Donald Weingarten, IBM TJW Research Center, writes in February SciAm about the center's investigations of quark theory by the "GF11" parallel processing computer dedicated solely to quantum chromodynamics (QCD) -- a computer which uses 566 parallel processors. He describes building the hardware and software of this unique tool and what two years of continuous computations revealed. An aside explains a die-rolling shortcut method called Monte Carlo to circumvent the enormous amount of computation that lattice QCD would otherwise entail. QCD_566