Clockless Chips

iarkin writes "TechReview is running a very interesting article about clockless chips. Clockless, or asynchronous, chips work very much faster and consume less power than their synchronous equivalents (Intel hade some experiments on these chips back in -97, the results showed that the asynchronous chips were three times faster and consumed only half the power)."

Comments

UltraSPARC-IIIi will have a bit of async logic

[ChrisRijk]

"How Sun swerved to avoid Rambus"
http://www.theregister.co.uk/content/3/22279.html

More details on the CPU:
http://www.theregister.co.uk/content/3/22274.html

Sun press release:
Extends UltraSPARC III Chip Family Tree--First Use of Sun-Developed Asynchronous Logic Design in Chip's Memory Interface

At Sun Labs:
feature article
async research home page

The main problem.

[aspillai]

The main problem with async. design is the asycnchronous part of it. In a typical computer, you have tons of parts that you use interchangably. These parts have operate at different speeds. How would two devices working at different speeds operate smoothly. Generally, this is very hard. But the thing is they can: But the devices themselves need to agree on a few things. But async. design is higly complicated because in a clockless environment you have to pretty much garauntee something like "I'll do this within 2 equivalent clock cycle." or have other types of signalling negotiation. You can't clock on a "clock" to do stuff. You have to clock on a "async" signal.

This is the problem in the large. When you go down to the chip level, there are tons of nightmares. There can be feedback loops causing race conditions that only occur at certain times. There are load problems that might increase complexity so much more than equivalent problems in a clocked design. Clocked design makes things a lot simpler and still designing a chip is extremely diffucult.

But the future I don't think is in clockless design, but "careful clock" design. For example, there are chips which are smart enough to disable sending the clock to certain part of a chip when it knows those parts will never be used. That saves a lot of power. There are chips which aim to spread the clock around carefully thus increasing the speed. And remember, almost 50% of the power in a chip is lost due to the wiring!

me.