OS X /ˌoʊ ɛs ˈtɛn/,[9] previously Mac OS X,[10] is a series of Unix-based graphical interfaceoperating systems developed, marketed, and sold by Apple Inc. It is designed to run exclusively on Mac computers, having been pre-loaded on all Macs since 2002. It was the successor to Mac OS 9, released in 1999, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 1984. The first version released was Mac OS X Server 1.0 in 1999, and a desktop version, Mac OS X v10.0 "Cheetah" followed on March 24, 2001. Previous releases of OS X were named after big cats; for example, OS X v10.8 was referred to as "Mountain Lion". However, with the announcement of OS X Mavericks this was dropped in favor of Californian landmarks.[11]
OS X, whose X is the Roman numeral for 10 and is a prominent part of its brand identity, is built on technologies developed at NeXT between the second half of the 1980s and Apple's purchase of the company in late 1996. The 'X' is also used to emphasize the relatedness between OS X and UNIX. Versions 10.5 "Leopard" running on Intel processors,[3] 10.6 "Snow Leopard",[4] 10.7 "Lion"[6] and 10.8 "Mountain Lion"[5] have obtained UNIX 03 certification. iOS, which runs on the iPhone, iPod Touch,[12] iPad, and the 2nd and 3rd generation Apple TV,[13]shares the Darwin core and many frameworks with OS X. An unnamed variant of v10.4powered the first generation Apple TV.[14]
Mac OS X 10.7 "Lion" was the first version of OS X to drop support for 32-bit Intel processors and run exclusively on 64-bit Intel CPUs.
The server edition, OS X Server, was architecturally identical to its desktop counterpart, and included tools to facilitate management of workgroups of OS X machines, and to providenetwork services. Starting with v10.7 "Lion", OS X Server is no longer offered as a separate operating system product; instead, the server management tools are available for purchase separately, and are preloaded on the server models of Mac Pro and Mac Mini along with OS X.
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History
Main article: History of OS X
OS X is based upon the Mach kernel. Certain parts from FreeBSD's and NetBSD's implementation ofUnix were incorporated in NeXTSTEP, the core of Mac OS X. NeXTSTEP was the graphical, object-oriented, and UNIX-based operating system developed by Steve Jobs' company NeXT after he left Apple in 1985.[15] While Jobs was away from Apple, Apple tried to create a "next-generation" OS through theTaligent, Copland and Gershwin projects, with little success.[16]
Eventually, NeXT's OS, then called OPENSTEP, was selected to be the basis for Apple's next OS, and Apple purchased NeXT outright.[17] Steve Jobs returned to Apple as interim CEO, and later became CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals. The project was first known as Rhapsody and was later renamed to Mac OS X.[18]
Mac OS X originally ran on PowerPC-based Macs. In 2006, the first Intel Macs had a specialized version of 10.4 "Tiger". In 2007, 10.5 "Leopard" was the first to run on both PowerPC and Intel Macs with the use of Universal Binaries. 10.6 "Snow Leopard" was the first version of OS X to drop support for PowerPCMacs.
Mac OS X Server 1.x, was incompatible with software designed for the original Mac OS and had no support for Apple's own IEEE 1394 (FireWire) interface. Mac OS X 10.x included more backward compatibility through Classic and more functionality by introducing the Carbon API as well as FireWire support. As the operating system evolved, it moved away from the legacy Mac OS to an emphasis on new "digital lifestyle" applications such as the iLife suite, enhanced business applications (iWork), and integrated home entertainment (the Front Row media center).[19] Each version also included modifications to the general interface, such as the brushed metal appearance added in version 10.3, the non-pinstriped titlebar appearance in version 10.4, and in 10.5 the removal of the previous brushed metal styles in favor of the "Unified" gradient window style.[20][21]
In 2012, with the release of OS X 10.8, the "Mac" prefix was officially dropped in all references to the operating system name within its web site.[22]
Description
OS X is the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, e.g. Mac OS 8 andMac OS 9. The letter X in OS X's name refers to the number 10, a Roman numeral. It is therefore correctly pronounced "ten" /ˈtɛn/ in this context.[9][23] However, a common mispronunciation is "X" /ˈɛks/.[24]
OS X's core is a POSIX compliant operating system (OS) built on top of the XNU kernel, with standard Unix facilities available from the command line interface. Apple has released this family of software as a free and open source operating system named Darwin. On top of Darwin, Apple layered a number of components, including the Aqua interface and the Finder, to complete the GUI-based operating system which is OS X.[25]
OS X introduced a number of new capabilities to provide a more stable and reliable platform than its predecessor, Mac OS 9. For example, pre-emptive multitasking and memory protection improved the system's ability to run multiple applications simultaneously without them interrupting or corrupting each other.[26] Many aspects of OS X's architecture are derived from OPENSTEP, which was designed to be portable, to ease the transition from one platform to another. For example, NeXTSTEP was ported from the original 68k-based NeXT workstations to x86 and other architectures before NeXT was purchased by Apple,[27] and OPENSTEP was later ported to the PowerPC architecture as part of the Rhapsody project.
