Bespoke Processors: A New Path to Cheap Chips

Engineers can cut size and power in half by stripping away unused logic gates from general-⁠purpose microcontrollers

4 min read
Photo: iStockphoto
Photo: iStockphoto

“Processors are overdesigned for most applications," says Rakesh Kumar, an associate professor of electrical and computer engineering at the University of Illinois. It's a well-known and necessary truth: In order to have programmability and flexibility, there's simply going to be more stuff on a processor than any one application will use. That's especially true of the type of ultralow-power microcontrollers that drive the newest embedded computing platforms such as wearables and Internet of Things sensors. These are often running one fairly simple application and nothing else (not even an operating system), meaning that a large fraction of the circuits on a chip never, ever see a single bit of data.

Kumar, University of Minnesota assistant professor John Sartori (formerly a student of Kumar's), and their students decided to do something about all that waste. Their solution is a method that starts by looking at the design of a general-purpose microcontroller. They came up with a rapid way of identifying which individual logic gates are never engaged for the application it's going to run. They then strip away all those excess gates. The result is what Kumar calls a “bespoke processor." It's a physically smaller, less⁠-⁠complex version of the original microcontroller, designed to perform only the application needed. Kumar and Sartori detailed the bespoke processor project in June at the 44th International Symposium on Computer Architecture, in Toronto.

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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