The Lowdown on 64-Bit Windows

March 8, 2008 – 4:09 PM

If you’re looking for a way to opt out of 64-bit Windows, you can stop right here. Windows XP Professional x64 is not going to knock your socks off. At least, not right away, and not unless you’re running apps that can take advantage of it.But in the very next breath, I have to say something. The future of desktop computing is 64-bit hardware, operating systems, and software. That might not be a serious reality for most of us on the desktop until the year 2010 or so. But it’s coming, and it’s going to be worth it. And it’s coming a lot sooner on servers.

You may not be aware of it, but most Windows XP applications are limited to 2GB of virtualized memory. An application and the data it loads in RAM can’t exceed 2GB. There are exceptions and workarounds that I’m not going to delve into. But bottom line, Windows XP 64-bit can virtually address 4GB for 32-bit applications, and it can virtually address 8 Terabytes for 64-bit apps. The physical memory story is similarly impressive in favor of 64-bit Windows: 4GB max. for 32-bit Windows and 128GB for 64-bit Windows.

Windows XP Pro 64-bit also supports the full power of 64-bit processors offered by AMD and Intel, and there are significant advantages to these processors. CPU-intensive tasks will see serious performance and reliability advantages under 64-bit Windows. Suffice it to say that when enough people have 64-bit hardware and software on their desktops, you can expect a paradigm shift or order-of-magnitude transformation of what your applications will be able to do for you. They are going to change, become larger, richer, do more things. The same thing happened when we moved from 16-bit apps to 32-bit apps when Windows 95 made 32-bit Windows widespread. I think the shift to 64-bit apps will take longer to evolve, but in the end will be even more profound.

Microsoft sees this coming, and it’s doing everything it can to create the building blocks now that will lead toward a true kick-off of 64-bit Windows when Longhorn ships. The next version of Windows will offer both 64-bit and 32-bit versions simultaneously. Meanwhile, AMD has been in the van, offering its first desktop 64-bit CPUs back in late 2003. Intel recently offered a similar desktop solution. So by the time Longhorn ships, the hardware will be out there in droves. AMD just introduced dual-core 64-bit CPUs, in fact. And Microsoft finally matched AMD and Intel by releasing Windows 2003 Server x64 and Windows XP Professional x64.

The desktop version of 64-bit Windows is based on the more reliable Windows Server 2003 kernel and it runs all your existing 32-bit apps just fine. In fact, they may run a little better under 64-bit Windows. And a few specific application areas could benefit seriously from 64-bit Windows right now or in the near future, including digital content creation, especially 2D and 3D animation for games or movies; CAD/CAM; digital photo management and manipulation; and advanced game users.

I can tell you that I’m running 64-bit Windows on one machine now, and I will be making the switch to 64 bits more primarily with Longhorn, if not before.

So that’s the good news. But there’s a downside, naturally. Win XP x64 doesn’t support 16-bit and 32-bit device drivers, like those that Windows XP supports. That starts with the CPU by the way. You can run either 32-bit or 64-bit Windows on a AMD’s (or Intel’s) 64-bit CPUs, but the reverse is not true. Windows XP Pro x64 requires a 64-bit CPU.

And it’s not just the CPU; all device drivers for pre-existing hardware must be rewritten to work with Win x64. That includes both internal components and external peripherals, like printers (although many generic USB devices will be fine). Microsoft includes a 64-bit device driver pack in Win XP x64, plus a small list of companies (including HP, Samsung, and several others) have already written 64-bit drivers. My 1995 HP LaserJet 5MP found a Windows-provided driver very easily.

AMD maintains a 64-bit Windows and Linux driver page that anyone trying out 64-bit Windows will find useful.

Other limitations of 64-bit Win XP Pro include the elimination of support for all these things: MS-DOS, OS/2, POSIX subsystems, IPX/SPX, AppleTalk Services for Macintosh, DLC LAN, NetBEUI, IrDA, and OSPF protocols.

Win x64 also comes with 32-bit versions of Internet Explorer, Outlook Express, Windows Media Player, and others because of issues with support of 32-bit DLLs. For example, 64-bit Internet Explorer (which is also included) can’t run 32-bit ActiveX applets.

There are also two Program Files folders in x64, one for 32-bit programs and one for 64-bit programs.

Other than those limitations and changes, and the fact that the desktop wallpaper is different, you’d be hard pressed to know that Win64 isn’t Windows XP.

Windows XP Pro x64 is a transitional operating system, literally designed to be an 18-to-24-month bridge that supports existing 64-bit processors now and helps make the world aware that Windows Longhorn will be the first real 64-bit desktop Windows.

Microsoft is offering a 120-day trial of Windows XP Pro x64. Download the 550MB ISO or order a CD for the cost of shipping.

You can bet that I’ll be returning to the topic of 64-bit Windows in the months to come.

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