OS X is the newest of Apple Inc.'s Mac OS line of operating systems. Although, under its original name of Mac OS X, it was officially designated as simply "version 10" of the Mac OS, "version 9" had a completely different codebase, file system, design, and hardware support. Mac OS had been Apple's primary operating system since 1984, and the family was backward compatible, so OS X supported an emulated version 9 until version 10.5.
Unlike its predecessor, OS X is a Unix-like operating system built on technology that had been developed at NeXT through the second half of the 1980s and up until Apple purchased the company in early 1997. It was first released in 1999 as Mac OS X Server 1.0, with a desktop-oriented version (Mac OS X v10.0) following in March 2001. Since then, six more distinct "client" and "server" editions of Mac OS X were released, thereafter 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. The most recent version OS X v10.8 was first made available on July 25, 2012. Releases of OS X are named after big cats; the current version of OS X is nicknamed "Mountain Lion".
On September 13, 2000 Apple released a $29.95 "preview" version of Mac OS X (internally codenamed Kodiak) in order to gain feedback from users.
The "PB" as it was known marked the first public availability of the Aqua interface and Apple made many changes to the UI based on customer feedback. Mac OS X Public Beta expired and ceased to function in Spring 2001.
On March 24, 2001, Apple released Mac OS X v10.0 (internally codenamed Cheetah). The initial version was slow, incomplete, and had very few applications available at the time of its launch, mostly from independent developers. While many critics suggested that the operating system was not ready for mainstream adoption, they recognized the importance of its initial launch as a base on which to improve. Simply releasing Mac OS X was received by the Macintosh community as a great accomplishment, for attempts to completely overhaul the Mac OS had been underway since 1996, and delayed by countless setbacks. Following some bug fixes, kernel panics became much less frequent.
On August 23, 2002, Apple followed up with Mac OS X v10.2 "Jaguar", the first release to use its code name as part of the branding. It brought great raw performance improvements, a sleeker look, and many powerful user-interface enhancements (over 150, according to Apple), including Quartz Extreme for compositing graphics directly on an ATI Radeon or Nvidia GeForce2 MX AGP-based video card with at least 16 MB of VRAM, a system-wide repository for contact information in the new Address Book, and an instant messaging client named iChat. The Happy Mac which had appeared during the Mac OS startup sequence for almost 18 years was replaced with a large grey Apple logo with the introduction of Mac OS X v10.2.
Mac OS X v10.4 "Tiger" was released on April 29, 2005. Apple stated that Tiger contained more than 200 new features. As with Panther, certain older machines were no longer supported; Tiger requires a Mac with a built-in FireWire port. Among the new features, Tiger introduced Spotlight, Dashboard, Smart Folders, updated Mail program with Smart Mailboxes, QuickTime 7, Safari 2, Automator, VoiceOver, Core Imageand Core Video. The initial release of the Apple TV used a modified version of Tiger with a different graphical interface and fewer applications and services. On January 10, 2006, Apple released the first Intel-based Macs along with the 10.4.4 update to Tiger. This operating system functioned identically on the PowerPC-based Macs and the new Intel-based machines, with the exception of the Intel release dropping support for the Classic environment.[19] Only PowerPC Macs can be booted from retail copies of the Tiger client DVD, but there is a Universal DVD of Tiger Server 10.4.7 (8K1079) that can boot both PowerPC and Intel Macs.
Mac OS X v10.5 "Leopard" was released on October 26, 2007. It was called by Apple "the largest update of Mac OS X". It brought more than 300 new features. Leopard supports both PowerPC- and Intel x86-based Macintosh computers; support for the G3 processor was dropped and the G4 processor required a minimum clock rate of 867 MHz, and at least 512 MB of RAM to be installed. The single DVD works for all supported Macs (including 64-bit machines). New features include a new look, an updated Finder, Time Machine, Spaces, Boot Camp pre-installed,[21] full support for 64-bit applications (including graphical applications), new features in Mail and iChat, and a number of new security features. Leopard is an Open Brand UNIX 03 registered product on the Intel platform. It was also the first BSD-based OS to receive UNIX 03 certification. Leopard dropped support for the Classic Environment and all Classic applications.
It was the final version of Mac OS X to support the PowerPC architecture.
Mac OS X v10.6 "Snow Leopard" was released on August 28, 2009. Rather than delivering big changes to the appearance and end user functionality like the previous releases of Mac OS X, Snow Leopard focuses on "under the hood" changes, increasing the performance, efficiency, and stability of the operating system. For most users, the most noticeable changes are: the disk space that the operating system frees up after a clean install compared to Mac OS X 10.5 Leopard, a more responsive Finder rewritten in Cocoa, faster Time Machine backups, more reliable and user friendly disk ejects, a more powerful version of the Preview application, as well as a faster Safari web browser.
