Cambridge A Level Computer Science 9608 — 2018 May/June Paper 1 · Variant 2

* 4 8 6 1 1 1 0 3 2 0 * This document consists of 14 printed pages and 2 blank pages. DC (SC/CGW) 144488/3 © UCLES 2018 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/12 Paper 1 Theory Fundamentals May/June 2018 1 hour 30 minutes Candidates answer on the Question Paper. No Additional Materials are required. No calculators allowed. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. No marks will be awarded for using brand names of software packages or hardware. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The maximum number of marks is 75.

2 9608/12/M/J/18 © UCLES 2018 1 An operating system (OS) is usually pre-installed on a new computer. (a) The OS performs a number of different tasks such as file management and peripheral management. (i) State three file management tasks the OS performs. 1 … … 2 … … 3 … … [3] (ii) State three printer management tasks the OS performs. 1 … … 2 … … 3 … … [3] (b) Utility software is usually pre-installed on a new computer. (i) The following table lists four programs. Put one tick (3) in each row to indicate whether or not the program is utility software. Program True False Database Virus checker Web browser Backup software [4] (ii) Name two other utility programs. Program 1 … Program 2 … [2]

3 9608/12/M/J/18 © UCLES 2018 [Turn over Question 2 begins on the next page.

4 9608/12/M/J/18 © UCLES 2018 2 (a) A greenhouse control system has four input parameters (H, D, T, W) and two outputs (X, Y). Parameter Description of parameter Binary value Condition H Humidity 0 Too low 1 Acceptable D Day 0 Night 1 Day T Temperature 0 Too high 1 Acceptable W Windows 0 Closed 1 Open The watering system turns on (X = 1) if: either it is daytime and the temperature is too high or the humidity is too low. The fan turns on (Y = 1) if the temperature is too high and the windows are closed. Draw a logic circuit to represent the greenhouse control system. H X Y D T W [6]

5 9608/12/M/J/18 © UCLES 2018 [Turn over (b) Complete the truth table for the logic expression: X = NOT A AND (B NAND 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 [4]

6 9608/12/M/J/18 © UCLES 2018 3 Parity bits can be used to verify data. (a) The following binary number is transmitted using odd parity. Add the missing parity bit. Parity bit 0 1 0 0 0 0 0 [1] (b) In the following data transmitted, the first column contains the parity bits, and the last row contains the parity byte. A device transmits the data using even parity. Circle the error in the data transmitted. Parity bit Data 1 0 1 0 1 1 1 1 0 1 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Parity byte 0 0 0 0 1 0 0 1 [1] (c) The following table shows five error detection measures. Put one tick (3) in each row to indicate whether the measure is validation or verification. Measure Validation Verification Checksum Format check Range check Double entry Check digit [5]

7 9608/12/M/J/18 © UCLES 2018 [Turn over 4 (a) The Accumulator is a register. The current contents of the Accumulator are: 1 1 0 1 1 0 1 1 The current contents of the Accumulator represent an unsigned binary integer. (i) Convert the value in the Accumulator into denary. …[1] (ii) Convert the value in the Accumulator into hexadecimal. …[1] (iii) The current contents of the Accumulator represent a two’s complement binary integer. Convert the value in the Accumulator into denary. …[1] (b) The binary integer represents a character from the computer’s character set. (i) Define the term character set. … …[1] (ii) Explain the differences between the ASCII and Unicode character sets. … … … …[2] (iii) The ASCII code for ‘A’ is 41 in hexadecimal. Calculate the ASCII code in hexadecimal for ‘Z’. Show your working. Working … … … ASCII code in hexadecimal for ‘Z’ … [2]

8 9608/12/M/J/18 © UCLES 2018 5 A student has recorded a sound track for a short film. (a) Explain how an analogue sound wave is sampled to convert it into digital format. … … … … … …[3] (b) Explain the effects of increasing the sampling resolution on the sound file. … … … …[2] (c) The original sound was sampled at 44.1 kHz. The sample rate is changed to 22.05 kHz. Explain the effects of this change on the sound file. … … … … … … … …[3]

9 9608/12/M/J/18 © UCLES 2018 [Turn over (d) The student uses sound editing software to edit the sound file. Name two features of sound editing software the student can use to edit the sound file. Describe the purpose of each feature. Feature 1 … Purpose … … … Feature 2 … Purpose … … … [4] Question 6 begins on the next page.

