Mac OS X Snow Leopard

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Mac OS X v10.6 Snow Leopard
A release of the Mac OS X operating system
Snow Leopard Desktop.png
Screenshot of Mac OS X Snow Leopard
DeveloperApple Inc.
Source modelClosed source (with open source components)
Released to
August 28, 2009; 5 years ago (2009-08-28)
Latest release10.6.8 v1.1 / July 25, 2011; 3 years ago (2011-07-25)[1]
Update methodApple Software Update
PlatformsIA-32, x86-64[2]
Kernel typeHybrid
LicenseCommercial software license and Apple Public Source License (APSL)
Preceded byMac OS X v10.5 Leopard
Succeeded byMac OS X v10.7 Lion
Support status
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Mac OS X v10.6 Snow Leopard
A release of the Mac OS X operating system
Snow Leopard Desktop.png
Screenshot of Mac OS X Snow Leopard
DeveloperApple Inc.
Source modelClosed source (with open source components)
Released to
August 28, 2009; 5 years ago (2009-08-28)
Latest release10.6.8 v1.1 / July 25, 2011; 3 years ago (2011-07-25)[1]
Update methodApple Software Update
PlatformsIA-32, x86-64[2]
Kernel typeHybrid
LicenseCommercial software license and Apple Public Source License (APSL)
Preceded byMac OS X v10.5 Leopard
Succeeded byMac OS X v10.7 Lion
Support status

Mac OS X Snow Leopard (version 10.6) is the seventh major release of Mac OS X, Apple's desktop and server operating system for Macintosh computers.

Snow Leopard was publicly unveiled on June 8, 2009 at the Apple Worldwide Developers Conference. On August 28, 2009, it was released worldwide,[3] and was made available for purchase from Apple's website and its retail stores at the price of US$29 for a single-user license. As a result of the low price, initial sales of Snow Leopard were significantly higher than that of its predecessors.[4] The release of Snow Leopard came nearly two years after the introduction of Mac OS X Leopard, the second longest time span between successive Mac OS X releases (the time span between Tiger and Leopard was the longest).

Unlike those of previous versions of Mac OS X, the goals of Snow Leopard were improved performance, greater efficiency and the reduction of its overall memory footprint. Addition of new end-user features was not a primary consideration: its name was intended to signify its goal to be a refinement of the previous OS X version, Leopard.[citation needed] Much of the software in Mac OS X was extensively rewritten for this release in order to take advantage fully of modern Macintosh hardware. New programming frameworks, such as OpenCL, were created, allowing software developers to use graphics cards in their applications. This is also the first Mac OS release since System 7.1.1 that does not support Macs using PowerPC processors, as Apple now intends to focus on its current line of Intel-based products.[5] As support for Rosetta was dropped in OS X Lion, Snow Leopard is the last version of Mac OS X that is able to run PowerPC-only applications.

Snow Leopard was succeeded by Mac OS X Lion (version 10.7) on July 20, 2011.[6] Since then, Apple has continued to sell Snow Leopard from its online store for the benefit of users that require Snow Leopard in order to upgrade to later versions of OS X, which have all been distributed through the Mac App Store introduced in the Snow Leopard 10.6.6 update.[7]

Snow Leopard is the last release of Mac OS X to support the 32-bit Intel Core Solo and Intel Core Duo CPUs.

System requirements[edit]

Apple states the following basic Snow Leopard system requirements are:

Additional requirements to use certain features:[8]

Snow Leopard does not support PowerPC-based Macs (e.g., Power Macs, PowerBooks, iBooks, iMacs (G3-G5), all eMacs, plus pre-February 2006 Mac minis and the Power Mac G4 Cube), although PowerPC applications are supported via Rosetta, which is now an optional install.

Use on unsupported hardware[edit]

Some ways of running Mac OS X Snow Leopard on certain unsupported Apple hardware have been discovered. Users who have access to supported hardware have installed Snow Leopard on the supported machine then simply moved the hard drive to the unsupported machine. Alternatively, the Snow Leopard Installation DVD can be booted on a supported Mac, then installed on an unsupported Mac via the Firewire Target Disk Mode.

