Digital Fundamentals

Digital Fundamentals

CHAPTER 2 Logic Gates and Boolean Algebra

Slide 1

Logic Gates

• • • • • • •

Inverter AND Gate OR Gate Exclusive-OR Gate NAND Gate NOR Gate Exclusive-NOR Gate

Slide 2

2.1 The Inverter

Truth table

Boolean expression

0 = LOW 1 = HIGH

Pulsed waveforms

The output of an inverter is always the complement (opposite) of the input.

Slide 3

2.2 The AND Gate

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of an AND gate is HIGH only when all inputs are HIGH.

Slide 4

2.2 The AND Gate (cont….)

3-Input AND Gate 4-Input AND Gate

Slide 5

2.3 The OR Gate (cont….)

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of an OR gate is HIGH whenever one or more inputs are HIGH

Slide 6

2.3 The OR Gate (cont….)

3-Input OR Gate 4-Input OR Gate

Slide 7

2.4 The NAND Gate

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of a NAND gate is HIGH whenever one or more inputs are LOW.

Slide 8

2.4 The NAND Gate (cont….)

3-Input NAND Gate

4-Input NAND Gate

Slide 9

2.5 The NOR Gate (cont….)

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of a NOR gate is LOW whenever one or more inputs are HIGH. Slide 10

2.5 The NOR Gate (cont….)

3-Input NOR Gate

4-Input NOR Gate

Slide 11

2.6 Exclusive-OR Gate

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of an XOR gate is HIGH whenever the two inputs are different.

Slide 12

2.7 Exclusive-NOR Gate

Boolean expression Truth table 0 = LOW 1 = HIGH

Pulsed waveforms

The output of an XNOR gate is HIGH whenever the two inputs are identical.

Slide 13