FAQ: Forty years of Moore's Law

Gordon Moore's famous law has been around for four decades. Not bad for an idea he thought wouldn't last. Photos: Moore and his law

Forty years ago, Electronics magazine asked Intel co-founder Gordon Moore to write an article summarizing the state of the electronics industry.

The article outlined what became known as Moore's Law, the observation that the number of transistors--tiny on/off switches that churn out electrical signals that get represented as 1s and 0s--on a chip can be doubled in a short period of time. Adopted as a yardstick by the tech industry, the concept is one of the reasons the industry evolved into a high-growth, but high-risk, affair.

This FAQ explains the impact and consequences of the principles set down in the April 19, 1965, article.

What is Moore's Law?
When writing the article, Moore noted that the number of devices (which then included transistors and resistors) inside chips was doubling every year, largely because engineers could shrink the size of transistors. That meant that the performance and capabilities of semiconductors was growing exponentially and would continue to. In 1975, Moore amended the law to state that the number of transistors doubled about every 24 months.

When the paper first came out, chips sported about 60 distinct devices. By contrast, Intel's latest Itanium chip comes with 1.7 billion silicon transistors.

As monumental as the article has become, it wasn't a big deal then. It started on page 114 of the magazine.

"It wasn't something you expected to join the archives," Moore said in a recent gathering with reporters. "I didn't think it would be especially accurate."

Why is it possible?
It's the miracle of industrial chemistry. Silicon is a good semiconductor (which means it can conduct electricity, but in a manner that can be controlled), and the crystalline structure remains intact despite shrinkage.

Is the law now dead?
No, though various analysts and executives have incorrectly predicted its demise. It will, however, likely begin to slow down to a three-year cycle in the next decade and require companies to adopt alternative technologies.

Some people, such as Stan Williams and Phil Kuekes of HP Labs, say the ability to shrink transistors will start to become problematic by around 2010. That should prompt manufacturers to adopt alternatives, such as HP's crossbar switches, to control electrical signals.

It wasn't something you expected to join the archives.
--Gordon Moore, co-founder, Intel

Others, such as Intel's director of technology strategy, Paolo Gargini, paint a more gradual picture. Around 2015, they say, manufacturers will start to move toward hybrid chips, which combine elements of traditional transistors with newfangled technology such as nanowires. A full conversion to new types of chips may not occur until the 2020s.

From a theoretical point of view, silicon transistors could continue to be shrunk until about the 4-nanometer manufacturing generation, which could appear about 2023. At that point, the source and the drain, which are separated by the transistor gate and gate oxide, will be so close

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