This group gathers operating systems built for mainframes, minicomputers and other large institutional or business computers, including IBM System/360 family systems DOS/360 and BOS/360 and its early batch systems IBSYS and BESYS, the Digital Equipment Corporation minicomputer systems RSTS/E, RSX-11 and OpenVMS, the Data General minicomputer system RDOS and its Convergent Technologies counterpart, the Control Data Corporation systems SCOPE, Kronos and NOS, the Prime Computer system PRIMOS, the HP Multi-Programming Executive, the Apollo Computer workstation system Domain/OS, the ICL system GEORGE, IBM Time Sharing System TSS, the SHARE Operating System user cooperative, the University of Manchester Atlas Supervisor, the earliest operating system for a commercial computer GM-NAA I/O, and the Cray Operating System for supercomputers. Their shared identity is serving large, expensive, institutionally owned computers from the mainframe and minicomputer era, as distinct from a university research prototype built to explore an idea, which belongs to Research and Academic Operating Systems.