Hexley, the mascot of Darwin

Unix-like, filiation on Unix's systems.

Darwin is an open-source operating system released by Apple Computer in 2000. Darwin is the operating system component of the Mac OS X operating environment. Apple first released Darwin to the open source community in 2000. Currently Darwin runs on both Apple's PowerPC architecture and on the Intel architecture, though the latter only has very limited driver support as of this writing. Picture of Hexley. ... Picture of Hexley. ... Image File history File links filiation in Unixs systems <a rel=license href=http://creativecommons. ... Image File history File links filiation in Unixs systems <a rel=license href=http://creativecommons. ... A Unix-like operating system is one that behaves in a manner similar to a UNIX system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... Open source denotes that the origins of a product are publicly accessible in part or in whole. ... In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... Apple Computer, Inc. ... This article is about the year 2000. ... Mac OS X is the latest version of the Mac OS, the operating system software for Macintosh computers. ... In computer software, an operating environment usually refers to a GUI front-end on top of an operating system. ... This article is about the year 2000. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple-IBM-Motorola alliance, known as AIM. Originally intended for workstations, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ...

Darwin is a Unix-like operating system that integrates a number of technologies including the open-source XNU kernel, a microkernel-based kernel architecture implementing the Mach microkernel. The operating system services and userland utilities are based on 4.4 BSD (Berkeley Software Distribution of Unix, particularly FreeBSD and NetBSD). Like other Unix-like operating systems, Darwin has the advantages of symmetric multiprocessing, high-performance networking facilities and support for multiple integrated file systems. A Unix-like operating system is one that behaves in a manner similar to a UNIX system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... XNU is the name of the kernel used in the open source Darwin computer operating system, that Apple uses as the foundation of its Mac OS X operating system. ... In computer engineering, the kernel is the core of an operating system. ... In computer engineering, the kernel is the core of an operating system. ... Mach is an operating system kernel developed at Carnegie-Mellon University to support operating system research, primarily distributed and parallel computation. ... In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ... For information on the company called UserLand, see UserLand Software. ... Berkeley Software Distribution (BSD) is the UNIX derivative distributed by the University of California, Berkeley starting in the 1970s. ... Unix or UNIX is a computer operating system originally developed in the 1960s and 1970s by a group of AT&T Bell Labs employees including Ken Thompson, Dennis Ritchie, and Douglas McIlroy. ... A rendering of the BSD daemon by Poul-Henning Kamp FreeBSD is a free, open source, Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through 386BSD and 4. ... NetBSD was the first of the freely redistributable, open source versions of the BSD Unix-like operating systems to produce a formal release, with NetBSD 0. ... A Unix-like operating system is one that behaves in a manner similar to a UNIX system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... Symmetric Multiprocessing, or SMP, is a multiprocessor computer architecture where two or more identical processors are connected to a single shared main memory. ...

The Darwin developers decided to adopt a mascot in 2000, and chose Hexley the platypus over other contenders, such as an Aqua Darwin fish, Clarus the dogcow, and an orca. Apple Computer does not sanction Hexley as a logo for Darwin. Mascots at the Mascot Olympics in Orlando, FL. A mascot is something, typically an animal or human character used to represent a group with a common identity, such as a school, professional sports team, or corporation. ... Hexley Hexley is the mascot of the open source operating system, Darwin, which is the core of Mac OS X. Hexley is a cartoon platypus that usually wears a cap which resembles a daemons horns and carries a trident, similar to the BSD Daemon. ... Mac OS X 10. ... A Darwin fish is an ichthys with stylized legs The Darwin fish is a parody of the ichthys, the Jesus fish. It is an ichthys that has evolved legs (and optionally, has the word Darwin written inside). ... The Dogcow The Dogcow is a bitmapped image first introduced by Apple Computer. ... The Italian word orca (sometimes translated as orc) also designates a monster in Ariostos Orlando Furioso Binomial name Orcinus orca Linnaeus, 1758 Orca range (in blue) The Orca (Orcinus orca), also known as the Killer Whale or Grampus, is the largest member of the oceanic dolphin family. ...

In April 2002 the ISC and Apple founded OpenDarwin.org, a community to foster cooperative Darwin development. OpenDarwin creates its own releases of the Darwin OS. Notable subprojects of OpenDarwin include DarwinPorts, which has the goal of assembling a next-generation collection of ports to Darwin (and also, over the long term, to the other BSD derivities. 2002 is a common year starting on Tuesday of the Gregorian calendar. ... Internet Software Consortium (ISC) was an organization that was founded by Rick Adams and Paul Vixie with funding from UUNET to develop and support a number of reference implementations of Internet software. ... Hexley, the mascot of OpenDarwin OpenDarwin is a freely available, multi-platform BSD / Mach 3. ...

Kernel design

Like most modern kernels, Darwin's is a hybrid, containing features of both monolithic and microkernels, attempting to make the best use of both technologies, such as the message passing capability of microkernels enabling larger portions of the OS to benefit from protected memory, as well as retaining the speed of monolithic kernels for certain critical tasks. In computer science, the kernel is the fundamental part of an operating system. ... Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ...

The design allows many parts of the kernel to be migrated out into userland, whereby they will be more easily debugged as they will be smaller, isolated programs, instead of being small parts entwined in a larger chunk of code. The migration of select kernel code into userspace has the additional benefit of making the system more robust; if a userspace driver crashes, it will not crash the kernel.

