Cambridge A Level Computer Science 9618 — 2022 Oct/Nov Paper 1 · Variant 3

This document has 20 pages. Any blank pages are indicated. [Turn over DC (RW/SG) 302753/2 © UCLES 2022 * 0 9 0 3 7 6 0 8 5 0 * COMPUTER SCIENCE 9618/13 Paper 1 Theory Fundamentals October/November 2022 1 hour 30 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. ● 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. ● You may use an HB pencil for any diagrams, graphs or rough working. ● 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. Cambridge International AS & A Level

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3 9618/13/O/N/22 © UCLES 2022 [Turn over 1 A digital audio message needs to be recorded. (a) Tick () one box in each row to identify the effect of each action on the accuracy of the recording. Action Accuracy increases Accuracy decreases Accuracy does not change Change the sampling rate from 40 kHz to 60 kHz. Change the duration of the recording from 20 minutes to 40 minutes. Change the sampling resolution from 24 bits to 16 bits. [2] (b) The audio message is recorded with a sampling rate of 50 kHz and a sampling resolution of 16 bits. The recording is 20 minutes in length. Calculate the file size of the recording. Give your answer in megabytes and show your working. Working … … … … Answer … megabytes [2] (c) A computer uses a buffer when playing the audio message. Explain the purpose of a buffer in a computer system using one other example. … … … … … … [3]

4 9618/13/O/N/22 © UCLES 2022 2 The relational database ASTRONOMY is used to store data about telescopes, the companies that own the telescopes and the photographs taken by the telescopes. The database has these three tables: COMPANY(TelephoneNumber, CompanyID, CompanyName) PHOTOGRAPH(PhotoID, TelescopeID, DateTaken, TimeTaken, Elevation) TELESCOPE(TelescopeID, CompanyID, SerialNumber) (a) Complete the following table by writing the correct answer for each item. Item Answer a suitable field for the primary key in COMPANY a candidate key in TELESCOPE the degree of relationship between TELESCOPE and PHOTOGRAPH [3] (b) A Database Management System (DBMS) has several features. Identify the feature that describes the relationship between data and its structure. … [1] (c) Complete the SQL script to return the total number of telescopes owned by the company whose ID begins with HW. SELECT … (…) FROM TELESCOPE WHERE … LIKE …; [4]

5 9618/13/O/N/22 © UCLES 2022 [Turn over (d) Write the SQL script to add one field to the table PHOTOGRAPH to store the resolution of the photograph, e.g. 1920 × 1068. … … … … [2] (e) The photographs are stored as bitmap images. Complete the statements about bitmap images by writing the missing words. The … of a bitmap image is the number of bits that are used to store each pixel. Metadata about the image is stored in the … of the file. [2] (f) Describe the purpose of a query processor in a DBMS. … … … … [2]

6 9618/13/O/N/22 © UCLES 2022 3 Draw one line from each Operating System (OS) management task to its most appropriate description. hardware management security management memory management process management OS Management task dynamically allocates memory to processes marks unallocated file storage for availability installs programs for devices connected to external ports allows processes to transfer data to and from each other validates user and process authenticity Description [4]

7 9618/13/O/N/22 © UCLES 2022 [Turn over 4 (a) A Central Processing Unit (CPU) contains several special purpose registers and other components. (i) State the roles of the following registers. Memory Address Register (MAR) … … … Memory Data Register (MDR) … … … [2] (ii) State when interrupts are detected during the Fetch-Execute (F-E) cycle. … … [1] (b) A computer system contains a system clock. Describe the purpose of the system clock. … … … … [2] (c) Upgrading secondary storage to solid state typically improves the performance of computer systems. Identify one other upgrade to the hardware and explain why it improves the performance of a computer system. Upgrade … Explanation … … … [2]

8 9618/13/O/N/22 © UCLES 2022 5 (a) Draw a logic circuit for the logic expression: X = NOT ((NOT (A AND B)) OR (NOT (B AND C))) A B X C [3] (b) Complete the truth table for the logic expression: Y = (NOT P AND Q) OR (Q AND NOT R) P Q R Working space Y 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]

