MRAM (Magnetoresistive Random-Access Memory)

MRAM (Magnetoresistive Random Access Memory) is being considered as a viable replacement for current DRAM technology. Its key difference to the latter is its use of magnetic fields to save memory bits which makes the memory "permanent." As such, MRAM technology allows for faster access and data security.

Current RAM Technology

Current RAM technology uses an electrical charge to store memory bits. Microminiaturized capacitors and transistors in an integrated circuit are 'stacked up' to create high-density, large-memory but physically small chips. A typical memory chip stores up to 1 Gb and allows for more programs and data to be cached for immediate use by the CPU.

The major problem with current RAM technology is that capacitors leak their electrical charge. This results in the loss of information. As such, the capacitor's electrical charge must be constantly refreshed to keep the information active and readily available. This implies the need for a constant power source – not an issue with computers plugged into electrical outlets (unless the power is inadvertently cut off) but a problem with laptops or portable computers that use batteries; constant refreshing of memory drains the batteries.

This also leads to another issue – turning off electrical power (deliberate or accidental shut down of the computer) means that all information cached in RAM disappears. Restarting requires some time for all the programs, systems and data to be reloaded and this results in 'idle time' for the user.

The Emergence of MRAM

MRAM uses magnetic elements to store information; usually in the form of two magnetic plates – separated by a thin insulating layer – which form a single cell. One plate has a specific magnetic polarity, while the other varies with an external field. An MRAM unit is composed of a grid of such cells.

The primary advantage of an MRAM chip is that there is no need to constantly refresh the information through the periodic application of an electrical charge; even shutting down the computer does not erase the information. As such, start-up routines go faster; just turn on the computer and the last session is immediately available. At the same time, there is reduced risk of data loss from unexpected power outages.

There are two downsides to MRAMs, however, which have prevented it from joining the mainstream. Changing data in magnetic fields requires a larger power input than conventional RAM chips; in effect, the need for a constant power supply is replaced by a larger power requirement. Moreover, the nature of magnetic fields implies physically larger memory 'cells' – an MRAM chip stores less memory than a RAM chip of the same size.

Ongoing research aims to resolve both these problems using a variety of approaches. Although some companies report readiness to mass manufacturer MRAM chips, it remains to be seen whether these will successfully solve the power input and size issues. If these are resolved and prices of MRAM chips match that of current RAM chips, we would be seeing a revolution in how computers start up and operate.