Cambridge International A Level · Computer Science (9618)

Data Representation: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Data Representation.

10 questions23 marksFree, no account

Question 1

1 mark

When representing character data, which statement best describes a reason for choosing Unicode (UTF-16) over standard ASCII?

Question 2

1 mark

A floating-point representation uses a \(10\)-bit two's complement mantissa and a \(6\)-bit two's complement exponent. A number is stored with the following bit pattern:
Mantissa: \(0.101100000_2\)
Exponent: \(000101_2\)
What is the denary equivalent of this floating-point value?

Question 3

1 mark

A random-access file uses a hashing algorithm to determine the address of records. When a collision occurs, the system uses progressive overflow (linear probing). How does this method resolve the collision?

Question 4

1 mark

What is the correct value for one Kibibyte (KiB)?

Question 5

1 mark

Consider the addition of two 8-bit two's complement signed integers:
\( X = 01101011_{2} \)
\( Y = 00100101_{2} \)
Perform the addition and identify the result and whether an overflow has occurred.

Question 6

2 marks

Convert the denary number \( 156 \) into its hexadecimal equivalent, showing the intermediate steps used in the conversion process.

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Question 7

3 marks

Explain the difference in the number of bytes between \( 1 \text{ Gibibyte (GiB)} \) and \( 1 \text{ Gigabyte (GB)} \), and identify which unit represents the larger amount of data.

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Question 8

5 marks

Explain the specific conditions under which an arithmetic overflow occurs when adding two signed 8-bit integers in two's complement form.

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Question 9

3 marks

Hexadecimal is frequently used in low-level computing for tasks such as specifying memory addresses or hardware identifiers.
(a) State two advantages of using hexadecimal over binary when representing data for a human programmer.
(b) A hardware device has the identifier C4-5D. Convert the hexadecimal value C4 into a denary integer and 5D into an 8-bit unsigned binary integer.

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Question 10

5 marks

A company needs to store a large collection of high-resolution architectural drawings. The technical team must choose between bitmap and vector graphic formats.
(a) Explain why a vector graphic format would be more suitable than a bitmap format for a logo that needs to be scaled to fit on both a business card and a large billboard.
(b) Describe two items of data that would be stored in the file header of a bitmap image.
(c) A bitmap image has a resolution of \( 1024 \times 768 \) pixels and a colour depth of \( 8 \text{ bits} \). Calculate the minimum file size in MiB. Show your working.

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