This group gathers operating systems built at a university or industrial research laboratory primarily to explore an idea in operating system design rather than to ship as a commercial product, including Bell Labs Multics, Research Unix and its Plan 9 and Inferno successors, the teaching systems MINIX, Minix 3, Xv6 and Xinu, the time-sharing pioneers the Compatible Time-Sharing System, TENEX, the Dartmouth Time-Sharing System and the Michigan Terminal System, the distributed-systems research systems Amoeba, Sprite, the V system, Barrelfish and ARX, Edsger Dijkstra THE multiprogramming system, Microsoft unreleased Cairo project, Intel iMAX 432, the database-systems research project DBOS, and hobbyist or small independent projects including Visopsys, SharpOS, VibeOS, Cosmos, VSTa, TRIPOS, Eumel and MNOS. Their shared identity is being built to test or teach an idea about how an operating system should work, as distinct from a system built to run production workloads on institutional hardware, which belongs to Mainframe and Historical Systems.