Games Gadgets n Technology

Friday, May 02, 2008

Lasting memories


No more waiting: New discovery in electronics could lead to computers that start instantly, and with the same programs running as when you shut it off


For nearly 40 years, scientists have speculated that basic electrical circuits have a natural ability to remember things even when the power is switched off. They just couldn’t find it.

Now, US researchers at Hewlett-Packard have proven them right with the discovery of an electrical circuit that could lead to a computer you never have to boot up.

The finding proves what until now had only been theory – but could save millions from the tedium of waiting for a computer to find its “place”, the researchers said.

The newly discovered circuit element – called a memristor – could enable PCs that start up

instantly, and laptops that retain your session information long after the battery dies.

Lasts long, really long

Basic electronics theory teaches that there are three fundamental elements of a passive circuit – resistors, capacitors and inductors.

But in the 1970s, Leon Chua of the University of California at Berkeley, theorised there should be a fourth called a memory resistor, or ‘memristor’, and he worked out the mathematical equations to prove it.

Now, the HP team – led by Stanley Williams – has proven that ‘memristance’ exists. They developed a mathematical model and a physical example of a memristor, which they described in the journal Nature.

“It’s very different from any other electrical device,” Williams said. “No combination of resistor, capacitor or inductor will give you this.”

It’s like water flowing in a pipe...

Williams likens the memristance to water flowing through a garden hose. In a regular circuit, the water flows from more than one direction.

But in a memory resistor, the hose remembers what direction the water (or current) is flowing from, and it expands in that direction to

improve the flow. If water or current flows from the other direction, the hose shrinks.

“It remembers both the direction and the amount of charge that flows through it… That is the memory,” Williams said.

The discovery is more than an academic pursuit for Williams, who said the finding could lead a new kind of computer memory that would never need booting up.

Conventional computers use Dynamic Random Access Memory or DRAM, which is lost when the power is turned off, and must be

accessed from the hard drive when the computer goes back on.

But a computer that incorporates this new kind of memory circuit would never lose it place, even when the power is turned off.

“If you turn on your computer it will come up instantly where it was when you turned it off. That is a very interesting potential application, and one that is very realistic,” Williams said.

But he said understanding this new circuit element could be critical as companies attempt to build ever smaller devices.

“It’s essential that people understand this to be able to go further into the world of nanoelectronics,” referring to electronics on the nano scale – objects tens of thousands of times smaller than the width of a human hair.

“It turns out that memristance gets more important as the device gets smaller. That is another major reason it took so long to find,” Williams said.

Chua, who wrote the first paper on the topic when he was a new professor at Berkeley, is now 71 years old and says he’s nearing retirement from the university.

“I never thought I’d live long enough to see this happen,” Chua said with a laugh. “I’m thrilled because it’s almost like vindication. Something I did is not just in my imagination, it’s fundamental.’’

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