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If you believe the prerelease hype, Sony’s PlayStation
3 is the machine that is going to change the way we
experience games. This past May, gamers got a taste of
some much-awaited PS3 titles during the E3 conference in
Los Angeles. In Resistance: Fall of Man, a first-person
shooter set in a devastated England overrun by creepy
creatures, bullets zip and thunk with stunning clarity,
and blood sprays with gruesome realism. In Heavenly
Sword, tables and bodies fly as in a martial arts movie
while you face enemy squads controlled by artificial
intelligence algorithms. And in Gran Turismo HD, a dozen
racing cars speed and skid through the streets of Tokyo
or on a dusty rally circuit that has the Grand Canyon as
a backdrop.
Sony Corp., in Tokyo, has a lot staked on the success
of the PS3—hundreds of millions of dollars, at least,
and maybe even its future as the preeminent maker of
consumer electronics. “Gamers are expecting a great deal
from the PS3, because Sony has promised a lot,” says
Brian O’Rourke, an analyst at market research firm
In-Stat, in Scottsdale, Ariz. “More realism, good online
experience, new and innovative games are probably the
primary expectations from gamers.” The console, after
one big delay, is supposed to go on sale in Japan on 11
November, and in the United States and Europe on 17 November.
Given the stakes involved, the press has lavished
considerable coverage on many of the PS3’s cutting-edge
technologies, including the console’s main brains, the
Cell microprocessor, which Sony developed with Toshiba
and IBM; the Blu-ray high-definition DVD system; and the
game machine’s graphics processor chip, from Nvidia,
which will be responsible for the promised
photorealistic graphics.
But one crucial technology set to debut in the new
console has received scant attention: the data-transfer
connections, or buses, that link the Cell processor to
both the console’s main memory and the graphics
processor. Chip-to-chip connections may not seem like
the most glamorous technology, but they are every bit as
important as the PS3’s other advances, because without
them the console’s chips would slow to a crawl.
In fact, the immersive experience Sony is aiming for
depends on data flowing to and from the Cell processor
at speeds way beyond anything achieved in a
home-electronics system. The bus between the Cell and
the PS3’s memory will achieve a peak data-transfer rate,
or bandwidth, of 25.6 gigabytes per second. That’s about
five standard DVDs per second—more than double what a
high-end PC equipped with today’s fastest memory system
can deliver. Meanwhile, the bus connecting the Cell to
the graphics chip will move data at 35 GB/s, or about
five to 10 times what you can get with today’s best
PC-bus technology.
The console’s connections were developed by Rambus
Inc., in Los Altos, Calif. Rambus has only recently
begun to position itself as a chip-to-chip and
board-to-board connection company. Most people still
think that DRAM, or dynamic random-access memory—the
most widely used type of memory—is the company’s main
focus. But despite some interesting technology and
initial support from Intel, Rambus’s DRAM didn’t win the
PC market. It did, however, make it into two gaming
systems: the Nintendo 64, released in 1996, and the
PlayStation 2, which has already sold over 100 million
units since its launch in 2000.
“Since the performance of the gaming sector is pushing
the envelope [of computing], and Rambus is about pushing
the envelope in those chip-to-chip connections, I think
the gaming sector is a very good match for them,” says
Michael Cohen, director of research at Pacific American
Securities LLC, in San Diego. (Cohen personally owns
shares of Rambus, but Pacific American has no financial
stake in the company.)
System designers have long been warning that the
performance of next-generation computer systems could be
limited by the bandwidth among their key chips. So the
need for speedier buses is acute. They could benefit not
just future game systems and PCs but workstations,
servers, high-definition TVs, and even supercomputers.
Rambus and others see these interface technologies as a
potential cash cow.
But creating superfast buses “is harder than most
people realize,” says Steven Woo, a senior principal
engineer at Rambus. “Basically, faster data rates
require higher frequencies, and as the frequencies go
up, it becomes increasingly difficult to maintain the
integrity of the electrical signals and keep them
synchronized.” To deal with those issues, the PS3’s
buses rely on a signaling technique to minimize
interference and attenuation, while a timing mechanism
compensates for time-control discrepancies. Those
features, Rambus says, will keep the bits flying in the
PS3.