Lawrence Livermore has a long history of fielding some of the world’s largest computers, fueled by our nearly insatiable need for both capacity and capability computing. Each new generation of computing brings with it the ability to perform simulations that were impossible with earlier computers. Streitz will discuss the development of a real-time, high-resolution model of the electrophysiology of a beating human heart on the Sequoia supercomputer at LLNL, and growing efforts to extend such models towards true predictive biology. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-_-AC52-_-07NA27344.