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Snow Leopard to see HFS+ compression, default gamma switch


Details of Apple's first Mac OS X 10.6 Snow Leopard build for developers since WWDC have been published on the web, including confirmation of a Cocoa Finder and HFS+ compression.

Cocoa Finder

The full build details published by World of Apple confirm that 10A190 now has a Finder rewrite in Cocoa, marking the first time it has moved away from Carbon since the introduction of Mac OS X.

The Cocoa object-oriented program environment has also been used for re-writes of "almost all" visible applications Apple ships with Mac OS X; the transition is expected be finished by the time Snow Leopard is available to the public.

64-bit kernel

The site leaking the details further notes that Snow Leopard's move to a 64-bit kernel is underway, although only some Macs can run natively in this mode with this early test version.

HFS+ file compression

Also, the new Mac OS X update is now known to include support for file compression to the HFS+ file system that focuses primarily on reducing the weight of Apple's system files and built-in apps in normal use. The compression applies just to read-only files and is also designed to be backwards-compatible in such a way that Tiger and Leopard systems won't render files unreadable.

New default display gamma

More conspicuous if still subtle changes have also been made, including one to the default gamma (luminance) settings for display output. Macs to date have typically employed a lower-contrast but lighter 1.8 gamma level, but the new Snow Leopard build now changes this to a deeper 2.2 gamma that was previously only an option in earlier Mac OS X editions. This is to appease both visual editors as well as the everyday user, according to Apple.


Individual apps have similarly been given a handful of changes, including rudimentary hooks for creating and viewing content pulled from Microsoft Exchange servers in Address Book, iCal and Mail. Automator can also send out its completed workflows as operating system services.

While many of these changes are significant, the new Snow Leopard build reveals a definite work in progress that reflects the several months to go before Apple's publicly planned mid-2009 release of the new software: several features are either suspended or exhibit quirky behavior.