We discussed an example of a computer that has been built here at Hewlett-Packard called Teramac. James Heath, a UCLA chemistry professor, and I spent at least a year and a half studying it before we were ready to build anything. We were having a series of discussions with a computer architect at HP, Philip Kuekes, about defect tolerance, and Phil started talking to us about this computer that he had helped build. They had decided to build it from imperfect or defective silicon components, because those would be much cheaper, and just deal with whatever problems that came up by using clever software. In other words, you pay for a material's perfection.
Perfection costs a lot of money.
And as you get more and more complex, the cost of perfection gets higher and higher. That's the main reason why the cost of fabs is increasing exponentially. What we're saying is that if we can make things that are imperfect but still work perfectly then we can build them a lot more cheaply. Teramac has an architecture that relies on very regular structures called crossbars, which allows you to connect any input with any output. If any particular switch or wire in the system is defective, you can route around it.