Cluster computing originated within just a few years of the inauguration of the modern electronic stored-program digital PC. Under an Air Force contract SAGE was a cluster system built for NORAD by IBM in the 1950s based on the MIT Whirlwind PC design. Using core memory technologies and vacuum tube, SAGE consisted of a number of separate stand-alone systems cooperating to control warning detection of antagonistic airborne intrusin of the northern US continent.
Early comercial applications of clusters employed paired loosely joined PCs with one performing user roles while the other managed numerous input / output devices. Discoveries in enabling technologies took place in the latter 1970s, both in hardware and software, that were to have a serious long-term effect on future cluster computing.
