MacOS is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop and home computers, by web usage, it is the second most used desktop OS, after Microsoft Windows.macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, introduced in 1984, the final release of, Mac OS 9 in 1999; the first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, tvOS; the latest version is macOS Mojave, publicly released in September 2018.
Between 1999 and 2009, Apple sold. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is pronounced as such; the X was a prominent part of the operating system's brand identity and marketing in its early years, but receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version have UNIX 03 certification. MacOS shares its Unix-based core, named Darwin, many of its frameworks with iOS, tvOS and watchOS.
A modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV. Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion run on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, do not support PowerPC applications. The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, launched in 1989; the kernel of NeXTSTEP is based upon the Mach kernel, developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent and Gershwin projects, but all of them were abandoned.
This led Apple to purchase NeXT in 1996, allowing NeXTSTEP called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase led to Steve Jobs returning to Apple as an interim, 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 officially named Mac OS X. Mac OS X was presented as the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, as with Mac OS 8 and Mac OS 9; the letter "X" in Mac OS X's name refers to a Roman numeral. It is therefore pronounced "ten" in this context. However, it is commonly pronounced like the letter "X"; the first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system.
Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; the consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing 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 Mac 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 developed several new releases of Mac OS X. Siracusa's review of version 10.3, 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 shocked executives at Microsoft by offering a number of features, such as fast file s
Macintosh operating systems
The family of Macintosh operating systems developed by Apple Inc. includes the graphical user interface-based operating systems it has designed for use with its Macintosh series of personal computers since 1984, as well as the related system software it once created for compatible third-party systems. In 1984, Apple debuted the operating system, now known as the "Classic" Mac OS with its release of the original Macintosh System Software; the system, rebranded "Mac OS" in 1996, was preinstalled on every Macintosh until 2002 and offered on Macintosh clones for a short time in the 1990s. Noted for its ease of use, it was criticized for its lack of modern technologies compared to its competitors; the current Mac operating system is macOS named "Mac OS X" until 2012 and "OS X" until 2016. Developed between 1997 and 2001 after Apple's purchase of NeXT, Mac OS X brought an new architecture based on NeXTSTEP, a Unix system, that eliminated many of the technical challenges that the classic Mac OS faced.
The current macOS is updated annually. It is the basis of Apple's current system software for its other devices, iOS, watchOS, tvOS. Prior to the introduction of Mac OS X, Apple experimented with several other concepts, releasing different products designed to bring the Macintosh interface or applications to Unix-like systems or vice versa, A/UX, MAE, MkLinux. Apple's effort to expand upon and develop a replacement for its classic Mac OS in the 1990s led to a few cancelled projects, code named Star Trek and Copland. Although they have different architectures, the Macintosh operating systems share a common set of GUI principles, including a menu bar across the top of the screen; the "classic" Mac OS is the original Macintosh operating system, introduced in 1984 alongside the first Macintosh and remained in primary use on Macs through 2001. Apple released the original Macintosh on January 24, 1984, it was named "System Software", or "System". Classic Mac OS is characterized by its monolithic design.
Initial versions of the System Software run one application at a time. System 5 introduced cooperative multitasking. System 7 supports virtual memory, allowing larger programs. Updates to the System 7 enable the transition to the PowerPC architecture; the system was considered user-friendly, but its architectural limitations are notably criticed, such as limited memory management, lack of protected memory and access controls, susceptibility to conflicts among extensions. Nine major versions of the classic Mac OS were released; the name "Classic" that now signifies the system as a whole is a reference to a compatibility layer that helped ease the transition to Mac OS X. Macintosh System Software – "System 1", released in 1984 System Software 2, 3, 4 – released between 1985 and 1987 System Software 5 – released in 1987 System Software 6 – released in 1988 System 7 / Mac OS 7.6 – released in 1991 Mac OS 8 – released in 1997 Mac OS 9 – final major version, released in 1999 macOS is the current Mac operating system that succeeded the classic Mac OS in 2001.
