This talk reviews the history of the changing “balances” between computation, memory latency, and memory bandwidth in deployed HPC systems, then discusses how the underlying technology changes led to these market shifts. Key metrics are the increasing relative “cost” of memory accesses and the massive increases in concurrency that are required to obtain increasing memory throughput. Invited Speaker Dr. John D. McCalpin is a Research Scientist in the High Performance Computing Group and Co-Director of the Advanced Computing Evaluation Laboratory (ACElab) at the Texas Advanced Computing Center (TACC) of the University of Texas at Austin. Learn more at https://www.hpcwire.com/off-the-wire/sc16-releases-latest-invited-talk-spotlight-dr-john-mccalpin/