Since Apple moved to using Intel processors in their computers, the OSx86 community has developed and now also allows Mac OS X Tiger and later releases to be installed and run successfully on non-Apple x86-based computers, albeit in violation of Apple's licensing agreement for Mac OS X.


Snow Leopard is available as an upgrade for Intel-based Macintosh computers. Single-user licenses and "family pack" licenses for up to five computers are available. For qualifying Mac computers bought after June 8, 2009, Apple offered a discounted price through their "up to date" program provided that customers' orders were faxed or postmarked by December 26, 2009. The standalone retail version of Snow Leopard is marketed as being restricted to users of Mac OS X Leopard, while the recommended upgrade path from Apple for Mac OS X Tiger is through the "Mac Box Set", which includes Mac OS X Snow Leopard and the current versions of iLife and iWork.

There are three licenses available.[9] These licenses differ in their requirements for pre-installed versions of Mac OS X:

If you have purchased an Upgrade for Mac OS X Leopard license, then subject to the terms and conditions of this License, you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on a single Apple-branded computer as long as that computer has a properly licensed copy of Mac OS X Leopard already installed on it.[10]

A "Family Pack Upgrade for Mac OS X Leopard" license is also mentioned as a subset of the Leopard Upgrade.

Subject to the terms and conditions of this License ... you are granted a limited non-exclusive license to install, use and run one (1) copy of the Apple Software on a single Apple-branded computer at a time.[10]

It is not entirely clear which license is offered with the retail version of Snow Leopard. As noted above, Apple's website advertised this version as an "upgrade from Mac OS X Leopard for $29" and suggest that others upgrade using the Mac Box Set, implying the stand-alone retail version to be a "Leopard Upgrade" license. On the other hand, some Apple press materials appear to indicate that this version is, in fact, the "Single Use" license:

The Snow Leopard single user license will be available for a suggested retail price of $29 (US)[11] (emphasis added)

However, even if the retail edition of Snow Leopard is in fact a "Leopard Upgrade", the company has acknowledged that there is no technical barrier in that edition preventing a direct upgrade from Mac OS X "Tiger".[12]

The Leopard Upgrade license explicitly applies to the Up-To-Date Program[13] (US$9.95) for Macs bought between June 8 and December 26, 2009[14] and the installation discs provided through this program are clearly marked as upgrades unlike either of the retail editions.

New or changed features[edit]

Mac OS X Snow Leopard is intended to be a release aimed to refine the existing feature set, expand the technological capabilities of the operating system, and improve application efficiency. Many of the changes involve how the system works in the background and are not intended to be seen by the user. For example, the Finder application was completely rewritten in the Cocoa application programming interface. Despite significant changes in the software, users will experience almost no changes in the user interface. Snow Leopard includes the following changes:

The 10.6.6 update introduced support for the Mac App Store, Apple's digital distribution platform for OS X applications.[20]

Refinements to the user interface[edit]

While the Finder was completely rewritten in Cocoa, it did not receive a major user interface overhaul. Instead, the interface has been modified in several areas to promote ease of use. These changes include:

New wallpapers[edit]

As with most upgrades of Mac OS X, new wallpapers are available. There are new wallpapers in the Nature (two of which are of snow leopards), Plants and Black and White sub-folders under the Apple folder. Furthermore, there are new Apple wallpaper sub-folders with multiple wallpapers:

New solid colors can be used as wallpapers as well. There is a new blue and gray, as well as a solid kelp which serves as the "green wallpaper." The default "space nebula" wallpaper has been updated as well.

Dropped features[edit]

Developer technologies[edit]

64-bit architecture[edit]

Mac OS X Tiger added limited support for 64-bit applications on machines with 64-bit processors; Leopard extended the support for 64-bit applications to include applications using most of Mac OS X's libraries and frameworks.