10 9608/12/M/J/18 © UCLES 2018 6 A web page includes the following HTML and JavaScript code. 01 <html> 02 <body> 03 04 <p>Enter your mark</p> 05 <input id="Mark" value="0"> 06 <button onclick="calcGrade()">Enter</button> 07 08 <script> 09 function calcGrade() { 10 var mark, grade; 11 mark = document.getElementById("Mark").value; 12 if (mark >= 90) { 13 grade = "A" 14 } else if (mark >= 80) { 15 grade = "B" 16 } else if (mark >= 70) { 17 grade = "C" 18 } else if (mark >= 60) { 19 grade = "D" 20 } else if (mark >= 50) { 21 grade = "E" 22 } else { 23 grade = "U" 24 } 25 alert("Your grade is " + grade) 26 } 27 </script> 28 29 </body> 30 </html> (a) Give the identifier of two variables used in the JavaScript code. 1 … 2 … [2] (b) Give the line number where the JavaScript code produces an output. …[1] (c) Describe the purpose of the statement on line 11. … …[2]

11 9608/12/M/J/18 © UCLES 2018 [Turn over (d) (i) State whether this JavaScript code will be run client-side or server-side. …[1] (ii) Explain the difference between client-side scripting and server-side scripting. … … … … … …[3]

12 9608/12/M/J/18 © UCLES 2018 7 A social media website has a relational database, WEBDATA, that stores the site’s information. The database has three tables to store users’ details, and details of the images and text that they post. USER(UserName, FirstName, SecondName, DateOfBirth) PHOTO(PhotoID, UserName, Comment, UploadDate) TEXTPOST(PostID, UserName, DateOfPost, TheText) (a) (i) Explain how the relationship between the tables USER and PHOTO has been implemented. … … … …[2] (ii) Draw the entity-relationship (E-R) diagram to show the relationships between the three tables. [2] (b) A database administrator decides to enforce referential integrity. Use an example from the database WEBDATA to explain what is meant by referential integrity. … … … … … …[3]

13 9608/12/M/J/18 © UCLES 2018 [Turn over (c) The database has been normalised to Third Normal Form (3NF). Define the three stages of database normalisation. 1NF … … 2NF … … 3NF … … [3] (d) The following shows sample data from the USER table. UserName FirstName SecondName DateOfBirth gem123 John Smith 01/01/1995 purpleSky Muhammed Ali 23/02/1956 OpenWindow Sunny Amir 03/03/1997 bluebird127 Raziya Bello 04/03/1982 (i) Write an SQL script to create the USER table. … … … … … … … … … …[5]

14 9608/12/M/J/18 © UCLES 2018 (ii) The database administrator needs to alter the USER table. A new field, Country, needs to be added. Write an SQL script to add the field Country to the USER table. … … … …[2]

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16 9608/12/M/J/18 © UCLES 2018 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 International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. BLANK PAGE

IGCSE™ is a registered trademark. This document consists of 9 printed pages. © UCLES 2018 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/12 Paper 1 Written Paper May/June 2018 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 2018 series for most Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 2 of 9 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.

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 3 of 9 Question Answer Marks 1(a)(i) 1 mark per bullet to max 3 • Storage space divided into file allocation units • Space allocated to particular files • Maintains/creates directory structures • Specifies the logical method of file storage (e.g. FAT or NTFS) • Provides file naming conventions • Controls access // implements access rights // implements password protection // Makes file sharing possible • Specifies tasks that can be performed on a file (e.g. open, close, delete, copy, create, move etc.) 3 1(a)(ii) 1 mark per bullet to max 3 • Installs printer driver • Sends data to the printer / buffer to print // sends documents to the print queue • Sends commands to printer • Receives and handles (error) messages/signals/interrupts from the printer 3 1(b)(i) 1 mark for each correct box ticked. Program True False Database 9 Virus checker 9 Web browser 9 Backup software 9 4 1(b)(ii) 1 mark for each valid utility program to max 2 e.g. • System clean up • Automatic update • Disk contents analysis / Disk checking / Disk repair • File compression • Disk formatter • Firewall • Disk Defragmenter 2

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 4 of 9 Question Answer Marks 2(a) 1 mark for each gate with the correct inputs. Final two gates must also have the correct output. 6 2(b) One mark for each pair of rows. A B C Working space X 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 0 4

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 5 of 9 Question Answer Marks 3(a) 1 mark for correct parity bit Parity bit 0 0 1 0 0 0 0 0 1 3(b) 1 mark for the correct bit circled. Parity bit Data 1 0 1 0 1 1 1 1 0 1 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Parity byte 0 0 0 0 1 0 0 1 1 3(c) 1 mark per each correct row Measure Validation Verification Checksum 9 Format check 9 Range check 9 Double entry 9 Check digit 9 5 Question Answer Marks 4(a)(i) 219 1 4(a)(ii) DB 1 4(a)(iii) −37 1 4(b)(i) 1 mark from: • The symbols that the computer recognises/uses • A list of characters recognised by the computer hardware and software 1

