Unit 3 : Logic Gates

Question 1

What devices control the movement of electrons, and consequently, electricity?

Answer 1

1. Transistors

Question 2

What is computer built up?

Answer 2

1. Integrated Circuits ( ICs )

Question 3

List out the example for Integrated Circults ( ICs )

Answer 3

1. CPU
2. Bus Interface
3. Memory Management Unit

• It was made up of transistors, resistors, capacitors and other electronic components

Question 4

What is the primary components of Integrated Circuits ( ICs )

Answer 4

1. Transistors

Question 5

How many pins are there in the Transitors ?

Answer 5

1. 3
   * 1st Pin ( Inlet )
   2nd Pin ( Controler )
   3rd Pin ( Outlet )

2nd Pin decides to let the electicity flow through 3rd Pin

Question 6

What does resistors do?

Answer 6

1. To resist the current of the electrity to control the electrity flowing to the devices

Question 7

What does capacitor do?

Answer 7

1. Stores small amount of electrical energy in a circult

Question 8

Does 0 means no electricity flows through the circut?

Answer 8

1. No, 0 has electricity, it was just a signal

Question 9

List out all the logic gates ( 7 )

Answer 9

1. Not Gate
2. Or Gate
3. And Gate ( Carry )
4. Exclusive-OR Gate ( XOR ) ( Sum )
5. NAND Gate
6. NOR Gate

Question 10

What will Not operators return?

Answer 10

1. Result True if single input value is False

• x = A
• Return the opposite value ( 0 -> 1 , 1 -> 0 )

Question 11

What is Truth Table do in logic gates

Answer 11

1. Specifies results for all possible input combination

Question 12

What will Or operators return?

Answer 12

1. Returns True if any input operands are true ( 0 + 0 = False ( 0 ) , 1 + 0 = True ( 1 ) , 0 + 1 = True , 1 + 1 = 1 ( True ) )
   * x = A + B
   * x will only be true when A or B is true

Question 13

What will Inclusive Or operators return?

Answer 13

1. Result True is both input operands are true ( 0 * 0 = False ( 0 ) , 1 * 1 = 1 ( True ) , 1 * 0 = False , 0 * 1 = False )

• x = A * B
  = A . B
  = AB
• Returns true if both input is true, one false will return in false

Question 14

What does Exclusive Or ( XOR ) operators return?

Answer 14

1. Result True if either A or B is True but not both ( 0 * 0 = False ( 0 ) , 1 * 1 = 0 ( False ) , 0 * 1 = True ( 1 ) )

• A xor B = ( A + B ) * ( A * B ) ‘
• A xor B = ( A * ( B ) ‘ ) + ( B * ( A ) ‘ )

’ means NOT
* It can be derived from OR, AND and NOT
* Can also named it the hating operator, which means that returns false if both value is the same

Question 15

What is VLSI stands for?

Answer 15

1. Very Large-Scale Integration

Question 16

What are the 3 fundamental operations?

Answer 16

1. AND
2. OR
3. NOT

Question 17

What is boolean logic?

Answer 17

1. Rules for handling Boolean constants and variables

Question 18

What operator does NAND gate combine?

Answer 18

1. And Gate
2. Not Gate

Question 19

What operator does NOR gate combine?

Answer 19

1. Not Gate
2. Or Gate

Question 20

What is basic for computer design?

Answer 20

1. Boolean Algebra

Question 21

What is combinatorial logic?

Answer 21

1. Combinatorial logic is a type of digital logic where the output depends solely on the present inputs, with no memory of previous operations

Question 22

List out of some examples for some of the things that uses combinatorial logic ( 4 )

Answer 22

1. Logic gates (AND, OR, NOT, XOR)
2. Multiplexers
3. Decoders
4. Arithmetic circuits like adders and subtractor

Question 23

What is sequantial logic?

Answer 23

1. A type of digital logic where the output depends on both the current inputs and the results of previous operations, typically using memory elements to store past state

Question 24

List out of some examples for some of the things that uses sequential logic ( 1 )

Answer 24

1. Counter

Question 25

What is gates or logical gates

Answer 25

1. Integrated circults constructured from transistor switched and other electronic components

Question 26

What are the main use for multiplexers?

Answer 26

1. Mainly used to increase the amount of data that can be sent over the network within a certain amount of time and bandwidth

Question 27

What does multiplexers also called as?

Answer 27

1. Data selector

Question 28

What is multiplexers

Answer 28

1. A device that selects one of several analog or digital input signals and forwards the selected input into a single line

Question 29

What is a half-adder circult?

Answer 29

1. It is a combinational circuit that adds two single-bit binary numbers and produces a sum and a carry

Question 29

What does Half-Adder Output?

Answer 29

1. Sum ( XOR Gate )
2. Carry ( AND Gate )

Question 29

What is a Full-Adder Circult ?

Answer 29

1. It is a combinational circuit that adds three single-bit binary numbers: two regular bits and an additional carry bit from a previous stage

• It will also outputs a sum and carry

Question 30

Full-Adder has how many value?

Answer 30

1. 3
   A , B and C ( Carry bit )

Question 31

Why XOR works as sum?

Answer 31

1. Because the calculation was like addition on binary digits

A B C
0 0 0
1 0 1
0 1 1
1 1 0

0 + 0 = 0
1 + 0 = 1
0 + 1 = 1
1 + 1 = 10 ( But C shows only 1 digits so it was 0 )

Question 32

Why AND works as a carry?

Answer 32

1. Carry is the carry over value ( 1 + 1 = 10 , 1 is carried over to the second digit )

A B C
0 0 0
1 0 0
0 1 0
1 1 1

0 + 0 = 0
1 + 0 = 0
0 + 1 = 0
1 + 1 = 10 ( This has a carry value, so it has 1)

Question 33

What is the table name for output for all combinations of input and previous states?

Answer 33

1. Truth Table

Question 33

What is the basic memory element for logic circuits?

Answer 33

1. Flip-Flop