2-1
CHAPTER 2
FUNDAMENTAL LOGIC CIRCUITS
LEARNING OBJECTIVES
Upon completing this chapter, you should be able to do the following:
1. Identify general logic conditions, logic states, logic levels, and positive and negative logic as
these terms and characteristics apply to the inputs and outputs of fundamental logic circuits.
2. Identify the following logic circuit gates and interpret and solve the associated Truth Tables:
a. AND
b. OR
c. Inverters (NOT circuits)
d. NAND
e. NOR
3. Identify variations of the fundamental logic gates and interpret the associated Truth Tables.
4. Determine the output expressions of logic gates in combination.
5. Recognize the laws, theorems, and purposes of Boolean algebra.
INTRODUCTION
In chapter 1 you learned that the two digits of the binary number system can be represented by the
state or condition of electrical or electronic devices. A binary 1 can be represented by a switch that is
closed, a lamp that is lit, or a transistor that is conducting. Conversely, a binary 0 would be represented by
the same devices in the opposite state: the switch open, the lamp off, or the transistor in cut-off.
In this chapter you will study the four basic logic gates that make up the foundation for digital
equipment. You will see the types of logic that are used in equipment to accomplish the desired results.
This chapter includes an introduction to Boolean algebra, the logic mathematics system used with digital
equipment. Certain Boolean expressions are used in explanation of the basic logic gates, and their
expressions will be used as each logic gate is introduced.
COMPUTER LOGIC
Logic is defined as the science of reasoning. In other words, it is the development of a reasonable or
logical conclusion based on known information.
