A computing platform or digital platform is the environment in which a piece of software is executed. It may be the hardware or the operating system a web browser and associated application programming interfaces, or other underlying software, as long as the program code is executed with it. Computing platforms have different abstraction levels, including a computer architecture, an OS, or runtime libraries. A computing platform is the stage. A platform can be seen both as a constraint on the software development process, in that different platforms provide different functionality and restrictions. For example, an OS may be a platform that abstracts the underlying differences in hardware and provides a generic command for saving files or accessing the network. Platforms may include: Hardware alone, in the case of small embedded systems. Embedded systems can access hardware directly, without an OS. A browser in the case of web-based software; the browser itself runs on a hardware+OS platform, but this is not relevant to software running within the browser.
An application, such as a spreadsheet or word processor, which hosts software written in an application-specific scripting language, such as an Excel macro. This can be extended to writing fully-fledged applications with the Microsoft Office suite as a platform. Software frameworks. Cloud computing and Platform as a Service. Extending the idea of a software framework, these allow application developers to build software out of components that are hosted not by the developer, but by the provider, with internet communication linking them together; the social networking sites Twitter and Facebook are considered development platforms. A virtual machine such as the Java virtual machine or. NET CLR. Applications are compiled into a format similar to machine code, known as bytecode, executed by the VM. A virtualized version of a complete system, including virtualized hardware, OS, storage; these allow, for instance, a typical Windows program to run on. Some architectures have multiple layers, with each layer acting as a platform to the one above it.
In general, a component only has to be adapted to the layer beneath it. For instance, a Java program has to be written to use the Java virtual machine and associated libraries as a platform but does not have to be adapted to run for the Windows, Linux or Macintosh OS platforms. However, the JVM, the layer beneath the application, does have to be built separately for each OS. AmigaOS, AmigaOS 4 FreeBSD, NetBSD, OpenBSD IBM i Linux Microsoft Windows OpenVMS Classic Mac OS macOS OS/2 Solaris Tru64 UNIX VM QNX z/OS Android Bada BlackBerry OS Firefox OS iOS Embedded Linux Palm OS Symbian Tizen WebOS LuneOS Windows Mobile Windows Phone Binary Runtime Environment for Wireless Cocoa Cocoa Touch Common Language Infrastructure Mono. NET Framework Silverlight Flash AIR GNU Java platform Java ME Java SE Java EE JavaFX JavaFX Mobile LiveCode Microsoft XNA Mozilla Prism, XUL and XULRunner Open Web Platform Oracle Database Qt SAP NetWeaver Shockwave Smartface Universal Windows Platform Windows Runtime Vexi Ordered from more common types to less common types: Commodity computing platforms Wintel, that is, Intel x86 or compatible personal computer hardware with Windows operating system Macintosh, custom Apple Inc. hardware and Classic Mac OS and macOS operating systems 68k-based PowerPC-based, now migrated to x86 ARM architecture based mobile devices iPhone smartphones and iPad tablet computers devices running iOS from Apple Gumstix or Raspberry Pi full function miniature computers with Linux Newton devices running the Newton OS from Apple x86 with Unix-like systems such as Linux or BSD variants CP/M computers based on the S-100 bus, maybe the earliest microcomputer platform Video game consoles, any variety 3DO Interactive Multiplayer, licensed to manufacturers Apple Pippin, a multimedia player platform for video game console development RISC processor based machines running Unix variants SPARC architecture computers running Solaris or illumos operating systems DEC Alpha cluster running OpenVMS or Tru64 UNIX Midrange computers with their custom operating systems, such as IBM OS/400 Mainframe computers with their custom operating systems, such as IBM z/OS Supercomputer architectures Cross-platform Platform virtualization Third platform Ryan Sarver: What is a platform
OS X El Capitan
OS X El Capitan is the twelfth major release of OS X, Apple Inc.'s desktop and server operating system for Macintosh computers. It is the successor to OS X Yosemite and focuses on performance and security. Following the Northern California landmark-based naming scheme introduced with OS X Mavericks, El Capitan was named after a rock formation in Yosemite National Park, signifying its goal to be a refined version of Yosemite. El Capitan is the final version to be released under the name OS X. El Capitan received far superior reviews; the first beta of OS X El Capitan was released to developers shortly following the 2015 WWDC keynote on June 8, 2015. The first public beta was made available on July 9, 2015. There were multiple betas released after the keynote. OS X El Capitan was released to end users on September 30, 2015, as a free upgrade through the Mac App Store. All Macintosh computers that can run Mountain Lion, Mavericks, or Yosemite can run El Capitan, although not all of its features will work on older computers.