Although the system was marketed as "version 10" of Mac OS, it has a history, independent of the classic Mac OS. It is a Unix-based operating system built on NeXTSTEP and other technology developed at NeXT from the late 1980s until early 1997, when Apple purchased the company and its CEO Steve Jobs returned to Apple. Precursors to the original release of Mac OS X include OpenStep, Apple's Rhapsody project, the Mac OS X Public Beta. MacOS makes use of the BSD codebase and the XNU kernel, its core set of components is based upon Apple's open source Darwin operating system; the first desktop version of the system was released on March 24, 2001, supporting the Aqua user interface. Since several more versions adding newer features and technologies have been released. Since 2011, new releases have been offered on an annual basis. Mac OS X 10.0 – code name "Cheetah", released to end users on Saturday, March 24, 2001 Mac OS X 10.1 – code name "Puma", released to end users on Tuesday, September 25, 2001 Mac OS X 10.2 – marketed as "Jaguar", released to end users on Friday, August 23, 2002 Mac OS X Panther – version 10.3, released to end users on Friday, October 24, 2003 Mac OS X Tiger – version 10.4, released to end users on Friday, April 29, 2005 Mac OS X Leopard – version 10.5, released to end users on Friday, October 26, 2007 Mac OS X Snow Leopard – version 10.6, publicly unveiled on Monday, June 8, 2009 Mac OS X Lion – version 10.7, released to end users on Wednesday, July 20, 2011 OS X Mountain Lion – version 10.8, released to end users on Wednesday, July 25, 2012 OS X Mavericks – version 10.9, released to end users on Tuesday, October 22, 2013 OS X Yosemite – version 10.10, released to end users on Thursday, October 16, 2014 OS X El Capitan – version 10.11, released to end users on Wednesday, September 30, 2015 macOS Sierra – version 10.12, released to end users on Tuesday, September 20, 2016 macOS High Sierra – version 10.13, released to end users on Monday, September 25, 2017 macOS Mojave – version 10.14, released to end users on Monday, September 24, 2018 An early server computing version
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
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
Open-source software is a type of computer software in which source code is released under a license in which the copyright holder grants users the rights to study and distribute the software to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration. Open-source software development generates an more diverse scope of design perspective than any company is capable of developing and sustaining long term. A 2008 report by the Standish Group stated that adoption of open-source software models have resulted in savings of about $60 billion per year for consumers. In the early days of computing and developers shared software in order to learn from each other and evolve the field of computing; the open-source notion moved to the way side of commercialization of software in the years 1970-1980. However, academics still developed software collaboratively. For example Donald Knuth in 1979 with the TeX typesetting system or Richard Stallman in 1983 with the GNU operating system.
In 1997, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the hacker community and free-software principles. The paper received significant attention in early 1998, was one factor in motivating Netscape Communications Corporation to release their popular Netscape Communicator Internet suite as free software; this source code subsequently became the basis behind SeaMonkey, Mozilla Firefox and KompoZer. Netscape's act prompted Raymond and others to look into how to bring the Free Software Foundation's free software ideas and perceived benefits to the commercial software industry, they concluded that FSF's social activism was not appealing to companies like Netscape, looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The new term they chose was "open source", soon adopted by Bruce Perens, publisher Tim O'Reilly, Linus Torvalds, others; the Open Source Initiative was founded in February 1998 to encourage use of the new term and evangelize open-source principles.
While the Open Source Initiative sought to encourage the use of the new term and evangelize the principles it adhered to, commercial software vendors found themselves threatened by the concept of distributed software and universal access to an application's source code. A Microsoft executive publicly stated in 2001 that "open source is an intellectual property destroyer. I can't imagine something that could be worse than this for the software business and the intellectual-property business." However, while Free and open-source software has played a role outside of the mainstream of private software development, companies as large as Microsoft have begun to develop official open-source presences on the Internet. IBM, Oracle and State Farm are just a few of the companies with a serious public stake in today's competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS; the free-software movement was launched in 1983. In 1998, a group of individuals advocated that the term free software should be replaced by open-source software as an expression, less ambiguous and more comfortable for the corporate world.
Software licenses grant rights to users which would otherwise be reserved by copyright law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition; the most prominent and popular example is the GNU General Public License, which "allows free distribution under the condition that further developments and applications are put under the same licence", thus free. The open source label came out of a strategy session held on April 7, 1998 in Palo Alto in reaction to Netscape's January 1998 announcement of a source code release for Navigator. A group of individuals at the session included Tim O'Reilly, Linus Torvalds, Tom Paquin, Jamie Zawinski, Larry Wall, Brian Behlendorf, Sameer Parekh, Eric Allman, Greg Olson, Paul Vixie, John Ousterhout, Guido van Rossum, Philip Zimmermann, John Gilmore and Eric S. Raymond, they used the opportunity before the release of Navigator's source code to clarify a potential confusion caused by the ambiguity of the word "free" in English.
