NuKernel was a microkernel

Microkernel

In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...

 developed at Apple Computer

Apple Computer

Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...

 during the early 1990s. Designed using concepts from Mach 3.0 with extensive additions for soft real-time

Real-time computing

In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...

 scheduling to improve multimedia performance, it was intended to be used as the basis for the Copland

Copland (operating system)

Copland was a project at Apple Computer to create an updated version of the Macintosh operating system. It was to have introduced protected memory, preemptive multitasking and a number of new underlying operating system features, yet still be compatible with existing Mac software...

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer 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 "Object oriented message passing system and method", filed March 19, 1996, granted December 31, 1996.

The one-time technical lead for NuKernel, Jeff Robbin

Jeff Robbin

Jeffrey L. "Jeff" Robbin is the vice president of consumer applications at Apple, Inc. He is an American computer engineer and entrepreneur notable for creating the MP3 player SoundJam MP with Bill Kincaid that was eventually bought by Apple and renamed iTunes...

, was one of the driving forces behind iTunes

ITunes

iTunes is a media player computer program, used for playing, downloading, and organizing digital music and video files on desktop computers. It can also manage contents on iPod, iPhone, iPod Touch and iPad....

 and the iPod

IPod

iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...

.

Apple's NuKernel should not be confused with nukernel, the name of the custom microkernel in BeOS

BeOS

BeOS is an operating system for personal computers which began development by Be Inc. in 1991. It was first written to run on BeBox hardware. BeOS was optimized for digital media work and was written to take advantage of modern hardware facilities such as symmetric multiprocessing by utilizing...

.