It is bigger than a palm device, smaller than a laptop computer, and instead of responding to spoken commands or reading back e-mail, it records hand-written notes so they can be stored and manipulated electronically.

As the Comdex computer trade show began in Las Vegas amid some uncertainty over whether the new generation of compact devices were supplanting the personal computer, Microsoft showed off a prototype of its "Tablet PC", which is a little bit PC and a little bit gadget.

The Tablet PC, which Microsoft hopes to bring to market by 2002, looks basically like a paper pad and, similarly, functions as a portable and informal way to take down notes. The difference is that once the notes are recorded in the Tablet, they can be edited, with users inserting more remarks halfway through the text or even searching for keywords.

Mr Bill Gates, who addressed Comdex for the first time since taking on the role of Microsoft's chief software architect, said the Tablet PC showed how the traditional PC could still be enhanced to become an even more essential work tool.

"For me, a tablet PC will automatically double the number of hours a day I can get out of a PC," Mr Gates said, adding that it could be used during informal meetings when a laptop with a keyboard was not appropriate.

The Tablet PC, which incorporates all the most advanced handwriting-recognition technology to execute an idea that has failed many times in the past, is now being promoted by Microsoft to demonstrate the multiple-device state of computing today, and the need for more advanced software to connect them all.

Mr Gates told the audience at Comdex that he had spent much of the past year thinking about the best ways to get different computing devices to interact, so consumers could access the same documents from different devices. He had concluded that some of the most widely used Internet software today was not up to the task.