Samsung Electronics plans to show a prototype hard-disk drive that includes flash memory, promising lower power usage and less hard disk drive trouble for laptop users.

The Hybrid Hard Drive, developed by Samsung and Microsoft, is meant for mobile PCs running Longhorn, the next version of the Windows operating system. By writing data to the flash memory there is no need to spin up the hard disk drive, saving power and sparing the drive, said Ivan Greenberg, director of strategic marketing at Samsung.

This leads to a reduction in power consumption of 10 percent and can also help prevent problems that occur when the drive is moved while in use, Greenberg said.

"The failing item in a returned notebook is typically the hard disk. If we keep that drive spun down, we believe that will have a huge impact," Greenberg said.

When the flash memory is full, the hard-disk drive is spun up and the data is written to disk. The prototype contains 128M bytes of flash memory, Greenberg said. Longhorn will also minimize reading from the hard-disk drive by storing more data, including application data in main memory, he said.

With 64-bit technology, Longhorn can support up to 128Gbytes of main memory. A user could keep all of a PCs data in the main memory, Microsoft Windows chief Jim Allchin said in a recent interview. "Let's suppose you had 10G bytes of primary memory, probably everything that you do could fit in memory," Allchin said.

A prototype of the hybrid hard drive will be shown for the first time this week at the Windows Hardware Engineering Conference (WinHEC) in Seattle. Commercial versions are planned for release in late 2006, the same time as Longhorn, with the first samples due mid-2006, Greenberg said.

The hybrid disk drives may cost more than regular hard disk drives, but Samsung believes that increase will be mitigated by the lower maintenance costs and power savings.