Bob Peterson sample_Embedded DRAM for Xbox 360

Bob Peterson sample_Embedded DRAM for Xbox 360

Bob Peterson writing sample
siliconvalleywriting.com
Self-published by client
(Layout and illustrations differ from published version.)
Client: NEC Electronics America, Inc.
NEC eDRAM in the Xbox 360:
Redefining Gaming Performance
To splash stunning high-end graphics onto highdefinition TVs, Microsoft’s Xbox 360 gaming
console takes excellent advantage of a large
block of embedded DRAM (eDRAM) from NEC
Electronics. This 10-Mbyte eDRAM enables
graphics memory bandwidth that would be all
but impossible with off-chip memory. The Xbox
graphics processing unit (GPU) relies on this
bandwidth to render real-time complex scenes at
high resolutions with high-quality anti-aliasing.
As Xbox Product Group corporate vice president
Todd Holmdahl explains, “Without NEC
Electronics embedded DRAM on the GPU and
the huge 256-Gbytes/second dedicated bus from
the GPU core to the eDRAM, it is impossible to
render true next-generation scene complexity at
high-resolution with anti-aliasing.” Xbox 360
supports all games with this dramatic
performance in high definition TV at 16:9, 720p
and 1080i.
A look at the GPU shows why it needs such an outrageous memory bandwidth. The 500MHz custom ATI graphics processor—fabricated by NEC Electronics—includes 48-wayparallel floating-point dynamically scheduled shader pipelines and a unified shader
architecture. Using external memory, the GPU would be limited to a 32- or 64-bit
interface. The NEC Electronics eDRAM expands the on-chip memory interface past 1000
bits in width to support the GPU’s 256-Gbytes/second bandwidth between the graphics
pipelines and memory.
The 10-Mbyte eDRAM block consists of several 20-Mbit macros, each capable of
supporting 500-MHz clock speeds. The macro was developed by NEC Electronics, and it
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offers versatile design parameters for easy integration with other intellectual property
(IP).
Cost-effective superpower
The NEC Electronics eDRAM in the Xbox 360 supports the platform’s extreme need for
speed and satisfies several other stringent specs. At the same time, the eDRAM provides
an affordable solution to enable Microsoft to sell millions of these products at the right
price point. The graphics chip also had to be ready within the tight market window
defined by the Christmas 2005 shopping season.
“NEC Electronics' cutting-edge embedded DRAM technology plays
a vital role in enabling our graphics engine's performance, while its
manufacturing process provides a reliable resource that can deliver
the volumes required to support what will be an extremely popular
gaming platform.”
— Todd Holmdahl, corporate vice president, Xbox Product Group
As the volume leader in eDRAM, NEC Electronics applies a great deal of experience in
fabricating this embedded memory, assuring that the graphics chip will meet Microsoft’s
tight time-to-market requirements. As [someone from Microsoft?] noted, “With so much
depending on the graphics chip in the Xbox 360, we wanted to work with a vendor who
has a mature eDRAM process. NEC Electronics provides the stable production and high
yield we were looking for.” NEC Electronics manufactures the chip in its 300-mm wafer
fabrication facility using the company’s 90-nm UX6D process.
This unique fully CMOS-compatible embedded DRAM process uses a single fab to
minimize cost. The process also ensures full-speed performance for both eDRAM and
standard CMOS devices on the same chip. The compatibility between eDRAM and
standard CMOS devices allowed ATI to use the same IP as for other CMOS chips, which
helped ensure that the GPU would meet the time-to-market requirement.
Containing the power
Superpower may be prized in the gaming world, but inside the gaming console it is
critical to limit power consumption. Because the eDRAM eliminates the need for a large
number of power-hungry I/Os to external memory, keeping the memory on board
significantly decreases power consumption. Such power reductions help minimize the
size of the GPU heat sink and make the Xbox smaller—a major goal of this design
project.
The project’s top goal was to push pulse-pounding graphics to a new high-definition
peak, whether the game of choice is Halo or Sonic the Hedgehog. NEC Electronics’
eDRAM makes it all possible.