For example, Apple notes that the newly available Metal API is available on "all Macs since 2012". These computers can run El Capitan, provided they have at least 2GB of RAM: MacBook: Late 2008 or newer MacBook Air: Late 2008 or newer MacBook Pro: Mid 2007 or newer Mac Mini: Early 2009 or newer iMac: Mid 2007 or newer Mac Pro: Early 2008 or newer Xserve: Early 2009Of these computers, the following models were equipped with 1GB RAM as the standard option on the base model when they were shipped originally, they can only run OS X El Capitan if they have at least 2GB of RAM. iMac: Mid 2007 - Early 2008 Mac Mini: Early 2009The following computers support features such as Handoff, Instant Hotspot, AirDrop between Mac computers and iOS devices, as well as the new Metal API: iMac: Late 2012 or newer MacBook: Early 2015 or newer MacBook Air: Mid 2012 or newer MacBook Pro: Mid 2012 or newer Mac Mini: Late 2012 or newer Mac Pro: Late 2013The upgrade varies in size depending upon which Apple Mac computer it is being installed on, in most scenarios it will require about 6 GB of disk space.
OS X El Capitan includes features to improve the security, performance and usability of OS X. Compared to OS X Yosemite, Apple says that opening PDFs is four times faster, app switching and viewing messages in Mail is twice as fast and launching apps is 40% faster; the maximum amount of memory that could be allocated to the graphics processor has been increased from 1024 MB to 1536 MB on Macs with an Intel HD 4000 GPU. OS X El Capitan supports Metal, Apple's graphics API introduced in iOS 8 to speed up performance in games and professional applications. Apple's typeface San Francisco replaces Helvetica Neue as the system typeface. OS X El Capitan adopts LibreSSL in replacement of OpenSSL used in previous versions. OS X El Capitan introduces new window management features such as creating a full-screen split view by pressing the green button on left upper corner of the window or Control+Cmd+F keyboard shortcut snapping any supported other window to that full screen application; this feature is similar to, although less extensive than, the snap-assist feature in Windows 7 and several Linux desktop environments, such as GNOME.
OS X El Capitan improves Mission Control to incorporate this feature across multiple spaces. It enables users to spot the pointer more by enlarging it by shaking the mouse or swiping a finger back and forth on the trackpad. OS X El Capitan adds multi-touch gestures to applications like Mail and Messages that allow a user to delete or mark emails or conversations by swiping a finger on a multi-touch device, such as a trackpad. OS X analyzes the contents of individual emails in Mail and uses the gathered information in other applications, such as Calendar. For example, an invitation in Mail can automatically be added as a Calendar event. Apple Maps in El Capitan shows public transit information similar to Maps in iOS 9; this feature was limited to a handful of cities upon launch: Baltimore, Chicago, Los Angeles, Mexico City, New York City, Philadelphia, San Francisco, Shanghai and Washington D. C; the Notes application receives an overhaul, similar to Notes in iOS 9. Both applications have more powerful text-processing capabilities, such as to-do lists, inline webpage previews and videos, digital sketches, map locations and other documents and media types.
The app can now be moved across the screen. Photos introduced editing extensions which allows Photos to use editing to
The Finder is the default file manager and graphical user interface shell used on all Macintosh operating systems. Described in its "About" window as "The Macintosh Desktop Experience", it is responsible for the launching of other applications, for the overall user management of files and network volumes, it was introduced with the first Macintosh computer, exists as part of GS/OS on the Apple IIGS. It was rewritten with the release of Mac OS X in 2001. In a tradition dating back to the Classic Mac OS of the 1980s and 1990s, the Finder icon is the smiling screen of a computer, known as the Happy Mac logo; the Finder uses a view of the file system, rendered using a desktop metaphor. It uses a similar interface to Apple's Safari browser, where the user can click on a folder to move to it and move between locations using "back" and "forward" arrow buttons. Like Safari, the Finder uses tabs to allow the user to view multiple folders. There is a "favorites" sidebar of used and important folders on the left of the Finder window.
