Transcript Logic Gates
Fundamental Logic
Gates
And, Or, Not
Logic Gates: The Basics
Regulate the flow of electricity within
circuits to perform desired functionalities
Each gate receives one or more inputs but
has only one output
Represented using Schematics, Words,
Symbols, and Boolean Equations
Logic Gates and Transistors
Logic Gates: AND
Schematic
Symbol
Boolean Equation
•
Y=A•B
(Output) Y is True:
Only if both (Inputs) A and B are true.
Aside Boolean Variables
Boolean variables are always capital
letters and can only take on the values T
(true) or F (false).
For Example:
A=True
B=False X=true…
Logic Gates: AND continued…
Ex. Are the following statements true or false ?
My
name is Mr.Kurz and this is Room 231.
I am a human and I am the Prime Minister of Canada.
Truth Tables:
A
F
F
T
T
B
F
T
F
T
Y
F
F
F
T
or
A
0
0
1
1
B
0
1
0
1
Y
0
0
0
1
Note on Truth Tables
There is only one pattern to follow!
A
F
F
T
T
B
F
T
F
T
Y
F
F
F
T
A
0
0
1
1
ANY other way is wrong!
B
0
1
0
1
Y
0
0
0
1
Logic Gates: OR
Schematic
Symbol
Boolean Equation
+
Y=A+B
(Output) Y is True:
Only if (Inputs) A, B, or both A and B are true.
Logic Gates: OR continued…
Ex. Are the following statements true or false ?
This
class is ICE4M or is in Room 503.
I am a human or I am the Prime Minister of Canada.
Truth Tables:
A
F
F
T
T
B
F
T
F
T
Y
F
T
T
T
or
A
0
0
1
1
B
0
1
0
1
Y
0
1
1
1
Logic Gates: NOT
Schematic
Symbol
Boolean Equation
¯
Y=A
Output (Y) is True:
Only if Input (A) is false.
Logic Gates: NOT continued…
Ex. Which of these are true or false?
This
class is not ICE4M.
I am not the Prime Minister of Canada.
Truth Tables:
A Y
F T
T F
or
A Y
0 1
1 0
Example:
Create a truth table for the following circuit:
Steps:
Create Table
Fill in A, B, C
Solve one gate at a
time using in between
columns on the table
Solve for Y
A
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
C A•B
0
0
1
0
0
0
1
0
0
0
0
1
1
0
1
1
(A+B)•C
0
1
0
1
0
1
1
1
Additional Info
Equivalent Terminology:
True
1
on
open
High V
False
0
off
closed
Low V
For ‘n’ inputs into any logic gate, there will
be 2n rows in your truth table.
The other three gates
NOR – “Not Or”
NAND – “Not And”
Xor - “One or the other, not both”
Today
1.
2.
Complete the Logic Gate Summary Chart
Use the IC schematics on the resources
page to set up and test each of the 6 logic
gates.
Pin 14 goes to Power Pin 7 to ground.