The rewrite of Finder in Apple's native Cocoa API allows the Finder to take advantage of the new technologies introduced in Snow Leopard. An update of the web browser, Safari 4, includes a boost in JavaScript and HTML performance, which results in faster web browsing. The majority of this performance boost is enabled by the new SquirrelFish JavaScript interpreter, improving the JavaScript rendering performance of Safariby over 50%. The new Top Sites also displays the most frequently visited and/or bookmarked sites in a panorama view, allowing the user to easily access their favorite sites along with a new Cover Flow view for the user's browsing history. Safari 4 is now also more crash resistant, being able to isolate plug-ins which are the main cause of web browser crashes.
Mac OS X v10.6 also features Microsoft Exchange Server support for Mail, iCal, and Address Book, new 64-bit technology capable of supporting greater amounts of RAM, an all new QuickTime X with a refreshed user interface and more functionality that used to be only available to QuickTime Pro owners.
Back-end platform changes include improved support for multi-core processors through Grand Central Dispatch which attempts to ease the development of applications with multi-core support, and thus improve their CPU utilization. It used to be that developers needed to code their programs in such a way that their software would explicitly take advantage of the multiple cores, which could easily become a tedious and troublesome task, especially in complex software. It also includes advanced GPU performance with OpenCL (a cross platform open standard for GPGPU distinct from CUDA, Dx11 Compute Shader or STREAM) by providing support to offload work normally only destined for a CPU to the graphic card's GPU. This can be especially useful in tasks that can be heavily parallelized.
An update introduced support for the Mac App Store, Apple's digital distribution platform for OS X applications.
Snow Leopard only supports machines with Intel CPUs, requires at least 1 GB of RAM, and drops default support for applications built for thePowerPC architecture (Rosetta can be installed as an additional component to retain support for PowerPC-only applications).
Mac OS X v10.7 "Lion" was released on July 20, 2011. It brought developments made in Apple's iOS, such as an easily navigable display of installed applications (Launchpad) and (a greater use of) multi-touch gestures, to the Mac. This release removed Rosetta, making it incapable of running PowerPC applications.
Changes made to the GUI (Graphical User Interface) include the Launchpad (similar to the home screen of iOS devices), auto-hiding scrollbars that only appear when they are being used, and Mission Control, which unifies Exposé, Spaces, Dashboard, and full-screen applications within a single interface. Apple also made changes to applications: they resume in the same state as they were before they were closed (similar to iOS). Documents auto-save by default.
OS X v10.8 "Mountain Lion" was released on July 25, 2012. It incorporates some features seen in iOS 5, which include Game Center, support for iMessage in the new Messages messaging application, and Reminders as a to-do list app separate from iCal (which is renamed as Calendar, like the iOS app). It also includes support for storing iWork documents in iCloud. Notification Center, which makes its debut in Mountain Lion, is a desktop version similar to the one in iOS 5.0 and higher. Application pop-ups are now concentrated on the corner of the screen, and the Center itself is pulled from the right side of the screen. Mountain Lion also includes more Chinese features including support forBaidu as an option for Safari search engine, QQ, 163.com and 126.com services for Mail, Contacts and Calendar, Youku, Tudou and Sina Weibo are integrated into share sheets.
Notification Center is added in the operating system. It provides an overview of alerts from applications and displays notifications until the user completes an associated action, rather than requiring instant resolution. Users may choose what applications appear in Notification Center, and how they are handled. There are three types of notifications: banners, alerts, and badges. Banners are displayed for a short amount of time in the upper right corner of the Mac's screen, and the slide off to the right. The icon of the application is displayed on the left side of the banner, while the message from it will be displayed on the right side. Alerts are the same as banners, but will not disappear from the screen until the user takes action. Badges are red notification icons that are displayed on the application's icon. They tell the number of items available for the application.
Notes, a new notes application, is added. It is now separate from Mail in its own application, with support for desktop notes added (syncs along with its iOS counterpart). Created notes are synced through all the user's Apple devices through the iCloud service. Notes can be arranged in folders, and pinned to the user's desktop. When the application is closed, the pinned note still remains.
Messages, an instant messaging software application, is added in Mountain Lion. It was announced on February 16, 2012, as part of the OS X Mountain Lion developer preview. Starting with this release, Messages replaces iChat as the default OS X instant-messaging client. A free beta version of Messages was available to download for Mac OS X Lion from the Apple website until late June 2012. The final version of Messages was included with the release version of OS X Mountain Lion.
As with its predecessor, Messages has text messaging, audio, and screen-sharing capabilities. Messages also contains native video conversation support, utilising Apple's FaceTime video calling application where possible. However, it does retain video capabilities for interfacing with other instant messaging clients. Messages supports Apple's iMessage, a free instant messaging service previously only available on devices running iOS 5. It also supports both XMPP (shown in the application under its former name, Jabber) and the AIM OSCAR. In addition, it also offers a direct connection to Yahoo! Messenger and Google Talk.
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