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 6 of 9 Question Answer Marks 4(b)(ii) 1 mark per bullet to max 2 • UNICODE has greater range of characters than ASCII • UNICODE represents most written languages in the world while ASCII does not ASCII used for English only • ASCII uses 7 or 8 bits or one byte whereas UNICODE uses up to 4 bytes per character • UNICODE is standardised while ASCII is not 2 4(b)(iii) 1 mark for correct working, 1 mark for correct answer Working: Code for Z = Code for A + 2510 Code for Z = 4116 +2510 Code for Z = 4116 + 1916 Code for Z = 5A16 Answer: 5A16 2 Question Answer Marks 5(a) 1 mark per bullet to max 3 • Amplitude (of the sound wave) measured • At set / regular time intervals / per time unit / time period • Value of the sample is recorded as a binary number 3 5(b) 1 mark per bullet to max 2 • (Increasing the sampling resolution means) more bits per sample // larger range of values • Larger file size • More accurate representation of sound 2 5(c) 1 mark per bullet to max 3 • Fewer samples (per unit time) • File size will decrease • Larger gaps / spaces between samples // Greater quantization errors • Sound accuracy will reduce // not as close to original sound 3

9 © Q Q Q 9608/12 © UCLES 2018 Question 5(d) Question 6(a) 6(b) 6(c) 6(d)(i) 6(d)(ii) Question 7(a)(i) 7(a)(ii) 1 mark for e.g. • F • C • R • D • C • R 1 mark ea • m • g 25 1 mark pe • T • S Client-side 1 mark pe • C • « • S • T 1 mark pe • U • U 1 mark for Cambridg r naming fea ading Change the v Removing so Delete sectio Copy Repeat elem ach ark rade er bullet akes the va tores (it) in e er bullet to m Client-side (s «when the ( erver-side ( he results a er bullet serName is serName is r each corre ge Internatio P ature/tool, 1 volume of a ound / elem ons of the so ments of the alue entered the variable max 3 script) is run (web page) (script) is ru are sent to t s the primar s (included ect relations onal AS/A L PUBLISHED Page 7 of 9 Answer 1 mark for d a section of ments ound wave sound wav Answer d in the text e mark // A n on the com data is rece un on the we the compute Answer ry key in US as) a foreig ship Level – Mar D r description. the sound f , for examp ve r t box / input Assigns (it) mputer mak eived by the eb server er that mad r SER gn key in PH k Scheme Max 2 feat for it get lou le, backgro t field 'Mar to the varia king the req e computer e the reque HOTO Ma tures uder/quieter ound noise k' able mark quest r est ay/June 201 Mark r Mark Mark 18 ks 4 ks 2 1 2 1 3 ks 2 2

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 8 of 9 Question Answer Marks 7(b) 1 mark per bullet to max 2 for explanation • Referential integrity is making sure tables do not try to reference data which does not exist // A value of one attribute of a table exists as a value of another attribute in a different table • A primary key cannot be deleted unless all dependent records are already deleted • Cascading delete • A primary key cannot be updated unless all dependent records are already updated • Cascading update / edit • Every foreign key value has a matching value in the corresponding primary key • The foreign keys must be the same data type as the corresponding primary key 1 mark for a suitable example e.g. • A UserName cannot be deleted from the USER table if they have a related photo/textpost • If UserName is updated in USER table, it must also be updated in PHOTO and TEXTPOST tables • Cannot create/edit a record in TEXTPOST / PHOTO without a matching entry in USER table 3 7(c) Max 1 mark from each bulleted group 1NF • No repeated groups of attributes • All attributes should be atomic • No duplicate rows 2NF (in 1NF and) • No partial dependencies 3NF (in 2NF and) • No non-key dependencies • No transitive dependencies 3 7(d)(i) 1 mark per bullet • CREATE TABLE USER and (); • UserName, FirstName and SecondName as VARCHAR and commas • DateOfBirth as DATE and comma • PRIMARY KEY(UserName) • An appropriate NOT NULL CREATE TABLE USER( UserName: varchar(15) NOT NULL, FirstName: varchar(25), SecondName: varchar(25), DateOfBirth: Date, PRIMARY KEY(UserName) ); 5

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 9 of 9 Question Answer Marks 7(d)(ii) 1 mark per bullet • ALTER TABLE USER • ADD COUNTRY varchar; ALTER TABLE USER ADD Country varchar; 2