John Gustafson's 1988 reevaluation of Amdahl's law argued that parallel machines are often used to solve larger problems in roughly fixed time, changing how speedup should be interpreted.
The Cray-1 combined vector registers, deep pipelining, fast semiconductor memory and unusually dense physical packaging into an iconic 1970s supercomputer optimized for scientific workloads.
MPI turned a fragmented landscape of parallel message-passing libraries into a portable standard that could span supercomputers, clusters and scientific applications.