The MK8007GAH is an 80GB two-platter hard drive whose 1.8inch diameter is small enough to fit into a portable device such as a digital music player. Toshiba will also sell a single-platter 40GB drive called the MK4007GAL.
Both use a storage technique called perpendicular recording, first proposed nearly 30 years ago. Hard drives are made up of areas of magnetic crystals that store data bit by bit according to their magnetisation. In normal longitudinal recording, these areas lie flat on the surface of the disk: in perpendicular media, they are stacked on end like straws in a box. This increases the density of bits per square millimetre.
The MK8007GAH and MK4007GAL both offer an areal density of 206 megabits per square millimetre, which Toshiba says is the highest ever achieved in a commercial hard disk.
"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," said Kazuyoshi Yamamori, Toshiba's vice-president of storage, in a statement.
Toshiba's previous 1.8-inch hard drives are used by Apple in its iPod range, so it's possible that the MK8007GAH could be used to power a future iPod with an 80GB capacity.
There are 80GB digital music players already on sale, but they use physically larger drives.
Toshiba says that it will also use perpendicular recording when building its 0.85-inch drives, which were announced back in January. This will double their capacity to 6-8GB per platter.
Toshiba claims it is the first storage company to deploy perpendicular recording in a commercial device. All the major storage companies have been developing products that use the technique. Last year Maxtor announced it had found a way of using perpendicular recording to cram twice as much storage capacity into a typical disk, at no additional cost.