Nukernel
NuKernel is a microkernel which was developed at Apple Computer during the early 1990s. Written from scratch at Apple and 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 cancellation of Copland in 1996.
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" name should not be confused with "nukernel", the name of the custom kernel in BeOS.