Cambridge A Level Computer Science 9608 — 2021 Oct/Nov Paper 1 · Variant 1

This document has 16 pages. Any blank pages are indicated. Cambridge International AS & A Level DC (PQ) 205102/2 © UCLES 2021 [Turn over * 1 9 2 7 1 4 1 1 1 6 * COMPUTER SCIENCE 9608/11 Paper 1 Theory Fundamentals October/November 2021 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.

2 9608/11/O/N/21 © UCLES 2021 1 An image can be either a bitmap image or a vector graphic. (a) Vector graphics are made up of drawing objects and their properties. (i) State what is meant by a drawing object. … … [1] (ii) Identify four properties of a drawing object. 1 … … 2 … … 3 … … 4 … … [4] (b) Identify three items that are stored in a bitmap file header. 1 … … 2 … … 3 … … [3]

3 9608/11/O/N/21 © UCLES 2021 [Turn over (c) A bitmap image needs to be compressed before it can be sent by email. Describe one lossy and one lossless method of compressing the image. Lossy … … … … … Lossless … … … … … [4]

4 9608/11/O/N/21 © UCLES 2021 2 Joanne wants to record sound files and videos for uploading to a social media website. (a) The following table contains terms about sound representation and encoding. Complete the table by writing the definitions for each term. Term Definition Sampling … … … Sampling resolution … … … Sampling rate … … … [3] (b) Joanne records a short video using interlaced encoding. Describe what is meant by interlaced encoding. … … … … [2]

5 9608/11/O/N/21 © UCLES 2021 [Turn over 3 Server-side scripting is used to access a company database over the Internet. Steps 1 to 6 describe the sequence of events. Four of the statements A, B, C, D, E and F are used to complete the sequence. Letter Statement A The web server processes the PHP code. B The server renders the HTML code and displays the web page. C The browser renders the HTML code and displays the web page. D The web server returns the (HTML) web page to the client web browser. E The web server accesses the page from its hard disk. F The web browser processes the PHP code. Write one of the letters A to F in each appropriate row to complete the sequence. 1. The browser requests the web page from the web server. 2. … 3. … 4. The web server produces the HTML code for the web page. 5. … 6. … [4]

6 9608/11/O/N/21 © UCLES 2021 4 Oliver needs to increase the secondary storage on his computer. He already has several hard disks. (a) Identify two other secondary storage devices that Oliver could use. Each device must be different. 1 … 2 … [2] (b) Oliver needs a scanner to make digital copies of some paper documents. Describe the basic internal operation of a scanner. … … … … … … … … [4]

7 9608/11/O/N/21 © UCLES 2021 [Turn over (c) Oliver wants to upgrade the RAM in his computer. He is not sure whether his computer has Static RAM (SRAM) or Dynamic RAM (DRAM). Draw one or more lines from each type of RAM to its appropriate description(s). Type of RAM Description SRAM DRAM Is less expensive to manufacture Needs to be refreshed Has more complex circuitry Is often used as cache Has faster access time [2]

8 9608/11/O/N/21 © UCLES 2021 5 Complete the truth table for the following logic expression: X = NOT(A OR B) AND NOT(NOT(B OR C) AND (NOT A)) 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 [4]

9 9608/11/O/N/21 © UCLES 2021 [Turn over 6 (a) Complete the following sentences that describe parts of a processor in a Von Neumann model for a computer system. There are … buses that transfer data between components in a computer system. The width of the … determines the number of directly accessible memory locations. The … sends signals on the … to direct the operation of system components. … pulses are used to synchronise the components on the motherboard. [5] (b) Describe the stages of the fetch-execute (F-E) cycle. … … … … … … … … … … [5]

10 9608/11/O/N/21 © UCLES 2021 7 (a) A computer has an operating system (OS). (i) State three memory management tasks performed by the OS. 1 … … 2 … … 3 … … [3] (ii) State two input/output device management tasks performed by the OS. 1 … … 2 … … [2] (b) Utility programs are also provided with the OS. Identify and describe two different utility programs. Utility program … Description … … Utility program … Description … … [4]

11 9608/11/O/N/21 © UCLES 2021 [Turn over (c) Some operating systems include library programs. State three benefits to a programmer of using library programs. 1 … … 2 … … 3 … … [3]

