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.