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Friday, June 12, 1998 Published at 03:10 GMT 04:10 UK


New computer fixes itself

Computers in the future could be able to repair themselves

American scientists say they have developed a computer that can mend itself. Although a single fault on most computers could stop them from working, hundreds of thousands of defects on the machine known as Teramac have no effect at all. Roland Pease of the BBC's Science Unit reports:

Anyone who has used a computer knows how easily the smallest slip will bring everything to a halt.

So it seems foolhardy to bring together hundreds of broken computer chips, wire them up, and expect something useful to happen.

Yet that is what Hewlett-Packard scientist Phil Kuekes did when he built the Teramac.

[ image: A programme avoids trouble spots]
A programme avoids trouble spots
Mr Kuekes explains: "It is broken, but it works perfectly. That's what's interesting about it. Of almost a thousand chips in this computer, three-quarters were bad.

"They were chips that HP (Hewlett-Packard) would never use.

"And yet people actually used it. And in fact they didn't know the computer was broken, because it possible for this computer to repair itself. that's what the interest is."

The machine mended itself using a special programme to avoid the trouble spots in the faulty components.

Mr Kuekes says: "It first of all has to find all the things that were wrong - and in the Teramac we found over 200,000 defects out of seven million possible things to look at.

"But still we had to find all 200,000 to make it work.

"And once you have found them you have to do something about it."

The result was a computer program that would re-route its instructions, so missing the defects. And with so many chips to work with, alternative routes were easy to find.

As a result the Teramac can work a hundred times faster than top-of-the range computers - using chips that other people would throw away.

But the machine is not a solution to today's problems as ordinary computers are too cheap for it to compete.

But in a decade, when computers will be far smaller, they will be made from molecular components and it will be impossible to make them perfect.

Jim Heath of the University of California at Los Angeles is one chemist who is working towards this chemical future.

He says: "People like myself have been exploring for many years the ways to make all the components of a computer in a [chemical] beaker.

[ image: Future machines will have molecular components]
Future machines will have molecular components
"And what's been holding them up is: how do you take the components from the beaker and turn them into a computer?

"The way you organise molecules is to turn them into a crystal, so you get a highly ordered pattern of molecules.

"But the crystal is always defective, because no matter how good you are as a chemist, if you react compounds A plus B together to make C, you'll always get a little bit of D and maybe a little bit of A and B left over.

"What Teramac shows us is how to take these possibly defective devices - molecular switches, gates, wires - and turn them into a computer."

He adds: "Teramac was composed of something like a thousand chips, arranged onto a number of boards.

"The chemical architectures that we're working on would give the same computer power on something a tenth of the size of a grain of sand."

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