Free until 14 Nov · 80% off for the first 100 · Pricing
Cambridge AS & A Level Computer Science (9618), Paper 1 Theory Fundamentals, May/June 2025. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
9618_s25_qp_119618_s25_ms_119618/11/M/J/25
Each question as it's printed, and the mark scheme's points for it, as text. Diagrams, tables and graphs are in the PDFs above.
Question
(a) Write the logic expressions for the following logic circuit. P X Q R Y S X = …… Y = …… [2] (b) Complete the truth table for the following logic circuit. A B X C A B C Working space 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]
Mark scheme
1(a) 1 mark each: 2 X = Q AND (NOT P OR R) Y = S XOR (Q NOR R) 1(b) 1 mark for first 4 rows, 1 mark for second 4 rows 2 A B C Working space X 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 1 1 1 1 1
Question
Programmers in a software development company take part in live video conferences to discuss their work. The live video conferences take place using real‑time bit streaming. The video is compressed before it is transmitted. (a) Explain how data is transferred using real‑time bit streaming. …… [4] (b) (i) Explain the reasons why a video is compressed before it is transmitted using real‑time bit streaming. …… [4] (ii) Identify whether the lossy or lossless compression method is more appropriate for real‑time bit streaming. Justify your answer. Compression method …… Justification …… [3] (c) The video conference is accessed over the internet. Complete the table by stating how modems and dedicated lines are used when data is transmitted over the internet. Hardware Use modems dedicated lines …… [2]
Mark scheme
2(a) 1 mark each to max 4 4 • Video is transmitted continuously • as a series of bits • The video is uploaded to a media server • The users download from the media server • On download, the media server sends the data to a buffer on the user's device • buffer is used when there is a difference in speed between transmission and receipt • Buffer stores data from server until recipient can receive it • Recipient views bit stream from the buffer 2(b)(i) 1 mark each to max 4 4 e.g. • Video is data-intensive • The file size needs reducing in order to • reduce the amount of bandwidth used • and reduce buffering • This means people are not behind in the conversation • and people with lower bandwidth can still take part 2(b)(ii) No mark for choice but lossy is most appropriate 3 1 mark each to max 3 e.g. • Reduces file size more than lossless • so significantly less bandwidth / data is needed • so buffering is reduced even more than with lossless • Data can be removed which cannot be seen • reducing quality without impacting experience • for example, because resolution of video can be reduced // sample rate of audio can be reduced 2(c) 1 mark each 2 modems: • Converts digital data into analogue for transmission down phone lines // Converts analogue data into digital after transmission down phone lines dedicated lines: • Used to provide a direct / private connection which therefore provides faster transmission
Question
A computer stores images and text files. (a) One of the images is a bitmapped image. Complete the table by writing the answer for each statement. Statement Answer the term for the smallest element that makes up an image the largest number of different colours that can be represented with a bit depth of 8 bits the term for the dots per inch (dpi) when an image is displayed [3] (b) The text in the files is stored using the Unicode character set. (i) Give two advantages of using the Unicode character set instead of using the ASCII character set. 1 …… 2 …… [2] (ii) The Unicode character '❮' has the binary value: 0010 0111 0110 1110 Convert the binary value for the character '❮' into denary. …… [1] (iii) The Unicode character '⅀' has the hexadecimal value 2140 Convert the hexadecimal code for the character '⅀' into denary. …… [1]
Mark scheme
3(a) 1 mark for each correct answer 3 Statement Answer The term for the smallest element that pixel makes up an image. The largest number of different colours that 256 // 28 can be represented with a bit depth of 8 bits. The term for the dots per inch (dpi) when an Screen resolution image is displayed. 3(b)(i) 1 mark each to max 2 2 • A wider range of characters can be represented • so characters from more languages can be represented • and symbols such as emojis can be used 3(b)(ii) 1 mark for: 1 10,094 3(b)(iii) 1 mark for: 1 8,512
Question
A shop installs a new system that allows users to purchase items without going through a manual checkout. The new system: • identifies customers when they enter the shop and matches them to their account • prevents a customer from walking through the automatic barriers if they do not have an account • automatically detects the items that a customer has taken from a shelf and charges these to the customer’s account. (a) The new system uses digital cameras and Artificial Intelligence (AI) to identify the customers. Explain how the new system uses AI to identify each customer. …… [4] (b) The new system uses sensors to identify the items taken from a shelf. Identify one type of sensor that can be used in this new system. State how the sensor can be used to identify the items taken from a shelf. Sensor …… Use …… [2]
Mark scheme
