson holds applied mathematics degrees from the California Institute of Technology and Iowa State University.