QNX is widespread in embedded systems, it's sadly closed source (it's a magnificent OS). L4 is a family of operating systems, sharing an API, not code. The anc

QNX is widespread in embedded systems, it's sadly closed source (it's a magnificent OS). L4 is a family of operating systems, sharing an API, not code. The ancestor was built to prove that microkernels could be fast. SeL4 is a formally proved variant. They are open source. They are also used in embedded systems, like baseband processors. Minix 3 is an academic project by Andrew Tanenbaum. A few eyebrows were raised when it turned out that it is present in all new Intel chipsets.