Mac OS X v10.6 Snow Leopard
Part of the Mac OS X family
Screenshot of Mac OS X Snow Leopard
Developer
Apple Inc.
Website	www.apple.com/macosx/
Releases
Release date	August 28, 2009 (info)
Current version	10.6.2 (November 9, 2009) (info)
Source model	Closed source (with open source components)
License	APSL and Apple EULA
Kernel type	32-bit or 64-bit Hybrid kernel
Update method	Apple Software Update
Platform support	IA-32, x86-64[1]
Support status
Supported

Mac OS X Snow Leopard (version 10.6) is the seventh major release of Mac OS X, Apple's desktop and server operating system. Apple CEO Steve Jobs announced Snow Leopard at WWDC on June 9, 2008, and it was privately demonstrated to developers by Senior Vice President of Software Engineering, Bertrand Serlet. A first public demonstration was given at WWDC 2009 by Serlet and Phil Schiller, Senior Vice President of Worldwide Marketing.^[2]

This version of Mac OS X focuses on improving performance, efficiency and reducing its overall memory footprint compared to its predecessor Mac OS X v10.5 "Leopard", rather than new end-user features. This is also the first Mac OS release since the introduction of System 7.1.2 that does not support the PowerPC architecture, as Apple now intends to focus on its current line of Intel-based products.^[2]

Snow Leopard was released on August 28, 2009,^[3] and is available as an upgrade for Intel-based Macintosh computers. Single-user licenses and "family pack" licenses for up to five computers are available, and for qualifying Mac computers bought after June 8, 2009, Apple offers a discounted price through their "up to date" program. While the Snow Leopard release was originally described as an upgrade for users of Mac OS X v10.5 "Leopard", the company later said that this will also work for Mac OS X v10.4 "Tiger" users as well.^[4] For users of OS X "Tiger", Apple has released the "Mac Box Set", which includes OS X Snow Leopard, iLife '09, and iWork '09.

Contents 1 System requirements 2 License 3 Changes 3.1 New features 3.1.1 Refinements to the user interface 3.1.2 New wallpapers 3.2 Dropped features 3.3 Developer technologies 3.3.1 64-bit architecture 3.3.2 Grand Central Dispatch 3.3.3 OpenCL 3.3.4 CUPS 3.3.5 Power management 4 Security 5 Compatibility 6 Reception 7 Development history 7.1 Version history 8 References 9 External links

[edit] System requirements

Apple states the following basic Snow Leopard system requirements, although, for some specific applications such as QuickTime H.264 hardware acceleration support and OpenCL, a supported GPU is required (NVIDIA GeForce 8600M GT or ATI Radeon HD 4850 and newer):^[5]

• Mac computer with an Intel processor (IA-32 "Yonah" processors such as Core Solo and Core Duo will only be able to run 32-bit applications; later x86-64 architecture processors such as Core 2 will also be able to run 64-bit applications)
• 1 GB of RAM
• 5 GB of free disk space
• DVD drive (also accessible via Remote Disc) or external USB or FireWire DVD drive for installation

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.

[edit] License

There are three licenses available.^[6] These licenses differ in their requirements for pre-installed versions of Mac OS X:

• Leopard Upgrade: requires that Mac OS X 10.5 Leopard already be installed.

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.^[7]

• Single Use: places no restriction on which (if any) version of Mac OS X should already be installed. Used for the non-upgrade and Mac Box Set versions of Snow Leopard.

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.^[7]

• Family Pack: identical to the Single Use license, in this respect.

The license Apple's website^[8] advertises as "upgrade from Mac OS X Leopard for $29" is not the Leopard Upgrade license, but the Single Use license.