The modern Finder uses macOS graphics APIs to display previews of a range of files, such as images, applications and PDF files. The Quick Look feature allows users to examine documents and images in more detail from the finder by pressing the space bar without opening them in a separate application; the user can choose how to view files, with options such as large icons showing previews of files, a list with details such as date of last creation or modification, a Gallery View, a "column view" influenced by macOS's direct ancestor NeXTSTEP. The modern Finder displays some aspects of the file system outside its windows. Mounted external volumes and disk image files can be displayed on the desktop. There is a trash can on the Dock in macOS, to which files can be dragged to mark them for deletion, to which drives can be dragged for ejection; when a volume icon is being dragged, the Trash icon in the Dock changes to an eject icon in order to indicate this functionality. Finder can record files to optical media on the sidebar.
From Yosemite onwards, the Finder contains official support for extensions, allowing synchronization and cloud storage applications such as Dropbox to display sync status labels inside the Finder display. The classic Mac OS Finder uses a spatial metaphor quite different to the more browser-like approach of the modern macOS Finder. In the classic Finder, opening a new folder opens the location in a new window: finder windows are'locked' so that they would only display the contents of one folder, it allows extensive customization, with the user being able to give folders custom icons matching their content. This approach emphasizes the different locations of files within the operating system, but navigating to a folder nested inside multiple other folders fills the desktop with a large number of windows that the user may not wish to have open; these must be closed individually. Holding down the option key when opening a folder would close its parent, but this trick was not discoverable and remained under the purview of power users.
Stewart Alsop II in 1988 said "It is testimony to either the luck or vision of the original designers" of Finder that "the interface has been able to survive tremendous evolution without much essential damage" from 1984. He praised its spatial file manager as "probably a more complete definition of a PC-based universe than any" competitor, with users able to seamlessly use floppies and remote hard disks, large and small file servers. Alsop said that if Apple had stolen Xerox's technology for Finder, it was now different. While criticizing the lack of a right mouse button and Multifinder's clumsiness, he concluded that "Apple remains the king of user interfaces. Finder is the only interface with 1.5 million people sitting in front of it daily. Apple is spending tremendous amounts of money on both development and basic research to remain the leader". Introducing Mac OS X in 2000, Steve Jobs criticized the original Finder, saying that it "generates a ton of windows, you get to be the janitor."Ars Technica columnist John Siracusa has been a long-standing defender of the spatial interface of the classic Mac OS Finder, a critic of the new design.
Daring Fireball blog author John Gruber has voiced similar criticisms. In a 2005 interview he said that the Finder in version 10.3 of Mac OS X had become "worse than in 10.0" and that "the fundamental problem with the OS X Finder is that it's trying to support two opposing paradigms at once – the browser metaphor... and the spatial metaphor from the original Mac Finder... and it ends up doing neither one well." Reviewing the same version of Mac OS X, Siracusa comments that the Finder "provides the same self-destructive combination of spatial and browser-style features as all of its Mac OS X predecessors". Third-party macOS software developers offer Finder replacements that run as stand-alone applications, such as ForkLift, Path Finder and XtraFinder; these replacements are shareware or freeware and aim to include and supersede the functionality of the Finder. After Mac OS X 10.4 Tiger the UNIX command line file management tools understand resource forks and can be used for management of Mac files.
