Someday in the future, once people have stopped giggling about how all telephones once were wired to the wall, they'll still have trouble containing their laughter about laptop computers.

	Bill Wade, Post-Gazette
	Casey Helfrich, left, Mahadev Satyanarayanan and Michael Kozuch, with laptops that their work may one day make obsolete. Satyanarayanan is a computer science professor at Carnegie Mellon University and founding director of the Intel Research Pittsburgh lab, where Helfrich and Kozuch are researchers.

In this future, computers are so ubiquitous that the idea of lugging your own will seem as odd as someone today carrying around their own TV. With computers everywhere, why bring your own?

Prices of computers continue to plummet, so the economics of ubiquitous computing may make sense. But getting people to feel comfortable about flitting from computer to computer ---- using whatever machine is available at work, at home or on the road ---- will require some innovations.

Despite their outward sameness, most computers are so personalized with desktop preferences and software that borrowing someone's computer can seem as creepy as borrowing their underwear.

Researchers at the Intel Research Pittsburgh laboratory in Oakland think they may have an answer in a project they call Internet Suspend/Resume.

By taking advantage of the Internet, distributed file systems and a concept called virtual machines, Internet Suspend/Resume allows a user to stop, or suspend, work on one computer and then move to another computer, perhaps at home, or even across the country, and instantly resume that work.

The computer desktop at the second machine would appear identical to what appeared on the first machine's monitor when work was suspended ---- the same programs and files open, even the cursor at the same spot.

It sounds simple, maybe even trivial to some. "People don't realize how hard we have to work to do this," said Mahadev Satyanarayanan, a Carnegie Mellon University computer scientist who just ended a two-year stint as the Intel lab's founding director.

Us & them, easier
Technological heavy lifting aside, this approach could profoundly change the way people interact with computers, Satyanarayanan said.

The same technology that helps Internet Suspend/Resume move an individual's computing environment from one machine to another also can make it painless to upgrade machines. Work on one computer would simply be suspended, the computer box disconnected and the new computer put in its place; the user could hit the resume button and have all of his programs and files available on the new machine.

Likewise, the failure of the computer's hard drive, now a major catastrophe, would be no big deal. The user could resume work on another computer until the hard drive was replaced, and then simply resume work on the repaired machine with the loss of little if any data.

"If this thing in front of me gets blown up," Satyanarayanan said, gesturing to a laptop, "I shed no tears."

And with a newly developed feature called Rollback, Internet Suspend/Resume would provide an almost painless antidote for computer viruses. If a user's computer becomes infected, she could use the Rollback feature to go back to an arbitrary point in time prior to the infection and resume work there, deleting the subsequent work -- and the virus.

Casey Helfrich, a research engineer at the Intel lab, recently demonstrated how the feature could work. "If you were ever interested in destroying a Windows system, this is how you do it," he said as he deleted several executable (.exe) files from a laptop. "Don't try this at home." Within a few seconds, his monitor blinked a few times until he was left with a black screen displaying only "NTLDR is missing" in white letters.

Normally, it might take hours to reload programs and resuscitate this dead machine. But with Internet Suspend/Resume, Helfrich was able to instantly restore his work and proceed as if nothing had happened.

This recovery from hardware failure is possible, in part, because data is stored in distributed files on Internet servers as well as in the hard drive of each PC.

Also critical is virtualization software that Internet Suspend/Resume sandwiches between the computer hardware and its operating system and other software. This virtualization software creates virtual machines ---- virtual computers that, to the user, operate like any other machine, yet exist only in software.

A virtual revival
Virtual machines are an old idea that researchers are now giving a new twist, Satyanarayanan said. IBM developed virtual machine software in the late 1960s as a way of running different operating systems on the same mainframe computer.

Interest faded as companies moved from mainframes to personal computers, but has flared again recently as companies look for ways to run different versions of operating systems on the same PC, or for a computer server to handle computers running either Windows or Linux operating systems.

While Satyanarayanan's group has used virtual machines to increase mobility over networks from one computer to another, a similar project at Stanford University called The Collective is emphasizing the ability of virtual machines to simplify system administrative tasks, particularly for home users.

Rather than have individual users load software onto their computer that later needs to be updated, The Collective would make available a number of virtual appliances via the Internet that users would open up when needed. Software manufacturers could maintain these virtual appliances, so users would automatically get the latest version every time they used one.

As a side benefit, these appliances also would improve a user's mobility, much as Internet Suspend/Resume would. But Monica Lam, a computer science professor at Stanford, emphasizes that this approach would help computers operate more efficiently and securely.

"Look, we have issues associated with security these days because people aren't keeping up with their system maintenance" by downloading updates and corrective patches, she said. That leaves many home Internet users vulnerable to viruses or other attacks.

Likewise, Internet Suspend/Resume would make it cheaper and easier to manage university or corporate computer systems, said Michael Kozuch, senior staff researcher at the Intel Pittsburgh lab.

The Pittsburgh researchers will begin to see how well this all works in the real world this fall, when they begin a two-year pilot test of Internet Suspend/Resume that eventually will include up to 100 volunteers from CMU's computer science and electrical engineering departments.

"By the time we get to 100 [users], we're hoping people will be using it for everyday use," Kozuch said.

"We do not know at this point exactly how this will be transformed into a commercial product," said Satyanarayanan, noting the Intel lab's work is not proprietary. But the simplicity of the system, at least from the user's point of view, suggests it could have broad impact.

"It is the simple ideas," he added, "that change the world."