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.