Digital Codes

Background

Computers process information using electrical signals to code and interpret information, and to send control signals.

A binary code is used by computers since a processor is essentially a series of on/off switches or transistors with information either stored or not stored. Information can be transferred using a series of electrical signals -- there is electricity flowing or there is no electricity flowing. This causes a motor or a pixel (point of light on a computer screen) to turn on or off or compare the pattern to an image stored in memory.

Materials Needed

• graph paper
• overhead transparency with graph paper grid
• simple pictures

What to Do

To encode sensory information in order to interpret images, computers turn a picture into digital code. To see how this can be accomplished, use a grid to turn a picture into a code of a series of 0's and 1's. Place a transparent grid over a picture. In each square with more than half of the square covered by part of the picture put on one. If there is less than « of the picture covered, put a 0 in the square. Read the series of 0's and 1's to another person who will fill in a blank grid to recreate the original picture by reversing the code. (Shading squares when a 1 is read.) Images can be transferred back and forth this way.

After information is encoded, computers can analyze the data in different ways. A mobile robot might look for areas with a sharp contrast in order to follow the edge of a road. A sorting robot might compare a picture in its memory with an object in the camera's view.

A picture of a square translates into the following code:

 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0