Computer Science 9618/13 October/November 2025: question paper and mark scheme
Cambridge AS & A Level Computer Science (9618), Paper 1 Theory Fundamentals, October/November 2025. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
(a) A student creates sound recordings.
Making changes to a sound recording may impact the accuracy of the resulting sound file or the size of the file.
Draw two lines from each change to the impacts it has on the sound file.
Change Impact
the file size gets bigger
increase the duration of the recording no change in the file size
the file size gets smaller increase the sampling rate the accuracy of the sound file improves
no change to the accuracy of the sound file decrease the sampling resolution
the accuracy of the sound file worsens
[3]
(b) The file names of the sound recordings are stored using the ASCII character set.
Explain how text is represented by the ASCII character set.
…… [2]
(c) Give two differences between the ASCII and UNICODE character sets.
1 ……
2 ……
[2]
* 0000800000003 * DFD
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Mark scheme
1(a) 1 mark for each correctly connected change box, max 3 marks 3
the file size gets
bigger
increase the duration
of the recording
no change in the file
size
the file size gets
smaller
increase the sampling
rate the accuracy of the
sound file improves
no change to the
accuracy of the sound
file
decrease the
sampling resolution
the accuracy of the
sound file worsens
1(b) 1 mark per bullet point, max 2 marks 2
• Each character has a unique code
• Each character in the text is replaced sequentially / in order by its code
1(c) 1 mark per bullet point, max 2 marks 2
• ASCII uses 7 / 8 bits Unicode can use many more / up to 32 bits
• Unicode can represent a wider range of characters including different
languages
(a) Data in a computer system is represented in binary.
Put one tick (3) in each row to identify the minimum number of bits used to store each example of data.
Number of bits
Example of data
4 8 16 24 32 64 128
the hexadecimal value F139
16 000 000 unique amplitude values
an IPv4 address
256 unique colours
an IPv6 address
the denary value 65 000
[3]
(b) Convert the denary number –108 into a 12‑bit two’s complement binary number.
…… [1]
(c) A three‑place arithmetic shift to the right is performed on the following two’s complement negative integer.
Show the result of this arithmetic shift.
10010011
…… [1]
(d) Convert the following positive binary integer into hexadecimal.
1110001100111011
…… [1]
* 0000800000004 * DFD
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Mark scheme
2(a) 3 marks for 6 correct ticks 3
2 mark for 4 or 5 correct ticks
1 mark for 2 or 3 correct ticks
Example of data Number of bits
4 8 16 24 32 64 128
the hexadecimal ✓
value F139
16 000 000 unique ✓
amplitude values
an IPv4 address ✓
256 unique colours ✓
an IPv6 address ✓
the denary value ✓
65 000
2(b) 1 mark 1
1111 1001 0100
2(c) 1 mark 1
1111 0010
2(d) 1 mark 1
E33B
(a) Complete the truth table for the following logic expression:
X = (A NOR B) NAND (C XOR B)
Working space
A B C X
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
[2]
(b) Draw a logic circuit for the logic expression:
X = NOT (((A AND B) OR C) AND (C NOR D))
A
B
X
C
D
[2]
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Mark scheme
3(a) 1 mark per shaded area, max 2 marks 2
A B C X
0 0 0 1
0 0 1 0
0 1 0 1
0 1 1 1
1 0 0 1
1 0 1 1
1 1 0 1
1 1 1 1
3(b) 1 mark per bullet point, max 2 marks 2
• A AND B OR C
• C NOR D and final two gates
A network engineer is setting up a Local Area Network (LAN) in an office. The network uses both wired and wireless connectivity.
(a) Give three advantages of a wireless network compared to a wired network.
1 ……
2 ……
3 ……
[3]
(b) Give one drawback of using a wireless network.
…… [1]
(c) Complete the table by writing the name of the type of memory technology for each description.
Description Memory technology
A read only memory where the contents can be erased using a voltage pulse. The contents can be changed multiple times without physically removing the memory.
A read only memory where the contents are erased using ultraviolet (UV) light. The memory must be physically removed to be reprogrammed.
A read only memory where the contents can be written only once after manufacture.
[3]
* 0000800000006 * DFD
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Mark scheme
4(a) 1 mark for each benefit, max 3 3
• Devices can be more mobile as no physical connection is required
• No cabling is needed so easier to set up
• Easier to add additional devices
• Multiple different device types can be connected
4(b) 1 mark for a drawback 1
• Can be less secure
• Transmission speed can be slow
• Interference is possible
• The signal degrades quickly without repeaters/boosters
4(c) One mark for each correct row 3
Description Memory
Technology
A read only memory where the contents EEPROM
can be erased using a voltage pulse. The
contents can be changed multiple times
without physically removing the memory.
