From 1980 to 1987, Apollo were the largest manufacturer of network workstations. Apollo workstations ran Aegis, a proprietary operating system with a Posix-compliant Unix alternative frontend. Apollo's networking was particularly elegant, among the first to allow demand paging over the network, and allowing a degree of network transparency and low sysadmin-to-machine ratio that is still unmatched.
Apollo's largest customers were Mentor Graphics (electronic design), GM, Ford, Chrysler, and Boeing (mechanical design). Apollo was acquired by Hewlett-Packard in 1989, and gradually closed down over the period 1990-1997.