Yesterday, Microsoft issued release candidate (RC1) builds for the x64 versions of Windows Server 2003 and Windows XP, both of which are scheduled for release in the first half of 2005. Microsoft declared build 1289 of Windows 2003 x64 Edition and XP Professional x64 Edition as RC1 on Monday.
In recent briefings with Microsoft, executives from the software giant have been effusive in their praise of the x64 platform, which provides 64-bit capabilities, better performance, and complete compatibility with the 32-bit x86 platform that today's PCs use. One of the highlights of the x64 platform, they've said, is that, unlike the Itanium, x64 provides full 32-bit application compatibility and performance, giving customers the best of both worlds.
"Whenever we do performance testing, we run \[various\] industry-standard tests on the previous operating system on the same piece of hardware \[as the x64 OS\]," Iain McDonald, a Microsoft group program manager told me recently. "Our goal was that customers could move to x64 without seeing a penalty in 32-bit application performance. We wanted to eliminate any sort of adoption barrier. We believe we've actually nailed it. The key is that there are some architectural benefits to x64 ... so 32-bit applications run at parity, or better, on x64 \[platforms\] than they do on x86."
One of the other huge advantages of x64 is that it finally shatters the 4GB memory model that 32-bit systems use, letting native 64-bit applications access stunning amounts of RAM. However, even 32-bit applications benefit from this situation when running on x64. McDonald told me that each 32-bit application gets a full 4GB of virtual address space when executing on x64 platforms, up from 2GB on 32-bit systems.
Unlike the recently released 32-bit version of Windows 2003 Service Pack 1 (SP1), the beta releases of Windows 2003 x64 Edition and XP Professional x64 Edition are currently available only to beta testers. However, Microsoft tells me that it will ship the build to MSDN customers and others within the month. Both products are functionally similar to the latest 32-bit versions of each product. So, for example, the x64 version of XP will be almost identical to 32-bit XP SP2, whereas the x64 versions of Windows 2003 will include the feature set from Windows 2003 SP1.