Logic Gates NOT Inverter Gate AND Gate OR Gate NAND Gate NOR Gate XOR Gate 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 ID: 815161
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Slide1
Logic Gates
Slide2Logic GatesDigital Signals Logic GatesNOT (Inverter) GateAND Gate
OR Gate
NAND Gate
NOR Gate
XOR Gate
Slide3Digital 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
Each column represents a small amount of time
1 (3V)
0 (0V)
1 0 0 1 0 1 1 0
Slide4Logic GatesAn electronic system that performsa 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
Slide51
0
NOT (Inverter) Gate
A logic gate that changes its input logic level to the opposite state
Symbol
0
1
Truth Table:
A table listing all possible inputs to a circuit and the corresponding outputs
Truth Table
NOT
Gate
Input (
A
)
Output (
Y
)
A
Y
0
1
1
0
Slide6Logic Word ProblemsIf 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.
Slide7AND GateIf I am hungry AND it is 5:00 p.m., then I will eat dinner.
A logic circuit whose:
Inputs both = 1 then,
Output = 1
Symbol
Slide81
0
0
0
1
0
1
1
1
0
0
0
AND Gate
Truth Table
AND
Gate
Input (
A
)
Input (
B
)
Output (
Y
)
A
B
0
0
0
Y
0
0
1
1
0
0
1
1
1
Slide9OR GateIf I pedal harder OR go downhill, then my bike will go faster.
A logic circuit when:
Either Input = 1 then,
Output = 1
Symbol
Slide100
0
0
1
0
1
0
1
1
1
1
1
OR Gate
Truth Table
OR
Gate
Input (
A
)
Input (
B
)
Output (
Y
)
A
B
0
0
0
Y
0
1
1
1
1
0
1
1
1
Slide11NAND GateIf it is windy AND cold, then I am
NOT
going to walk home.
A logic circuit whose:
Inputs both = 1
then,
Output = 0
Symbol
Slide120
0
1
1
0
1
0
1
1
1
1
0
NAND Gate
Truth Table
NAND
Gate
Input (
A
)
Input (
B
)
Output (
Y
)
A
B
0
1
0
Y
0
1
1
1
1
0
1
0
1
Slide13NOR GateIf my battery is dead OR I forget headphones, then I will
NOT
listen to my music.
A logic circuit when:
Either Input = 1 then,
Output = 0
Symbol
Slide140
0
1
1
0
0
0
1
0
1
1
0
NOR Gate
Truth Table
NOR
Gate
Input (
A
)
Input (
B
)
Output (
Y
)
A
B
0
1
0
Y
0
0
1
1
0
0
1
0
1
Slide15XOR GateI 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.
A logic circuit when:
If A or B = 1, but not both,
then Output = 0
Symbol
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
F
F
F
T
T
T
F
T
TT
F
Slide160
0
1
0
0
1
1
1
XOR Gate
Truth Table
XOR
Gate
Input (
A
)
Input (
B
)
Output (
Y
)
0
0
0
0
1
1
1
1
0
1
0
1
0
0
1
1
A
B
Y
Slide17Logic GatesDigital Signals Logic GatesNOT (Inverter) GateAND Gate
OR Gate
NAND Gate
NOR Gate
XOR Gate
Slide18Image ResourcesMicrosoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx