"Burroughs Machines: Implementation: A series of minicomputers" This is misleading; these were often very well regarded military grade and size, 48/51 bit stack based machines, hundreds of disk spindles and massive I/O, up to 8 CPU symmetric multiprocessing (7 IIRC cause you needed an I/O cabinet). And a sophisticated OS called MCP. Virtual memory. In 1977, or 1969, or earlier. https://en.wikipedia.org/wiki/Burroughs_large_systems Datamation archives tell the story.