SLR 2.4 Computational logic

Question 1

What is a truth table?

Answer 1

A notation used in Boolean algebra for defining the output of a logic gate or logic circuit for all possible combinations of inputs.

Question 2

Which logic gate has the following truth table?

Input A  ¦  Input B ¦   Output
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
    0       ¦      0       ¦       0
    0       ¦       1       ¦        1
     1       ¦      0       ¦        1
     1       ¦       1       ¦        1

Answer 2

The OR gate has the truth table

Input A  ¦  Input B ¦   Output
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
    0       ¦      0       ¦       0
    0       ¦       1       ¦        1
     1       ¦      0       ¦        1
     1       ¦       1       ¦        1

Question 3

Which logic gate has the following truth table?

Input A  ¦  Input B ¦   Output
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
    0       ¦      0       ¦       0
    0       ¦       1       ¦       0
     1       ¦      0       ¦       0
     1       ¦       1       ¦        1

Answer 3

The AND gate has the truth table

Input A  ¦  Input B ¦   Output
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
    0       ¦      0       ¦       0
    0       ¦       1       ¦       0
     1       ¦      0       ¦       0
     1       ¦       1       ¦        1

Question 4

Which logic gate has the following truth table?

Input A ¦ Output
_____________
0 ¦ 1
1 ¦ 0

Answer 4

The NOT gate has the truth table

Input A ¦ Output
_____________
0 ¦ 1
1 ¦ 0

Question 5

Why is binary used to represent data in a computer?

Answer 5

Circuits only need to check for two states (they can use switches). The states are electricity flowing or not flowing (on / off OR 1 / 0). This results in more reliable circuits.

Question 6

What is the computational symbol for addition?

Answer 6

+

Question 7

What is the computational symbol for subtraction?

Answer 7

-

Question 8

What is the computational symbol for multiplication?

Answer 8

*

Question 9

What is the computational symbol for division?

Answer 9

/

Question 10

What is the pseudocode for integer division (no remainder)?

Answer 10

DIV (note this is the pseudocode for integer division, python uses //)

Question 11

What is the pseudocode for modulus (just the remainder of division)?

Answer 11

MOD (note this is the pseudocode for modulus, python uses %)

Question 12

What is the pseudocode for raising one number to the power of another (e.g. 2 cubed)?

Answer 12

^ (note this is the pseudocode for ‘exponentation’ - powers - python uses ** for example 2 ** 3 is 2 cubed)