In Snow Leopard, most built-in applications have been rebuilt to use the 64-bit x86-64 architecture (excluding iTunes, Front Row, Grapher and DVD Player applications).[29] They will run in 32-bit mode on machines with 32-bit processors, and in 64-bit mode on machines with 64-bit processors.

In addition, the Mac OS X kernel has been rebuilt to run in 64-bit mode on some machines. On those machines, Snow Leopard supports up to 16 terabytes of RAM. Newer Xserve and Mac Pro machines will run a 64-bit kernel by default; newer iMac and MacBook Pro machines can run a 64-bit kernel, but will not do so by default.[30] Users wishing to use the 64-bit kernel on those machines must hold down the numbers 6 and 4 on the keyboard while booting to get the 64-bit kernel to load.[31][32] A change to the will also enable users with compatible computers to permanently boot into 64-bit for those wishing to do so.

Stuart Harris, software product marketing manager at Apple Australia, said, "For the most part, everything that they experience on the Mac, from the 64-bit point of view, the applications, the operating system, is all going to be 64-bit, but that at this stage there were very few things, such as device drivers, that required 64-bit mode at the kernel level".[32]

With Mac OS X Snow Leopard only the following Apple computers run or are capable of running the 64-bit kernel:[33]

ProductModel identifierK64 status on client versionK64 status on server version
Xserve early 2008 and laterXserve2,1 and higherCapableDefault
Mac Pro early 2008MacPro3,1CapableDefault
Mac Pro early 2009MacPro4,1CapableDefault
Mac Pro mid-2010MacPro5,1DefaultDefault
MacBook Pro early 2008MacBookPro4,1CapableCapable
MacBook Pro late 2008MacBookPro4,1 and 5,1CapableCapable
MacBook Pro early 2009MacBookPro5,2CapableCapable
MacBook Pro mid-2009MacBookPro5,3 and 5,4 and 5,5CapableCapable
MacBook Pro mid-2010MacBookPro6,1 and 6,2 and 7,1CapableCapable
MacBook Pro early 2011MacBookPro8,1 and 8,2 and 8,3DefaultDefault
iMac early 2008 and lateriMac8,1 and higherCapableCapable
Mac Mini mid-2010Macmini4,1CapableDefault

^* Amit Singh has reported that the early 2009 Mac Mini and MacBook may be capable of running the 64-bit kernel; however, Apple has set these models to boot into the 32-bit kernel. With some tweaking, the Unibody MacBook can be set to boot the 64-bit kernel.[34]

Grand Central Dispatch[edit]

Grand Central Dispatch uses the multiple processor cores now in every new Macintosh for more efficient performance. Due to the technical difficulties traditionally involved in making applications optimized for multicore CPUs, the majority of computer applications do not effectively use multiple processor cores.[35] As a result, processing power often goes unused. Grand Central Dispatch includes APIs to help programmers efficiently use these cores for parallel programming.

Grand Central Dispatch shifts thread handling focus to itself rather than leaving it to specific applications to distribute jobs evenly across cores and clears up unused memory created by inactive or old threads to achieve maximum performance. Apple is also releasing APIs for Grand Central Dispatch for developers to use in their applications and also to analyze specific blocks of code running on Grand Central Dispatch.[36]

A new C and Objective-C language feature named "Blocks" facilitates creation of code that will easily optimize to take advantage of Grand Central Dispatch.[37][38][39]


OpenCL (Open Computing Language) addresses the power of graphics processing units (GPUs) to leverage them in any application, and not just for graphics-intensive applications like 3D games. OpenCL automatically optimizes for the kind of graphics processor in the Mac, adjusting itself to the available processing power. OpenCL provides consistent numeric precision and accuracy, fixing a problem that has hampered GPU-based programming in the past.[40]

OpenCL is a C-based programming language with a structure that is already familiar to Mac OS X programmers, who can use Xcode developer tools to adapt their programs to work with OpenCL. Only the most process intensive parts of the application need to be written in OpenCL C without affecting the rest of the code. OpenCL is an open standard that has been supported by AMD, Intel, and Nvidia; it is maintained by Khronos Group.[17]

It serves a similar purpose to Nvidia's C for CUDA and Microsoft's Direct3D 11 compute shaders.

