So that's our tour of the inside of the computer.
Let's look at one other hardware item in a similar way: The mouse.
There are basically two types of mice. The simpler kind looks like this on
the bottom:
The ball presses against the desk, and when you move the mouse one way, it rolls the other way.
Let's take out the ball:
Here's what's under the ball:
One sensor tracks the ball's motion in the horizontal direction, the other in the vertical direction. If you move the mouse on a diagonal, the computer gets data from both sensors and can put it together to figure out how far the mouse has moved and in what direction.