12 9608/11/O/N/21 © UCLES 2021 8 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 Op code Operand LDD <address> Direct addressing. Load the contents of the location at the given address to the ACC LDI <address> Indirect addressing. The address to be used is at the given address. Load the contents of this second address to the ACC STO <address> Store the contents of the ACC at the given address ADD <address> Add the contents of the given address to the ACC INC <register> Add 1 to the contents of the register (ACC or IX) JMP <address> Jump to the given address The current contents of the main memory are: Address Instruction 130 LDI 160 131 ADD 153 132 STO 153 133 LDD 160 134 INC ACC 135 STO 160 136 JMP 130 … 150 13 151 23 152 11 153 0 … 160 150

13 9608/11/O/N/21 © UCLES 2021 [Turn over Complete the trace table for two iterations of the loop. Instruction address ACC Memory address 150 151 152 153 160 13 23 11 0 150 [4]

14 9608/11/O/N/21 © UCLES 2021 9 An airline company uses a relational database to store data about passengers and flights. Part of the database is shown. PASSENGER(PassengerID, FirstName, LastName) FLIGHT(FlightID, FlightDate, FlightTime) PASSENGER_LIST(FlightID, PassengerID, SeatNo) (a) Complete the entity-relationship (E-R) diagram to show the relationships between the given tables. PASSENGER FLIGHT PASSENGER_LIST [2] (b) The following is example data for the table FLIGHT: FlightID FlightDate FlightTime MO126 05/05/21 09:00 GK6708 06/09/21 00:30 BA0897 08/12/21 15:30 Write Data Definition Language (DDL) statements to define the table FLIGHT. … … … … … … … [5]

15 9608/11/O/N/21 © UCLES 2021 10 Janaka is developing a new computer program. She decides to use an interpreter instead of a compiler. (a) State three benefits of using an interpreter. 1 … … 2 … … 3 … … [3] (b) State one drawback of using an interpreter. … … [1] 11 The Internet uses a client-server model. (a) Describe the role of clients and servers on the Internet. … … … … [2] (b) Computers on the Internet have IP addresses. Describe the format of an IP address. … … … … … … [3]

16 9608/11/O/N/21 © UCLES 2021 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 the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge. BLANK PAGE

This document consists of 10 printed pages. © UCLES 2021 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9608/11 Paper 1 Theory Fundamentals October/November 2021 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 2021 series for most Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level components.

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 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.

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 3 of 10 Question Answer Marks 1(a)(i) An individual shape (in a vector graphic) // a shape defined using mathematics/geometry // a distinct element within an image // possible to alter without affecting the other objects within the image 1 1(a)(ii) One mark per bullet point to max 4 E.g. • Line colour • Line width • Fill colour • Shape • Outline style • Dimensions / size • Position 4 1(b) One mark per bullet point to max 3 E.g. • Dimensions e.g.100 × 100 pixels // image size • File size • Colour depth // bit depth • Location/offset of data within the file • Compression type • Confirmation that it is a bitmap // filetype • Image resolution • Colour palette 3 1(c) One mark per bullet point to max 2 for each method. Lossy • Reduce the resolution • …fewer pixels per unit measurement • …fewer pixels / binary numbers are stored • Reduce the colour depth • …reduce the number of bits per colour • …each pixel has fewer bits Lossless • RLE (Run Length Encoding) • ...looks for runs of consecutive pixels of the same colour • ...stores the colour value once and the number of times it occurs 4

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 4 of 10 Question Answer Marks 2(a) One mark per correct definition Term Definition Sampling Measuring the amplitude of the wave at regular/set time intervals Sampling resolution The number of bits used to represent each sample Sampling rate The number of samples taken per unit of time 3 2(b) One mark per bullet point to max 2 • The data from a single frame are encoded as two separate fields • One containing the data for the even numbered rows / lines and the other has the data for the odd numbered rows / lines • The image is rendered by alternating between the even field and the odd field (of each successive frame) • The viewer sees data from two frames simultaneously • The rate of picture display (the field rate) is twice the rate of image frame display (the frame rate) • Produces what appears to the eye to be a high refresh rate • Halves the transmission bandwidth requirements 2 Question Answer Marks 3 One mark for each correct letter in the correct position 1 The browser requests the web page from the web server. 2 E 3 A 4 The web server produces the HTML code for the web page. 5 D 6 C 4 Question Answer Marks 4(a) One mark per bullet point to max 2 E.g. • Optical Disc Drive // CD/DVD Drive/Writer • Solid State Drive // USB Flash drive 2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 5 of 10 Question Answer Marks 4(b) One mark per bullet point to max 4 • Main component of a scanner is a CCD (Charge Couple Device) array • CCD is a collection of light sensitive diodes • Laser beam / light shines onto the source document/barcode • The scanned image reaches the CCD through mirrors and lenses • Sensors detect levels of reflected light • Brighter light results in greater electrical charge • Light intensity is converted (by software) to a digital value 4 4(c) One mark for correct lines from each type of RAM 2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 6 of 10 Question Answer Marks 5 One mark per pair of rows (shaded and unshaded) A B C Working space X 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 0 4 Question Answer Marks 6(a) One mark for each term in bold. There are three buses that transfer data between components in a computer system. The width of the address bus determines the number of directly accessible memory locations. The control unit sends signals on the control bus to direct the operation of system components. Clock pulses are used to synchronise the components on the motherboard. 5 6(b) One mark per bullet point to max 5 • The address in the program counter is the address of next item to be fetched • The address is copied into MAR ... • …using the address bus • The instruction from that address moved/copied from main memory to MDR ... • …using the data bus • The instruction is transferred from MDR to CIR • The processor’s instruction set is used to decode the instruction// the instruction is decoded in the CIR • …into op code and operand • The processor executes the instruction // the processor processes the data as required • The address in PC is incremented ready for next loop 5

