  I give a brief introduction to the scope of lattice QCD calculations in our
effort to extract the fundamental parameters of the standard model. This goal
is illustrated by two examples. First I discuss the extraction of CKM matrix
elements from measurements of form factors for semi-leptonic decays of
heavy-light pseudoscalar mesons such as $D \to Ke\nu$. Second, I present the
status of results for the kaon $B$ parameter relevant to CP violation. I
conclude the talk with a short outline of our experiences with optimizing QCD
codes on the CM5.