It only works with the following Mac GPUs: NVIDIA GeForce 320M, GT 330M, 9400M, 9600M GT, 8600M GT, GT 120, GT 130, GTX 285, 8800 GT, 8800 GS, Quadro FX 4800, FX 5600 and ATI Radeon HD 4670, HD 4850, HD 4870, HD 5670, HD 5750, HD 5770, HD 5870, HD 6490M, HD 6750M, HD 6770M, HD 6970M.[8] If the system does not possess one of these compatible GPUs, OpenCL code will instead execute on the system's CPU.[41]


CUPS (the printing system used in many Unix-like operating systems) has been updated to version 1.4 which provides improved driver, networking, and Kerberos support along with performance improvements. CUPS 1.4 is also the first implementation of the Internet Printing Protocol version 2.1.[42]

Power management[edit]

Power management has been improved, with implementation of a new wake on demand feature supported on more recent Macintosh hardware.[43] Wake on demand takes advantage of the sleep proxy service implemented in AirPort and Time Capsule routers,[44] so that the computer can sleep while the router responds to mDNS queries. Should the request require the host computer to wake up, the router sends the necessary special wake-up-packet[45] to the sleeping computer.


Apple strengthened Mac OS X by implementing stack protection, and sandboxing more Mac OS X components such as the H.264 decoder in QuickTime and browser plug-ins as a separate process in Safari.[46] An anti-malware feature was also added to the system that alerts the user if malware is detected.[47] Mac OS X 10.6.8 added daily malware definition updates.[48]

Computer security researcher Charlie Miller claims that OS X Snow Leopard is more vulnerable to attack than Microsoft Windows for lacking full address space layout randomization (ASLR) since Mac OS X Leopard,[49] a technology that Microsoft started implementing in Windows Vista.[50]

The Safari web browser has received updates to version 6.0 in Lion and Mountain Lion, but not in Snow Leopard.[51]


Snow Leopard breaks compatibility with several older versions of some applications, such as Parallels Desktop 3.0, versions of Aperture before 2.1.1, and versions of Keynote before 2.0.2, among other software.[52] Apple has also published a list of applications with known compatibility issues with Snow Leopard.[53]

Printer and scanner drivers used by previous versions of Mac OS X are not compatible with Snow Leopard and will be replaced during Snow Leopard installation. Since the initial release of Snow Leopard many manufacturers have provided compatible drivers that are available via Software Update.[54] If a native driver is not available Snow Leopard also includes CUPS and Gutenprint open source drivers that may provide limited functionality.

10.6.0 introduced a bug that frequently prevented DNS queries from returning IPv6 addresses.[55][56][57] This was resolved in 10.6.8.[58]


At the WWDC in 2009, Apple stated that Snow Leopard features no new major visual changes.[59] Instead, the release focuses on refining the operating system to enable better performance.[59]

OSNews reported that Mac OS X Snow Leopard was well received by critics.[60][61]

Engadget reviewed Snow Leopard and pointed out that the price of Snow Leopard dropped from the $129 Apple charged for previous versions of Mac OS X to $29. Engadget's opinion was that this could be largely because most users would not see a noticeable change in the look and feel of the system.[62] However, most reviews commented on the large improvement in speed of the native Mac OS X applications Finder, iCal, Mail, etc.[62]

CNET editors gave it 4 stars out of 5, stating "Intel Mac users will like Snow Leopard's smartly designed interface enhancements, and its Exchange support is a must-have (especially with Outlook for Mac on the way). With a ton of technological improvements, Snow Leopard is worth the $29 upgrade fee."[63]