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 7 of 10 Question Answer Marks 7(a)(i) One mark per bullet point to max 3 • Prevents two processes occupying the same memory space • Organises memory e.g. paging/segmentation • Makes uses of virtual memory • Keeps track of allocated and free memory locations • Allocates memory to processes • Ensures fair use of memory • Releases memory when a process stops 3 7(a)(ii) One mark per bullet point to max 2 • Installs drivers • Sends/receives data from a buffer // buffer management // • Sends commands to the device • Receives/handles messages/signals/interrupts from the device • Control of hardware usage by processes • Device detection • Power management • Keep track of device status (free or busy) 2 7(b) One mark for name and one for description × 2, max 4 The description must match the name • Virus/Malware checker • …scans disk for viruses and reports, quarantines or deletes them • File compression • …reduces the size of a file • Back up • …creates a copy of data in case of loss, so that the images can be restored • Defragmenter • …finds files that are not stored in contiguous blocks and moves them together • Disk formatter • …creates a logical drive on a hard drive // reformats a previously used hard drive // creates logical partitions // prepares a disk for first use • Disk repair/Disk contents analysis • …attempts to recover damaged files // checks disk for space and usage // to identify/mark the errors / bad sectors 4

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 8 of 10 Question Answer Marks 7(c) One mark per bullet point to max 3 • Already tested • Should be relatively free from errors // more robust • Used by many others • Make use of another programmer’s knowledge • Precompiled • Saves (programming/testing) time 3 Question Answer Marks 8 One mark for each set of rows (shaded and unshaded) Instruction address ACC Memory address 150 151 152 153 160 13 23 11 0 150 130 13 131 13 132 13 133 150 134 151 135 151 136 130 23 131 36 132 36 133 151 134 152 135 152 136 4

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 9 of 10 Question Answer Marks 9(a) One mark per correct relation 2 9(b) One mark per bullet point • Create table FLIGHT with open and close brackets (and ;) • FlightID as VARCHAR restricted to max 6 • FlightDate as DATE • FlightTime as TIME • Declaring FlightID as Primary Key Example CREATE TABLE FLIGHT ( FlightID VARCHAR(6), FlightDate DATE, FlightTime TIME, PRIMARY KEY (FlightID)); 5 Question Answer Marks 10(a) One mark per bullet point to max 3 • Easier de-bugging • Errors can be corrected in real time • Errors are reported as the interpreter finds them. • An error can be corrected and translation continued from where it stopped • The effect of any change made to the code can be seen immediately • Parts of the program can be tested, without all the program code being available. 3 10(b) One mark for a correct answer Source code is needed at run time // No executable file produced, (so source code can be edited) // Translation software needed every time the program is run // execution time increased 1

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2021 © UCLES 2021 Page 10 of 10 Question Answer Marks 11(a) One mark per bullet point to max 2 • Web pages/files are saved on servers • Clients send requests to the web servers • Web servers process the requests • …and return the results to the client • ... client displays the results to the user 2 11(b) One mark per bullet point to max 3 IPv4 • Four groups of (denary or Hexadecimal integers • Numbers between 0 and 255 / 0 and FF • Each stored in 1 byte / 8 bits // the whole is stored in 32 bits / 4 bytes • Separated by full stops • Correct example OR IPv6 • Eight groups of (Hexadecimal) digits • Numbers between 0 and FFFF • Each stored in 2 bytes/16 bits // the whole stored in 128 bits / 16bytes • Separated by colons • The first instance of multiple groups of zero can be replaced by a double colon • correct example 3