Virtualization. The term may conjure up sci-fi images of Star Trek's holodeck or virtual reality, but both AMD and Intel are putting big bets on virtualization as a CPU technology -- one that ultimately could deliver some major changes in how our home and business PCs work.

Virtualization isn't new, but few PC users are familiar with the concept because it premiered on the huge research mainframes of yesteryear and on RISC servers rather than x86 platforms. Basically, it enables users to run multiple operating systems (or instances of the same OS) on a single computer and switch between operating systems on the fly.

This is more ambitious than mere multitasking, in which different applications run simultaneously. Under Windows, for example, individual programs don't have the right to access "privileged" areas of the system such as input/output; only the kernel -- the Windows OS itself -- can tap these resources on behalf of applications, and the computer is limited to running one kernel at a time.

Virtualization is also different from Intel's Hyper-Threading Technology, though both require some special hardware features in the processor. Hyper-Threading enables a CPU to execute more than one thread or part of an application at once, but there's still only one operating system or layer between the application and the hardware. Even multiprocessor systems or multicore processors don't necessarily support multiple operating systems.

"Conceptually, virtualization really enables the user or any IT infrastructure to separate the hardware from the software in a logical format," explains David Auster, division marketing manager in AMD's commercial marketing organization.

"Traditionally, we've had a very one-to-one relationship between the hardware and the operating system -- say, Windows. [Virtualization] allows you to have a one-to-many relationship between the hardware and operating systems. Operating systems are totally separate and mutually exclusive from one another, sitting on one piece of hardware."

Why Go Virtual?

While they're taking different technical approaches to the challenge, both Intel and AMD are betting that virtualization can add benefits and capabilities lacking in today's PCs -- and that small-business IT managers, administrators of relatively low-end servers and corporate workstations, and even home PC users will eventually want to take advantage of what's so far been mostly a Unix server perk.

One reason is that virtualization allows one PC to run multiple kernels. Some applications, such as low-level diagnostics, require a bare machine interface to do their thing; with virtualization, such tasks become eligible for multitasking. Additionally, a driver upgrade or other activity that might disrupt or even reboot the OS can take place in one virtual machine, while a user continues working with another.

Virtualization can assist in testing -- virtual machines can "fool" applications into detecting a hardware configuration that isn't actually present, or create a simulated computer network within a single machine -- as well as system backup and migration. Game developers might use virtualization to create multiple environments in which to test their code. Enterprises might use it to create virtual machines for old legacy applications.

The technology also can help in consolidating servers, whether they're in big enterprises or small offices. "A lot of organizations are looking at consolidating Web infrastructure, like domain controllers -- DHCP [and] DNS servers," Auster says. "A lot of these are very low-utilization [or frequently idle] servers, and they want the ability to consolidate those on a single box."

There's also an important draw for the security-conscious: Untested programs can be run securely in a protected, isolated environment. In theory, at least, users could create additional environments as needed -- for instance, launching a newly downloaded package with no risk to the rest of the system should it prove to contain a virus.

Remote workers or telecommuters could use the technology to run two virtual machines -- one optimized and safeguarded for work, and another for home and personal use -- on the same hardware. Similarly, an office could set up a secure virtual machine with limited access to sensitive data for a temporary contract worker, to be deleted after the employee leaves. Or a home-office entrepreneur might just want to keep personal files in a separate virtual machine.

"A small business doesn't have a 500-person IT organization to clean up the mess when you get a virus or you break an application ... so one of the interesting small-business-specific use models is hosting multiple environments," says Patrick Bohart, marketing manager for Intel's Virtualization Technology.

"A user [may want] to do Web mail or browsing or online gaming that's reserved for the consumer space, but that when brought into the small business space causes a lot of problems -- viruses, trojans, and so on. But that can be done [safely] through virtualization, which can divide [a PC into] a place where you can do work and a place where you can do personal activities."

Virtualization at Home

For that very reason, the ability to run multiple virtual machines might one day be an important feature of the home PC. Running multiple operating systems simultaneously may seem extravagant even to the PC enthusiast. But to the user with one foot in the Windows and one in the Linux or Mac OS camp, it promises a major change for the better: Virtualization technology doesn't care whether its multiple kernels belong to the same OS, so it'll be possible to switch operating environments as easily as Windows users today switch among applications, making dual-booting a thing of the past.

It's also possible that PC operating systems will become less crash-prone in the process: Virtual machines can offer application environments with resource limits and guarantees, providing fault- and error-containment.

Earlier this month, Bohart says, an exec at Intel's Developer Forum in San Francisco showed how at-home virtualization might work. "What he had was a very simple system, it looked like a normal system, and he downloaded Kazaa. Now if you download Kazaa, your system becomes infected with adware and spyware. And instantly after he hit that 'Install' button, it began flooding with pop-ups. But when he opened the [Internet Explorer] window, it was actually running in its own separate partition, and all that adware was contained in that partition.