There are minor differences between Finder versions and Classic OS to System 7. From System 6 onward, the version numbers are unified. Since the introduction of Mac OS X, the largest rewrite of the Finder was with the 2009 release of Mac OS X 10.6, into the Cocoa API, though little change was visible to the user. Spatial file manager Miller columns List of file managers
Social networking service
A social networking service is an online platform which people use to build social networks or social relations with other people who share similar personal or career interests, backgrounds or real-life connections. The social network is distributed across various computer networks; the social networks are inherently computer networks, linking people and knowledge. Social networking services vary in the number of features, they can incorporate a range of new information and communication tools, operating on desktops and on laptops, on mobile devices such as tablet computers and smartphones. They may feature "web logging" diary entries online. Online community services are sometimes considered social-network services by programmers and users, though in a broader sense, a social-network service provides an individual-centered service whereas online community services are group-centered. Defined as "websites that facilitate the building of a network of contacts in order to exchange various types of content online," social networking sites provide a space for interaction to continue beyond in person interactions.
These computer mediated interactions link members of various networks and may help to both maintain and develop new social ties. Social networking sites allow users to share ideas, digital photos and videos, to inform others about online or real-world activities and events with people in their network. While in-person social networking – such as gathering in a village market to talk about events – has existed since the earliest development of towns, the Web enables people to connect with others who live in different locations, ranging from across a city to across the world. Depending on the social media platform, members may be able to contact any other member. In other cases, members can contact anyone they have a connection to, subsequently anyone that contact has a connection to, so on; the success of social networking services can be seen in their dominance in society today, with Facebook having a massive 2.13 billion active monthly users and an average of 1.4 billion daily active users in 2017.
LinkedIn, a career-oriented social-networking service requires that a member know another member in real life before they contact them online. Some services require members to have a preexisting connection to contact other members; the main types of social networking services contain category places, means to connect with friends, a recommendation system linked to trust. One can categorize social-network services into three types: socializing social network services used for socializing with existing friends online social networks are decentralized and distributed computer networks where users communicate with each other through internet services. Networking social network services used for non-social interpersonal communication social navigation social network services used for helping users to find specific information or resources There have been attempts to standardize these services to avoid the need to duplicate entries of friends and interests. A study reveals that India recorded world's largest growth in terms of social media users in 2013.
A 2013 survey found that 73% of U. S. adults use social-networking sites. There is a variety of social networking services available online. However, most incorporate common features: social networking services are Web 2.0, Internet-based applications user-generated content is the lifeblood of social networking services. Users create service-specific profiles for the site or app that are designed and maintained by the SNS organization social networking services facilitate the development of online social networks by connecting a user's profile with those of other individuals or groups; the variety and evolving range of stand-alone and built-in social networking services in the online space introduces a challenge of definition. Furthermore, the idea that these services are defined by their ability to bring people together and provides too broad a definition; such a broad definition would suggest that the telegraph and telephone were social networking services – not the Internet technologies scholars are intending to describe.
The terminology is unclear, with some referring to social networking services as social media. A recent attempt at providing a clear definition reviewed the prominent literature in the area and identified four commonalities unique to current social networking services: social networking services are interactive Web 2.0 Internet-based applications, user-generated content, such as user-submitted digital photos, text posts, "tagging", online comments, diary-style "web logs", is the lifeblood of the SNS organism, users create service-specific profiles for the site or app that are designed and maintained by the SNS organization, social networking services facilitate the development of social networks online by connecting a user's profile with those of other individuals or groups. The potential for computer networking to facilitate newly improved forms of computer-mediated social interaction was suggested early on. Efforts to support social networks via computer-mediated communication were made in many early online services, including Usenet, ARPANET, LISTSERV, bulletin board services.
Many prototypical features of social networking sites were present in online services such as America Online, CompuServe, ChatNet, The WELL. Early social netw
IPhone is a line of smartphones designed and marketed by Apple Inc. All generations of the iPhone use Apple's iOS mobile operating system software; the first-generation iPhone was released on June 29, 2007, multiple new hardware iterations with new iOS releases have been released since. The user interface is built around the device's multi-touch screen, including a virtual keyboard; the iPhone can connect to cellular networks. An iPhone can shoot video, take photos, play music and receive email, browse the web and receive text messages, follow GPS navigation, record notes, perform mathematical calculations, receive visual voicemail. Other functionality, such as video games, reference works, social networking, can be enabled by downloading mobile apps; as of January 2017, Apple's App Store contained more than 2.2 million applications available for the iPhone. Apple has released twelve generations of iPhone models, each accompanied by one of the twelve major releases of the iOS operating system.
