Cube could spell the death of the disc as memory moves into the third dimension

Researchers are on the verge of massively increasing data storage efficiency

Researchers are on the verge of massively increasing data storage efficiency

Current disc-based storage technologies are restricted because data is stored in two dimensions, on the face of the disc. Des Mapps, head of the Centre for Information Storage Technology at the University of Plymouth, has been investigating techniques to extend disc storage into the third dimension and improve the efficiency of Ram by using magnetism instead of transistors.

Mapps' team, consisting of experts in electronics, materials technology, physics, optics and mathematics, is looking at a variety of methods of improving storage that could potentially boost existing capacity thousands of times over. The team's ultimate aim is to replicate the storage methods of the human brain.

Research is focusing on three core areas: the Opticube, magnetic Ram and perpendicular recording.

The Opticube

Based on optical technology from the Centre for Information Storage Technology in collaboration with Dave Newman of the University of Exeter, the Opticube aims to provide terabyte data storage which can be accessed at the speed of light.

The Opticube turns the current method of disc reading on its head. Optical media rely on a fixed laser and a fast spinning optical disc, where the data is accessed only when the relevant section of the disc is in line with the laser read-write head. The difference with the Opticube is that it is the the lasers themselves that move to read and write data.

"When you play a CD you gain higher speeds of retrieval by running the CD at speeds of up to 40x - that is, moving the CD at high speed past the head. It is obvious that there is a limitation on how fast you can make the disc go," Mapps said.

With the Opticube, the problem of disc access is approached the other way round. "The memory is stationary and we move the laser using no moving parts," said Mapps.

The Opticube is actually two cubes - a small one the size of a sugar cube inside another larger cube. The larger cube is clad with storage cells.

Using liquid crystal phase plates, laser light is directed at storage cells on the inside of the outer cube. Reading and writing data involves precise control to direct the beams of laser light onto the millions of cells that line the walls of the outer cube. The readout process will be both "inertia-less" and offer the potential for massive parallel processing. According to Mapps, such technology could replace PC disc drives within five years.

Magnetic Ram

Although the Opticube is designed to replace disc-based storage, Mapps hopes to develop a technique to boost the performance of PC Ram speed by up to 100 times.

In a radical departure from the way random access memory is now built, Mapps' team is looking to replace the electrical switching within the tiny transistors that comprise modern semiconductor Ram with manipulation of magnetism at a sub-atomic level.

An item of data in a computer's memory is stored as an electrical signal within the transistors that make up Ram. A transistor that has been switched on represents the binary digit 1, when it is off, it represents the binary digit 0.

The speed of switching a transistor between its "on" mode and "off" mode is limited by the time it takes for an electrical charge to reach a threshold within the transistor. Magnetic Ram does not rely on this build-up of electrical charge.

Instead, Mapps is developing a technique to re-orientate the polarity of atomic magnets, where the switch between north and south poles can mirror the transistor switch between on and off to represent binary digits 1 and 0.

Mapps said, "Semi-conductor chips are expensive and the cycle time per bit is between 10 and 100 nanoseconds. With magnetic Ram, cycle times are as low as one nanosecond and are twice as dense."

According to Mapps, Motorola is already producing a hybrid semiconductor-magnetic chip, but the Centre for Information Storage Technology's magnetic Ram technology is about three years away from commercial viability as a replacement for Ram.

Perpendicular recording

Capacity on a disc is limited by the amount of data that can be packed onto each disc platter and the ability of the disc's head to read this information.

By altering the layout of magnetic cells on a disc drive, the Centre for Information Storage Technology's researchers have discovered how to boost drive capacities from 100 gigabits per square inch to 1,000 gigabits per square inch.

In the current configuration, cells are placed alongside each other with both north and south poles on the surface. In the new configuration, cells are placed in the upright position with one pole at the top. This allows many more cells to be placed on a disc with the uppermost end of the cell being given the appropriate charge.

Mapps said the technique would avoid the problem of like poles facing each other - an inefficiency in modern disc design where the two like poles can cancel each other out, thus reducing storage capacity on the disc.

Replicating the brain

The Centre for Information Storage Technology's most far-reaching project is to replicate the way the brain stores and retrieves information. Although this project is still at concept stage, Mapps believes that the building blocks exist for it to be successful.

He said the Opticube has already begun to show that it is possible to work in three dimensions - the way the brain works - as opposed to the two dimensional approach taken by today's storage media.

Mapps has spoken about the work at the Centre for Information Storage Technology at a number of events run by UK Trade and Investment, a DTI/ Foreign Office initiative to generate interest in UK research.

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UK Trade and Investment

The work of the Centre for Information Storage Technology at the University of Plymouth is supported by UK Trade and Investment.

UK Trade and Investment is a government organisation set up to support the UK's trade and investment strategy. It brings together the work of the Foreign and Commonwealth Office and the Department of Trade and Industry.

The role of UK Trade and Investment is twofold: to help UK companies trading overseas; and to promote the whole of the UK as an inward investment location.

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