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10 9618/13/O/N/22 © UCLES 2022 6 The following table shows part of the instruction set for a processor. The processor has one general purpose register, the Accumulator (ACC), and an Index Register (IX). Instruction Explanation Opcode Operand LDM #n Immediate addressing. Load the number n to ACC LDD <address> Direct addressing. Load the contents of the location at the given address to ACC LDX <address> Indexed addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC LDR #n Immediate addressing. Load the number n to IX MOV <register> Moves the contents of the accumulator to the given register (IX) STO <address> Store contents of ACC at the given address ADD <address> Add the contents of the given address to the ACC ADD #n Add the denary number n to the ACC SUB #n Subtract the denary number n from the ACC INC <register> Add 1 to the contents of the register (ACC or IX) JMP <address> Jump to the given address CMP #n Compare the contents of ACC with number n CMI <address> Indirect addressing. The address to be used is at the given address. Compare the contents of ACC with the contents of this second address JPE <address> Following a compare instruction, jump to <address> if the compare was True JPN <address> Following a compare instruction, jump to <address> if the compare was False OUT Output to the screen the character whose ASCII value is stored in ACC END Return control to the operating system <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001101

11 9618/13/O/N/22 © UCLES 2022 [Turn over (a) The current contents of main memory and selected values from the ASCII character set are given. (i) Trace the program currently in memory using the trace table. Address Instruction 75 LDR #0 76 LDD 100 77 CMP #2 78 JPE 91 79 LDX 110 80 SUB #32 81 CMP #65 82 JPN 86 83 LDM #1 84 ADD 101 85 STO 101 86 LDM #1 87 ADD 100 88 STO 100 89 INC IX 90 JMP 76 91 LDD 101 92 ADD #48 93 OUT 94 END … 100 1 101 0 … 110 97 111 98 112 97 ASCII value Character 49 1 50 2 51 3 52 4 65 A 66 B 67 C 68 D Instruction address ACC IX Memory address Output 100 101 110 111 112 1 0 97 98 97 [4]

12 9618/13/O/N/22 © UCLES 2022 (ii) Explain the purpose of relative addressing in an assembly language program. … … … … [2] (b) The following table shows another part of the instruction set for the processor. Instruction Explanation Opcode Operand AND #n Bitwise AND operation of the contents of ACC with the operand AND Bn Bitwise AND operation of the contents of ACC with the binary number n AND <address> Bitwise AND operation of the contents of ACC with the contents of <address> XOR #n Bitwise XOR operation of the contents of ACC with the operand XOR <address> Bitwise XOR operation of the contents of ACC with the contents of <address> OR #n Bitwise OR operation of the contents of ACC with the operand OR Bn Bitwise OR operation of the contents of ACC with the binary number n OR <address> Bitwise OR operation of the contents of ACC with the contents of <address> LSL #n Bits in ACC are shifted logically n places to the left. Zeros are introduced on the right-hand end LSR #n Bits in ACC are shifted logically n places to the right. Zeros are introduced on the left-hand end <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001101 (i) The current contents of the ACC are: 0 0 1 1 0 1 1 0 Show the contents of the ACC after the execution of the following instruction. AND B01001100 … … [1]

13 9618/13/O/N/22 © UCLES 2022 [Turn over (ii) The current contents of the ACC are: 1 0 0 1 0 1 0 1 Show the contents of the ACC after the execution of the following instruction. OR B01001111 … … [1] (iii) The current contents of the ACC are: 1 0 0 1 1 1 0 1 Show the contents of the ACC after the execution of the following instruction. LSR #2 … … [1] (c) One instruction group is data movement. Give the name of one other instruction group. … … [1]

14 9618/13/O/N/22 © UCLES 2022 7 (a) The diagram shows the hardware and software used to retrieve files stored on the cloud. Laptop Internet Service Provider A X B Firewall Complete the following table by writing the answer for each row. Answer The name of device A that allows the laptop to connect to the internet A type of cloud, X An example of an application, B, that can run on the cloud [3] (b) Give one advantage and two disadvantages of transmitting data using satellites instead of copper cables. Advantage 1 … … Disadvantage 1 … … Disadvantage 2 … … [3]

15 9618/13/O/N/22 © UCLES 2022 [Turn over (c) Local Area Networks (LANs) can be made up of several subnetworks. (i) Give two benefits of dividing a network into subnetworks by subnetting the LAN. 1 … … 2 … … [2] (ii) A subnet mask is used when subnetting a LAN. Two devices on the LAN are located in different subnetworks. The IP addresses and corresponding subnet masks are shown: Device IP address Subnet mask 10.10.12.1 255.0.0.0 192.168.12.4 255.255.255.0 Identify the following network ID and host ID. The network ID for the device with the IP address 10.10.12.1 … The host ID for the device with the IP address 192.168.12.4 … [2]

