Happy 50th birthday, the hard drive

Fifty years ago, in September 1956, IBM invented the hard disk drive, called the RAMAC (short for random-access method of accounting and control).

It weighed over a ton, was the size of a large fridge-freezer, and each disk was over 24in in diameter.

It needed compressed air to work (making it incredibly noisy), stored a total of 5Mb and cost over $50,000 (about £26,500, in 1956 money). Today the cost of digital storage has dropped to less than one tenth of one cent per megabyte.

According to Hitachi Global Storage Technologies hard drives could soon hold one terabyte (Tb) of data and the average home will have between 10-20 hard drives in the next five years.

Marking the hard drive's 50th birthday, Hitachi highlighted the work it is doing around disks having an areal density (the number of bits of data that can be recorded onto the surface of a disk or platter) of 345Gbits/sq inch using perpendicular magnetic recording (PMR) technology.

This areal density represents an increase of more than two and a half times compared to today’s highest-capacity products.

By 2009, Hitachi predicts that hard drive areal density of 345Gbits/sq in would result in a 2Tb 3.5in desktop drive, a 400Gb 2.5in notebook drive or a 200Gb 1.8in drive. In the first half of 2007, Hitachi expects to be half way towards the 345 Gbits/sq inch mark with a 1Tb 3.5in drive.

Researchers at Hitachi anticipate that this is "clearly within grasp in the next two to three years", and that extensions to PMR technology "will take hard drive advancements out beyond the next two decades, using ever more complex and sophisticated means such as patterned media and thermally-assisted recording".

With these technologies, Hitachi predicts that continued areal density advancements would be possible 10 or so years into the future. For example, the company anticipates as much as 100Tbits/sq inch areal density will be possible, which would enable a 0.65Pb (petabyte - 1,000 terabytes) 3.5-inch drive.

“The inventors of the original RAMAC could not have seen five decades of innovation in 1956, but here we are today celebrating its golden anniversary.

"We are very optimistic about the future for the hard disk drive industry with research on these technologies strongly underway,” said Hiroaki Nakanishi, CEO of Hitachi Global Storage Technologies.

Hitachi's researchers say the major challenge hard disk drive designers face because of increasing data densities is that the magnetic grains on the disk that store the data must become smaller.

Eventually they will become too small to be thermally stable at room temperature. Patterned media and thermally-assisted recording are solutions to this problem.

Today, roughly 100 magnetic grains make up a single bit of data. With patterned media, researchers are creating isolated magnetic islands with one magnetic grain representing a bit of data.

By using fewer magnetic grains, patterned media allows more bits of data per square inch of disk space while maintaining thermal stability.

Rather than using fewer grains to represent a bit of data, thermally-assisted recording allows magnetic grains to be smaller while resisting thermal fluctuations at room temperature.

Thermally-assisted recording uses a laser to heat up the media while the magnetic head is writing the smaller bits of data. This enables the use of media that is stable at room temperature with the very small magnetic grains required for high-density storage.

Hitachi researchers predict that patterned media technology could ship in products as early as 2010.