The Snow Leopard single user license will be available for a suggested retail price of $29 (US)^[9]

The Snow Leopard Upgrade license applies to the Up-To-Date Program^[10] (US$9.95) for Macs bought between June 8 and December 26, 2009.^[11]

[edit] Changes

Snow Leopard includes the following changes:

[edit] New features

• Boot Camp now allows Windows partitions to read and copy files from HFS+ partitions. The new version also adds support for advanced features on Cinema Displays and a new command-line version of the Startup Disk Control Panel.
• The Finder has been completely rewritten in 64-bit Cocoa to take advantage of the new technologies introduced in Snow Leopard. This has resulted in a much smaller OS footprint, taking up about 7 GB less space than Mac OS X v10.5 did. The large amount of recovered disk space has also been attributed to the fact that printer drivers are now downloaded or installed only as needed, rather than being all installed at once. The default install only contains those drivers needed for existing printers and a small subset of popular printers.^[12]
• iChat enhancements include greater resolution video chats in iChat Theater and lowered upload bandwidth requirements.
• Microsoft Exchange support is now integrated into the Mail, Address Book, and iCal applications. However, only Microsoft Exchange 2007 is supported and customers using prior versions of Exchange must either upgrade or use Microsoft Entourage.
• Full multi-touch support has been added to notebooks prior to those introduced in October 2008. While the original MacBook Air and other early multi-touch enabled notebooks had support for some gestures, they were unable to use four-finger gestures. This limitation has now been removed in Snow Leopard.
• Preview now has artificial intelligence algorithms that allow it to infer the structure of a paragraph in a PDF document.
• QuickTime X, the next version of QuickTime player and multimedia framework, has been completely rewritten into a full 64-bit Cocoa application and builds on the media technologies in Mac OS X, such as Core Audio, Core Video, and Core Animation, to deliver playback. Apple has redesigned the QuickTime user interface to resemble the full-screen QuickTime view in prior versions, where the entire window displays the video and all controls including the title bar fade in and out as needed. QuickTime X also supports HTTP live streaming and takes advantage of ColorSync to provide high-quality color reproduction.^[13] If Snow Leopard is installed on a Mac with an nVidia GeForce 9400M graphics card, QuickTime X will be able to use its video-decoding capabilities to reduce CPU load.
• Safari 4 features Top Sites, Cover Flow, VoiceOver, expanded standards support, and built-in crash resistance, which prevents browser crashes caused by plug-ins by running them in separate processes. Safari 4 is not new to Snow Leopard, as it is available for free in Mac OS X 10.4 (Tiger) and 10.5 (Leopard).
• Time Machine connection establishment and backups are now much faster.
• VoiceOver has also been greatly enhanced in Snow Leopard. Reading of web pages is improved with Auto Web Spots — areas of a page automatically designated for quick access. On newer Apple portables, trackpad gestures can be used to control many VoiceOver functions, including the "rotor" gesture first seen in VoiceOver for the iPhone 3GS, allowing for the changing of certain VoiceOver navigation options by rotating fingers on the trackpad. Braille Display support is also improved, with Bluetooth displays supported for the first time.^[14]

[edit] Refinements to the user interface

While the Finder was completely rewritten in 64-bit Cocoa, it has not received a major user interface overhaul. Instead, the interface has been slightly modified to allow better ease of use. These changes include:

• Exposé can now display all windows for a single program by left clicking and holding its icon in the dock. Windows are arranged in a new grid pattern.
• Contextual menus which come out of Dock icons now have more options and have a new look, with a semi-transparent charcoal background and white type.
• Stacks, when viewed as a grid, will now allow viewing of a subfolder without launching a separate Finder window. When viewed as grids and lists, it includes scroll-bars for folders with many files.^[15]
• The default gamma has been changed from 1.8 to 2.2 to better serve the color needs of digital content producers and consumers.^[12]
• Windows can now be minimized directly onto their application's icon in the dock.^[16]
• Faster PDF and JPEG icon refreshes.^{[citation needed]}
• When searching for a network, the AirPort menu-bar animates until it finds a network and shows network strength in the drop down menu.
• Prefixes for bytes are now used in strictly decimal meaning when describing disk space, such that an indicated file size of 1 MB corresponds to 1,000,000 bytes, as commonly used by hard disk manufacturers.^[17]
• Snow Leopard shuts down, wakes up, and goes to sleep faster. Depending on what computer is being tested, Snow Leopard can shut down in about 3 seconds.^{[citation needed]}

[edit] New wallpapers

As with most upgrades of Mac OS, 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:

• Art: Dancer on the Stage, Nighthawks, Poppies Blooming, Sunday Afternoon, Suprematism, The Great Wave, and, Water Lilies.
• Patterns: Pinstripe and Saree.

