Xinu

Xinu, whose recursive name reads Xinu Is Not Unix, is an operating system Douglas Comer built for educational use at Purdue University in the 1980s, with its first release in 1981. It targets teaching and embedded computing rather than production use, is written in C, distributed as open source, and uses a monolithic kernel in roughly ten thousand lines of code with a command line interface. Comer designed it independently of the Unix source code and without a goal of compatibility, giving it different abstractions and system calls despite the similar sounding name. It has since been ported to many platforms, including x86, ARM, MIPS, PowerPC and Arduino microcontrollers. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/