4(a) 1 mark each to max 4 4 e.g. • Uses image recognition / facial recognition • Measures the distance between facial features of the customer • and stores the values in a database of user information • An image is captured using the digital camera • the AI identifies that the image is a face • by analysing the pixels to find patterns • the distance between features is calculated and compared to those in database 4(b) 1 mark for sensor, 1 mark for corresponding use 2 e.g. Sensor Use Pressure Detects when the pressure of an item is removed from a shelf / put back on a shelf Infrared Detects when the beam is broken for an item removed / added
Question
A company builds and sells furniture to customers. The company stores data about customers, their payment cards and their furniture orders in a database. The database, FURNITURE, has the following tables: CUSTOMER(CustomerID, Name, Phone) CUSTOMER_CARD_DATA(CardID, CustomerID, CardType, CardNumber, EndDate) ORDER(OrderID, CustomerID, TotalCost, Paid, OrderDate, Complete) ORDER_ITEM(OrderItemID, OrderID, Type, Height, Width, Depth, Details) The primary keys are underlined in each table. The attribute Complete in the table ORDER stores the Boolean value TRUE if the order has been built and FALSE if the order has not been built. (a) Complete the entity‑relationship (E‑R) diagram for the database. CUSTOMER CUSTOMER_CARD_DATA ORDER ORDER_ITEM [3] (b) Identify one attribute in the table CUSTOMER_CARD_DATA that could be a candidate key. …… [1] (c) Identify two tables in the database that contain one or more foreign keys. Give one attribute that is a foreign key in each table. Table Foreign key 1 2 [2] (d) Explain the reasons why the data in the table ORDER_ITEM cannot be stored in the table ORDER …… [3] (e) Write an Structured Query Language (SQL) script to output the customer ID, the customer’s name and the total cost of the customer’s orders that have not been paid. The output of the total cost must have an appropriate title. …… [4]
Mark scheme
5(a) 1 mark for each relationship. Max 2 if any extra 3 5(b) 1 mark for: 1 CardNumber 5(c) 1 mark per row to max 2 2 Table Foreign key ORDER_ITEM OrderID ORDER CustomerID CUSTOMER_CARD_DATA CustomerID 5(d) 1 mark each to max 3 3 e.g. • Each order would only be able to have one item • or the database would not be normalised • it would not be in 1NF • due to repeated groups of attributes • in the ORDER table 5(e) 1 mark each 4 • Selecting the customer ID, customer name and sum of TotalCost with appropriate identifier • FROM clause with suitable join of tables (ON or WHERE) • ORDER.Paid = FALSE condition (with correct key word) • GROUP BY condition e.g. SELECT CUSTOMER.CustomerID, CUSTOMER.Name, Sum(ORDER.TotalCost) AS TotalOwed FROM CUSTOMER INNER JOIN ORDER ON CUSTOMER.CustomerID = ORDER.CustomerID WHERE ORDER.Paid = FALSE GROUP BY CUSTOMER.CustomerID; Alternative JOIN Statement SELECT CUSTOMER.CustomerID, CUSTOMER.Name, Sum(ORDER.TotalCost) AS TotalOwed FROM CUSTOMER,ORDER WHERE CUSTOMER.CustomerID = ORDER.CustomerID AND ORDER.Paid = FALSE GROUP BY CUSTOMER.CustomerID;
Question
A programmer is buying a new computer. (a) The programmer is considering the following two computers: Quad‑core 2.2 GHz processor 16‑bit architecture Computer 1 1 GB Random Access Memory (RAM) 500 GB magnetic hard disk Dual‑core 3.8 GHz processor 32‑bit architecture Computer 2 2 GB RAM 500 GB solid state drive (SSD) (i) Computer 1 has a magnetic hard disk. Complete the description of the principal operation of a magnetic hard disk by writing the missing words. The magnetic hard disk has one or more …… that can be magnetised. These are mounted on a …… and rotate at high speed. A …… is moved across the surface on an arm. When data is read, the changes in the …… produce a change in the electric current. [4] (ii) The two computers have different amounts of RAM. Explain how different amounts of RAM affect the performance of a computer. …… [3] (iii) The two computers have different bus widths. Explain how different bus widths affect the performance of a computer. …… [2] (b) Both computers have an Operating System (OS). Describe the purpose of an OS in a computer. …… [5]
Mark scheme
6(a)(i) 1 mark for each correctly completed space 4 • platters • spindle • read/write head • magnetic field The magnetic hard disk has one or more platters that can be magnetised. These are mounted on a spindle and rotate at high speed. A read/write head is moved across the surface on an arm. When data is read the changes in the magnetic field produce a change in the electric current. 6(a)(ii) 1 mark each to max 3 3 • More RAM means more currently running data and instructions can be stored • without needing to use virtual memory • without having to fetch the data from secondary storage first • which has a slower access time • Less latency / delay waiting for instructions / data 6(a)(iii) 1 mark each to max 2 2 e.g. • Wider data bus means more data can be transferred between components at a time • there is less delay / latency when fetching data for a running process • Wider address bus means larger memory addresses can be used • allowing more memory locations to be accessed directly • so less likely to run out of memory 6(b) 1 mark each to max 5 5 e.g. • To provide a user interface • so that the user is able to communicate with the hardware • To manage memory • so that data can be stored and accessed • and multitasking is possible • To manage files • allowing the user to create, edit, update and delete files and folders • To manage inputs and outputs from hardware/peripherals • To handle processes • to make sure each process has fair access
Question