A read only memory where the contents EPROM
are erased using ultraviolet (UV) light. The
memory must be physically removed to be
reprogrammed.
A read only memory where the contents PROM
can be written only once after manufacture.
A company creates a relational database to store data about its customers.
The database, REVIEWS, stores data about the customers, products, complaints and staff.
The database has four tables:
CUSTOMER(CustomerID, CustomerFirstName, CustomerLastName, CustomerEmail)
PRODUCT(ProductID, ProductName, ProductDetail, Price, Rating)
COMPLAINT(ComplaintID, ProductID, CustomerID, ComplaintDetails, StaffID)
STAFF(StaffID, StaffFirstName, StaffLastName, Department, RemoteWorker)
(a) Complete the entity‑relationship (E‑R) diagram for the database REVIEWS.
CUSTOMER PRODUCT
COMPLAINT STAFF
[3]
* 0000800000007 * DFD
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(b) Some example data from the STAFF table is shown.
StaffID StaffFirstName StaffLastName Department RemoteWorker
1 Ralph Jura E Yes
2 Luca Emcee A Yes
3 Darwin Acula F No
Write a Structured Query Language (SQL) script to define the table STAFF.
…… [4]
(c) Products are given a rating between 1 and 10 inclusive.
Write an SQL script to return only the ProductID, ProductName and ComplaintDetails for all products with a rating of 5 or less. The results need to be displayed in descending order of rating.
…… [5]
* 0000800000008 * DFD
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(d) A Database Management System (DBMS) is used to maintain and manage the database.
Describe two ways in which the DBMS can be used to ensure the security of the customer data.
1 ……
2 ……
[4]
* 0000800000009 * DFD
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Question 6 starts on the next page.
* 0000800000010 * DFD
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Mark scheme
5(a) 1 mark for each correct relationship, max 3 marks 3
5(b) 1 mark per bullet point, max 4 marks 4
• Create table with opening and closing brackets and commas separating
the attributes
• Appropriate data types for StaffFirstName, StaffLastName and
Department
• Appropriate data types for StaffID and RemoteWorker
• Primary key correctly defined
Example Answer 1:
CREATE TABLE STAFF(
StaffID INTEGER,
StaffFirstName VARCHAR,
StaffLastName VARCHAR,
Department CHAR,
RemoteWorker BOOLEAN,
PRIMARY KEY (StaffID)
);
Example Answer 2:
CREATE TABLE STAFF(
StaffID INTEGER NOT NULL PRIMARY KEY,
StaffFirstName VARCHAR,
StaffLastName VARCHAR,
Department CHAR,
RemoteWorker BOOLEAN
);
5(c) 1 mark per bullet point, max 5 marks 5
• SELECT and the correct attributes
• FROM and the correct tables
• Tables joined correctly
• Correct condition for the rating
• Correct ORDER BY clause
Example Answer 1
SELECT PRODUCT.ProductID, ProductName, ComplaintDetails
FROM PRODUCT, COMPLAINT
WHERE PRODUCT.ProductID = COMPLAINT.ProductID
AND Rating <=5
ORDER BY Rating DESC;
Example Answer 2
SELECT PRODUCT.ProductID, ProductName, ComplaintDetails
FROM PRODUCT INNER JOIN COMPLAINT
ON PRODUCT.ProductID = COMPLAINT.ProductID
WHERE Rating <=5
ORDER BY Rating DESC;
5(d) One mark for identification of method one mark for corresponding description 4
max 4 marks
• Authentication methods / passwords / biometrics / 2-factor authentication
can be implemented
• ... which prevents unauthorised access to the customer’s data
• Access rights / privileges can be set
• ... so that only those with correct permissions can read / edit customer’s
data
• Regular backups can be scheduled
• ... so that a second copy of the customer’s data is available in case of
loss/damage
• The data can be encrypted
• ... so that the customer’s data cannot be understood by anyone who
gains unauthorized access
• Different views can be created
• ... so that not everyone can see the customer’s data
The following table shows part of the instruction set for a processor. The processor has two registers: the Accumulator (ACC) and the Index Register (IX).
