Fujitsu will soon join two other major PC makers in putting on sale a portable computer that uses flash memory in place of the traditional hard-disk drive.

The company will offer a 16GB or 32GB flash memory disk as an option with new B-series machines due on sale in late October and new Q-series machines that will be available from early November, it said Friday.

The disks are made by Samsung and can already be found in two Samsung machines, the Q30 laptop Q1-SSD ultra-mobile PC. Both machines went on sale in South Korea earlier this year. In Japan Sony is also offering a version of its small-size UX90 portable PC with 16GB of flash in place of a hard-disk drive.

The flash disk has several advantages over a conventional hard-disk drive. These include longer battery life because the flash memory uses less power and a slight weight reduction. Fujitsu said the B-series machine will run an extra 15 minutes and the Q-series will run an extra 30 minutes on flash disk compared to hard-disk drive.

Most noticeable to the user will be faster startup. Because data can be accessed from the flash memory much faster than a hard-disk drive, the B-series machine takes about 19 seconds to boot up Windows XP Home Edition compared to 32 seconds for a hard-disk drive version of the same machine.

The company is also offering a hard-disk drive that automatically encrypts data as an option with the B-series machines. The drive, produced by Seagate Technology, uses hardware to encrypt all data being written on the drive and decrypt data as it is read.

Fujitsu said plans to sell the computers overseas are under consideration.