A banker stores personal data on their work computer. (a) The banker needs to transfer confidential data across the internet. Identify and describe one method of restricting the risks posed by an unauthorised person intercepting the data whilst it is being transferred across the internet. Method …… Description …… [3] (b) The banker receives confidential data across the internet. The data includes a digital signature. Explain how a digital signature can make sure the data has not been changed during transmission. …… [5] (c) The data that is transferred can also be verified using a checksum. Explain how data can be verified using a checksum. …… [3]
Mark scheme
7(a) 1 mark for a correct method: 3 1 mark each to max 2 for a corresponding description Method: Encryption Description: • Data is encoded/scrambled using a key to create cipher text • if intercepted it cannot be understood • without being decrypted using a key 7(b) 1 mark each to max 5 5 • The sender hashes the document / message • to produce a digest • The sender encrypts the digest to create the digital signature • The message and the signature are sent to the banker / receiver • The receiver decrypts the signature to reproduce the digest • The receiver uses the same hashing algorithm on the document received to produce a second digest • The receiver compares this digest with the one from the digital signature • If both of the receiver’s digests are the same the document has not changed 7(c) 1 mark each to max 3 3 • The data is put through an algorithm to create a checksum value • The data and checksum are sent to the receiver • The receiver performs the same algorithm on the data • if both checksums match the data is verified
Question
(a) The following table shows part of the instruction set for a processor. The processor has two registers: the Accumulator (ACC) and an Index Register (IX). Instruction Explanation Opcode Operand LDM #n Immediate addressing. Load the number n to ACC Direct addressing. Load the contents of the location at the given LDD <address> address to ACC Indirect addressing. The address to be used is at the given LDI <address> address. Load the contents of this second address to ACC INC <register> Add 1 to the contents of the register (ACC or IX) STO <address> Store the contents of ACC at the given address ADD #n/Bn/&n Add the number n to the ACC DEC <register> Subtract 1 from the contents of the register (ACC or IX) JMP <address> Jump to the given address CMP <address> Compare the contents of ACC with the contents of <address> Following a compare instruction, jump to <address> if the JPE <address> compare was True END Return control to the operating system ACC denotes Accumulator <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A The current contents of memory are: address Instruction 80 10 81 8 82 80 83 81 ... 200 LDD 81 201 INC ACC 202 STO 83 203 LDI 82 204 CMP 83 205 JPE 209 206 LDD 83 207 ADD #10 208 JMP 210 209 DEC ACC 210 STO 81 211 END Trace the program currently in memory using the following trace table. Memory address Instruction address ACC 80 81 82 83 10 8 80 81 [4] (b) The table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction Explanation Opcode Operand Bitwise AND operation of the contents of ACC with the AND #n/Bn/&n operand Bitwise AND operation of the contents of ACC with the AND <address> contents of <address> Bitwise XOR operation of the contents of ACC with the XOR #n/Bn/&n operand Bitwise XOR operation of the contents of ACC with the XOR <address> contents of <address> Bitwise OR operation of the contents of ACC with the OR #n/Bn/&n operand Bitwise OR operation of the contents of ACC with the OR <address> contents of <address> Bits in ACC are shifted logically n places to the left. LSL #n Zeros are introduced on the right‑hand end Bits in ACC are shifted logically n places to the right. LSR #n Zeros are introduced on the left‑hand end <address> can be an absolute or symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A (i) Write the bit manipulation instruction that can be used to set the least significant bit to 1 in an 8‑bit register. All other bits must remain unchanged. The instruction needs to work on a register that contains any 8‑bit binary number. …… [1] (ii) The ACC currently contains the following binary value. 0 1 0 1 0 1 0 1 Write the result after the instruction XOR &FE is run. [1] (iii) The ACC currently contains the following binary value. 0 1 1 0 1 0 1 1 Write the result after the instruction LSR #5 is run. [1]
Mark scheme
8(a) 1 mark for each shaded section 4 Instruction Memory address address ACC 80 81 82 83 10 8 80 81 200 8 201 9 202 9 203 10 204 206 9 207 19 208 210 19 8(b)(i) 1 mark for: 1 OR B0000 0001 // OR #1 // OR &1 8(b)(ii) 1 mark for: 1 1010 1011 8(b)(iii) 1 mark for: 1 0000 0011
Checked your answers against these? Let AI mark the whole paper, on your own working.
Mark my 9618/11Examiners follow the generic marking principles at the front of the scheme, then each question's points: method (M), accuracy (A) and independent (B) marks, error carried forward where the scheme allows it, and positive marking, so you're credited for what you got right.
Done this paper? Upload your script and CIE Buddy's AI marker marks it question by question against this exact scheme, puts the ticks on your own working and says what each lost mark needed.
Question papers and mark schemes © Cambridge University Press & Assessment. CIE Buddy is independent and not connected to Cambridge.
On this page, free: the mark scheme for AS & A Level Computer Science 9618/11, May/June 2025 (9618_s25_ms_11), and the question paper (9618_s25_qp_11), to read or download, with each question's marking points written out underneath.
Computer Science 9618/11 for May/June 2025 is out of 75 marks, with 1 hour 30 minutes to answer it.
Yes. Upload your answers to 9618/11/M/J/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.