16 9618/13/O/N/22 © UCLES 2022 8 (a) (i) Explain why some programs are distributed under an open source licence. … … … … [2] (ii) Explain how a programmer benefits from distributing a program under a commercial licence. … … … … [2] (b) A commercial program for a vehicle repair garage includes an Artificial Intelligence (AI) module that can diagnose faults and suggest repairs. Describe one economic impact the AI module may have on the garage. … … … … [2]

17 9618/13/O/N/22 © UCLES 2022 [Turn over 9 (a) (i) Convert the unsigned binary value into hexadecimal. 10010011 Answer … [1] (ii) Convert the unsigned binary value into denary. 10010011 Answer … [1] (b) State two benefits of using Binary Coded Decimal (BCD) to represent values. Benefit 1 … … Benefit 2 … … [2]

18 9618/13/O/N/22 © UCLES 2022 10 (a) Explain the importance of feedback in a control system. … … … … … … [3] (b) (i) Identify one sensor that could be used in a car alarm system. Justify your choice. Sensor … Justification … … … … [2] (ii) The car alarm is an example of an embedded system. Describe the characteristics of an embedded system. … … … … … … [3]

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20 9618/13/O/N/22 © UCLES 2022 BLANK PAGE 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.

This document consists of 10 printed pages. © UCLES 2022 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/13 Paper 1 Theory Fundamentals October/November 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 October/November 2022 series for most Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level components.

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 2 of 10 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.

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 3 of 10 Question Answer Marks 1(a) 1 mark for one or two correct ticks, 2 marks for three correct ticks. Action Accuracy increases Accuracy decreases Accuracy does not change Change the sampling rate from 40 kHz to 60 kHz. ✓ Change the duration of the recording from 20 minutes to 40 minutes. ✓ Change the sampling resolution from 24 bits to 16 bits. ✓ 2 1(b) 1 mark for answer; 1 mark for working. Working: Size = 50KHz * (20  60) * 16 bits = 50 000 * 1200 * 16 bits // 50 000 *1200 * 2 bytes = 960 000 000 bits = 120 000 000 bytes = 120 000 kilobytes = 120 megabytes Answer = 120 megabytes 2 1(c) 1 mark for purpose (max 2): Purpose: • to act as temporary storage // to store (downloaded) data • ... before it is used by the receiving device • ... to allow processes / devices to operate at different speeds // independently of each other 1 mark for each example (max 1): Examples: • printer buffer used when data is transferred from a computer to a printer • video buffer when streaming videos • keyboard buffer when performing data entry 3

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 4 of 10 Question Answer Marks 2(a) 1 mark for each correct answer. Item Answer a suitable field for the primary key in COMPANY CompanyID a candidate key in TELESCOPE SerialNumber // TelescopeID the degree of relationship between TELESCOPE and PHOTOGRAPH 1:M / 1 to many 3 2(b) Logical schema 1 2(c) 1 mark for each correctly completed missing part: SELECT COUNT (TelescopeID) FROM TELESCOPE WHERE CompanyID LIKE 'HW%'; 4 2(d) 1 mark for each bullet point: • ALTER TABLE PHOTOGRAPH • ADD Resolution TEXT; ALTER TABLE PHOTOGRAPH ADD Resolution TEXT / VARCHAR(11); 2 2(e) 1 mark for each correctly completed term; The bit depth of a bitmap image is the number of bits that are used to store each pixel. Metadata about the image is stored in the header of the file. 2 2(f) 1 mark for each bullet point (max 2): • allows the user to enter criteria • searches for the data that meets the entered criteria • organises the results to be displayed to the user 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 5 of 10 Question Answer Marks 3 1 mark for each correct line: 4 Question Answer Marks 4(a)(i) 1 mark for each register: MAR: • holds address in memory from which data will be read / to which data will be written MDR: • holds the data/instructions which has been read from or is to be written to the address in the MAR 2 4(a)(ii) after completion of the execute stage // before the cycle begins 1 4(b) 1 mark for each bullet point (max 2): • synchronise operations • ... by creating timing signals • to keep track of the date and time / timestamp files • to process operations in the correct order / sequence 2 hardware management security management memory management process management OS Management task Description dynamically allocates memory to processes marks unallocated file storage for availability installs programs for devices connected to external ports validates user and process authenticity allows processes to transfer data to and from each other

