MRAM - Magnetoresistive Random Access Memory

Every now and then I like to catch up on the latest developments in current and emerging technologies. Reading through various blogs and journals I recently came across a relatively new type of memory called Magnetoresistive Random Access Memory, or MRAM for short.

To see where this fits and and why this is an exciting development, you need to consider current solid state memory devices of which there are two main types: the volatile Random Access Memory used in all computing devices (i.e. RAM) and non-volatile memory comonly used in USB Flash drives, memory-cards and even solid-state hard disks.

I'm not an expert on the subject matter so I'll describe this the way I understand it. Basically RAM is very, very fast to read and write. Data is stored in what can be thought of as millions of tiny capacitors inside a small chip. A full capacitor represents a one whereas an empty capacitor represents a zero. If left alone however, capacitors lose their charge over time. So to keep the data in memory, each capacitor is constantly refreshed or recharged thousands of times a second! That is, RAM requires constant electricity running through it to keep it alive. Once the power goes out, all capacitors discharge and everything is effectivelly zeroed out. It is thus only useful as temporary 'working' memory.

Non-volatile Flash memory commonly used in current USB drives on the other hand is much slower to read and write compared to RAM, but does not require a constant electric current to retain the data. That is, once the data is written, it will remain in the same state even when the power goes out. This is great as a permanent storage solution, but not very good as working memory due to the much smaller throughput. Flash memory also has a limited lifespan, each time data is written, it damages the sector a little. Some sources list the number of writes limited to around 100,000 per block but this number continues to grow as technology improves. Also, intelligent firmware counts the number of writes per sector and moves data around to balance the load across the entire memory chip. Since we now have solid-state hard disks, I don't think this is a real limitation anymore.

MRAM on the other hand is the best of both worlds. It's non-volatile memory with no limit to the number of writes, and is just as fast, if not faster, than even the best RAM available to date. This makes it extreamly useful for use as traditional RAM as it will use less power and will be able to retain state once the computer is powered down (i.e. same as being able to put the computer to sleep, but without a battery). It's also a great replacement for current Flash memory sticks as the read/write speeds are increased tremendously, and also as future solid-state hard drives. 

The only down-side of course is cost. The technology is still in infancy and current modules are produced in very small sizes (less than a MB). It will take some time for manufacturing processes to improve in efficiency and for costs to come down. Of course, by then Flash memory will be so cheap that it'll remain as the primary large storage technology for a long time to come.

Check out this site for the latest MRAM news.


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