Hitachi is set to use perpendicular recording to enable engineers to continue increasing drive storage capacity beyond today's limits.

The company is already testing sample drives based on perpendicular recording and says the technology could allow for desktop drives of 1TB (terabyte - a thousand gigabytes) or microdrives of 20GB in 2007.

Perpendicular recording is perhaps the most significant near-term step in the evolution of hard drive technology. Like the drives currently in use, it relies on magnetically charged particles for data storage. But where in today's drives the north and south poles of the magnetic particles run parallel to the disc, in the new method they are arranged perpendicular to the disc.

The result of this new arrangement is that each particle occupies a smaller area of the disk's surface and there is a greater areal density - meaning more particles can be crammed onto the disk.

"Without [perpendicular recording], existing technology will stall at about 120-130GBpin2 (gigabytes per square inch)," says a Hitachi spokesperson. "Longitudinal recording is running into significant problems with bit size."

In contrast, Hitachi sees drives based on the new method with areal densities of around 230GBpin2 in 2007. Such a density would enable a 3.5in 1TB drive and a 1in 20GB drive.

Hitachi's first drives are likely to offer a more conservative storage density of about 120GBpin2 and be available later this year. The company is currently field testing a 2.5-inch 100GB,drive based on an 80GBpin2 version of the technology.

Good news for users is that the new drives shouldn't be substantially different from current drives in terms of mechanical performance or price.