In one of those technology puff sessions every hi-tech company gives in to some time, Seagate has told the world it is going to talk about HAMR, heat-assisted magnetic recording, at an American Physical Society conference on 25th March.

As disk storage areal density increases it heads towards the super-paramagnetic limit. With this, as the data bits get smaller, the energy used to maintain them reduces to the point where it can't be separated from the background energy. Perpendicular recording (PR) overcomes this but then runs into its own problems and HAMR is said to overcome them.

A laser beam is used to heat the recording surface at the same time as data bits are being written. Despite the addition of a laser, the cost structure of HAMR disks will be, according to Seagate, "on pace with the hard disk drives of today". The company envisages no lack of penetration of consumer device products by disk drives. Indeed, physically smaller drives will be able to be used more easily inside PDAs and mobile phones.

In servers, Seagate is promoting the use of 2.5in drives, as opposed to 3.5in ones, as a way of increasing the data rate from a unit of rack storage. If it can have HAMR-assisted densities, it will be better able to compete with other vendor's 3.5in drives.

In notebooks and PDAs, Toshiba is currently setting the pace with an 0.85in drive and Hitachi is in hot pursuit. No doubt Seagate has an eye on this market too. The company has said that it expects PR to provide a recording density of 1Tb/sq inch with a 3in disk storing 1TB.

A HAMR proponent would scoff at such figures. Seagate's Dr Terry McDaniel, a recording physicist, suggests that HAMR could provide densities of 50Tbits/sq inch - 50 times higher.

Our three-inch disk could then hold 50TB. Only it won't be a three-inch disk. It will be a sub-one-inch disk and hold between 1 and 10TB or so. That's quite enough space for all of Kylie Minogue's videos, her CD collection and the entire run of Neighbours with space to spare. And it will be installed in your mobile phone which will also be an MPEG4 video player, or some such.

The first HAMR drives are expected to have only a 1Tbit/sq inch density and appear in 2010. Don't get rid of your Kylie VHS tapes just yet.