Logic Gates

Question 1

Gate

Answer 1

A device that performs a basic operation on electrical signals and consists of transistors

Question 2

Circuits

Answer 2

Gates combined to perform more complicated tasks

Question 3

What is a transistor?

Answer 3

• semiconductor devise for amplifying, controlling, and generating electrical signals.

Question 4

Two main roles of a transistor?

Answer 4

Amplify or switch electrical signals and power.

Question 5

NOT Gate Inputs and Outputs?

Answer 5

• Accepts one input signal and returns the opposite of what was inputted

Question 6

NOT Gate Boolean Expression

Answer 6

X= A’ and X=NOT(A)

Question 7

AND Gate Input and Output?

Answer 7

• Accepts two output signals

- If both are 1=1, otherwise the output is 0

Question 8

AND Gate Boolean and Excel Expression

Answer 8

X= A . B and X = AND(A,B)

Question 9

OR Gate Input and Outputs

Answer 9

• Accepts two signals

- If both 0=0, otherwise, the output is 1

Question 10

OR Gate Boolean and Excel Expression

Answer 10

X =A+B and X = OR(A,B)

Question 11

NAND Gate Input and Output

Answer 11

Combination of NOT and AND

• Accepts two signals
• If both are 1=1, otherwise output is 0

Question 12

NAND Gate Boolean and Excel Expression

Answer 12

(A . B )’ and X= NOT(OR(A,B))

Question 13

XOR Gate Input and Output

Answer 13

• Accepts two inputs

- If both are the same, the output is 0, otherwise they are the same

Question 14

XOR Gate Boolean and Excel Expression

Answer 14

-They are special circuits that carry out additional operations

Question 15

What is a Half-Adder?

Answer 15

• A circuit that computes the sum of two bits and produces the correct carry bit
• Has two inputs and produces two outputs (sum and carry-in)

Question 16

What is a Full-Adder?

Answer 16

• A circuit that computes the sum of two bits and a carry bit and produces the correct carry bit
• Has three inputs (A, B, carry-in) and two outputs (sum and carry)

Question 17

What are some limitations of transistor gates?

Answer 17

• Power is consumed even if nothing is

connected to the output

Question 18

What are other transistor-based circuits?

Answer 18

-CMOS is much better because power used only during switching from one state to another

Question 19

What kind of transistors do modern computers use?

Answer 19

-CMOS logic circuits

Question 20

Why do we need to use transistors?

Answer 20

1. Be able to implement the logic functions in hardware
2. Perform complex operations
3. Power-efficient and can be very fast
4. Transistors are building blocks for modern computer microchips