Topic 1.2 - Logical Operations

Question 1

What is the truth table for OR?

Answer 1

• 0 0 = 0
• 1 0 = 1
• 0 1 = 1
• 1 1 = 1

Question 2

What is the truth table for AND?

Answer 2

• 0 0 = 0
• 1 0 = 0
• 0 1 = 0
• 1 1 = 1

Question 3

What is the truth table for XOR?

Answer 3

• 0 0 = 0
• 1 0 = 1
• 0 1 = 1
• 1 1 = 0

Question 4

How does XOR encryption work?

Answer 4

The data is XOR’ed with a key to produce encrypted data. To retrieve the data, the the encrypted data is XOR’ed with the key again

Question 5

What is the process of bit masking?

Answer 5

This is where the AND operation is used to mask part of a binary number to return only the relevant parts

• 01011101
• 00000111 AND
• 00000101 (Returns last 3 digits

Question 6

What is the purpose of a subnet mask?

Answer 6

A mask is used to check that one computer is on the same segment of network as another computing by only comparing the relevant bits from their IP addresses.

Question 7

How would you go about setting the 4 least significant bits to 1 in the byte 01010101?

Answer 7

You would ‘OR’ it with another bit which would leave the value of the first 4 bits and changing the value of the last 4 bits to 1

• 01010101
• 00001111 OR
• 01011111

Question 8

What does A.A simply to?

Answer 8

A

Question 9

What does A.<a> simply to?</a>

Answer 9

0

Question 10

What does 1 + A simply to?

Answer 10

1

Question 11

What does 0 + A simply to?

Answer 11

A

Question 12

What does A + A simply to?

Answer 12

A

Question 13

What does A + <a> simply to?</a>

Answer 13

1

Question 14

What does 0.A simplify to?

Answer 14

0

Question 15

What does 1.A simply to?

Answer 15

A

Question 16

What does A + A.B simply to?

Answer 16

A

Question 17

What does A + <a>.B simply to?</a>

Answer 17

A + B

Question 18

What does > simply to?

Answer 18

<a> + B</a>