1. Logic Gates Logic Gates Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Logic Gates

2. Logic Gates Digital Signals Logic Gates NOT (Inverter) Gate AND Gate
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Logic Gates
Digital Signals
Logic Gates
NOT (Inverter) Gate
AND Gate
OR Gate
NAND Gate
NOR Gate
XOR Gate

3. Each column represents a small amount of time
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Digital Signals
Digital signals 0 (false) or 1 (true)
Digital signal 1 is represented by a small voltage.
Digital signal 0 is represented by no voltage.
Digital Waveforms
1 (3V)
0 (0V)
Each column represents a small amount of time

4. Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Logic Gates
An electronic system that performs
a logical operation on an input signal
Gates process digital inputs to produce digital outputs.
How do computer processors make decisions? How do they do math? Display images? Etc.?
LOGIC

5. 1 1 NOT (Inverter) Gate Symbol
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
NOT (Inverter) Gate
Symbol
A logic gate that changes its input logic level to the opposite state 1 1 A Y
Truth Table: A table listing all possible inputs to a circuit and the corresponding outputs
Input (A)
Output (Y)
Truth Table
NOT Gate 1 1

6. Logic Word Problems
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
If I am hungry and it is 5:00 p.m., then I will eat dinner.
If I pedal harder or go downhill, then my bike will go faster.
If it is windy and cold, then I am not going to walk home.
If my battery is dead or I forget headphones, then I cannot listen to my music.
If either friend (but not both) want to go to dinner, we’ll go out to dinner.
Each word problem uses the same logic as a common gate.

7. AND Gate A logic circuit whose: Inputs both = 1 then, Output = 1
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
AND Gate
Symbol
A logic circuit whose:
Inputs both = 1 then,
Output = 1
If I am hungry AND it is 5:00 p.m., then I will eat dinner.

8. AND Gate 1 1 1 1 Input (A) Input (B) Output (Y) Truth Table AND Gate A
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
AND Gate 1 1 1 A 1 Y B
Input (A)
Input (B)
Output (Y)
Truth Table
AND Gate 1 1 1

9. OR Gate A logic circuit when: Either Input = 1 then, Output = 1 Symbol
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
OR Gate
A logic circuit when:
Either Input = 1 then,
Output = 1
Symbol
If I pedal harder OR go downhill, then my bike will go faster.

10. OR Gate 1 1 1 1 1 1 Input (A) Input (B) Output (Y) Truth Table OR Gate
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
OR Gate 1 1 1 A 1 1 1 Y B
Input (A)
Input (B)
Output (Y)
Truth Table
OR Gate 1 1 1

11. NAND Gate A logic circuit whose: Inputs both = 1 then, Output = 0
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
NAND Gate
A logic circuit whose:
Inputs both = 1 then,
Output = 0
Symbol
If it is windy AND cold, then I am NOT going to walk home.

12. NAND Gate 1 1 1 1 1 1 Input (A) Input (B) Output (Y) Truth Table
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
NAND Gate 1 1 1 A 1 1 1 Y B
Input (A)
Input (B)
Output (Y) 1
Truth Table
NAND Gate 1 1 1

13. NOR Gate A logic circuit when: Either Input = 1 then, Output = 0
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
NOR Gate
A logic circuit when:
Either Input = 1 then,
Output = 0
Symbol
If my battery is dead OR I forget headphones, then I will NOT listen to my music.

14. NOR Gate 1 1 1 1 Input (A) Input (B) Output (Y) Truth Table NOR Gate A
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
NOR Gate 1 1 1 A 1 Y B
Input (A)
Input (B)
Output (Y) 1
Truth Table
NOR Gate 1 1 1

15. XOR Gate A logic circuit when: If A or B = 1, but not both,
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
XOR Gate
A logic circuit when:
If A or B = 1, but not both,
then Output = 0
Symbol
I only have enough money for one of my two friends to go to dinner. If either one (but not both) want to go to dinner, we’ll go to dinner.
Possible Inputs (conditions)
Outputs
First Friend wants to go to dinner (T or F)
Second friend wants to go to dinner (T or F)
We will go to dinner (T or F) F T

16. XOR Gate 1 1 1 1 1 Input (A) Input (B) Output (Y) Truth Table XOR Gate
Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
XOR Gate 1 1 1 A B Y 1 1
Input (A)
Input (B)
Output (Y)
Truth Table
XOR Gate 1 1 1

17. Logic Gates Digital Signals Logic Gates NOT (Inverter) Gate AND Gate
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Logic Gates
Digital Signals
Logic Gates
NOT (Inverter) Gate
AND Gate
OR Gate
NAND Gate
NOR Gate
XOR Gate

18. Logic Gates
Gateway To Technology
Unit 6 – Lesson 6.3 – Digital Electronics
Image Resources
Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from