Instruction
Explanation
Opcode Operand
LDM #n Immediate addressing. Load the number n to the ACC
AND #n / Bn / &n Bitwise AND operation of the contents of the ACC with the operand
AND <address> Bitwise AND operation of the contents of the ACC with the contents of
<address>
XOR #n / Bn / &n Bitwise XOR operation of the contents of the ACC with the operand
XOR <address> Bitwise XOR operation of the contents of the ACC with the contents of
<address>
OR #n / Bn / &n Bitwise OR operation of the contents of the ACC with the operand
OR <address> Bitwise OR operation of the contents of the ACC with the contents of
<address>
CMP #n Compare the contents of the ACC with number n
CMP <address> Compare the contents of the ACC with the contents of <address>
LSL #n Bits in the ACC are shifted logically n places to the left. Zeros are introduced on the right‑hand end
LSR #n Bits in the ACC are shifted logically n places to the right. Zeros are introduced on the left‑hand end
<address> can be an absolute or symbolic address
# denotes a denary number, e.g. #127
B denotes a binary number, e.g. B10010001
& denotes a hexadecimal number, e.g. &4A
The current contents of main memory are shown:
Address Data
100 0000 0011
101 1010 1110
102 1100 1100
103 1111 1111
104 1100 1100
* 0000800000011 * DFD
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(a) Complete the table by writing the contents of the ACC after the execution of each instruction.
Current contents of the Contents of the ACC after the
Instruction
ACC execution of the instruction
0000 1111 AND 101
0000 0000 LDM #100
0000 0001 XOR &F1
0001 0001 CMP 101
[4]
(b) The Von Neumann model for a computer system uses registers.
Describe the role of the Memory Address Register (MAR) and Memory Data Register (MDR)
in the fetch‑execute (F‑E) cycle.
…… [4]
(c) Assembly language instructions are grouped.
Complete each statement by writing the name of the appropriate instruction group.
Loading data into the accumulator is an example of an instruction in the
…… group. Incrementing the index register is an example
of an instruction in the …… group. Branching to another
address is an example of an instruction in the …… group.
[3]
* 0000800000012 * DFD
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Mark scheme
6(a) 1 mark for each correct row 4
Current contents Instruction Contents of the ACC
of the ACC after the execution of
the instruction
0000 1111 AND 101 0000 1110
0000 0000 LDM #100 0110 0100
0000 0001 XOR &F1 1111 0000
0001 0001 CMP 101 0001 0001
6(b) 1 mark for each bullet point, max 4 marks 4
• MAR stores the address of the next instruction / data to be read from /
or written to memory
• The address is received from the Program Counter (PC)
• The MDR stores the data / instruction in the address stored in the MAR
which has been read / written
• The instruction passes to the CIR for decoding and executing
6(c) 1 mark for each bullet point, max 3 marks 3
• Data movement
• Arithmetic operations
• Conditional and unconditional (jump) instructions
A digital video camera records students in a classroom. The data is transferred from the digital video camera over the internet to a server. Artificial Intelligence (AI) is used to analyse the video on the server to identify when students are interacting with the lesson and the teacher.
(a) Describe one ethical impact of this use of AI in the classroom.
…… [2]
(b) A video is made of many bitmap images called frames. 30 frames are recorded every second.
Each frame is 4000 pixels wide by 3000 pixels high. The video records using 16‑bit colour depth.
Calculate an estimate for the file size for one second of the video in gigabytes.
Show your working.
File size …… gigabytes
[2]
(c) Identify and describe one method of data verification that can be used when transferring data from the digital video camera to the server.
Method ……
Description ……
[3]
* 0000800000013 * DFD
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(d) Describe two reasons why the server that stores the videos uses magnetic hard disks instead of solid state (flash) memory.
1 ……
2 ……
[4]
* 0000800000014 * DFD
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(e) The table contains three algorithms that perform data validation. The third algorithm uses the functions MID and LENGTH.
The functions MID and LENGTH are defined as follows:
• MID(ThisString : STRING, x : INTEGER, y : INTEGER) RETURNS STRING returns a string of length y starting at position x from ThisString
• LENGTH(ThisString : STRING) RETURNS INTEGER returns the integer value representing the length of ThisString
Complete the table to identify the method of data validation for each algorithm. Each method of data validation must be different.
