The active area is the top part of the chip where all the action takes place. It contains the layers of transistors, resistors and interconnection layers that make up the circuits and perform the actual computing. Although the thickness of the entire chip is only about 1/30th of an inch, the active area is just a few micrometers. See
chip,
half-adder and
Boolean logic.
Entirely Magical
No man-made object is more incredible than the chip. Today's state-of-the-art CPUs and SoCs contain billions of transistors, many millions of which are simultaneously switching their state from on to off and off to on every second. In fact, so many transistors are changing at the same time that, in total, there are quadrillions of transistor state changes taking place every second. Think about that number... quadrillions of changes every second for hours on end in absolute digital perfection. See
head of a pin,
transistor and
SoC.
A Digital Miracle
When people look at a chip package, they see an object the size of a cracker, but its active area is thinner than a postage stamp. Chip packages can be as large as this example or as small as the tip of a lead pencil (see
microcontroller). See
Boolean logic and
chip package.
There Are Many Layers on a Chip
The transistors in the circuits interact with each other, and the connections are routed through multiple layers on the chip. The entire active area with all the layers is only a couple micrometers from top to bottom. In contrast, a human hair is from 8,000 to 10,000 micrometers in diameter. See
process technology.