The original first-generation iPhone was a GSM phone and established design precedents, such as a button placement that has persisted throughout all releases and a screen size maintained for the next four iterations. The iPhone 3G added 3G network support, was followed by the 3GS with improved hardware, the 4 with a metal chassis, higher display resolution and front-facing camera, the 4S with improved hardware and the voice assistant Siri; the iPhone 5 featured Apple's newly introduced Lightning connector. In 2013, Apple released the 5S with improved hardware and a fingerprint reader, the lower-cost 5C, a version of the 5 with colored plastic casings instead of metal, they were followed by the larger iPhone 6, with models featuring 4.7-and-5.5-inch displays. The iPhone 6S was introduced the following year, which featured hardware upgrades and support for pressure-sensitive touch inputs, as well as the SE—which featured hardware from the 6S but the smaller form factor of the 5S. In 2016, Apple unveiled the iPhone 7 and 7 Plus, which add water resistance, improved system and graphics performance, a new rear dual-camera setup on the Plus model, new color options, while removing the 3.5 mm headphone jack found on previous models.
The iPhone 8 and 8 Plus were released in 2017, adding a glass back and an improved screen and camera. The iPhone X was released alongside the 8 and 8 Plus, with its highlights being a near bezel-less design, an improved camera and a new facial recognition system, named Face ID, but having no home button, therefore, no Touch ID. In September 2018, Apple again released 3 new iPhones, which are the iPhone XS, an upgraded version of the since discontinued iPhone X, iPhone XS Max, a larger variant with the series' biggest display as of 2018 and iPhone XR, a lower end version of the iPhone X; the original iPhone was described as "revolutionary" and a "game-changer" for the mobile phone industry. Subsequent iterations of the iPhone have garnered praise; the iPhone is one of the most used smartphones in the world, its success has been credited with helping Apple become one of the world's most valuable publicly traded companies. Development of what was to become the iPhone began in 2004, when Apple started to gather a team of 1,000 employees to work on the confidential "Project Purple."
Apple CEO Steve Jobs steered the original focus away from a tablet towards a phone. Apple created the device during a secretive collaboration with Cingular Wireless at the time—at an estimated development cost of US$150 million over thirty months. According to Steve Jobs, the "i" word in "iMac" stands for internet, instruct and inspire. Apple rejected the "design by committee" approach that had yielded the Motorola ROKR E1, a unsuccessful collaboration with Motorola. Among other deficiencies, the ROKR E1's firmware limited storage to only 100 iTunes songs to avoid competing with Apple's iPod nano. Cingular gave Apple the liberty to develop the iPhone's hardware and software in-house and paid Apple a fraction of its monthly service revenue, in exchange for four years of exclusive US sales, until 2011. Jobs unveiled the iPhone to the public on January 9, 2007, at the Macworld 2007 convention at the Moscone Center in San Francisco; the two initial models, a 4 GB model priced at US$499 and an 8 GB model at US$599, went on sale in the United States on June 29, 2007, at 6:00 pm local time, while hundreds of customers lined up outside the stores nationwide.
The passionate reaction to the launch of the iPhone resulted in sections of the media dubbing it the'Jesus phone'. Following this successful release in the US, the first generation iPhone was made available in the UK, Germany in November 2007, Ireland and Austria in the spring of 2008. On July 11, 2008, Apple released the iPhone 3G including the original six. Apple released the iPhone 3G in upwards of eighty territories. Apple announced the iPhone 3GS on June 8, 2009, along with plans to release it in June and August, starting with the US, Canada and major European countries on June 19. Many would-be users objected to the iPhone's cost, 40% of users had household incomes over US$100,000; the back of the original first generation iPhone was made of aluminum with a black plastic accent. The iPhone 3G and 3GS feature a full plastic back to increase the strength of the GSM signal; the iPhone 3G was available in
IPad is a line of tablet computers designed and marketed by Apple Inc. which run the iOS mobile operating system. The first iPad was released on April 3, 2010; as of May 2017, Apple has sold more than 360 million iPads, though sales peaked in 2013. It is the most popular tablet computer by sales as of the second quarter of 2018; the user interface is built around the device's multi-touch screen, including a virtual keyboard. All iPads can connect via Wi-Fi. IPads can shoot video, take photos, play music, perform Internet functions such as web-browsing and emailing. Other functions – games, reference, GPS navigation, social networking, etc. – can be enabled by downloading and installing apps. As of March 2016, the App Store has more than million apps for the iPad by third parties. There have been eight versions of the iPad; the first generation established design precedents. The 2nd-generation iPad introduced a new thinner design, a dual-core Apple A5 processor, VGA front-facing and 720p rear-facing cameras designed for FaceTime video calling.
