HelenOS

HelenOS is an operating system. It is made by staff and students of the Mathematical and Physical Faculty of Charles University in Prague. It is running on some architectures.
Technical overview.
HelenOS is a microkernel operating system, which supports multitasking, memory management, inter-process communication and symmetric multiprocessing. File system, device drivers and other services are implemented like user processes. It can run on some architectures like IA-32, x86-64, SPARC V9, IA-64, Power PC, ARM and MIPS.
License of the source code is BSD license.
History.
Jakub Jermář made HelenOS as a student project at the University. A few years later worked on the HelenOS kernel group of students and some students are using it for self-education of programming until now. In 2011 the project HelenOS took part on Google Summer of Code.