Computer Science Illuminated, 7th Edition

4.2 Gates

The gates in a computer are sometimes referred to as logic gates because each performs just one logical function. That is, each gate accepts one or more input values and produces a single output value. Because we are dealing with binary information, each input and output value is either 0, corresponding to a low-voltage signal, or 1, corresponding to a high-voltage signal. The type of gate and the input values determine the output value.

Let’s examine the processing of the following six types of gates. We then show how they can be combined into circuits to perform arithmetic operations.

• NOT

• AND

• OR

• XOR

• NAND

• NOR

In this book we have colorized the logic diagram symbols for each gate to help you keep track of the various types. When ...