Microsoft's Craig Mundie and his room-based computing prototype.

Portable devices are all the rage, from music players to phones to notebook and netbook computers. That's an important trend, but the industry also needs to renew its focus on the machines that don't move -- "fixed" computing -- Microsoft's top research executive told university researchers during a conference today in Redmond.

"Today if you say in the PC industry, what's the dominant form of personal computing, they'll say, well, it's the laptop," said Mundie, Microsoft's chief research and strategy officer, during a session at Microsoft Research's annual Faculty Summit.

He continued, "I contend that it's actually a failure of the industry and even Microsoft itself that we have not continued to go back and ask ourselves the question about, well, isn't there something more to do if you don't have to move it. And I think that day is coming now."

But he wasn't thinking about traditional desktop PCs. Mundie explained his comments by demonstrating the latest version of a Microsoft prototype that turns an executive's wall into an interactive computer screen. Using a touch-screen tabletop and his voice, Mundie showed how to use the computer to have a conversation with a realistic digital assistant, check key business information, and hold a conference call with a life-sized image of the person on the other end.

"There will be a successor to the desktop; it will be the room," he said.

Afterward, an attendee asked Mundie how much of the demonstration was real working code, as opposed to a video and other recorded media being displayed on the screen. Elements such as the digital personal assistant were video, Mundie acknowledged, but he noted that other elements were live code, such as the interaction with the tabletop screen.

But even the recorded elements are clearly within the realm of possibility, Mundie said. "If we don’t actually know how  we’re going to make that work over the course of the next few years, we won’t include it in one of these prototypes," he explained.