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".

[edit] Dropped features

• It is no longer possible to change an application's language using the Finder "Get Info" dialogue. While there are workarounds for some applications, others (such as Adobe After Effects) will not be able to be run in a different language than the one installed.^[18].

[edit] Developer technologies

[edit] 64-bit architecture

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 leverage the 64-bit x86-64 architecture (excluding iTunes, Front Row, Grapher and DVD Player applications).^[19] 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 machines can run a 64-bit kernel, but will not do so by default.^[20] Users wishing to use the 64-bit kernel on those machines must hold down the numbers 6 & 4 while booting to get the 64-bit kernel to load.^[21][22] A change to the com.apple.Boot.plist 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".^[22]

As of version 10.6.0, only the following Apple computers are capable of running the 64-bit kernel:^[23][24]

Product	Model name	K64 status
Early 2008 Mac Pro	MacPro3,1	Capable
Early 2008 Xserve	Xserve2,1	Default
MacBook Pro 15"/17"	MacBookPro4,1	Capable
iMac	iMac8,1	Capable
UniBody MacBook 13"	MacBook5,1	Capable
UniBody MacBook Pro 13"	MacBookPro5,5	Capable
UniBody MacBook Pro 15"	MacBookPro5,1	Capable
UniBody MacBook Pro 17"	MacBookPro5,2	Capable
Mac Pro	MacPro4,1	Capable
iMac	iMac9,1	Capable
Early 2009 Xserve	Xserve3,1	Default
Early 2009 Mac mini	Macmini3,1	Capable

^*  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 and possibly other models as well.^[25]

[edit] Grand Central Dispatch

Grand Central Dispatch utilizes 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 utilize multiple processor cores.^{[citation needed]} 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.^[26]

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.^[27][28][29]

[edit] OpenCL

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.^[30]

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.^[13]

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

It only works with the following Mac GPUs: NVIDIA GeForce 8800 GS, 8800 GT, 8600M GT, 9400M, 9600M GT, GT 120, GT 130, GTX 285, Quadro FX 4800, FX 5600 and ATI Radeon HD 4670, HD 4850, HD 4870.^[5]

[edit] CUPS

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 many performance improvements. CUPS 1.4 is also the first implementation of the Internet Printing Protocol version 2.1.^[31]

[edit] Power management

Power management has been improved, with implementation of a new wake on demand feature supported on more recent Macintosh hardware.^[32] Wake on demand takes advantage of the sleep proxy service implemented in AirPort and Time Capsule routers,^[33] so that the computer can sleep while the router responds to any mDNS queries. Should the request require the host computer to wake up, the router sends the necessary special wake-up-packet^[34] to the sleeping computer.

[edit] Security

An anti-malware feature was added to the system that alerts the user if malware is detected.^[35]

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 OS X v10.5,^[36] which Microsoft has implemented since Windows Vista.^[37]

Despite the lack of ASLR, Apple's developer community has been pleased with their efforts to strengthen OS X by implementing stack protection, migrating to 64-bit applications and components, and sandboxing more OS X components such as the H.264 decoder in QuickTime and browser plug-ins as a separate process in Safari.^[38]

[edit] Compatibility

Snow Leopard breaks compatibility with versions of some applications, including Parallels Desktop 3.0, versions of Aperture before 2.1.1, and versions of Keynote before 2.0.2, among other software.^[39] Apple has also published an official list of applications with compatibility issues with Snow Leopard.

