After years of delays, Microsoft Corp. on Monday started selling new flavors of the Windows operating system that can address vastly more memory than previous versions yet can still run software designed for older computers.
Windows XP Professional x64 Edition and Windows Server 2003 x64 Editions operate on systems running 64-bit microprocessors from Advanced Micro Devices Inc. and Intel Corp. The new software costs the same as their 32-bit counterparts.
The biggest gain will be seen by businesses and PC users who are running 64-bit systems with more than 4 gigabytes of memory, which is the upper limit of 32-bit processors. Today, most PCs come with 256 megabytes to 512 megabytes of random access memory, or RAM.
Business users are likely to be the biggest buyers at first, as programs already exist for 64-bit systems. Ultimately, chip makers and Microsoft believe consumer-oriented programs such as video editors and games will become widely available.
"With this move to 64 bit, we think it's going to be a watershed moment that few realize right now," said Neil Charney, director of product management in Microsoft's Windows group. "In a few years, we'll look at this time and see really how big this move to 64-bit computing was - not just for the industry but for our daily lives."
But early adopters could run into trouble as they try to get their peripherals to work with the new operating system. That's because the drivers - software that controls hardware - need to be rewritten to work on 64-bit computers.
Microsoft estimates as many as 16,000 drivers are available in the box. Charney acknowledges older components may not be supported.
"It's the only one thing we're going to continue to urge the industry to move forward with - to continue to build those drivers," he said.
Intel, International Business Machines Corp. and Sun Microsystems Inc. were the first to launch 64-bit chips for high-end servers and workstations. But those used different instruction sets than the x86 standard that has been the foundation of PCs for decades.
In 2003, AMD launched 64-bit chips that are extensions to the existing instruction set, meaning older programs don't require a performance-sapping emulator to run. Over the next two years, Intel has played catch up, ultimately releasing its own 64-bit x86 chips.
While Microsoft pushed back the release date of specialized versions of Windows for the new AMD and Intel chips, Linux distributors jumped at the market opportunity.
On Monday, Hewlett-Packard Co. and Dell Inc. announced business desktops and workstations that will run Microsoft's 64-bit operating system.
MATTHEW FORDAHL, AP Technology Writer