Nvidia unveiled tablets using its Tegra 3 quad-core processors at the Consumer Electronics Show in Las Vegas, including a developer prototype that was running Windows 8.

Microsoft is not expected to ship the Windows 8 operating system before mid-year, but Nvidia was eager to provide a sneak peek of the OS's Metro user interface running on a tablet using Tegra 3, a 1.3 GHz quad-core ARM-based processor. Another prototype showed a high-definition video running over HDMI to a larger monitor.

Windows 8 running on an ARM processor in a tablet was first announced at CES a year ago, a booth agent noted. No information on tablets shipping with Windows 8 has been announced.

In the three tablet prototypes, one 10-inch tablet showed the Metro user interface comprised of tiles with real-time information, with one tile displaying the latest stock quotes being updated. That's a similar concept used on Windows Phone 7.5, also called Mango.

No other specs were offered.

Also on display was an Acer Iconica A510 tablet (above) running a quad-core Tegra 3 processor. The tablet has a 10.1in touchscreen and was shown running Android 4.0 Ice Cream Sandwich. No price or availability has been announced.