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. While drivers for many printers and scanners are available, many printers and scanners are not yet supported ^[40]. Manufacturers such as HP and Epson have contributed additional drivers that have been incorporated into the 10.6.1 release.

[edit] Reception

Mac OS X Snow Leopard was well received by critics.^[41][42] Apple had stated in the advertising of Snow Leopard from its first demo at the WWDC 2009 that Snow Leopard features no new visual improvements but instead focuses on redesigning the core applications of Mac OS X to enable them to perform at their best using Apple's new APIs.

The price of Snow Leopard has dropped from the $129 Apple charged for previous versions of Mac OS X to $29 (when upgrading from OS X 10.5 "Leopard"). This could be largely due to the fact that most users would not see any noticeable change in the look and feel of the system.^[43] However, most reviews commented on the large improvement in speed of the native Mac OS X applications Finder, iCal, Mail, etc.^[43]

Other unexpected improvements were the release of a new version of Boot Camp, version 3.0, 10-20 GB of space regain compared to the advertised 7 GB, a cleaner, popup software update process and screen and video recording in the new QuickTime Player.^[44]

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."^[45]

The single-user upgrade and Family Pack units of Snow Leopard ranked 1 and 2 respectively on Amazon.com's software bestseller charts when Apple announced it would release it within the week.^[46]

More critically, 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". Benjamiin complained of slowness even after an upgrade install and a later clean install on the older machine, which he ended up downgrading back to Leopard.^[47]

A bug existed in Mac OS X versions 10.6 and 10.6.1 which 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. The bug was fixed as of version 10.6.2.^[48]

[edit] Development history

Mac OS X Server includes all of 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 over licensing issues.^[49]

On Monday, 11 May 2009, after Build 10A354, Apple issued a code freeze on Snow Leopard's APIs.^[50]

[edit] Version history

Version	Build	Release date		Major changes	Notes
		Developers	General public
10.6	10A96	June 10, 2008	Developer-only release	Applications no longer have PowerPC support	Released after WWDC 2008
	10A190	June 10, 2008		Finder partially rewritten in Cocoa, default gamma changed from 1.8 to 2.2
	10A286	March 6, 2009		QuickTime X player, Cocoa-based Finder, ZFS version 11, visual tweaks[51]
	10A354	May 8, 2009
	10A380	June 8, 2009			Released after WWDC 2009
	10A394	June 26, 2009[52]		Dock Exposé, speed improvements	Pushed to developers via Software Update
	10A411	July 17, 2009
	10A421	July 24, 2009
	10A432 (Client)[53]	August 12, 2009	August 28, 2009		Available on first-released retail DVD
	10A433 (Server)[54]
10.6.1	10B504[55]	September 8, 2009[56]	September 10, 2009	Bug fixes, updates Adobe Flash Player	Apple download page
10.6.2	10C514f	October 5, 2009[57]	Developer-only release
	10C519f	October 9, 2009[58]
	10C527f	October 16, 2009[59]		Corrections to video errors, crashes in OpenCL, iMovie problems, iChat, and reliability improvements for iLife, iWork, Final Cut Studio, MobileMe, iDisk and Safari plug-ins.[60]
	10C531	October 21, 2009[61]
	10C535	October 28, 2009[62]
	10C540	November 4, 2009[63]	November 9, 2009	Fixed the guest account data deletion bug; improved reliability and stability of several applications; fixed bug in 4-finger swipe gesture; fixed problem with NTFS and WebDAV file servers; fixed spontaneous logout issue[64]	Apple download page

[edit] References

[edit] External links

• Mac OS X Snow Leopard at Apple.com
• Mac OS X Server Snow Leopard at Apple.com
• Mac OS X 10.6 Application Compatibility List A user-edited list of Mac applications that have been tested on Snow Leopard
• Mac OS X 10.6 Review at Ars Technica, by John Siracusa

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