Algorithm Method of data validation
INPUT x
IF x < 1 or x > 26 THEN
OUTPUT "Invalid"
ENDIF
INPUT x
IF x <> 'R' AND x <> 'G' AND x <> 'B' THEN
OUTPUT "Invalid"
ENDIF
INPUT x
FLAG FALSE
FOR INDEX 1 TO LENGTH(x)
IF MID(x, INDEX, 1) = "@" THEN
FLAG TRUE
ENDIF
NEXT INDEX
IF NOT FLAG THEN
OUTPUT "Invalid"
ENDIF
[3]
* 0000800000015 * DFD
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Mark scheme
7(a) 1 mark per point, max 2 marks 2
e.g.
• The learning experience could be improved
• … by identifying students who are struggling
• …. and employing more personalised learning
• There could be early Intervention
• … to determine which students require extra support
•
• Teachers and students could understand the challenges better
• …and identify optimal times for learning
• There could be privacy concerns
• …. students / teachers could be uncomfortable with constant surveillance
• ... students might not want their data / actions passed to third parties
• There could be Mental Health concerns
• …. due to constant monitoring and pressure
• …. contributing to student stress and anxiety
7(b) 1 mark for the working 2
1 mark for the correct answer
Working:
(4000*3000*30*16) / (8*1000*1000*1000)
//(4000*3000*30*2) / (1000*1000*1000)
Answer: 0.72 gigabytes
7(c) 1 mark for the name 2 marks for the matching description, max 3 marks 3
• Parity Byte Check
• a parity bit is added to each byte to make the number of 1s match the
parity, odd or even
• each byte can be checked on receipt and request to be resent if the byte
does not match parity
• Parity Block Check
• a bit is added to each byte, but a parity byte is also set for each block
• the location of an error can be found using vertical and horizontal parity
• Checksum
• A calculation is made from the data and transmitted with the data
• The receiver performs the same calculation and compares with received
checksum to see if they match
7(d) 1 mark per reason, 1 mark for corresponding justification x2 4
max 4 marks
• Lower cost per unit of storage
• ... so the high capacity of storage required for large number of video files
will be less costly
• A large number of read/write operations are being performed
continuously
• ... and magnetic storage is likely to have a longer life span compared with
solid state
7(e) 1 mark for each validation check correctly identified, max 3 marks 3
Range Check
Existence Check
Format Check
Compilers and interpreters are used to translate programs written in a high‑level language into a low‑level language.
(a) State two disadvantages of using a compiler compared to an interpreter during program development.
1 ……
2 ……
[2]
(b) Explain how a programmer benefits from using program libraries during program development.
…… [3]
(c) A programmer is developing an Operating System (OS).
Identify two types of software licence the programmer can use to allow other people to edit and redistribute the OS.
1 ……
2 ……
[2]
(d) Memory management is one key management task performed by an OS.
Give three other key management tasks that are performed by an OS.
1 ……
2 ……
3 ……
[3]
* 0000800000016 * DFD
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Mark scheme
8(a) 1 mark per bullet point, max 2 2
• Large amounts of source code take time to compile
• It can be slower to produce the object code than an interpreter
• The code must be recompiled when it is changed
• The program cannot run if there are errors
• It is not possible to correct errors in real-time
• One error can cause false reporting of multiple further errors
• Sections of code / unfinished code cannot easily be tested
8(b) 1 mark per bullet point, max 3 marks 3
• Programming time is saved as code does not have to written from scratch
• Testing time is saved as code is already tested / documented
• A library routine is more likely to work, as code is already tested
• Library routines automatically update if they are changed / improved
• The programmer can use library routines to perform complex functions /
procedures that they may not be able to write themselves
8(c) 1 mark per bullet point, max 2 marks 2
• Open Source (Initiative)
• Free Software (Foundation)
8(d) 1 mark for each bullet point, max 3 marks 3
• File management
• Security management
• Hardware / peripheral management // input / output management
• Process management
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Where can I find the 9618/13 October/November 2025 mark scheme?+
On this page, free: the mark scheme for AS & A Level Computer Science 9618/13, October/November 2025 (9618_w25_ms_13), and the question paper (9618_w25_qp_13), to read or download, with each question's marking points written out underneath.
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Computer Science 9618/13 for October/November 2025 is out of 75 marks, with 1 hour 30 minutes to answer it.
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Yes. Upload your answers to 9618/13/O/N/25 as a PDF or photos, and CIE Buddy marks every question against this paper's official mark scheme, using Cambridge's marking rules. You get your score, each lost mark explained on your own script, and the topics to revise. It's a guide, not an official Cambridge grade.