In 1971, Professor Raymond Chua, at the University of California, Berkeley, first described the memristor; it's short for memory resistor because the resistance of a memristor varies with the current applied to it and, when the current ceases, it retains that level of resistance. Chua argued that the memristor was a theoretically necessary fundamental circuit element because no combination of the other three — resistor, capacitor, and inductor — could substitute for it. The theory remained unproven for nearly 40 years although evidence of memristance can now be seen in anomalous results reported over the last hundred years.
In 2008, a team at Hewlett-Packard's Automation and Quantum Systems Lab, utilizing nanoscale technology, succeeded in proving the theory and constructing memristors, in part because they found that the property of memristance is actually stronger at atomic distances. In a recent New York Times article about memristors, John Markoff wrote:
"The H.P. technology is based on the ability to use an electrical current to move atoms within an ultrathin film of titanium dioxide. After the location of an atom has been shifted, even by as little as a nanometer, the result can be read as a change in the resistance of the material. That change persists even after the current is switched off, making it possible to build an extremely low-power device."
Hewlett-Packard is already developing memristor replacements for flash memory devices; the memristor replacements require less energy and offer higher storage densities than current technology. Memristors are also essentially immune to radiation. These devices are expected to be available within two to three years, helped by the fact that memristor production uses industry-standard fabrication techniques.
The ability of memristors to "remember" opens the possibility of creating non-volatile RAM, potentially eliminating the need to constantly transfer information to and from permanent storage, and greatly reducing power-up times. It would also remove one of the most common sources of user problems: the need to "save" work.
Last month, in an article in the journal Nature, HP Labs announced a further breakthrough: Memristors have been shown to be capable of performing logic functions. Memristor circuits that can both store and process information suggest the eventual possibility that data could "work at home," avoiding the necessity to commute to the CPU for processing and then back for storage.
Imagine a computer whose data is never at risk of evaporating if the power fails, is immune to interference from radiation, is an order of magnitude smaller and faster than current computers, and powers up instantly. Memristors may be the key.
More information about memristors
- Demystifying the memristor (HP Labs, April 2008)
- HP Memristor FAQ (HP Labs)
- HP research could yield faster, more powerful PCs (CNET)
- Memristors combine memory, logics set in one device (Ars Technica)
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