Samsung is joining the ranks of companies making tiny hard drives, with a device under development that will have a disk that measures just 0.85 inches in diameter.

A Samsung representative said Wednesday that the 0.85-inch drive is "in the R&D stage," and did not offer details about when a final product might be available.

Toshiba and GS Magicstor already have announced efforts to build drives of that size, which likely will be candidates to handle storage duties in cell phones with advanced functions. The massive cell phone market is seen as a potential new arena for hard drives. But it's not clear that 0.85-inch drives will be competitive against flash memory, a rival storage technology that is based on semiconductors.

Dave Reinsel, analyst with research company IDC, said cell phones of the future that store music and other sorts of data are likely to require 4 gigabytes of capacity, an amount that can be squeezed into a 0.85-inch drive. A tiny drive could store 4GB of data more cheaply than flash memory, he said, but flash is starting to encroach on the territory. "Flash is doing an amazing job of getting its price down," he said.

Samsung and Toshiba are rather unusual players in the hard drive market because they also make flash memory. Samsung pays Toshiba royalties for NAND, a type of flash.