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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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The Transistor at 75

The past, present, and future of the modern world’s most important invention

2 min read
A photo of a birthday cake with 75 written on it.
Lisa Sheehan
LightGreen

Seventy-five years is a long time. It’s so long that most of us don’t remember a time before the transistor, and long enough for many engineers to have devoted entire careers to its use and development. In honor of this most important of technological achievements, this issue’s package of articles explores the transistor’s historical journey and potential future.

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