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Mac OS X

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Mac OS X is a line of proprietary, graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessor, Mac 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.

The operating system 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, four more distinct "end-user" and "server" editions of Mac OS X have been released, the most recent being Mac OS X v10.4, which was first made available in April 2005. Releases of Mac OS X are named after big cats; Mac OS X v10.4 is usually referred to by Apple and users as "Tiger".

The server edition, Mac OS X Server, is architecturally identical to its desktop counterpart but usually runs on Apple's line of Macintosh server hardware. Mac OS X Server includes workgroup management and administration software tools that provide simplified access to key network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others.

Apple also produces customized versions of the Mac OS X operating system for use on two of their consumer devices, the Apple TV and the iPhone.


[edit] History

Despite its branding as simply "version 10" of the Mac OS, Mac OS X has a history that is almost completely independent of the earlier Mac OS releases.

Mac OS X is based on the Mach kernel and is derived from the BSD implementation of Unix in NEXTSTEP. NEXTSTEP was the object-oriented operating system developed by Steve Jobs's NeXT company after he left Apple in 1985. Meanwhile, during the years without Jobs at the helm, Apple attempted to create a "next-generation" operating system of its own through the Taligent and Copland projects, with little success.

Eventually, NeXT's OS — called OPENSTEP at the time — was selected to form the basis for Apple's next OS, and Apple purchased NeXT outright. Steve Jobs came back to Apple as interim CEO with the purchase of NeXT by Apple, and later returned to the leadership of the company, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be welcomed by Apple's primary market of home users and creative professionals. The project was first known as Rhapsody, and was later renamed to Mac OS X.

With each new version, Mac OS X evolved away from a focus on backward compatibility with the earlier versions of Mac OS toward an emphasis on "digital lifestyle" applications such as the iLife suite, enhanced business applications (iWork), and integrated home entertainment (the Front Row media center). Each version also included modifications to the general interface, such as the brushed metal appearance that was added in version 10.2, the unified appearance in version 10.4, and the slight differences in the "streetlight" buttons between versions.

[edit] Description

Mac OS X was a radical departure from previous Macintosh operating systems; its underlying code base is completely different from previous versions. Its core, named Darwin, is an open source, Unix-like operating system built on top of the XNU kernel, with standard Unix facilities available from the command line interface. Apple layered over Darwin a number of proprietary components, including the Aqua interface and the Finder, to complete the GUI-based operating system which is Mac OS X.

Mac OS X included a number of features intended to make the operating system more stable and reliable than Apple's previous operating systems. Pre-emptive multitasking and memory protection, for example, improved the ability of the operating system to run multiple applications simultaneously without them interrupting or corrupting each other. Many aspects of Mac OS X's architecture are derived from OPENSTEP, which was designed with portability in mind, thus easing the transition from one platform to another. For example, NEXTSTEP was ported from the original 68k-based NeXT workstations to other architectures before NeXT was purchased by Apple, and OPENSTEP was subsequently ported to the PowerPC architecture as part of the Rhapsody project.

The most visible change was the Aqua theme. The use of soft edges, translucent colors, and pinstripes — similar to the hardware design of the first iMacs — brought more texture and color to the interface than OS 9's "Platinum" appearance had offered. Numerous users of the older versions of the operating system decried the new look as "cutesy" and lacking in professional polish. However, Aqua has been said to be a bold and innovative step forward in a time when user interfaces were seen as being "dull and boring". Despite the controversy, the look was instantly recognizable, and even before the first version of Mac OS X was released, third-party developers started producing skins for customizable applications which mimicked the Aqua appearance. To some extent, Apple has used the successful transition to this new design as leverage, at various times threatening legal action against people who make or distribute software with an interface the company claims is derived from its copyrighted design.

Mac OS X includes its own software development tools, most prominently an integrated development environment called Xcode. Xcode provides interfaces to compilers that support several programming languages including C, C++, Objective-C, and Java. For the Apple Intel Transition, it was modified so that developers could easily create a universal binary to remain compatible with both the Intel-based and PowerPC-based Macintosh.

