Frank Vorstenbosch wrote:

> My current favourite is the StrongARM, which will do
> internal cycles at 235Mhz, with a bus of up to 66MHz.

I hear a key part of the DEC Alpha is a 40W
RF transistor just to drive the clock!

ARM have implemented the Amulet microprocessor,
which avoids the problems of getting an RF clock
round an entire chip by using asynchronous logic.

Thus, data flows through it as fast as the signals
can travel in the chip. This varies a little from
one manufacturer's fabrication process to another.

The power and EMI are lowered, because only the silicon
doing any work switches states. If you upgrade to a chip
which can run faster, you don't have to change a clock
crystal.