The third generation added a Retina Display, the new Apple A5X processor with a quad-core graphics processor, a 5-megapixel camera, HD 1080p video recording, voice dictation, 4G. The fourth generation added the Apple A6X processor and replaced the 30-pin connector with an all-digital Lightning connector; the iPad Air added the Apple A7 processor and the Apple M7 motion coprocessor, reduced the thickness for the first time since the iPad 2. The iPad Air 2 added the Apple A8X processor, the Apple M8 motion coprocessor, an 8-megapixel camera, the Touch ID fingerprint sensor; the iPad introduced in 2017 added the Apple A9 processor, while sacrificing some of the improvements the iPad Air 2 introduced in exchange for a lower launch price. There have been five versions of the iPad Mini; the first generation has similar internal specifications to the iPad 2 but uses the Lightning connector instead. The iPad Mini 2 added the Retina Display, the Apple A7 processor, the Apple M7 motion coprocessor matching the internal specifications of the iPad Air.
The iPad Mini 3 added the Touch ID fingerprint sensor. The iPad Mini 4 features the Apple M8 motion coprocessor; the 5th generation features the Apple A12 SoC. There have been three generations of the iPad Pro; the first generation came with 9.7" and 12.9" screen sizes, while the second came with 10.5" and 12.9" sizes, the third with 11" and 12.9" sizes. The iPad Pros have unique features such as the Smart Connector, which are exclusive to this series of iPads. Apple co-founder Steve Jobs said in a 1983 speech that the company's strategy was simple: "What we want to do is we want to put an great computer in a book that you can carry around with you and learn how to use in 20 minutes... and we want to do it with a radio link in it so you don't have to hook up to anything and you're in communication with all of these larger databases and other computers." Apple's first tablet computer was the Newton MessagePad 100, introduced in 1993, powered by an ARM6 processor core developed by ARM, a 1990 spinout of Acorn Computers in which Apple invested.
Apple developed a prototype PowerBook Duo based tablet, the PenLite, but decided not to sell it in order to avoid hurting MessagePad sales. Apple released several more Newton-based PDAs. Apple re-entered the mobile-computing markets in 2007 with the iPhone. Smaller than the iPad, but featuring a camera and mobile phone, it pioneered the multi-touch finger-sensitive touchscreen interface of Apple's iOS mobile operating system. By late 2009, the iPad's release had been rumored for several years; such speculation talked about "Apple's tablet". The iPad was announced on January 27, 2010, by Steve Jobs at an Apple press conference at the Yerba Buena Center for the Arts in San Francisco. Jobs said that Apple had begun developing the iPad before the iPhone. Jonathan Ive in 1991 had created an industrial design for a stylus-based tablet, the Macintosh Folio, as his first project for Apple. Ive stated that after seeking to produce the tablet first, he came to agree with Jobs that the phone was more important, as the tablet's innovations would work as well in it.
