The Power of Two Is an Aesthetic

Apr 26, 2005
Naoki Asami, Editor-in-chief of Nikkei Electronics
By Naoki Asami, Editor-in-chief of Nikkei Electronics

On the other hand, it takes real technologies to realize a dream.

I intend to stick to 90nm technology. I know some people who suggested going into mass production using such outrageous technologies as 65nm or 45nm, but you can't make something only by dreaming. In my management role, I'm determined to start mass production with the 90nm. Unlike in the past, it has become extremely difficult to establish a single process technology. What used to take six months after the delivery of manufacturing equipment now takes two or even three years. In other words, once technology uses fine scale processing, you now have to face ten or twenty new problems that bubble up along the way, where in the past, one action was enough. It takes strong conviction and confidence to move on. That is why a stable process technology is so important for the mass production of Cell. Whether we like it or not, we cannot slow down the adoption of fine scale processes in the future, and that is a fact. In this sense, the significance of "PSP" is enormous. Through mass production of PSP chips, Sony succeeded in stabilizing 90nm manufacturing technology. And with that, we were fully prepared-including the injection of new material - to take on new challenges for Cell.

Do you have any idea of what the yield will be?

I'm not going to give a green light unless we attain a certain yield rate level. Just think of the amount of chips we are to produce - 20 million for game consoles alone, an estimated 10% of TV sets, as well as home servers. At this scale, brute strength alone won't do. We are not aiming to produce 100,000-yen chips. As Mr. Masatoshi Shima, who had designed the "4004" chip with Intel once wrote, Intel usually starts with the yield of 40% and then brings it up to 85%. That is a good curve. I believe there is universality in these figures that stands up regardless of time and use.

Cell has 8 embedded "SPE" CPU cores. What is the basis for this number?

Because it's a power of two, that's all there is to it. It's an aesthetic. In the world of computers, the power of two is the fundamental principle - there's no other way. Actually, in the course of development, there's this one occasion when we had an all-night, intense discussion in a U.S. hotel. The IBM team proposed to make it six. But my answer was simple - "the power of two." As a result of insisting on this aesthetic, the chip size ended up being 221mm2, which actually was not desirable for manufacturing.

In terms of the one-shot exposure area, a size under 185 mm2 was preferable. I knew being oversized meant twice the labor, but I on the other hand, I thought these problems of chip size and costs would eventually be cleared as we go along. But in this challenge of changing the history of computing, I could not possibly accept any deviation from the rule of the power of two. For example, the world of communication also has gone to the rule of the power of ten. Ethernet, which started with 10M bit/s, has gone through stages of 100M and 1G, and 10G is certain to come next. You won't go with, say, 4G just because 10G is technologically difficult. It is my belief that real technological innovation is born from such persistence.

To be continued.

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