Cambridge IGCSE™

COMPUTER SCIENCE 0478/12

Paper 1 Computer Systems October/November 2023
MARK SCHEME
Maximum Mark: 75

Published

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.

Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.

Cambridge International will not enter into discussions about these mark schemes.

Cambridge International is publishing the mark schemes for the October/November 2023 series for most
Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level
components.

This document consists of 10 printed pages.

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Generic Marking Principles

These general marking principles must be applied by all examiners when marking candidate answers.
They should be applied alongside the specific content of the mark scheme or generic level descriptors
for a question. Each question paper and mark scheme will also comply with these marking principles.

GENERIC MARKING PRINCIPLE 1:

Marks must be awarded in line with:

• the specific content of the mark scheme or the generic level descriptors for the question
• the specific skills defined in the mark scheme or in the generic level descriptors for the question
• the standard of response required by a candidate as exemplified by the standardisation scripts.

GENERIC MARKING PRINCIPLE 2:

Marks awarded are always whole marks (not half marks, or other fractions).

GENERIC MARKING PRINCIPLE 3:

Marks must be awarded positively:

• marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit
is given for valid answers which go beyond the scope of the syllabus and mark scheme,
referring to your Team Leader as appropriate
• marks are awarded when candidates clearly demonstrate what they know and can do
• marks are not deducted for errors
• marks are not deducted for omissions
• answers should only be judged on the quality of spelling, punctuation and grammar when these
features are specifically assessed by the question as indicated by the mark scheme. The
meaning, however, should be unambiguous.

GENERIC MARKING PRINCIPLE 4:

Rules must be applied consistently, e.g. in situations where candidates have not followed
instructions or in the application of generic level descriptors.

GENERIC MARKING PRINCIPLE 5:

Marks should be awarded using the full range of marks defined in the mark scheme for the question
(however; the use of the full mark range may be limited according to the quality of the candidate
responses seen).

GENERIC MARKING PRINCIPLE 6:

Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should
not be awarded with grade thresholds or grade descriptors in mind.

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Mark scheme abbreviations

/ separates alternative words / phrases within a marking point

// separates alternative answers within a marking point
underline actual word given must be used by candidate (grammatical variants accepted)
max indicates the maximum number of marks that can be awarded
( ) the word / phrase in brackets is not required, but sets the context

Note: No marks are awarded for using brand names of software packages or hardware.

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Question Answer Marks

1(a) − A 1

1(b) Any one from: 1

− Spyware // Keylogger
− Adware
− Trojan horse

1(c) − Anti-malware 1

Question Answer Marks

2(a) − 227 1

2(b) One mark for each correct character in the correct order: 2
− E3

2(c) 1
1 0 0 0 1 1 0 0

2(d) One mark for suitable working method e.g. flip and add 1 2
One mark for correct answer

− 10011101

2(e) One mark for each correct nibble (max 2) 4

One mark for correct working e.g. correct carry
One mark for showing overflow bit

1
1 1 1 0 0 0 1 1
+ 0 1 0 0 1 1 0 0
1 0 0 1 0 1 1 1 1

Question Answer Marks

3(a)(i) − The maximum number of FDE cycles/instructions a CPU can 1

perform/process/execute in a second

3(a)(ii) − Increases/improves the performance // Tasks can be performed 2

quicker/faster
− … because more FDE cycles/instructions can be processed in a second

3(b) − Stores addresses … 2

− … of next instruction/data to be fetched // where data is to be written to

3(c) − Instruction set 1

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Question Answer Marks

4(a) Any two from: 2

− Performs a single/limited/dedicated function/task
− It has a microprocessor
− It has dedicated hardware
− Uses firmware
− It is normally built into a larger device/system
− User normally cannot reprogram
− It does not require much power
− It is cheap to manufacture
− Works automatically // works without human intervention
− It is small (in size)
− It is a real-time system

4(b) One mark for each correct system: 3

− security light system
− freezer
− vending machine

Question Answer Marks

5(a) Any one from: 1

− The recording of the song is more accurate/closer to original

5(b) Any one from: 1

− The file size will be increased
− The file will require more storage space

5(c) Any two from: 2

− The number of bits that are used per sample
− … that provides the variation in amplitude that can be stored for each
sample // defines the number of different amplitudes that can be recorded
− … that determines how quiet/loud the sounds are that can be recorded
− Example e.g. 16-bit

5(d) − Lossless 1

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Question Answer Marks

6 One mark for each correct data transmission method: 4

Data transmission method Description

Data is transmitted down a single

serial simplex wire, one bit at a time, in one
direction only.

