DragonFlyBSD 5.8.1Description by the Software Developer:
"DragonFly is an operating system and environment originally based on FreeBSD. DragonFly branched from FreeBSD in 2003 in order to develop a radically different approach to concurrency, SMP, and most other kernel subsystems.
DragonFly belongs to the same class of operating system as BSD and Linux and is based on the same UNIX ideals and APIs. DragonFly gives the BSD base an opportunity to grow in an entirely different direction from the one taken in the FreeBSD-5 series."