Nukernel
NuKernel was a microkernel developed at Apple Computer during the early 1990s. Designed using concepts from Mach 3.0 with extensive additions for soft real-time scheduling to improve multimedia performance, it was intended to be used as the basis for the Copland operating system. Only one version was seen publicly, in the Copland "alpha" release, and proved to be extremely unstable. Development apparently ended with the ending of Copland development in 1996 and 1997.
NuKernel was written from scratch, without using existing Mach code.
The ERS (External Reference Specification) for NuKernel is contained in its entirety in U.S. Patent 5,590,334 "Object oriented message passing system and method", filed March 19, 1996, granted December 31, 1996.
The one-time technical lead for NuKernel, Jeff Robbin, was one of the driving forces behind iTunes and the iPod.
Apple's NuKernel should not be confused with nukernel, the name of the custom kernel in BeOS.