Cambridge IGCSE™

* 5 4 1 6 5 1 8 6 8 7 *

COMPUTER SCIENCE 0478/11

Paper 1 Computer System May/June 2023

1 hour 45 minutes

You must answer on the question paper.

No additional materials are needed.

INSTRUCTIONS
● Answer all questions.
● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
● Write your name, centre number and candidate number in the boxes at the top of the page.
● Write your answer to each question in the space provided.
● Do not use an erasable pen or correction fluid.
● Do not write on any bar codes.
● Calculators must not be used in this paper.

INFORMATION
● The total mark for this paper is 75.
● The number of marks for each question or part question is shown in brackets [ ].
● No marks will be awarded for using brand names of software packages or hardware.

This document has 12 pages.

DC (PQ) 303744/3
© UCLES 2022 [Turn over
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1 A shopping mall has an information point. Visitors can use it to find out which shops are in the mall
and where they are located.

(a) Identify one input device that could be built into the information point.

Give an example of how that device would be used.

Input device ..............................................................................................................................

Example ....................................................................................................................................
[2]

(b) Identify one output device that could be built into the information point.

Give an example of how that device would be used.

Output device ...........................................................................................................................

Example ....................................................................................................................................
[2]

(c) Identify one example of primary storage that could be built into the information point.

State what would be stored in your example of primary storage.

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2 Phil has a computer that is designed using the Von Neumann model. The computer has a
central processing unit (CPU).

(a) One type of component within the CPU is an address bus.

Identify two other types of bus and state what each is responsible for transmitting in the CPU.

Bus 1 ........................................................................................................................................

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Bus 2 ........................................................................................................................................

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[4]

(b) The CPU performs a cycle that has three stages. One of these stages is execute.

Identify one other stage of the cycle that is performed by the CPU.

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(c) Identify the component within the CPU that the accumulator is built into and describe the
purpose of the accumulator.

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3 Error codes for a computer are often displayed as hexadecimal values. Each error code is stored
in a 12-bit binary register.

(a) The error code 404 means ‘file not found’.

Give the 12-bit binary value that would be stored for the hexadecimal error code 404

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Working space

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[2]

(b) The error code 12B means ‘hardware fault’.

Give the 12-bit binary value that would be stored for the hexadecimal error code 12B

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Working space

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[2]

(c) Hexadecimal values can also be represented as denary values.

The hexadecimal error code 022 means ‘file system error’. The hexadecimal error code 0AC
means ‘insufficient memory’.

Convert the hexadecimal error codes 022 and 0AC to denary values.

022 ...........................................

0AC ...........................................

Working space

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[2]
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(d) The register stores the binary value 100111100000

Give the hexadecimal error code that would be displayed for the binary value 100111100000

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Working space

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[2]

(e) Give two reasons why error codes are represented in hexadecimal, instead of binary.

Reason 1 ..................................................................................................................................

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Reason 2 ..................................................................................................................................

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[2]
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4 Rebekah discovers that her bank details have been used fraudulently.

She thinks her bank details were stolen electronically, whilst she was using the Internet.

(a) Identify and describe two methods that could have been used to steal Rebekah’s bank details
electronically.

Method 1 ...................................................................................................................................

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Method 2 ...................................................................................................................................

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[6]
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(b) Rebekah decides to encrypt the data that she transmits whilst using the Internet. She does
this to keep the data safe.

(i) State why encryption helps keep the data safe.

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(ii) The data is encrypted using symmetric encryption.

Describe how the data is encrypted using symmetric encryption.

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(iii) Identify three other methods Rebekah could use to help keep her data safe.

Method 1 ...........................................................................................................................

Method 2 ...........................................................................................................................

Method 3 ...........................................................................................................................
[3]
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5 A computer sends the data for an image to the print buffer, to wait to be processed for printing,
until the buffer is full.

When the buffer is no longer full, it sends a signal back to the computer to state it is ready for more
data.

State the name of this signal and give two other examples of when this type of signal is used.

Signal name .....................................................................................................................................

Examples .........................................................................................................................................

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[3]
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6 Cameron writes software for coffee machines. He uses assembly language to write his software.

(a) Tick (3) to show whether assembly language is an example of a high-level language,
a low-level language or machine code.

Tick (3)

High-level language

Low-level language

Machine code
[1]

(b) Identify the translator that is required for assembly language.

............................................................................................................................................. [1]

(c) Give two reasons why Cameron chooses to write the software for the coffee machines in
assembly language.

Reason 1 ..................................................................................................................................

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Reason 2 ..................................................................................................................................

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[2]

(d) Give two drawbacks of using assembly language to write programs.

Drawback 1 ...............................................................................................................................

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Drawback 2 ...............................................................................................................................

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[2]
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7 (a) Eleanor uses a secure connection to allow customers to buy the cakes from her website.

Describe how the secure connection is created.

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(b) Eleanor’s website uses cookies.

Explain what is meant by the term cookies and give two examples of how cookies can be
used.

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(c) Eleanor is worried about a denial of service (DoS) attack on her web server.

She wants to help prevent a DoS attack reaching the web server.

Identify a security method that she could use to help prevent a DoS attack.

Explain how the method you identify helps to prevent the attack.

Security method ........................................................................................................................

Explanation ...............................................................................................................................

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[4]
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8 (a) Complete the following sentences that describe parts of a processor in a Von Neumann
model for a computer system.

There are ....................................... buses that transfer data between components in a

computer system.

The width of the ....................................... determines the number of directly accessible

memory locations.

The ....................................... sends signals on the ....................................... to direct the

operation of system components.

....................................... pulses are used to synchronise the components on the motherboard.

[5]
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9 A computer has Random Access Memory (RAM) and Read Only Memory (ROM).

Tick (✓) one or more boxes in each row to identify whether each statement refers to RAM, ROM
or both.

Statement RAM ROM

Stores data permanently

It is volatile

Stores the start-up instructions for the computer

Directly accessed by the CPU

Type of main memory

Stores currently running applications

Can be static or dynamic

[3]

10 A travel company is designing a website.

(a) The bitmap logo for the travel company is shown.

Each colour is represented by a letter, for example, R = red, B = black, W = white.

Bitmap Logo

R R R R R R R R

R B B B B B W R

R B W W W B W R

R B W W W W W R

R B W W B B W R

R B W W W B W R

R B B B B B W R

R R R R R R R R

(i) State the minimum number of bits needed to represent each pixel in the bitmap logo.

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(ii) Calculate the minimum file size, in bytes, of the bitmap logo. Show your working.

Working .............................................................................................................................

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File size .............................................................................................................................

[3]

11 (a) Convert the following two’s complement binary integer into denary. Show your working.

11001011
Working .....................................................................................................................................

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Answer ......................................................................................................................................

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[2]

12 Daniel is creating a sound file for a school project.

(a) Daniel records the sound using a sampling rate of 44.1 kHz and a sampling resolution of
16 bits.

(i) State what is meant by a sampling rate of 44.1 kHz.

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(ii) State what is meant by a sampling resolution of 16 bits.

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