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COMPUTER SCIENCE 0478/11

Paper 1 Computer Systems October/November 2024

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 (SL) 336979/3
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1 The size of a file can be measured using different units.

(a) Tick (3) one box to show which of these is not a unit of measurement for a file.

A bit

B bot

C nibble

D byte

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[1]

(b) The size of a file can be reduced by compressing it.

(i) Give two types of compression that can be used to reduce the size of a file.

lossless
1 ........................................................................................................................................
lossy
2 ........................................................................................................................................
[2]

(ii) Give three benefits of reducing the size of a file for storage and transmission.

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will take less time ti transmit
1 ........................................................................................................................................

...........................................................................................................................................
will require less storage space
2 ........................................................................................................................................

...........................................................................................................................................
will be within the limits size of the apps or emails when getting transmitted
3 ........................................................................................................................................

...........................................................................................................................................
[3]

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2 A student has a smartphone.

(a) Identify two input devices that can be built into the smartphone.
touchscreens
1 ................................................................................................................................................
microphone
2 ................................................................................................................................................
[2]

(b) Identify two output devices that can be built into the smartphone.
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speackers
1 ................................................................................................................................................
screen
2 ................................................................................................................................................
[2]

(c) The smartphone contains secondary storage.

(i) Explain the purpose of the secondary storage in the smartphone.

to store data permanently
...........................................................................................................................................
to store users files
...........................................................................................................................................
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for create virtual memory

...........................................................................................................................................

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

(ii) Identify the most suitable type of secondary storage for the smartphone.

Explain your choice.

SSD/ solid state
Secondary storage type ....................................................................................................

Explanation .......................................................................................................................
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fast access to data which will take less time to load on screen
...........................................................................................................................................

...........................................................................................................................................
low power consumption so it own take much power for the battery
...........................................................................................................................................

...........................................................................................................................................
runs quitely so it wont annoy the user while using it
...........................................................................................................................................

...........................................................................................................................................
runs in low temperature so it wont heat up the smartphone [4]
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3 A user enters text into a computer system, using a keyboard.

An American standard code for information interchange (ASCII) character set is used to convert
the text to binary.

(a) Identify one other character set that could be used to convert the text to binary.
unicode
............................................................................................................................................. [1]

(b) The character ‘A’ is represented by the denary ASCII number 65.

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The character ‘m’ is represented by the denary ASCII number 109.

(i) Convert the two denary ASCII numbers to binary.

01000001
65 ......................................................................................................................................

01101101
109 ....................................................................................................................................
[2]

Working space

...........................................................................................................................................

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...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

(ii) Convert the two denary ASCII numbers to hexadecimal.

41
65 ......................................................................................................................................
6D
109 ....................................................................................................................................
[2]

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Working space

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................
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(c) The character ‘y’ is represented by the binary ASCII number 01111001.

(i) Convert the binary ASCII number to denary.

64+32+16+8+1 = 121
..................................................................................................................................... [1]

Working space

...........................................................................................................................................

...........................................................................................................................................
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...........................................................................................................................................

...........................................................................................................................................

(ii) Convert the binary ASCII number to hexadecimal.

79
..................................................................................................................................... [1]

Working space

...........................................................................................................................................
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...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

(iii) A logical right shift of two places is performed on the binary ASCII number 01111001.

Give the binary number after the logical right shift of two places is performed.
00011110
..................................................................................................................................... [1]
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Working space

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................
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(d) The character ‘T’ is represented by the binary ASCII number 01010100.

The character ‘t’ is represented by the binary ASCII number 01110100.

Add the two binary numbers using binary addition. Give your answer in binary. Show all your
working.

...................................................................................................................................................

01010100
...................................................................................................................................................
+

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01110100
...................................................................................................................................................

...................................................................................................................................................

11001000
...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

............................................................................................................................................. [3]

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4 A company decides to create a network for its devices.

All the company devices are within a single room.

The employees will need to use their devices to send data to each other and share files.

The company decides to send data across the network using packet switching.

(a) An employee sends an email to another employee. The email is broken down into packets.

Describe the structure of a packet of data for the email.

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a data packet is made of 3 sections
...................................................................................................................................................

...................................................................................................................................................
A header which contains data such as the destination address
...................................................................................................................................................

...................................................................................................................................................
A payload which contains the main data for the email
...................................................................................................................................................

...................................................................................................................................................
A trailer which contains data such as the error detection system
...................................................................................................................................................
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............................................................................................................................................. [4]

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(b) The company decides to use parallel full-duplex data transmission to send the data across
the network.

(i) Explain the reasons why the company have chosen this method of data transmission.
data can be sent in both direction at the same time so the network can send data
...........................................................................................................................................
with no delay
...........................................................................................................................................

