COMPUTER SCIENCE
EXAMINATION PAPER 2 Mark
Scheme
A bit pattern is shown in Figure 1.
Figure 1
01001110
0 1. 1 Convert the bit pattern in Figure 1 into decimal.
[1 mark] - Correct Answer 78
0 1. 2 Convert the bit pattern in Figure 1 into hexadecimal.
[2 marks] - Correct Answer 1 mark: 4;
1 mark: E;
0 1. 3 A student's answer to the question "Why is hexadecimal often used instead of
Binary?" is shown in Figure 2.
Figure 2
Because it uses fewer digits it will take up less space in a computer's memory.
Explain why the student's answer is incorrect.
[2 marks] - Correct Answer 1 mark: The answer is incorrect because number will be
represented
Using binary in a computer's memory;
1 mark: so it will take up the same amount of memory space;
0 1. 4 Explain how a binary number can be multiplied by 8 by shifting bits.
[2 marks] - Correct Answer (Shifting the bit pattern) three places; to the left;
Mark as follows:
1 mark: for correct direction of shift
1 mark: for correct number of times to shift
0 1. 5 Shade one lozenge to indicate which character is represented by the numeric
code
70.
[1 mark] - Correct Answer 1 mark: B: F;
0 1. 6 Unicode is an alternative to the ASCII coding system.
Describe one advantage and one disadvantage of using Unicode to represent
Characters instead of using ASCII.
[2 marks] - Correct Answer Advantages:
Can represent a wider range of characters;
Can represent characters from a wider range of languages;
Can represent characters used in