The kernel xnu, is derived from a number of sources, particularly Mach 3.0 and FreeBSD 5.x. XNU is the name of the kernel used in the open source Darwin computer operating system, that Apple uses as the foundation of its Mac OS X operating system. ... Mach is an operating system kernel developed at Carnegie-Mellon University to support operating system research, primarily distributed and parallel computation. ... A rendering of the BSD daemon by Poul-Henning Kamp FreeBSD is a free, open source, Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through 386BSD and 4. ...

Mach

The core of the xnu kernel, Mach provides kernel threads, message-passing (used in inter-process communication), protected memory, virtual memory management, real-time support, kernel debugging support and console I/O. The Mach component also allows the OS to host binaries for multiple distinct CPU architectures within a single file (example x86 and PowerPC) due to its use of the Mach-O binary format. A thread in computer science is short for a thread of execution or a sequence of instructions. ... The expression Inter-process communication (IPC) describes the exchange of data between one process and another, either within the same computer or over a network. ... Mach-O, short for Mach object file format, is a file format for executables and object code. ...

BSD

The BSD portion of the kernel provides the POSIX API (BSD system calls), the process model, basic security policies, user ids, permissions, the networking code, the virtual filesystem code, cryptographic framework, System V IPC, and some of the locking primitives. POSIX is the collective name of a family of related standards specified by the IEEE to define the application program interface for software designed to run on variants of the Unix OS. They are formally designated as IEEE 1003 and the international standard name is ISO/IEC 9945. ... API redirects here. ... AT&T UNIX System V was one of the versions of the UNIX operating system. ...

I/O Kit

This is the device driver framework, written in a subset of C++. Due to it's object-oriented design, device drivers can be written more quickly using less code as features common to any class of driver is provided within the framework itself. The I/O Kit is multi-threaded, SMP safe, and allows for hot pluggable devices and automatic and dynamic device configuration. A device driver, often called a driver for short, is a computer program that enables another program, typically, an operating system (e. ... C++ (pronounced see plus plus) is a general-purpose computer programming language. ... Object-oriented programming (OOP) is a computer programming paradigm in which a software system is modeled as a set of objects that interact with each other. ... SMP is a Three letter abbreviation which can refer to the following: In computing: Symmetric multiprocessing, the use of multiple CPUs. ...

Many drivers can be written to run from user-space, which further enhances the stability of the system; if a userspace driver crashes, it will not crash the kernel.

Protecting shared resources

In order to run safely on multiprocessor machines, access to shared resources (files, data structures etc.) must be serialized so that threads or processes do not attempt to modify the same resource at the same time. Atomic operations, spinlocks, critical sections, mutexes and serializing tokens are all possible methods that can be used to prevent concurrent access. Like both Linux and FreeBSD 5, Darwin employs a fine-grained mutex model to achieve higher performance on multiprocessor systems. (disputed — see talk page) busy waiting is now its own page. ... Mutual exclusion (often abbreviated to mutex) algorithms are used in concurrent programming to avoid the concurrent use of un-shareable resources by pieces of computer code called critical sections. ... Multiprocessing is traditionally known as the use of multiple concurrent processes in a system as opposed to a single process at any one instant. ...

Supported processors

Currently, Darwin runs on x86 (Intel and AMD) based computers, as well as PowerPC based machines, both single processor and SMP models. x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... Intel Corporation (NASDAQ: INTC) (founded 1968) is a U.S.-based multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Advanced Micro Devices, Inc. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple-IBM-Motorola alliance, known as AIM. Originally intended for workstations, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... SMP is a Three letter abbreviation which can refer to the following: In computing: Symmetric multiprocessing, the use of multiple CPUs. ...

Development and distribution

Version management

The Darwin developers use a version control system called CVS to manage changes to the Darwin source code. The Concurrent Versions System (CVS), also known as the Concurrent Versioning System, implements a version control system: it keeps track of all work and all changes in a set of files, typically the implementation of a software project, and allows several (potentially widely separated) developers to collaborate. ... Source code (commonly just source or code) is any series of statements written in some human-readable computer programming language. ...

Quality control

Like most modern operating systems, Darwin employs a built-in kernel debugger to help the developers find kernel bugs.

License

In July 2003 Apple released Darwin under version 2.0 of the APSL license, which the Free Software Foundation (FSF) approved as a free software license. Previous releases had taken place under an earlier version of the APSL that did not meet the FSF's definition of free software, although it met the requirements of the Open Source Definition. 2003 is a common year starting on Wednesday of the Gregorian calendar. ... The Apple Public Source License is the open source license under which Apple Computers Darwin Project was released. ... The GNU logo, drawn by Etienne Suvasa Free Software Foundation (FSF) is a non-profit organization founded in 1985 by Richard Stallman to support the free software movement (free as in freedom), and in particular the GNU project, through the use of GNU Licenses (see below). ... It has been suggested that Free Software Replacements be merged into this article or section. ... The Open Source Definition is used by the Open Source Initiative to determine whether or not a software license can be considered open source. ...

Releases

The current version

Darwin 8.2 corresponds to Mac OS X v10.4.2. Mac OS X is the latest version of the Mac OS, the operating system software for Macintosh computers. ...

External links

• Apple Developer Site about Darwin
• Apple - Mac OS X - Technologies - Darwin
• OpenDarwin community development site
• DarwinPorts project
• Hexley, the Darwin mascot
• Apple Public Source License 2.0
• The Free Software Foundation's opinion of the APSL
• Apple Press Release: Apple to Use Intel Microprocessors Beginning in 2006
• Differences between Mac OS X and BSD