Processing The Truth: An Interview With David Shippy
January 16, 2009 Page 1 of 3
A recent, sensational Wall Street Journal article about a book called 'The Race For A New Game Machine' raised a number of new questions about IBM's co-creation of the Cell chip for the PlayStation 3 -- near-simultaneous to its creation of the PowerPC Xenon CPU used in the Xbox 360.
The co-authors of 'The Race For A New Game Machine', David Shippy and Mickie Phipps, were two leading figures in the design of the Cell at the Sony-Toshiba-IBM design center, which jointly spent an estimated $400 million to develop the technology.
Shippy was the chief architect of the power processing unit for the Cell, and overall technical leader and architect for the team that created the Power Architecture-related microprocessors that ended up in both the Xbox 360 and the PlayStation 3.
The idea that the Xbox 360's processor shared some of the same design lessons as the PlayStation 3's Cell -- and the apparent claim that Microsoft's Xenon CPU might have taken any of IBM, Sony and Toshiba's PS3 learnings and applied them to the Xbox 360 -- has been controversial. So Gamasutra decided to talk to David Shippy, co-author of the book in question, to find out more details from his perspective.
Although Shippy was a distinguished IBM engineer for many years, his story in relation to the Cell chip began in 2000 when Sony first contacted IBM asking for an "order of magnitude increase in processing performance" to use in their next game machine. IBM demonstrated for the company all of its in-house tech, and other chips Shippy himself had worked on -- "and Sony said, 'That's really not what we're looking for,'" he recalls.
"They said, 'We want you to start from scratch, throw out everything you've ever done before, and come up with this groundbreaking new architecture with more performance than anything out there, any game machine, any PC,'" Shippy says. "Ken Kutaragi had this bold vision -- 'Don't come to me with anything you've got; go and invent something new.'"
The goal, Shippy says, was to create a "supercomputer on a chip." At the time, most PCs' processing power peaked at about 1.5 gigahertz, and dual cores were still a relatively new idea. The Cell, on the other hand, featured eight parallel processing engines. "We came along with Cell and we were double the frequency of any PC out there," Shippy says.
The larger feat, however, was to provide that level of processing power on as little an energy budget as possible. "Game machines can't really afford a huge fan and a heatsink," Shippy says -- so the plan was to create a high-performance chip with a smaller footprint.
The Cell project kicked off with a full team in March 2001. The Sony-Toshiba-IBM Design Center was established in Austin to build the chip, and for some two years, Shippy said the team was "heads down" designing the next-gen CPU chip for PlayStation 3.
According to Shippy: "And then, along comes Microsoft in 2003, and says, 'Hey, IBM -- can you design a chip for us?" Just like its rival, Microsoft was not easily impressed by IBM's existing offerings.
But the company did take an interest in IBM's PowerPC chipset, the latest versions of technology first implemented in 1992 by the firm, and previously used in simpler form by Nintendo for the Gamecube. Where Microsoft differed, says Shippy, was that it wanted multiple cores on the same chip.
"But what caught their eye, I would say, was the R&D effort that we had put into the Cell technology," he says, apparently referencing some of the high-level PowerPC advances made to help build elements such as the power processing unit of the Cell, which he was lead architect on. (The Cell architecture consists of a central PPU, and a set of parallel processing SPUs.)
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