Cambridge IGCSE™
COMPUTER SCIENCE 0478/13
Paper 1 Theory May/June 2022
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 May/June 2022 series for most
Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some
Cambridge O Level components.
This document consists of 13 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.
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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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Please note the following further points:
The words in bold in the mark scheme are important text that needs to be present, or some notion of it needs to be present. It does not have to
be the exact word, but something close to the meaning.
If a word is underlined, this exact word must be present.
A single forward slash means this is an alternative word. A double forward slash means that this is an alternative mark point.
Ellipsis (…) on the end of one-mark point and the start of the next means that the candidate cannot get the second mark point without being
awarded the first one. If a mark point has an ellipsis at the beginning, but there is no ellipsis on the mark point before it, then this is just a follow-on
sentence and can be awarded without the previous mark point.
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Question Answer Marks
1(a) One mark for each correct row 5
Device Input Output Storage
() () ()
keyboard
microphone
headphones
hard disk drive (HDD)
actuator
1(b) Optical 2
Solid state
Question Answer Marks
2(a) Per each binary conversion, one mark for 2 correct character conversions, two marks for three correct character 6
conversions
0000 0101 1010
0001 1000 1100
0010 1001 1111
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Question Answer Marks
2(b) Any two from: 2
It has a bright screen/colours
It does not consume much power
It runs at a cool temperature
Longevity
Can operate in cold conditions
Can be small/compact/thin
2(c) Per each hex conversion, one mark for 2 correct character conversions, two marks for three correct character conversions 4
40D
07E
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Question Answer Marks
3(a) One mark for each correct row 4
Statement AND OR XOR
() () ()
if both inputs are 0, the output is 0
if both inputs are different, the output is 1
if both inputs are 1, the output is 1
if both inputs are the same, the output is always 0
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Question Answer Marks
3(b) One mark for the correct name and one mark for the correct truth table 4
NOR
A B Output
0 0 1
0 1 0
1 0 0
1 1 0
NAND
A B Output
0 0 1
0 1 1
1 0 1
1 1 0
Question Answer Marks
4(a) Three from: 3
Protocol
Domain name / Web server name
Filename / web page name / folder name
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Question Answer Marks
4(b) It is sent to a DNS … 2
which looks up the corresponding/matching IP address
4(c)(i) HTTPS 1
4(c)(ii) Any one from: 1
It encrypts it
It applies encryption algorithm
It applies an encryption key
Question Answer Marks
5(a) Any two from: 5
It processes data
It processes/executes instructions
It carries out calculations
It carries out logical operations
Any three from:
Fetch
Decode
Execute
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Question Answer Marks
5(b)(i) Any four from: 4
Memory data register / MDR
Control unit / CU
Arithmetic logic unit / ALU
Program counter / PC
Current instruction register / Instruction register / CIR / IR
Accumulator / ACC
Address bus
Data bus
Control bus
5(b)(ii) Any two from: 2
To temporarily store
… the address of the next data/instructions required
… the address of the location in memory where data is to be stored
Stores the address that is to be collected by the address bus
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Question Answer Marks
5(c)(i) Any four from: 7
It is RAM …
… which is volatile storage
It is ROM …
… which is non-volatile storage
It is directly accessible by the CPU
Any three from:
BIOS
Start-up instructions
Programs that are currently in use
Data that is currently in use
Parts of OS currently in use
5(c)(ii) Any two from: 2
Data can be permanently stored
… meaning that (application) software can be loaded/retrieved
… meaning that operating system can be loaded/retrieved
… meaning that user data/files can be accessed/retrieved
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Question Answer Marks
6(a) Image 1
6(b) Lossy compressed file 1
6(c) Any four from: 4
A light is shone onto the surface of the document
The light is moved across/down/under the document
The reflected light is captured (using mirrors and lenses)
The reflections are converted to binary
6(d) Lossless compression 1
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Question Answer Marks
7(a) Data is sent multiple bits at a time 3
… down multiple wires
Data is sent in one direction only
7(b) Any two from: 2
Parallel is not suitable for long distances // only suitable for short distances
… the data could become skewed
Parallel cables are not manufactured above approx. 5m
7(c) Any three from (MAX 2 for ARQ): 3
Checksum used to detect errors (during transmission)
… using a calculated value
ARQ checks if data is received
… uses acknowledgement and timeout
… requests data be sent again if (checksum) detects error / not received
Question Answer Marks
8 One mark per each correct term in the correct place 6
high-level language
line by line
all at once
executable file
is not required
debugging
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