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 6 of 10 Question Answer Marks 4(c) 1 mark for identification of a correct upgrade: 1 mark for a corresponding explanation: Examples: • increase quantity of RAM • ... so allowing more applications to reside in memory at the same time, saving disk access times • increase the size of cache memory • ... so that the CPU can continue working without waiting for data • increase clock speed • ... so that more instructions are performed in a time period • increase the number of processors / cores • ... so that more instructions are performed in parallel 2 Question Answer Marks 5(a) 1 mark for each bullet point: • NOT (A AND B) • NOT (B AND C) • NOT(NOT(A AND B) OR NOT(B AND C)) 3 5(b) 1 mark for each set of highlighted rows. P Q R Y 0 0 0 0 0 0 1 0 0 1 0 1 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 1 1 1 1 0 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 7 of 10 Question Answer Marks 6(a)(i) 1 mark for each set of highlighted rows: Instruction address ACC IX Memory address Output 100 101 110 111 112 1 0 97 98 97 75 0 76 1 77 78 79 97 80 65 81 82 83 1 84 85 1 86 87 2 88 2 89 1 90 76 77 78 91 1 92 49 93 1 94 4 6(a)(ii) 1 mark for each bullet point: • To allow for re-locatable code • ... because all (target) addresses can be specified by the base address + offset 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 8 of 10 Question Answer Marks 6(b)(i) 0000 0100 1 6(b)(ii) 1101 1111 1 6(b)(iii) 0010 0111 1 6(c) 1 mark for a correct name: • input and output of data • arithmetic operations • unconditional and conditional instructions • compare instructions 1 Question Answer Marks 7(a) 1 mark for each correct answer: Answer The name of device A that allows the laptop to connect to the internet Router A type of cloud, X Public (cloud) An example of an application, B, that can run on the cloud, Email / Graphics / Word processor / Spreadsheet / Game / Database, etc. 3 7(b) 1 mark for a correct advantage: • not fixed to a single location • allows access in remote / rural areas 1 mark for each correct disadvantage (max 2): • high latency / lag / slow to connect • more expensive than wired methods, as need extra equipment • signal is affected by bad weather • the transmission speed is slower than fixed line broadband • direct line of sight needed 3 7(c)(i) 1 mark for each bullet point (max 2) Examples: • improves security • reduces congestion • allows extension of the network / devices attached • aids day-to-day management • improves performance 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 9 of 10 Question Answer Marks 7(c)(ii) 1 mark for each correct answer: • network ID = 10 • host ID = 4 2 Question Answer Marks 8(a)(i) 1 mark for each bullet point (max 2): • to allow users to customise the code • to allow errors to be reported / identified / fixed by users • to allow additional features to be added to the code • to allow for collaboration 2 8(a)(ii) 1 mark for each correct point (max 2) Example: • enables the program to be copyrighted • prevents illegal changes to the program / protects the source code • prevents illegal copies of the program being made • a fee can be charged for the program 2 8(b) 1 mark for a correct economic impact and 1 mark for corresponding description Example: • reduce costs to the garage • ... because less time taken for diagnosis • increase profits for the garage • ... as technicians spend more time repairing, so completing more jobs in a day • decrease costs passed to customer • ... so garage may gain customers • profit margins can be reduced • ... because program may be expensive to buy / maintain / update 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2022 © UCLES 2022 Page 10 of 10 Question Answer Marks 9(a)(i) 93 1 9(a)(ii) 147 1 9(b) 1 mark for each correct benefit (max 2) Examples: • straightforward to convert to / from BCD and denary • ... so it is less complex to encode and decode for programmers • easier for digital equipment use BCD to display output information • can represent monetary values exactly 2 Question Answer Marks 10(a) 1 mark for each bullet point: • to ensure the system operates with the given criteria • ... by enabling system output to affect subsequent system input • ... thus allowing conditions to be automatically adjusted 3 10(b)(i) 1 mark for identification of a suitable sensor 1 mark for corresponding justification Example: • sound sensor • if a sound occurs inside the car the alarm is activated • infra-red sensor • senses the heat of person in the car / infra-red beams are broken • pressure sensor • an intruder sits in the driver’s seat 2 10(b)(ii) 1 mark for each bullet point (max 3): • the embedded system is built into / integrated (into the car alarm) • combination of hardware and software designed for a specific function • must have a processor, memory and input / output • The system is not easily changed/updated by the car owner 3