Rubbish chips save power

A top researcher says that it is time to stop making chips super-precise and start allowing them to make a few mistakes.

Christian Enz, the new Director of the Institute of Microengineering, taling to Extreme Tech believes it is time that chip designers started to adopt a “good enough” approach. He said that this could save lots of power.

For example if software can tolerate “3.14″ as opposed to “3.14159265358,” you can save quite a bit of power in computation, he pointed out.

Enz said since chips are extremely complex and defect densities are notoriously difficult to control, engineers have to compensate with additional circuitry that adds die size and reduces the performance and power consumption benefit of moving to a smaller process node.

He thinks that one way of fixing these bugs is to intentionally create imperfect designs. This does not mean that they are broken, but that imperfections are placed extremely carefully in areas where humans can control the final output.

Enz said that the problem with allowing imperfection is that chips have to be capable of detecting the difference between a “good enough” answer and a wrong answer.

“There are a huge number of areas — GPS navigation, autopilots, robot-assisted surgery, spreadsheets, and scientific computing, for example — where “good enough” simply isn’t an option,” he said.

But crucially there are an equal number of areas where “good enough” might be just fine. Audio/video playback, web browsing, gaming, and other casual uses all involve trade-offs where people might choose “good enough” as a way to improve battery life.

This is not the first time that imperfection has been seen as a possible design tool. Intel looked at an idea of a variable FPU that can drop to 6-bit computation when a full eight bits isn’t required.

This power saving option relies on circuit gating to shut parts of an individual function unit off rather than power gating a larger element.

Of course there might be a problem marketing such a chip to the great unwashed. How do you sell a product which is “near enough” while accuracy and perfection is praised. We guess you could call it “human.”