Many people claimed that the birth of the Internet, since 1969, started the open-source movement, while others do not distinguish between open-source and free software movements. The Free Software Foun
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
X86-64 is the 64-bit version of the x86 instruction set. It introduces two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mode. With 64-bit mode and the new paging mode, it supports vastly larger amounts of virtual memory and physical memory than is possible on its 32-bit predecessors, allowing programs to store larger amounts of data in memory. X86-64 expands general-purpose registers to 64-bit, as well extends the number of them from 8 to 16, provides numerous other enhancements. Floating point operations are supported via mandatory SSE2-like instructions, x87/MMX style registers are not used. In 64-bit mode, instructions are modified to support 64-bit addressing mode; the compatibility mode allows 16- and 32-bit user applications to run unmodified coexisting with 64-bit applications if the 64-bit operating system supports them. As the full x86 16-bit and 32-bit instruction sets remain implemented in hardware without any intervening emulation, these older executables can run with little or no performance penalty, while newer or modified applications can take advantage of new features of the processor design to achieve performance improvements.
A processor supporting x86-64 still powers on in real mode for full backward compatibility. The original specification, created by AMD and released in 2000, has been implemented by AMD, Intel and VIA; the AMD K8 processor was the first to implement it. This was the first significant addition to the x86 architecture designed by a company other than Intel. Intel was forced to follow suit and introduced a modified NetBurst family, software-compatible with AMD's specification. VIA Technologies introduced x86-64 with the VIA Nano; the x86-64 architecture is distinct from the Intel Itanium architecture, not compatible on the native instruction set level with the x86 architecture. Operating systems and applications written for one cannot be run on the other. AMD64 was created as an alternative to the radically different IA-64 architecture, designed by Intel and Hewlett Packard. Announced in 1999 while a full specification became available in August 2000, the AMD64 architecture was positioned by AMD from the beginning as an evolutionary way to add 64-bit computing capabilities to the existing x86 architecture, as opposed to Intel's approach of creating an new 64-bit architecture with IA-64.
The first AMD64-based processor, the Opteron, was released in April 2003. AMD's processors implementing the AMD64 architecture include Opteron, Athlon 64, Athlon 64 X2, Athlon 64 FX, Athlon II, Turion 64, Turion 64 X2, Phenom, Phenom II, FX, Fusion/APU and Ryzen/Epyc; the primary defining characteristic of AMD64 is the availability of 64-bit general-purpose processor registers, 64-bit integer arithmetic and logical operations, 64-bit virtual addresses. The designers took the opportunity to make other improvements as well; some of the most significant changes are described below. 64-bit integer capability All general-purpose registers are expanded from 32 bits to 64 bits, all arithmetic and logical operations, memory-to-register and register-to-memory operations, etc. can now operate directly on 64-bit integers. Pushes and pops on the stack default to 8-byte strides, pointers are 8 bytes wide. Additional registers In addition to increasing the size of the general-purpose registers, the number of named general-purpose registers is increased from eight in x86 to 16.
It is therefore possible to keep more local variables in registers rather than on the stack, to let registers hold accessed constants. AMD64 still has fewer registers than many RISC instruction sets or VLIW-like machines such as the IA-64. However, an AMD64 implementation may have far more internal registers than the number of architectural registers exposed by the instruction set. Additional XMM registers Similarly, the number of 128-bit XMM registers is increased from 8 to 16; the traditional x87 FPU register stack is not included in the register file size extension in 64-bit mode, compared with the XMM registers used by SSE2, which did get extended. The x87 register stack is not a simple register file although it does allow direct access to individual registers by low cost exchange operations. Larger virtual address space The AMD64 architecture defines a 64-bit virtual address format, of which the low-order 48 bits are used in current implementations; this allows up to 256 TB of virtual address space.
The architecture definition allows this limit to be raised in future implementations to the full 64 bits, exten