The end of Moore's Law?

kw: observations, computers, analysis

This chart (click to see detail), from the Wikipedia article Moore's Law, shows the total transister count for CPU chips for nearly forty years. As Gordon Moore originally stated it, the density of transisters per square inch was doubling each year. For at least the last thirty years, the doubling time has actually been closer to 18 months. The total transistor count is a bit different, because total chip sizes have increased also, but it is easier to determine (not all transistors are the same size due to power flow requirements).

The "feature size" of chips circa mid-2010 is 45nm, or about 200 silicon atoms across. Integrated circuit engineers keep finding ways to make transistors work as the feature size decreases. If we suppose that the minimum feature size is two atoms, there is a factor of 100 yet to go, or about seven doublings. That means that Moore's Law will reach a limit in ten years.

Smaller transistors switch faster, so chip speeds have increased also. The relentless push of technology has increased the speed and capacity of disks, motherboards, and all components. The "personal power law" I have experienced centers on two measures, CPU clock speed and hard disk capacity. I've had a variety of "boxes" since 1985 when I first got a TI Pro "PC compatible" with a 4Mhz processor and no hard disk (nor mouse; there was no MS Windows yet). Since then, the progression has been:

• 1987 - PC/AT - 10 Mhz - 40 Mby HDD
  
• 1991 - Pentium - 75 Mhz - 500 Mby HDD (2d disk 1995 - 2.5 Gby)
  
• 1998 - Pent III - 800 Mhz - 30 Gby HDD
  
• 2000 - Pent IV - 1.3 Ghz - 40 Gby HDD
  
• 2008 - Core 2 - 2.7 Ghz - 160 Gby HDD
  

Note how CPU speed increases have become less aggressive. Now, even though 4-, 6- and 8-core processors are available, the top speed of a single core is 3.5 Ghz, and this hasn't changed for three or four years. However, hard disks are continuing to grow in capacity. Current "standard" is 1-2 Tby, which costs less than $100. There is more room for disk capacity to continue to grow than there is for CPU speeds to increase. Suppose 100 atoms will do, for a persistent "on" or "off" bit. A 15-cm disk could hold 200 Tby, and multi-platter stacks are common. The Pby (petabyte) personal disk drive is probably no more than twelve years away. At that point, the exponential law for disk capacity will also be about played out.

Personally, I once thought I'd never use a full Gby. Now I have 10 Gby of pictures! (and a similar size stash of music files) But what will we do about a decade from now when the limits I've noted are reached? I suspect technology has some surprises in store for us. The Moore's Law that I can see may be coming to an end, but I'm probably not much of a prophet.