The iPad's internal codename was K48, revealed in the court case surrounding leaking of iPad information before launch. Apple began taking pre-orders for the first-generation iPad on March 12, 2010; the only major change to the device between its announcement and being available to pre-order was the change of the behavior of the side switch to perform either sound muting or screen rotation locking. The Wi-Fi version of the iPad went on sale in the United States on April 3, 2010; the Wi-Fi + 3G version was released on April 30. 3G service in the United States is provided by AT&T and was sold with two prepaid contract-free data plan options: one for unlimited data and the other for 250 MB per month at half the price. On June 2, 2010, AT&T announced that effective June 7 the unlimited plan would be replaced for new
OS X Mountain Lion
OS X Mountain Lion is the ninth major release of OS X, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Mountain Lion was released on July 25, 2012 for purchase and download through Apple's Mac App Store, as part of a switch to releasing OS X versions online and every year, rather than every two years or so. Named to signify its status as a refinement of the previous Mac OS X version, Apple's stated aims in developing Mountain Lion were to allow users to more manage and synchronise content between multiple Apple devices and to make the operating system more familiar; the operating system gained the new malware-blocking system Gatekeeper and integration with Apple's online Game Center and iCloud services, while the Safari web browser was updated to version 6. As on iOS, Notes and Reminders became full applications, separate from Mail and Calendar, while the iChat application was replaced with a version of iOS's Messages. Mountain Lion added a version of iOS's Notification Center, which groups updates from different applications in one place.
Integrated links allowing the user to transfer content to Twitter were present in the operating system from launch. Facebook integration was planned but unfinished at launch date, it was released as a downloadable update later. OS X Mountain Lion received positive reviews, with critics praising Notification Center and speed improvements over Mac OS X Lion, while criticizing iCloud for unreliability and Game Center for lack of games. Mountain Lion sold three million units in the first four days, has sold 28 million units as of June 10, 2013, making it Apple's most popular OS X release. Mountain Lion was the last paid upgrade for an OS X major release, with OS X Mavericks and being free. OS X Mountain Lion was announced by Apple on their website on February 16, 2012, as a successor to Mac OS X 10.7 Lion. It achieved golden master status on July 9, 2012. Following a soft transition started with Mac OS X Lion, Apple refers to OS X Mountain Lion as "OS X" rather than "Mac OS X". During the Apple Worldwide Developers Conference keynote on June 11, 2012, Apple announced a "near final" release version of Mountain Lion for developers, with the public version arriving in July 2012 at a price tag of US$19.99.
The third generation MacBook Pro, revised MacBook Air, iPad Smart Case, third-generation AirPort Express were announced at the keynote as well. The specific release date of July 25 was not confirmed until the day before, July 24, by Apple CEO, Tim Cook, as part of Apple's 2012 third-quarter earnings announcement, it was released to the Mac App Store on July 25, 2012, where it sold 3 million units in the first four days of release. An update for Mountain Lion, version 10.8.1, was released on August 23, 2012. It resolved issues with iMessages, Migration Assistant, Microsoft Exchange Server and many other applications. Tests of the update revealed that 10.8.1 improved battery life on laptops, albeit gaining back only half of the battery life, lost in updating to Mountain Lion. Although 10.8.1 improved battery life for some customers, others continue to complain about reduced battery life and a constant drop in battery health resulting in a "Service Battery" message. The official system requirements of OS X 10.8 are 2 GB RAM, 8 GB available storage, OS X 10.6.8 or on any of the following Macs: iMac MacBook, MacBook Pro MacBook Air Mac Mini Mac Pro Xserve As in 10.7, the earliest models supporting AirDrop are the late-2008 MacBook Pro, late-2010 MacBook Air, late-2008 MacBook, mid-2010 Mac Mini, early-2009 Mac Pro with an AirPort Extreme card.
Any Mac released in or after 2011, except the MacBook, supports AirPlay Mirroring. Power Nap is supported on the MacBook Pro with Retina display; the technical basis for these requirements is incompatibility with 32-bit EFI and 32-bit kernel extensions. In order to prevent incompatible systems from installing 10.8, the installer contains a whitelist of supported motherboard IDs. Users have bypassed these limitations so that 10.8 may run with varying functionality on some unsupported computers. Notification Center was 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, how they are handled. There are three types of notifications: banners and badges. Banners are displayed for a short period of time in the upper right corner of the Mac's screen, slide off to the right; the icon of the application is displayed on the left side of the banner, while the message from the application will be displayed on the right side.
Alerts will not disappear from the screen until the user takes action. Badges are red notification icons, they indicate the number of items available for the application. Notification Center can be accessed by clicking the icon in the right corner of the menu bar; when open, the user can click a button to tweet, post status updates to Facebook, or view all notifications in the sidebar pane. Swiping up will reveal the option to disable Notification Center for on