On October 21, 2009, SFGate blogger Yobie Benjamin wrote that the "MacBook Pro that came preloaded with Snow Leopard kicks butt and is a screaming fast machine", but "when I tried to upgrade one of my 'older' MacBooks, it was a fricking disaster from hell". Apart from upgrading, Benjamin also tried a clean install. But he complained of slowness even after his clean install. He wrote, "I ended up downgrading back to OSX 10.5.8" then he concluded by writing, "I might try to do it again but it won't be till Apple releases at least 2 major fix updates. If you want to roll the dice and try, go ahead... your upgrade might work, however, random installs not working is not good for me. Lesson learned --- I'll wait."[64]

The single-user upgrade and Family Pack units of Snow Leopard ranked 1 and 2 respectively on's software bestseller charts when Apple announced it would release it within the week.[65] highlighted other unexpected improvements including the release of a new version of Boot Camp, version 3.0, a cleaner, popup software update process and screen and video recording in the new QuickTime Player.[66]

The BBC reported that a bug in Mac OS X versions 10.6.0 and 10.6.1 which, in rare cases, caused loss of user account data after use of a previously existing guest account by users who had upgraded from a previous version of Mac OS X, received wide publicity.[67] The bug was fixed as of version 10.6.2.[68]

Release history[edit]

Former Apple CEO Steve Jobs announced Snow Leopard at WWDC on June 9, 2008,[69] and it was privately demonstrated to developers by Senior Vice President of Software Engineering Bertrand Serlet. On Monday, May 11, 2009, after build 10A354, Apple issued a code freeze on Snow Leopard's APIs.[70] The first public demonstration was given at WWDC 2009 by Serlet and Vice President of Mac OS Engineering, Craig Federighi.[5][71]

VersionBuild[72]DateOS nameNotesDownload
10.610A432August 28, 2009Darwin 10.0Original retail DVD releaseN/A
10A433Server edition; Original retail DVD release
10.6.110B504September 10, 2009Darwin 10.1About the Mac OS X v10.6.1 UpdateMac OS X v10.6.1 Update
10.6.210C540November 9, 2009Darwin 10.2About the Mac OS X v10.6.2 UpdateMac OS X v10.6.2 Update
10.6.310D573March 29, 2010Darwin 10.3About the Mac OS X v10.6.3 UpdateMac OS X v10.6.3 Update
10D575April 1, 2010Second retail DVD releaseN/A
10D578April 13, 2010About the Mac OS X v10.6.3 Update; v1.1Mac OS X v10.6.3 v1.1 Update (Combo)
10.6.410F569June 15, 2010Darwin 10.4About the Mac OS X v10.6.4 UpdateMac OS X v10.6.4 Update (Combo)
10.6.510H574November 10, 2010Darwin 10.5About the Mac OS X v10.6.5 UpdateMac OS X v10.6.5 Update (Combo)
10.6.610J567January 6, 2011Darwin 10.6About the Mac OS X v10.6.6 UpdateMac OS X v10.6.6 Update (Combo)
10.6.710J869March 21, 2011Darwin 10.7About the Mac OS X v10.6.7 UpdateMac OS X v10.6.7 Update (Combo)
10J3250March 21, 2011For the early 2011 Macbook ProMac OS X v10.6.7 Update for early 2011 MacBook Pro
10J4138May 4, 2011For the early 2011 Macbook ProMacBook Pro Software Update 1.4
10.6.810K540June 23, 2011Darwin 10.8About the Mac OS X v10.6.8 UpdateMac OS X v10.6.8 Update (Combo)
10K549July 25, 2011About the Mac OS X v10.6.8 Update; v1.1Mac OS X v10.6.8 v1.1 Update (Combo)

Mac OS X Server includes these features and other server-related features. Apple initially stated that Server would include ZFS support, but mention of this feature later disappeared from Apple's website and it was not included in the final release due to licensing issues.[73]

See also[edit]


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External links[edit]