Today, HP announced a joint development agreement with Hynix Semiconductor Inc., to develop a new kind of computer memory – one that will employ memristor technology pioneered by researchers at HP Labs.
This memory, called ReRAM, holds the potential to surpass Flash in terms of affordability, total capacity, speed, energy efficiency, and endurance.
And its potential doesn’t stop there. “We believe that the memristor is a universal memory technology that over time could replace Flash, DRAM, and even hard drives,” says Stan Williams, HP Senior Fellow and founding Director of the Information and Quantum Systems Lab (IQSL).
But what is a memristor and how might it change the evolution of information technology?
A short history on memristor
Previous to the prediction of the memristor by Prof. Leon Chua of UC Berkeley in 1971, there were three recognized passive circuit elements: the resistor, capacitor, and inductor. These three passive elements have provided the fundamental building blocks on which all electronic circuits today are based.
HP’s demonstration that so-called ReRAM (resistive-RAM) devices were actually memristors provided the mathematical foundation for completely new types of electronics.
What is “Flash memory”?
Flash is a type of solid-state storage commonly used in mobile phones, mp3 players, and some laptops (among other devices).
What is ReRAM?
The agreement between HP and Hynix will see them jointly developing memristor technology in the form of Resistive Random Access Memory (ReRAM). ReRAM is a non-volatile memory built using materials that change resistance when a voltage is applied across them.
“People have been attempting to make resistive memory for a long time,” explains Williams. “But because they didn’t understand that the devices they had were memristors, they weren’t making good progress. Once you understand the mathematical framework for memristors, you can design circuits that perform the way they are intended to perform.”
What will be the first device using memristors?
In the near term, the most obvious application for memristor technology is as a replacement for Flash memory. “Memristor memory chips promise to run at least ten times faster and use ten times less power than an equivalent Flash memory chip,” says Williams.
Experiments in his lab also suggest that memristor memory can be erased and written over many more times than flash memory. And on top of that, says Williams, “we believe we can create memristor ReRAM products that, at any price point, will have twice the capacity of flash memory.”
What does this mean for my laptop or smartphone?
Memristors can retain information even when the power is off and are highly energy efficient. This means that your laptop could boot up much faster and last longer on one charge since it consumes less energy. Given the number and sophistication of apps running on smartphones, this should also significantly extend the usable time between charges.
In the future, because both compute and memory functions could be conducted within the same chip, this also means that laptops and smartphones could be much thinner and much faster than they are now. (Why? Because data have less distance to travel since memory and logic are performed on the same chip).
How does this benefit HP and open industry standards?
“Almost every product offered by HP uses memory in some fashion: PC’s, phones, printers, servers, storage, networking and so on,” notes Williams. He suggests that the company can use its unique insight into memristor to bring highly differentiated products to market before its rivals.
At the same time, says Williams, HP isn’t planning to become a memory chip maker itself, or to restrict the licensing of its memristor technology.
“Our long term goal,” he explains, “is to see this technology spread through the entire IT ecosystem.”
What is the advantage of memristors?
Laboratory trials conducted at HP Labs have shown that memristor ReRAM circuits require less energy to operate, are faster, and have higher endurance than Flash, and these advantages are anticipated to increase into the future.
Since memristors are based on a thin film technology, the memory elements can be easily stacked on top of each other, and thus more bits can be built onto a single chip. They also are virtually immune to interference from ionizing radiation – making them attractive for inclusion in ever-smaller but ever-more-powerful devices.
Still, the memristor is a relatively recent discovery and new properties are yet to be found.
Research from the HP Labs IQSL team published earlier this year showed that, in addition to acting as memory devices, memristors can also perform logic functions. This suggests that computation might eventually be performed where data is stored, something that could result in computers running significantly faster than at present since data will not have to be passed around among multiple chips.
Are there potential future uses for memristors in ”artificial intelligence”?
Memristors fundamentally operate in a similar fashion as the biological synapses in the human brain.
One potential application of memristor technology would be an 'artificial synapse' in a circuit designed for analog computation. Professor Leon Chua at the University of Berkeley, who first postulated the memristor in 1971, is currently pursuing research in this area.
“Professor Chua himself pointed out the connection between the properties of his proposed memristor and those of a synapse in his earliest papers,” says Stan Williams, HP Senior Fellow and Director of the Information and Quantum Systems Lab, HP Labs. “We also think that this is a very interesting and potentially valuable research direction.”
HP’s research has revived Chua’s own interest in memristors. He was recently awarded a Guggenheim Fellowship to pursue the application of memristor technology in artificial intelligence and neural computing.
“H.P. Reports Big Advance in Memory Chip Design,” by John Markoff, The New York Times, May 1, 2008
“H.P. Sees a Revolution in Memory Chip,” by John Markoff, The New York Times, April 7, 2010.