The most visible change was the Aqua theme. The use of soft edges, translucent colors, and pinstripes—similar to the hardware design of the firstiMacs—brought more texture and color to the user interface when compared to what OS 9 and OS X Server 1.0's "Platinum" appearance had offered. According to John Siracusa, an editor of Ars Technica, the introduction of Aqua and its departure from the then conventional look "hit like a ton of bricks."[28] Bruce Tognazzini (who founded the original Apple Human Interface Group) said that the Aqua interface in Mac OS X v10.0 represented a step backwards in usability compared with the original Mac OS interface.[29][30] Third-party developers started producing skins for customizable applications and other operating systems which mimicked the Aqua appearance. To some extent, Apple has used the successful transition to this new design as leverage, at various times threatening legal action against people who make or distribute software with an interface the company says is derived from its copyrighted design.[31]
The architecture of OS X incorporates a layered design.[32] The layered frameworks aid rapid development of applications by providing existing code for common tasks.[33]
OS X includes its own software development tools, most prominently an integrated development environment called Xcode. Xcode provides interfaces to compilers that support several programming languages including C, C++, Objective-C, and Java. For the Apple–Intel transition, it was modified so that developers could build their applications as a universal binary, which provides compatibility with both the Intel-based and PowerPC-based Macintosh lines.[34]
The Darwin sub-system in Mac OS X is in charge of managing the filesystem, which includes the Unix permissions layer. In 2003 and 2005, twoMacworld editors expressed criticism of the permission scheme; Ted Landau called misconfigured permissions "the most common frustration" in Mac OS X, while Rob Griffiths suggested that some users may even have to reset permissions every day, a process which can take up to 15 minutes.[35] More recently, another Macworld editor, Dan Frakes, called the procedure of repairing permissions vastly overused.[36] He argues that OS X typically handles permissions properly without user interference, and resetting permissions should just be tried when problems emerge.[37]
Distribution and languages
See also: Usage share of operating systems
As of September 2011, OS X is the second-most-active general-purpose client operating system in use on the World Wide Web, (after Microsoft Windows), with an 8.45% usage share according to statistics compiled by W3Counter.[38] It is the most successful Unix-like desktop operating system on the web, estimated at over 5 times the usage of Linux (which has 1.5%).[38]
There are twenty-two "System Languages" available for the user at the moment of installation (the "system language" is the entire operating system environment). As of Mac OS X Lion, the languages are Arabic, Chinese (Simplified), Chinese (Traditional), Czech, Danish, Dutch, English, Finnish, French, German, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Brazilian), Portuguese (European), Russian, Spanish, Swedish and Turkish. Input methods for typing in dozens of scripts can be chosen independently of the system language.[39]
Compatibility
Software
The APIs that OS X inherited from OpenStep are not backward compatible with earlier versions of Mac OS. These APIs were created as the result of a 1993 collaboration between NeXT Computer and Sun Microsystems and are now referred to by Apple as Cocoa. This heritage is highly visible for Cocoa developers, since the "NS" prefix is ubiquitous in the framework, standing variously for Nextstep or NeXT/Sun. The official OpenStep API, published in September 1994, was the first to split the API between Foundation and Application Kit and the first to use the "NS" prefix.[27] Apple's Rhapsody project would have required all new development to use these APIs, causing much outcry among existing Mac developers. All Mac software that did not receive a complete rewrite to the new framework would run in the equivalent of the Classic environment. To permit a smooth transition from Mac OS 9 to (Mac) OS X, the Carbon Application Programming Interface (API) was created. Applications written with Carbon can be executed natively on both systems. Carbon was not included in the first product sold as "Mac OS X": Mac OS X Server (now referred to as Mac OS X Server 1.x).
