Documentation of Operating Systems and Developers

Darwin

Darwin is the from Apple named operating system core for Mac OS X. Darwin is Mac OS X without the user interface. The BSD Unix and Mach 3.0 based Kernel connects since the first release in 1999 characteristics of the booth worlds Apple and UNIX. Mac OS X has beside the Mac OS predecessor his origin in the know how of NeXT technology, taken over by Apple in 1997. NeXT has developed the OPENSTEP operating system which was the further development of NEXTSTEP which in turn is based on 4.3 BSD. Apple supports actively the BSD community, because Darwin is compatibly with the FreeBSD distribution as a reference and takes advance of much open source projects. Mac OS X merge therefore the efficiency and stability of UNIX (protected memory area) with the simple usability of Mac OS. Hexley the platypus is the mascot of the operating system Darwin.

Affected by the open source concept developers of Apple and the open source community work together for the PowerPC and x86 operating system version. Modifications and further developments flow back to the public, after a free registration the source code can be downloaded from the Apple web site. It can not be excluded that Darwin with his operating system core xnu splits up into independent distribution. All developed applications for the Darwin system core work also under Mac OS X, except for special Mac OS X applications which do not run directly under Darwin. Standard format for executable applications in Darwin is Mach-O. Support for the primarily by Linux program used .ELF format is not possible at present, but Linux applications can be ported.

Darwin Architecture

By the related UNIX design Mac OS X profits from the protected memory area and established preemptive multitasking. The Kernel consists of 5 components. Includet are the Mach Mikrokernel with the BSD subsystem, file system, network ability and the I/O Kit. The file system supports file names with up to 255 characters and unicode. The Mach Micro kernel cares about the resource management like processor performance, scheduler, memory protection and the communication between the system layers. The core is enclosed by a specified version of the 4.4 BSD-Lite2 Kernel and userland. This contains POSIX APIs and abstracts the file system and the network communication. The BSD Kernel takes care for the administration of system processes and security policies and threading of program parts for Mac OS X.
The I/O Kit introduced with Darwin is a object-oriented development software which provides the resources for the development of driver software with the support of SMP and preemptive multitasking.

OpenDarwin

The project OpenDarwin was founded in 2002 with the goal to provide a development environment for the Mac OS X source code and to develop a Darwin derivat. The new created community is a test platform for bug fixes as well as new functions for Mac Os X and Darwin that Apple integrate into the official source code.
At 2006-07-25 the OpenDarwin Core Team and the Administrators announced the termination of this project on their website. Quote: "Over the past few years, OpenDarwin has become a mere hosting facility for Mac OS X related projects. The original notions of developing the Mac OS X and Darwin sources has not panned out. Availability of sources, interaction with Apple representatives, difficulty building and tracking sources, and a lack of interest from the community have all contributed to this.".

PureDarwin was launched in 2007 as new project to bring Darwin closer to open source enthusiasts and developers. Every enthusiast can access the documentation, learn, modify and distribute Darwin. One of the goals is to provide a bootable ISO-file of Darwin 10.x and Darwin 9.x.

Apple Darwin website 2003	PureDarwin nano screenshot	PureDarwin bash command line

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