Using two different processors is at odds with most practices, where the mantra is to pile in as much power as possible into one processor, says Mark Zwolinski, of the electronic systems design group at the University of Southampton. “It’s quite a neat idea. It’s like all great ideas—it’s blindingly obvious in hindsight,” he says.
The A7 processor is more efficient, primarily because it is physically much smaller. At just 0.5 millimeters square, it is one-fifth the size of typical smart-phone processors, and it uses 20 percent of the power.
Normally, this would reduce the speed of the processor. But ARM used new techniques, including a 28-nanometer chip fabrication process instead of a 45-nanometer one. As a result, the A7 is still powerful enough to run a basic smart phone. Because the chips are smaller, and a larger number can be cut from a silicon wafer, the price of these processors should be low enough to make smart phones that will sell for less than $100, which could make smart phones affordable in developing countries.
“Even $200 handsets today can run browsers and most games that the $500 high-end handset runs,” says Nayampally. The cheaper phones just might be a little slower and less responsive. But ARM says Cortex-A7 will match the performance of many existing smart phones. The Cortex-A15 will provide a level of performance well beyond what is available today.
“What’s not clear is how much of this power management is automatic and built into the hardware, and how much needs to be built into the software operating system,” says Zwolinski. Operating systems such as Google’s Android and Apple’s iOS will need to be modified to take advantage of these power savings. “So by itself, it is not a game-changer,” he says.
The new processors are now available to customers including Texas Instruments, Samsung, and Apple for testing. They should appear in devices by 2014, says Nayampally.
Even without the new technology, it will be tough for others to compete with ARM. “The company was the first to develop low-power CPU cores for licensing,” says Linley Gwennap, principle analyst at the Linley Group. “Nokia chose ARM for its early cell phones, and other mobile companies followed suit. Today, all software for mobile phones is developed on ARM, making it difficult for other instruction sets to break into that market. With more than 1.6 billion cell phones shipping per year, the volume of this market swamps that of PCs, servers, and most other processor applications.”