[edit] Compatibility

[edit] Software

To permit a smooth transition from Mac OS 9 to Mac OS X, the Carbon Application Programming Interface (API) was created. Applications written with Carbon can run natively on both systems. On the other hand, as mentioned before, Mac OS X inherited from OPENSTEP's APIs, which are not backward compatible with earlier versions of Mac OS. These APIs are now referred by Apple as Cocoa. This heritage is highly visible for Cocoa developers, since most Cocoa class names begin with the "NS" prefix, for NEXTSTEP.

Mac OS X used to support the Java Platform as a "first class citizen" — in practice this means that applications written in Java fit as neatly into the operating system as possible while still being cross-platform, and that graphical user interfaces written in Swing look almost exactly like native Cocoa interfaces. Traditionally, Cocoa programs have been mostly written in Objective-C, with Java as an alternative. However, on July 11 2005, Apple announced that "features added to Cocoa in Mac OS X versions later than 10.4 will not be added to the Cocoa-Java programming interface."

Because Mac OS X is based on UNIX, most software packages written for BSD or Linux can be recompiled to run on it. Projects such as Fink, MacPorts and Pkgsrc offer a service similar to APT on Debian, providing precompiled or preformatted packages for many standard packages. Since version 10.3, Mac OS X has included, the company's version of the X Window System graphical interface for Unix applications, as an optional component during installation. Up to and including Tiger, Apple's implementation was based on the X11 Licensed XFree86 4.3 and X11R6.6. All bundled versions of X11 feature a window manager which is similar to the Mac OS X look-and-feel and has fairly good integration with Mac OS X (see Criticisms section), also using the native Quartz rendering system. Earlier versions of Mac OS X (in which X11 has not been bundled) can also run X11 applications using XDarwin.

[edit] Hardware

For the early releases of Mac OS X, the standard hardware platform supported was the full line of Macintosh computers (laptop, desktop, or server) based on PowerPC G3, G4, and G5 processors. Later versions of Mac OS X discontinued support for some older hardware; for example, Panther does not support "beige" G3s, and Tiger does not support systems that pre-date Apple's introduction of FireWire ports. However, tools such as XPostFacto and patches applied to the installation disc have been developed by third parties to enable installation of newer versions of Mac OS X on systems not officially supported by Apple, including some pre-G3 systems. Except for features requiring specific hardware (e.g. graphics acceleration, DVD writing), the operating system offers the same functionality on all supported hardware.

PowerPC versions of Mac OS X retain compatibility with older Mac OS applications by providing an emulation environment called Classic, which allows users to run Mac OS 9 as a process within Mac OS X, so that most older applications run as they would under the older operating system. Classic is not supported on newer Intel-based Macs.

In April 2002, eWeek reported a rumor that Apple had a version of Mac OS X code-named Marklar which ran on Intel x86 processors. The idea behind Marklar was to keep Mac OS X running on an alternative platform should Apple become dissatisfied with the progress of the PowerPC platform. These rumors subsided until late in May 2005, when various media outlets, such as the Wall Street Journal reported that Apple would unveil Marklar in the coming months.

On June 6 2005, Steve Jobs confirmed these rumors when he announced in his keynote address at the annual Apple Worldwide Developers Conference that Apple would be making the transition from PowerPC to Intel processors over the following two years, and that Mac OS X would support both platforms during the transition. The last time that Apple switched CPU families — from the Motorola 68K CPU to the IBM/Motorola PowerPC — Apple included a Motorola 68K emulator in the new OS that made almost all 68K software work automatically on the new hardware. Apple has supported the 68K emulator for 11 years; however, Apple will be dropping support for the 68K emulator during the transition to Intel CPUs. Included in the new OS for the Intel-based Macs is Rosetta, a binary translation layer which enables software compiled for PowerPC Mac OS X to run on Intel Mac OS X machines. However, Apple dropped support for Classic mode on the new Intel Macs. Third party emulation software such as Mini vMac, Basilisk II and SheepShaver provides support for some early versions of Mac OS. A new version of Xcode and the underlying command-line compilers support building universal binaries that will run on either architecture.