...........................................................................................................................................
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it sends data multiple bits at the same time so transimmison would be faster
...........................................................................................................................................

...........................................................................................................................................

data can avoid traviling long distance because its within single room
...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [4]

(ii) Give two drawbacks of the company using this method of data transmission.
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data could be out of sequance or skewed

1 ........................................................................................................................................

...........................................................................................................................................
high chance of data collision
2 ........................................................................................................................................

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

(iii) Give one other method of data transmission the company could have chosen.
serial full-duplex
..................................................................................................................................... [1]
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5 A central processing unit (CPU) performs the fetch–decode–execute (FDE) cycle.

(a) Give the name of two registers that are used in the fetch stage of the cycle.
MDR
1 ................................................................................................................................................
MAR
2 ................................................................................................................................................
[2]

(b) Describe what happens at the decode stage of the cycle.

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CIR recives the instructions from the MDR using the data bus
...................................................................................................................................................

...................................................................................................................................................

the instruction then separted to opcode and operand

...................................................................................................................................................

...................................................................................................................................................
then the control unit decodes the instruction using an instruction set
...................................................................................................................................................

............................................................................................................................................. [3]

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(c) Give one register in the CPU that is used in the execute stage of the cycle.
MAR
............................................................................................................................................. [1]

(d) Buses are used in the CPU to transmit data through the FDE cycle.

Circle three buses that are used in the CPU.

fetch address register execute

data decode calculation

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central value binary control
[3]

(e) A user changes their CPU from one with a dual core and a clock speed of 2.4 GHz to one with
a dual core and a clock speed of 3.5 GHz.

Explain the effect this change will have on the performance of the CPU.

it now can execute more instructions per second which will increase the CPU
...................................................................................................................................................
performance
...................................................................................................................................................
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...................................................................................................................................................

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

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6 A computer programmer uses assembly language to create a computer program for an embedded
system in a washing machine.

(a) State what is meant by an embedded system.

a computer that contains a microprocessor
...................................................................................................................................................

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

(b) Give the name of the translator that will be used for the program.
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assembler
............................................................................................................................................. [1]

(c) The washing machine needs to display error codes on a small screen if there is a problem
with the washing machine.

The error codes are stored as binary. The binary numbers are too long to be displayed on the
washing machine.

State how the error codes could be reduced in length to be displayed on the screen.
convert them into hexadecimal
............................................................................................................................................. [1]
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(d) Give one benefit to the programmer of using assembly language to write the program.

they can use machine specific instructions

...................................................................................................................................................

............................................................................................................................................. [1]
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(e) The programmer uses an integrated development environment (IDE) to write the program.

A built-in translator to convert the program into machine code is one way that the IDE helps
the computer programmer.

Describe three other ways the IDE can help the programmer.

...................................................................................................................................................

...................................................................................................................................................

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...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

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...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

............................................................................................................................................. [6]

7 A computer has an operating system.

(a) The operating system provides several functions.

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(i) Tick (3) one box to show which of these is not a function of the operating system.

A managing files

B providing an interface

C handling interrupts

D loading the bootstrap

[1]
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(ii) Identify one other function of an operating system.

Describe the purpose of this function.

memory manegment
...........................................................................................................................................
managing what gets alocated in the memory
...........................................................................................................................................

...........................................................................................................................................

..................................................................................................................................... [2]
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(b) Give the name of the set of instructions that are provided to the operating system to allow it to
run.

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

8 Draw and annotate a diagram to show how a payment transaction is made using digital currency
and blockchain.

2. the transaction is being stored in the block

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block hash
digital ledger
block

3. when block is full it is added

to the blockchain
payment
data sent
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device blockchain

1. customer device
encrypts payment data
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[4]
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9 A doctor’s surgery has an expert system that helps diagnose the illnesses of its patients.

(a) Complete the paragraph about the operation of the expert system.

Use the terms from the list.

Some of the terms in the list will not be used. Some terms may be used more than once.

artificial binary central processing unit (CPU) data

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inference engine interface knowledge base primary storage

process real read only memory (ROM) rule base

artificial
An expert system is a type of ............................................ intelligence. The doctor will type
interface
data about the symptoms of the illness into the ...................................................................... .
inference engine
The ................................................................ will decide which questions to ask the doctor.
knowlegde base
It will do this by linking the facts in the ....................................................................... to the

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rule base
.................................................................... .
inference engine
The ..................................................................... will decide on a diagnosis and this will be
interface
output on the .................................................................... .
[7]

(b) The expert system has the ability to automatically adapt its own processes and data.

Give the name of this ability.

machine learning
............................................................................................................................................. [1]

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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.

To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.

Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge
Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.
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