The advent of CDs, DVDs, flash drives and portable hard drives only took storage technology to a different level. However, large corporations, which function around the data they create, are voraciously in need of huge storage capacities. Manufacturing companies are constantly trying to invent the ultimate digital storage device. The devices of the future are definitely holographic memory, molecular memory and MRAM chips.

Holographic Memory

Holographic memory is definitely going to revolutionise the concept of storage devices and take it to another level. Like other storage media, holographic memory is divided into write once and rewritable media. Write once media refers to media which undergo irreversible change whereas with rewritable media, the change is reversible. Rewritable holographic storage is achieved via photorefractive effect in crystals.

In theory, holograms can store data equal to one bit per cubic block the size of the wavelength of light in writing. This capacity is almost unimaginable when compared to current storage capacities. Perfect holographic storage could store 4 gigabits per cubic millimetre. In reality, however, the density is lower because of the need to add error-correction, the need to accommodate limitations in the optical system and design technique limitations in parallel with a single flash of light.

A single laser beam is split into two beams, the signal beam for data transfer and a reference beam. A hologram is created when the two beams intersect the recording medium. A spatial light modulator device helps to encode the data into a signal beam. This device translates electronic data into an optical pattern of light and dark pixels. This data is then arranged in an array of about 1 million bits. The hologram is recorded in a light-sensitive storage medium where a chemical reaction occurs. Eventually, the data is decoded by reflecting the reference beam off holograms, which finally reconstructs the stored information. The hologram is then projected onto a detector that reads the data in parallel.

Molecular Memory

Like holographic memory, molecular memory too is slowly gaining ground as a primary storage device of the future. Molecular memory refers to data storage technologies that utilise molecular species as data storage elements. Usually, regular storage devices use circuits, magnets and inorganic materials. One can describe a molecular component as a molecular switch. This function will be performed by mechanisms like charge storage or photochromism. Ideally, in a molecular memory device, each individual molecule contains a bit of data. This results in massive data capacity.

In reality however, molecular memory devices are likely to use large numbers of molecules for each bit like in 3D optical data storage. Molecular memory refers to very fast, electronically-addressed solid-state data storage. Currently, molecular memory isn't being marketed, but remains in laboratories. Molecular memories are based on special compounds like porphyrin polymers, which are capable of storing electric charge. The process is reversible and allows for great capacity per unit area.

MRAM Chips

Magnetoresistive Random Access Memory or MRAM is a non-volatile computer memory technology. This form of memory has been under development since the 1990s. Unlike regular RAM chips, in MRAM, data is stored by magnetic storage elements instead of electric charge or current flows. The elements are formed from two ferromagnetic plates, each of which holds a magnetic field, separated by a thin insulating layer. A memory device is basically built from a grid of cells.

Data is decoded by measuring the electrical resistance of the cell. Typically, a particular cell is selected by powering a transistor, which switches current from a supply line through the cell to the ground. The magnetic effect causes the electrical resistance of the cell to change. The resulting current is measured and the resistance inside a particular cell can be measured. If two plates have the same polarity, it is considered to mean ?0? and if they have opposite polarity, it means ?1?.

A variety of means are used to write data to cells. When current is passed through, an induced magnetic field is created at the junction, which is picked up by the writable plate. There are other ways that are constantly being experimented and improved upon. The determining factor of a memory system's cost is the density of the components used to make it up. Small and fewer components mean that more cells can be packed, onto a single chip. This, in turn, means more can be produced from a single silicon wafer. MRAM requires no time to refresh at all.

MRAM's characteristics give it a universal appeal and eliminate the need to combine memories. Stand-alone MRAM chips are economical and reliable. It enhances performances and enables the flexibility to handle many applications with a single circuit design.