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Xbox One's massive, custom CPU can pick you out of a lineup

Mark Hachman | Aug. 27, 2013
At the Hot Chips conference at Stanford, Microsoft designers reveal the chips at the heart of the Xbox One console as well as its Kinect depth sensor.

Microsoft's Xbox One has a problem: you, and your family.

One of the problems that Microsoft had to solve when developing the Xbox One game console was a simple one: how to tell apart the player using the interactive gaming console from his friends, the lamp, the couch, and the coffee table. To solve that issue, Microsoft developed its own light sensor that can figure out what it's seeing by a variety of calculations.

In talking up the innards of its upcoming gaming console, Microsoft didn't reveal any new capabilities of the One--due this November--during a presentation at the Hot Chips conference Monday at Stanford University. But company executives discussed the so-called "speeds and feeds" of the main Xbox One processor in detail, as well as the problems that the new Kinect team had to overcome.

One massive chip

Physically, the system-on-a-chip at the heart of the Xbox One is 363 square millimeters. But the real whopper is the amount of logic integrated within it: 5 billion transistors. Although Wikipedia isn't necessarily the final arbiter, the Xbox One is possibly the largest chip manufactured to date, with a comparable number to Intel's 64-core Xeon Phi coprocessor for supercomputers, and easily topping Intel's 8-core "Poulsen" Itanium that the chip maker launched in 2012.

Unfortunately, Microsoft didn't disclose how much power that chip will consume. However, the chip will be power gated down to 2.5 percent of its power, said John Sell, a hardware architect at Microsoft who gave the Xbox One silicon presentation at Hot Chips. It will be manufactured in 28-nm process technology by TSMC, Microsoft's foundry partner.

Nor did Microsoft disclose how fast the chip will run. All told, the Xbox One system contains 500GB of storage, 8GB of DDR3 memory and 47MB of on-die storage that can be used as cache memory.

The system CPU is based on the AMD Jaguar processor architecture; the system uses eight cores with 32 KB of instruction and data cache, with four of the cores connected to a shared 2 MB shared level-2 cache.

The Xbox One chips are highly customized, Sell said. One significant change from the previous-generation Xbox 360 is that the graphics core is integrated with the CPU, as are most of today's PCs chips. Sel referred to the GPU chip as a "DirectX 11.1+" chip, as it contains optimized graphics processing unique to the Xbox One. "There's more than a CPU's worth of processing in there," Sell said.

Kinect challenges

Each Xbox One will contain a Kinect depth camera, designed by Microsoft. (The camera used in the Xbox 360 was designed by PrimeSense, an Israeli developer.)


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