Software that is only available for PowerPC is supported with Rosetta. However, Apple encourages developers to produce universal binaries with support for both PowerPC and x86. Universal binary software should run faster on Intel-based Macs than PowerPC-only software running on Rosetta. Moreover, some PowerPC software, such as kernel extensions and System Preferences plugins, are not supported on Intel Macs. While Intel Macs will be able to run PowerPC, x86 and universal binaries, PowerPC Macs will only support universal and PowerPC builds.

Support for the PowerPC platform will remain in version 10.5. Jobs also confirmed rumors that Apple has had versions of Mac OS X running on Intel processors for most of its developmental life. Such cross-platform capability already existed in Mac OS X's lineage, as said earlier; OPENSTEP was ported to many architectures, including x86, and Darwin included support for both PowerPC and x86. Although Apple stated that Mac OS X would not run on Intel-based personal computers aside from its own, a hacked version of the OS compatible with conventional x86 hardware has been developed by the OSx86 community and is available illegally through file-sharing networks.

[edit] Prominent features

  • Quartz's internal imaging model correlates well with the Portable Document Format (PDF) imaging model, making it easy to output PDF to multiple devices.
  • Full-color, continuously scalable icons.
  • Drop shadows around window and isolated text elements to provide a sense of depth.
  • Global application Services menu - spell checker, special characters palette, color picker, font chooser and dictionary.
  • Anti-aliasing of widgets, text, graphics and window elements.
  • New interface elements including sheets (document modal dialog boxes attached to specific windows) and drawers.
  • Interweaving windows of different applications (not necessarily adjacent in the visible stacking order).
  • ColorSync color matching built into the core drawing engine, for print and multimedia professionals.
  • OpenGL composites windows onto the screen to allow hardware accelerated drawing. This technology (introduced in version 10.2) is called Quartz Extreme.
  • Dashboard (introduced in version 10.4) supports small applications called desktop widgets that can be called up and dismissed in one keystroke.
  • Exposé (introduced in version 10.3) instantly displays all open windows as thumbnails for easy navigation to different tasks, displays all open windows as thumbnails from the current application, and hides all windows to access the desktop.
  • Pervasive use of Unicode throughout the operating system.
  • Straightforward architecture for localization of applications and other code, fully separating language dependencies from the core code of a program.
  • FileVault (introduced in version 10.3) encrypts the user's Home folder with Advanced Encryption Standard (AES) 128-bit keys.
  • Spotlight search technology (introduced in version 10.4) allows rapid real-time searches of data files, mail messages, photos, and other information, based on item properties (meta data) and/or content.
  • Automator (introduced in version 10.4) — an application designed to create an automatic work-flow for different tasks.
  • Smart Folders (introduced in version 10.4) allow for dynamically updated folders depending on a set criteria.
  • A well defined set of Human Interface Guidelines followed by almost all applications giving them intuitive, consistent user interface and keyboard shortcuts.
  • Xgrid allows networked Macs to form a distributed computing system.
  • Built in virtual file system images .dmg supporting encryption and compression, and optionally read/write capability.
  • Integrated Sync Services (introduced in version 10.4) allows applications to access a centralized extensible database for various elements of user data, including calendar and contact items. The operating system manages conflicting edits and data consistency.

[edit] Versions

The character X is a Roman numeral and is officially pronounced "ten". It is the next logical release following the numbering of previous Macintosh operating systems such as Mac OS 8 and Mac OS 9. However, it is common to hear it pronounced as the letter "X".

Mac OS X versions are named after big cats. Prior to its release, version 10.0 was code named "Cheetah" internally at Apple, and version 10.1 was code named internally as "Puma". After the immense buzz surrounding version 10.2, codenamed "Jaguar", Apple's product marketing began openly using the code name to promote the operating system. 10.3 was similarly marketed as "Panther". Version 10.4 is marketed as "Tiger". "Leopard" has been announced as the name for the next release of the operating system, version 10.5. While "Panther", "Tiger" and "Leopard" are registered as trademarks of Apple, "Cheetah", "Puma" and "Jaguar" have never been registered. Apple has also registered "Lynx" and "Cougar" as trademarks.

Apple faced a lawsuit from a computer retailer named Tiger Direct regarding its use of the name "Tiger". However, on May 16, 2005 a federal court in the Southern District of Florida ruled that Apple's use of the name "Tiger" does not infringe upon Tiger Direct's trademark.

