Process control
OS4000 Rel 3 arrived around 1980, and included Linked-OS — support for Linked OS4000 operating systems to enable multi-node systems to be constructed. The main customer for this was the central computing service of University College London (Euclid), where a multi-node system consisting of a "Hub" file server and multiple "Rim" multi-access compute server systems provided service for over 100 simultaneous users. Linked-OS was also used to construct fail-over Process control systems with higher resilience.