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OS X (pronounced ;〔 originally Mac OS X) is a series of Unix-based graphical interface operating systems (OS) developed and marketed by Apple Inc. It is designed to run on Macintosh computers, having been pre-installed on all Macs since 2002. OS X is the fourth most popular general purpose OS; within the market of desktop, laptop and home computers, and by web usage, OS X is the second most widely used desktop OS after Windows.
OS X 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; a desktop version, Mac OS X v10.0 "Cheetah" followed on March 24, 2001. All consumer releases of OS X up to 2013 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 in June 2013, this was dropped in favor of Californian landmarks.
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. UNIX 03 certification has been achieved for versions 10.5 for Intel CPUs,〔
(【引用サイトリンク】 title=Mac OS X Version 10.5 on Intel-based Macintosh computers )〕 and versions 10.6 through 10.11.〔(【引用サイトリンク】 title=Mac OS X Version 10.6 on Intel-based Macintosh computers )〕〔(【引用サイトリンク】 title=Apple technology brief on UNIX )〕〔(【引用サイトリンク】 title=Mac OS X Version 10.8 on Intel-based Macintosh computers )〕〔(【引用サイトリンク】 title=OS X Version 10.9 on Intel-based Macintosh computers )〕〔(【引用サイトリンク】 title=OS X version 10.10 Yosemite on Intel-based Mac computers )〕〔(【引用サイトリンク】 title=OS X version 10.11 El Capitan on Intel-based Mac computers )〕 iOS, the mobile OS for the iPhone, iPod Touch, iPad, and the 2nd and 3rd generation Apple TV, shares the Unix-based core and many frameworks with OS X. An unnamed variant of v10.4 powers the first generation Apple TV.
Apple sells an application suite for OS X called OS X Server, for use on servers. It includes tools to facilitate management of workgroups of OS X machines, and to provide network services. It is sold separately through the Mac App Store as a single item; in the past it was sold separately or preinstalled on dedicated server computers.
The first releases of Mac OS X from 1999 to 2006 can run only on the PowerPC based Macs of the period. After Apple announced it would shift to using Intel x86 CPUs from 2006 onwards, Tiger and Leopard were released in versions for Intel and PowerPC processors. Snow Leopard is the first version released only for Intel Macs. Since the release of Mac OS X 10.7 "Lion", OS X has dropped support for 32-bit Intel processors as well. It now runs exclusively on 64-bit Intel CPUs.
The latest version of OS X is 10.11 "El Capitan", which was released to the public on September 30, 2015.
(詳細はNeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, and then launched in 1989. The kernel of NeXTSTEP is based upon the Mach kernel, which was originally developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from select parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the programming language.
Throughout the early 1990s, Apple had tried to create a "next-generation" OS through the Taligent, Copland and Gershwin projects, although these were eventually abandoned.〔
〕 This led Apple to purchase NeXT in 1996, allowing NeXTSTEP, then called OPENSTEP, to serve as the basis for Apple's next generation OS.
This purchase also led to Steve Jobs returning to Apple as first an interim and then the permanent 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 code named "Rhapsody" and then officially named "Mac OS X".〔 〕
The first version of Mac OS X, Mac OS X Server 1.x, is a transitional product, featuring an interface resembling Mac OS. It was not compatible with software designed for the original Mac OS. Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; many could also be run directly through the Classic Environment with a reduction in performance.
The consumer version of Mac OS X was launched in 2001. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticising it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for OS X. ''Ars Technica'' columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as 'dog-slow, feature poor' and Aqua as 'unbearably slow and a huge resource hog'.〔〔
Apple rapidly developed several new releases of OS X. Siracusa's review of version 10.3, Panther, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger, reportedly shocked executives at Microsoft by offering a number of features, such as fast file searching and improved graphics processing, that Microsoft had spent several years struggling to add to Windows with acceptable performance.
In 2006, the first Intel Macs released used 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 PowerPC Macs.
As the operating system evolved, it moved away from the legacy Mac OS, with applications being added and removed. Targeting the consumer and media markets, Apple emphasised its new "digital lifestyle" applications such as the iLife suite, integrated home entertainment through the Front Row media center and the Safari web browser.〔
〕 With increasing popularity of the internet, Apple offered additional online services, including the .Mac, MobileMe and most recently iCloud products. It also began selling third-party applications through the Mac App Store.
New OS X versions also included modifications to the general interface, moving away from the striped gloss and transparency of the initial versions. Some applications began to use a brushed metal appearance, or non-pinstriped titlebar appearance in version 10.4. In Leopard, Apple announced a unification of the interface, with a standardised gray-gradient window style.
A key development for OS X was the announcement and release of the iPhone from 2007 onwards. While Apple's previous iPod mobile devices used a minimal operating system, the iPhone used an operating system based on OS X, which would later be called "iPhone OS" and then iOS. The simultaneous release of two operating systems based on the same frameworks placed tension on Apple, which cited the iPhone as forcing it to delay OS X Leopard. However, after Apple opened the iPhone to third-party developers is commercial success drew attention to OS X, with many iPhone software developers showing interest in Mac development.
In two succeeding versions, Lion and Mountain Lion, Apple moved some applications to a highly skeumorphic style of design inspired by contemporary versions of iOS, at the same time simplifying some elements by making controls such as scroll bars fade in when needed. This direction was, like brushed metal interfaces, unpopular with some users, although it continued a trend of greater animation and variety in the interface previously seen in design aspects such as the Time Machine backup utility, which presented past file versions against a swirling nebula, and the glossy translucent dock of Leopard and Snow Leopard.
Apple removed the head of OS X development, Scott Forstall, in 2012, and switched designs towards a more minimal direction. Apple's new user interface design, using deep color saturation, text-only buttons and a minimal, 'flat' interface, was first debuted in iOS 7 in 2013. With OS X engineers reportedly diverted to working on iOS 7, the version of OS X released in 2013, Mavericks, was something of a transitional release, with some of the skeumorphic design of iOS removed but the general interface of OS X largely unchanged. The next version, Yosemite, adopted a design similar to iOS 7 but with greater complexity suitable for an interface controlled with a mouse.
From 2012 onwards, OS X shifted to an annual release schedule similar to that of iOS, after releases generally coming every second year in the 10.3-10.7 period. It also steadily cut the cost of updates from Snow Leopard onwards, before removing upgrade fees altogether from 2013 onwards. Some journalists and third-party software developers have suggested that this decision, while allowing more rapid feature release, meant less opportunity to focus on stability, with no version of OS X recommendable for users requiring stability and performance above new features. Apple's 2015 update, El Capitan, was announced to focus specifically on stability and performance improvements.
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.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』