Data is transmitted down multiple

wires, multiple bits at a time, in both
parallel half-duplex
directions, but only one direction at
a time.

Data is transmitted down a single

serial full-duplex wire, one bit at a time, in both
directions at the same time.

Data is transmitted down multiple

parallel simplex wires, multiple bits at a time, in one
direction only.

Question Answer Marks

7(a) Any two from e.g. 2

− Barcode scanner
− QR code scanner
− Digital camera

7(b) Any six from: 6

− Proximity/infrared/pressure sensor used
− Sensor continually sends digitised data to microprocessor // When
driver pushes button, sensor sends digitised data to the microprocessor
− Microprocessor compares data to stored value(s)
− If in range/out of range/matches, microprocessor sends signal to close
the door
− Actuator used to close door
− If not in range/out of range/does not match door will not close //
If not in range/out of range/does not match actuator not activated/signal
not sent as passenger in door //
If not in range/out of range/does not match a timer is set to check again //
If not in range/out of range/does not match a signal is sent to alert the
driver/output a message
− This process repeats until the door can close

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Question Answer Marks

8(a) The diagram demonstrates (One mark for each part of the diagram): 4
− Data is being sent from one device to another
− The data is being examined during transmission
− Packet sniffer is used
− Intercepted data is reported to a third-party during transmission …
− … and analysed for anything useful
− Connection hacked to spoof destination address
e.g.

8(b) − Encryption … 2
− … if the data is intercepted it will be meaningless (because they do not
have the decryption key)

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Question Answer Marks

9 6
Term Description

the collective name for all the

world wide web
web pages available

a small text file, stored by the

cookie web browser, that can store a
user’s personal data

the text-based address for a

website // It is made up of the
uniform resource locator (URL)
protocol, domain name and
filename/folder name

Stores web pages // receives

web server requests from clients and returns
requested web page

the language used to create a

hypertext markup language //
website. Example tags are
HTML
<head> and <body>

hypertext transfer protocol // a protocol that is used to request

HTTP and send web pages

Question Answer Marks

10(a) Any one from: 1

− The ability to learn/adapt // machine learning abilities
− The collection of data and the rules for using that data
− The ability to reason // has problem solving abilities // makes predictions
− Simulates intelligent/human behaviour
− Analyses patterns

10(b) Any six from: 6

− It has an interface …
− … used to input data/view output

− It has a knowledge base

− It has a rule base
− It has an inference engine

− Applies the rule base to/and the knowledge base to provide

output/diagnosis/result/solution/decision
− Decides what to ask next based on the data input

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Question Answer Marks

11(a) − Amount of liquid/gas/steam flowing/moving through an environment 1

11(b) Two from (for benefit and matching description) 2

e.g.:
− Increases safety
− …meaning that workers do not need to go into dangerous areas to collect
data/make checks/do dangerous tasks

− Can increase jobs/skills

− …as employees are needed to learn/maintain the equipment

− No need to do repetitive tasks

− … so, they can use their time on other/more skilled tasks

11(c) Two from (for drawback and matching description) 2

e.g.:
− High set-up/installation costs
− … it would mean the company need to find a lot of money up front to pay
for the equipment // employees will need training

− Utility/maintenance/repair costs
− … increase in bills such as electricity // skilled employees will be required
to maintain the system // equipment will break/need updating

− Deskilling of the workforce

− … may mean that workers will no longer have the skills for some of the
manufacturing jobs, should the equipment break

Question Answer Marks

12(a) Any two from: 2

− Only exists electronically
− Can be a decentralised system
− Can be a centralised system
− Usually encrypted

12(b) − Blockchain 1

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Question Answer Marks

13(a)(i) − C 1

13(a)(ii) Any one from: 1

− Directly accessed by the CPU
− Has both volatile and non-volatile storage

13(b) One mark for each correct term in the correct order: 5
− Random access memory (RAM)
− Hard disk drive (HDD)
− Pages
− Random access memory (RAM)
− Virtual memory // Hard disk drive (HDD)

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