NuKernel is a microkernel which was developed at Apple Computer during the early 1990s. Written from scratch and designed using concepts from the operating system (OS) 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 OS Copland. Only one version was seen publicly, in the Copland alpha release. It proved to be very unstable. Development ended in 1996 with the cancellation of Copland. The one-time technical lead for NuKernel, Jeff Robbin, was one of the driving forces behind iTunes and the iPod.