In 1985, the National Science Foundation established five supercomputer centers to open high-performance computing to the US academic research community. Before the NSF centers, access to supercomputers was limited to defense contractors, national labs, and a handful of well-funded groups. The centers were networked together through NSFNet — the direct precursor to the modern internet. Three of the original five remain active today, continuously refreshing their systems through XSEDE and NSF ACCESS. Hover any machine node for details.