Seagate Technology on Monday launched its first combination disk storage and flash memory hard drive, joining rival Samsung Electronics in offering hybrid drives that manufacturers say speed the boot-up time of PCs and significantly boost battery life.

The Seagate Momentus 5400 PSD, which stands for "power savings drive," offers 160 Gbytes of traditional rotating disk storage and 256 Mbytes of flash memory. Sony is the first PC maker to offer the new product, making it available in its Vaio SZ650, Melissa Johnson, product-marketing manager for Seagate, said. Three other PC manufacturers also plan to offer products with the new drive, but Johnson declined to name them.

The Momentus sells for $190, which is almost a 30% premium over a traditional drive of equal storage. The higher price, however, gets the buyer technology that Seagate claims can quicken the time it takes to boot a PC by 20%, and uses half as much power as a traditional hard drive. The Sony Vaio gets 25% more battery life from using the hybrid drive, Johnson said. "There's good value across the board for this hybrid technology."

Samsung started shipping its hybrid flash/hard drive in March. Samsung and Seagate offer the same size drive, but Samsung also sells models of 80 Gbytes and 120 Gbytes. Over the next 10 years, Seagate plans to offer hybrid drives as an option across its entire line of disk drives for notebooks, desktops, and ultramobile PCs, Johnson said.

Seagate and Samsung have been working with Microsoft to take advantage of technology in Vista that can leverage their hybrid drives. ReadyDrive in Vista treats flash and disk as one memory space, so it can be used for caching frequently needed data, or as a disk-write cache when the disk is spun down in order to save battery power.

Vista's ReadyBoot technology speeds up the processes of booting the system and recovering from hibernation by keeping track of the files most often needed when the system boots and building a temporary cache when the system starts.

Despite the enhancements in Vista, however, PC buyers won't get full advantage of hybrid drives until other makers of PC components jump onboard in a big way. BIOS makers and manufacturers of device drivers have yet to take advantage of the flash memory in hybrid drives. BIOS, or basic input/output system, is the firmware code in a PC that identifies and initiates component hardware, such as hard drives and CD drives. Device drivers run everything from printers and scanners to digital cameras.

Makers of hard disk drives, however, have banded together to promote hybrid drives for notebooks and to work with PC makers in helping them adopt the technology. Founding members of the Hybrid Storage Alliance include Fujitsu, Hitachi, Samsung, Seagate, and Toshiba.

Besides Sony, Dell offers hybrid drives in its Latitude line of corporate PCs. The computer maker plans to eventually offer the same drives in consumer PCs, a spokeswoman said.

The number of new notebook computers using some form of flash memory for data storage will soar from a negligible number today to more than 50% in two years, according to iSuppli. The research firm sees three approaches to flash data storage evolving over the next couple of years: Intel's Robson, hybrid hard-disk drives, and solid-state drives. Robson is the code name for a platform technology that uses flash memory to increase system responsiveness, make multitasking faster, and extend battery life.