[edit] Mac OS X 10.0 (Cheetah)

On March 24, 2001, Apple released Mac OS X v10.0 (internally codenamed Cheetah). The initial version was slow, not feature complete, and had very few applications available at the time of its launch, mostly from independent developers. Many critics suggested that while the OS 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, and Mac OS X began garnering praise for its stability at an early point in its development.

[edit] Mac OS X 10.1 (Puma)

Later that year on September 25, 2001, Mac OS X v10.1 (internally codenamed Puma) was released. The upgrade increased the performance of the system and provided missing features, such as DVD playback. Apple released 10.1 as a free upgrade CD for 10.0 users, in addition to the US$129 boxed version for people running only Mac OS 9. It was discovered that the upgrade CDs were actually full install CDs that could be used with Mac OS 9 systems by removing a specific file; Apple subsequently re-released the CDs in an actual stripped-down format that didn't facilitate installation on such systems.

On January 7, 2002, Apple announced that Mac OS X was to be the default operating system for all Macintosh products by the end of that month.

[edit] Mac OS X 10.2 (Jaguar)

On August 24, 2002, Apple followed up with Mac OS X v10.2 "Jaguar" (the first release to use its code name as part of the branding) which brought profound performance enhancements, a newer, sleeker look, and many powerful enhancements (over 150, according to Apple), including Quartz Extreme for compositing graphics directly on the AGP-based video card, a system-wide repository for contact information in the new Address Book, and its own instant messenging client, named iChat.

Some consider version 10.2, or Jaguar, the "first good release" of Mac OS X. Due to significant API changes between 10.1 and 10.2, most third party developers currently support 10.2 as a minimum requirement.

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 10.2.

[edit] Mac OS X 10.3 (Panther)

Mac OS X v10.3 "Panther" was released on October 24, 2003. In addition to providing much improved performance, it also incorporated the most extensive update yet to the user interface. The update included as many or more new features as Jaguar had the year before. On the other hand, support for some early G3 computers such as "beige" Power Macs and "WallStreet" PowerBooks was discontinued. New features of "Panther" include an updated Finder, incorporating a brushed-metal interface, Exposé, Fast User Switching, FileVault, Safari (web browser), iChat AV which added video-conferencing features to iChat, improved PDF rendering and much greater Microsoft Windows interoperability.

[edit] Mac OS X 10.4 (Tiger)

Mac OS X v10.4 "Tiger" was released on April 29, 2005. Apple stated that Tiger contains more than 200 new features. As with the release of Panther certain older machines have been dropped from the list of supported hardware; Tiger requires a Mac with a built-in FireWire port. Among the new features, the release of Tiger introduced Spotlight, Dashboard, Smart Folders, updated Mail program with Smart Mailboxes, QuickTime 7, Safari 2, Automator, VoiceOver, Core Image and Core Video.

The retail package of Mac OS X Tiger was updated one year later around the end of April, 2006 to be sold in a smaller-size package. This installer, which replaced the first release in the retail market supply chain, was Mac OS X 10.4.3.

On January 10th, 2006, Apple released the first Intel Macintoshes along with the 10.4.4 update to Tiger. This operating system functioned identically on the PowerPC-based Macintoshes and the new Intel-based machines. Because the implementation of the operating system is built separately for the two processors, in implementation the PowerPC version and Intel versions are two separate installers (one cannot use the PowerPC installer to install the OS onto an Intel-based Mac).

At some time in 2006 the retail packages were again updated with 10.4.6, also a PowerPC-only DVD installer. As of yet, no retail package for an Intel-based Tiger Installer exists or has been released by Apple (customers who own an Intel-based Mac received Tiger along with their computer).

[edit] Mac OS X 10.5 (Leopard)

Mac OS X v10.5 "Leopard" was announced at the Worldwide Developers Conference on June 6, 2005, and was shown to developers for the first time at the 2006 Worldwide Developers Conference on August 7, 2006. There Steve Jobs stated that Apple plans to "ship it this coming Spring", referring to the second quarter of 2007. However, due to the developer resources needed to keep the iPhone on track, Apple later revised the estimate to October of 2007, with a feature complete beta ready for the WWDC conference in June.

[edit] See also

[edit] External links

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