Toshiba has developed what it claims are the world's first hard disk drives based on perpendicular recording, a technology that can boost data density on a single 1.8in hard-disk platter to 40GB.

The electronics giant has incorporated the technology into its latest MK4007GAL drive which packs 40GB into a drive 5mm thick.

The technique has also been used to create the 80GB MK8007GAH, which boasts the largest capacity yet achieved in the 1.8in form factor, according to Toshiba.

Conventional longitudinal recording stores data on a magnetic disk as microscopic magnetic bits aligned in plane.

Although advances in magnetic coatings continue to improve data recording densities on hard disk drives, Toshiba explained that the magnetic bits repulse each other due to in-plane alignment.

Squeezing more bits on to a disk will eventually reach a point where crowding degrades recorded bit quality, placing fast-approaching limits on storage capacities.

By standing the magnetic bits on end, perpendicular recording reinforces magnetic coupling between neighbouring bits, achieving stable higher recording densities and improved storage capacity.

Commercialisation of the high density technology depends on the development of a magnetic disk structured to support perpendicular recording, a high performance perpendicular magnetic head, and disk and head integration technology that maximises the combined performance.

Kazuyoshi Yamamori, vice president of the storage device division at Toshiba's Digital Media Network Company, said: "Our research confirmed the superior potential of perpendicular recording technology, and we have now achieved the core head and disk technologies required for reliable, high-density recording."

Toshiba plans to start mass production of the 40GB and 80GB drives in the first and second quarters of fiscal 2005.

The firm will also apply the technology to the 0.85in hard disk drives announced in January this year, a move that will push capacity to 6GB to 8GB per platter.