By Prince McLean

Published: 10:00 AM EST

While Microsoft is working to refine its flagship operating system to be more palatable to a wide audience of PC users, Apple is working to keep Mac OS X a key attraction to Mac hardware to woo potential switchers and retain its loyal users. Here's what's known about Mac OS X 10.6 Snow Leopard.

Previous Windows 7 vs. Mac OS X Snow Leopard segments

Windows 7 vs. Mac OS X Snow Leopard: competitive origins
Windows 7 vs. Mac OS X Snow Leopard: Microsoft's comeback plan

Apple initially seemed to suggest that Mac OS X 10.6 Snow Leopard would be a minor release following 2007's 10.5 Leopard, citing support for Exchange Server push messaging as the only customer-facing feature. However, Apple historically directs attention upon its currently shipping products rather than its future plans. As the Snow Leopard release grows closer (remarks at WWDC last summer indicated it would ship "in about a year," or Summer 2009), more details have been released.

New kernel features in Snow Leopard

Snow Leopard will deliver a full 64-bit kernel, requiring the same significant "all at once" upgrade in device drivers that Vista's significant kernel changes did. Apple will likely have an easier time pulling this off, as Snow Leopard is only designed to run on a relatively small number of higher end PCs, all made by Apple. Rather than trying to get lots of vendors on board as Microsoft must, Apple will be supplying the majority of kernel-level drivers for Snow Leopard.

While Microsoft has sold a 64-bit version of Windows for Intel x86 PCs since mid-2005, actual 64-bit adoption has been slow. Apple has incrementally supported 64-bit background servers and applications in Mac OS X since the release of the PowerMac G5 in 2003; all 64-bit capable Macs can already run 64-bit Mac OS X software because Apple doesn't offer two versions of its operating system; the same version of today's Leopard runs both 32-bit and 64-bit code.

In Snow Leopard, this will improve as the entire operating system, including all bundled apps, will be compiled for both 32-bit and 64-bits. This results in a roughly 15% increase in performance across the board for 64-bit Macs, such as those with Core 2 Duo processors (most models released since 2006, as the chart below depicts). It also has implication related to security hardening. Windows users also benefit from running the 64-bit version of Microsoft's operating system, but compatibility problems have made the move less attractive, leaving mainstream Windows users stuck on a 32-bit platform. Windows 7 perpetuates this problem by delaying the move to 64-bits to a future release.

In addition to bringing 64-bit processors into the mainstream of Mac computing by making 64-bit the default rather than an option, Snow Leopard also debuts the fruits of Apple's efforts in making full use of multiple cores and multiple processors. Snow Leopard's new Grand Central Dispatch is used to aggressively and efficiently schedule processes across all available processor cores in parallel, and OpenCL is being made available to allow developers to take advantage of the raw processing power that often lays idle in the system's GPU.



Strategic improvements

Apple is also advertising QuickTime X as a streamlined, highly efficient media playback library (originally developed for the iPhone), as well as new advancements to Safari 4.0 and its SquirelFish Extreme JavaScript engine. The latter two will help to accelerate a new wave of sophisticated web applications, including Apple's own SproutCore-based MobileMe and iWork.com, as well as other HTML5 applications from partners such as Google, which are similarly working to develop open, interoperable, and high performance web apps with desktop-style features based upon industry standards.

Microsoft, in contrast, is betting upon its own Silverlight, a Flash-like, proprietary platform for web development that ties web applications to the company's own development tools and runtime rather than leveraging open web standards for interoperability.

Like Microsoft, Apple hopes to bridge its desktop operating system with online cloud computing services offered as subscription software. The difference is that Apple is again working within open standards and in partnership with companies like Google, rather than offering entirely proprietary services. That strategy appears to be paying off, as Apple now has millions of paid MobileMe subscribers which represent more than ten percent of the Mac installed base, while Microsoft has yet to move its Live Mesh out of beta, and has struggled to put together a consistent strategy for its web services.

Next month, Microsoft is expected to announce SkyBox as a new mobile cloud sync service to take on MobileMe (and later its SkyMarket to rival Apple's iPhone App Store), despite having its Windows Mobile platform eclipsed by the iPhone and splintered among various hardware makers and service providers, each of whom might not want to cede the potential for software sales and cloud sync revenues exclusively to Microsoft.

Touch and Office features

While Microsoft made a lot of announcements about integrating touch screen features into Windows 7 back in 2007 around the rollout of the iPhone and its own Surface project, Apple will be delivering a more practical version of new touch functionality in Snow Leopard, one which enables developers to make use of the multitouch trackpads now built into all of Apple's notebooks (which make up more than half of the company's sales).

Apple has already delivered multitouch gestures that can be used system wide, as well as pinch and zoom features that work in its own specific apps. Snow Leopard will extend touch frameworks to developers to allow them to take full advantage of multitouch trackpads in innovative ways, all without users having go out and purchase their own touch screen monitors.

Other silent but practical additions to Snow Leopard include new text processing features that will give all Mac applications the kind of auto-complete and auto-correction features Microsoft provides inside Word. Mac OS X has already extended Word-style spelling and grammar checking to be a system wide service. Windows offers those services in Microsoft-authored apps but they don't yet extend to third party apps.

Open software updates

For Windows NT, Microsoft developed its own new sophisticated file system called NTFS, but it never shared or licensed the technology so that other vendors could build interoperable systems that used it. The result was a selection of patent-threatened, mostly-compatible software libraries that enable Linux, Solaris, and Mac OS X to use NTFS volumes in a limited way. That vacuum prompted Sun to develop its own sophisticated file system to go well beyond the capabilities of NTFS.

Sun has released its 128-bit ZFS as part of OpenSolaris, enabling Apple to build a compatible, read-only implementation in Mac OS X Leopard. In Snow Leopard, Sun's ZFS will be fully supported as a read/write file system, enabling mainstream Mac users to start taking advantage of its storage pooling, data redundancy, automatic error correction, dynamic volume expansion, and snapshot features.

Other open software improvements to make their way into Snow Leopard include the CUPS printing libraries used by both Mac OS X and Linux, which Apple acquired and maintains with the support of the community. Apple has also funded development of the open source LLVM compiler, which is intended to build upon and eventually replace GCC (the GNU C Compiler). LLVM is already resulting in major new code optimizations, but the explicit optimizations for parallel execution it supports will also help Snow Leopard apps take full advantage of Grand Central dispatching across multiple cores.

Microsoft develops its own kernel, file systems, printing technology, compilers, and other operating system components, resulting in less opportunity to take advantage of advancements by the open source community.

On page 2 of 2: Where's the open beta?; and Rumored enhancements.