Mac OS X Snow Leopard

Mac OS X 10.6 "Snow Leopard" is a version of Mac OS X. "Leopard" had been a large success, having finally unified support for Intel and PowerPC machines onto one DVD release, with full 64-bit support for the PowerMac G5. Despite these advances, 10.5 still lacked a complete switch from the kernel down to 64-bit throughout the whole system for the newly-released Intel machines (the Mac Pro was already 64-bit capable, and several Mac models quickly switched from using the Core Duo (32-bit) to the then-new Core 2 Duo (64-bit) processor.) A successor to 10.5 "Leopard" was first announced at the WWDC on June 9, 2008, then again in 2009, and finally was released to the public August 28 of the same year.

10.6 "Snow Leopard" was not advertised as competing against Windows as Leopard had done previously, nor was it toted as containing a groundbreaking feature set. Rather, the mission of 10.6 "Snow Leopard" was to further Mac OS X by adding support for new technologies, fine tuning, and refining frameworks and the OS as a whole from the previous release on Apple desktops and notebooks. Part of this change, as previously mentioned, was the introduction of full 64-bit support for x86_64 Macs, though "Snow Leopard" was also designed to run as a 32-bit OS on hardware such as the early Core Duo-based Mac Mini, iMac, and MacBook models.

History
Despite being smaller, "Snow Leopard" is a release to be reckoned with, as it improved the overall performance of the system, fixing several bugs that caused overall sluggishness in the previous large-scale release, 10.5 "Leopard". Accessibility features, including the drastic changes made to VoiceOver and to several underlying features, were improved to be more responsive to input. Time Machine backups were smoother on average, Finder file operations, such as copying and emptying the Trash, were tweaked overall for faster performance, and both CUPS (the underlying printing service for OS X and other *nix-like systems) and network operations were improved. Smaller improvements, such as better support for mDNS packets and energy improvements were made as well. A minor, but welcome change often overlooked is the addition of a Restore button in the Trash on the Mac, that has existed in the Recycle Bin for Windows users since 95. The memory footprint and disk footprint were significantly reduced for a lighter and faster install (10.5 required 9 GB; 10.6 reduced this to 5 GB minimum). A clean installation of "Snow Leopard" took 15-20 minutes less on average than an install of "Leopard" on the same hardware with its initial release, making it easier for system administrators to upgrade hardware. The addition of OpenCL and several notable improvements to CoreAudio, CoreAnimation, and CoreVideo made it easier for developers to release media-rich applications without impacting the performance of their system; it also solidified the work from earlier releases of the above frameworks, and allowed new applications to be built in this category as well. In addition, application sandboxing, the shift of major applications to 64-bit (note: these only run as 64-bit on 64-bit hardware), address randomization and advances to securing memory helped to further protect Mac OS X.

Finder finally finished the long transition to being a completed Cocoa application, and Boot Camp allowed Windows-on-Mac users to access their OS X formatted partitions (HFS+). Multi-touch trackpad support was also greatly improved from Leopard, and allows all-new gestures on all supported Mac magic mice and trackpads. Other features include fixes to TextEdit and Preview when editing or selecting text versus earlier versions (where text may have been highlighted accidentally), Microsoft Exchange support, improved iChat video quality, and a new release of Safari 4.0 that added the then-popular Cover Flow feature, Top Sites, and crash resistance and (limited) process isolation (this would not be completed until Mavericks, 4 years later). Lastly, QuickTime X was introduced with an all-new overlay controls style with a translucent title bar that floated on top of the video, making the active video or QuickTime window look like a large thumbnail. It also added new controls, such as the ability to cut, all-new HD support for HD videos and content, and allowed screen captures, video recording, and audio recording built into Mac OS X natively for the first time (previous versions required third-party applications to record sound or to screencast).

Changes in user interface
Other minor improvements include small tweaks to the Aqua UI, such as to window buttons and the Menubar, as well as to the Aurora wallpaper (which appears smoother), and a gamma change from the old 1.8 Macintosh default to a lower, more crisp gamma default to help aid photography and media professionals better calibrate their work to industry-standard displays. New "Art" wallpaper and other additions were stealthily added to Desktop & Screen Saver preferences as well and an optional eject button is shown in the Menubar for devices.

Updates & Security
The final cumulative update to "Snow Leopard", 10.6.8, added several security patches, performance and reliability fixes, and also backported the Mac App Store to "Snow Leopard" as well, where a user is then able to upgrade to 10.8 "Mountain Lion", 10.9 "Mavericks", or even 10.10 "Yosemite" through the App Store. However, 10.6.8 "Snow Leopard", along with previous Mac OS X releases, are vulnerable to the potential "Shellshock" holes that may affect the underlying BSD subsystem by exploiting bash to gain unwanted control and access on an unpatched system. Since Apple only provides an official patch to this issue for 10.7 "Lion" and above, solutions include compiling a recent build of bash from the GNU FTP and copying the binaries manually, or extracting the installer package for Lion with Pacifist and placing the pre-compiled binaries into the intended folders using Terminal (which may be an easier method for non-developers).

General reception
10.6 "Snow Leopard" is a unique, well-loved, and critical release for several reasons, as it is the last stable and longest supported OS X version before the major changes made in 10.7 "Lion" and later that mimicked the feature set in iOS. It is the final release to retain the original Dashboard and Expose functionality by default (rather than Mission Control) and is the final version to include QuickTime 7 (needed for legacy video support). "Snow Leopard", however, mainly owes its long life to the fact that it is also the last release to support 32-bit Intel Core Duo and Core Solo models, and is the last Mac OS X release to include the Rosetta compatibility layer, making it possible to run most (though not all) applications written for PowerPC, such as Photoshop for the G4. While Universal applications can still run on "Lion" and later, it is this support that is treasured by many Macintosh enthusiasts who still wish to run older software on their Intel Macs, making it perhaps one of the most-loved releases in OS X history.

It is also by far the version of choice for veteran Hackintosh users, and in this sense is comparable to XP for Microsoft, and a third-party hack makes "Snow Leopard" the only version that can boot and install on AMD64 machines. However, perhaps the driving factor behind this was the low $29 price point that Apple offered this release for, making owning personal copies affordable and thereby a much more likely target to install. With "Snow Leopard", Apple solidified their operating system as a world-class, enterprise ready system that was not just fun and dynamic, but that was tuned well with solidified frameworks, proving to be reliable. With this release, Apple began to focus on the next set of major features and finally dropped support for G4 and G5 (PowerPC) processors, just as it had dropped the lower-powered G3 in "Leopard".

New or changed features
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 new version of Boot Camp included with 10.6 allows Windows to read HFS+ file system using a driver.. The new version also adds support for advanced features on Cinema Displays and a new command-line version of the Startup Disk Control Panel. Finder has been rewritten in Cocoa to allow certain features to function in 10.6. Drivers needed are downloaded instead of preinstalled to save space. This makes the OS smaller than 10.5 by 250MB. There are also improvements which lessen the size of the OS compared to 10.5 by 7GB.

Mac OS X 10.6.6 update added Mac App Store from newer versions.