OS X also used to support the Java Platform as a "preferred software package"—in practice this means that applications written in Java fit as neatly into the operating system as possible while still being cross-platform compatible, and that graphical user interfaces written in Swing look almost exactly like native Cocoa interfaces. Traditionally, Cocoa programs have been mostly written in Objective-C, with Java as an alternative. However, on July 11, 2005, Apple announced that "features added to Cocoa in Mac OS X versions later than 10.4 will not be added to the Cocoa-Java programming interface."[40]
Since OS X is POSIX compliant, many software packages written for the *BSDs, Linux, or other Unix-like systems can be recompiled to run on it. Projects such as Homebrew, Fink, MacPorts and pkgsrc provide pre-compiled or pre-formatted packages. From version 10.3 to version 10.7, OS X included X11.app, Apple's version of the X Window System graphical interface for Unix applications, as an optional component during installation.[41] Up to and including Mac OS X v10.4 (Tiger), Apple's implementation was based on the X11 Licensed XFree86 4.3 and X11R6.6. All bundled versions of X11 feature a window manager which is similar to the OS X look-and-feel and has fairly good integration with Mac OS X, also using the native Quartz rendering system. Earlier versions of OS X (in which X11 has not been bundled) can also run X11 applications usingXDarwin. With the introduction of version 10.5 Apple switched to the X.org variant of X11.[42] Version Mac OS X 10.7 "Lion" uses X.org Server version 1.10.x[43] Starting with OS X Mountain Lion, X11 is not bundled in OS X; instead, it has to be installed from, for example, the open source XQuartzproject.[44]
Hardware
For the early releases of Mac OS X, the standard hardware platform supported was the full line of Macintosh computers (laptop, desktop, or server) based on PowerPC G3, G4, and G5 processors. Later versions discontinued support for some older hardware; for example, Panther does not support "beige" G3s,[45] and Tiger does not support systems that pre-date Apple's introduction of integrated FireWire ports (the ports themselves are not a functional requirement). Mac OS X v10.5 "Leopard", introduced October 2007, has dropped support for all PowerPC G3 processors and for PowerPC G4 processors with clock rates below 867 MHz. Mac OS X v10.6 "Snow Leopard" supports Macs with Intel processors, not PowerPC. Mac OS X 10.7 "Lion" requires a Mac with an Intel Core 2 Duo or newer processor.
Tools such as XPostFacto and patches applied to the installation disc have been developed by third parties to enable installation of newer versions of Mac OS X on systems not officially supported by Apple. This includes a number of pre-G3 Power Macintosh systems that can be made to run up to and including Mac OS X 10.2 Jaguar, all G3-based Macs which can run up to and including Tiger, and sub-867 MHz G4 Macs can run Leopard by removing the restriction from the installation DVD or entering a command in the Mac's Open Firmware interface to tell the Leopard Installer that it has a clock rate of 867 MHz or greater. Except for features requiring specific hardware (e.g. graphics acceleration, DVD writing), the operating system offers the same functionality on all supported hardware.
PowerPC versions of Mac OS X prior to Leopard retain compatibility with older Mac OS applications by providing an emulation environment calledClassic, which allows users to run Mac OS 9 as a process within Mac OS X, so that most older applications run as they would under the older operating system. Classic is not supported on Intel-based Macs or in Mac OS X v10.5 "Leopard", but users still requiring Classic applications on Intel Macs can use the SheepShaver emulator to run Mac OS 9 on top of Leopard.
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