contains original Unix (SVR4) code SSS-PC Developed at Tokyo University Syllable VSTa Nonproprietary non-Unix-like Research non-Unix-like Amoeba (research OS by Andrew S. Tanenbaum ) Croquet House Haskell User's Operating System and Environment, research OS written in Haskell and C. ILIOS Research OS designed for routing EROS microkernel, capability-based CapROS microkernel EROS