Cambridge A Level Computer Science 9608 — 2017 Oct/Nov Paper 1 · Variant 2

This document consists of 12 printed pages. DC (ST/SW) 129950/3 © UCLES 2017 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 5 0 1 3 8 1 0 8 8 7 * COMPUTER SCIENCE 9608/12 Paper 1 Theory Fundamentals October/November 2017 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/O/N/17 © UCLES 2017 1 One of the tasks of the operating system (OS) is the management of the main memory of the computer system. State and describe three other operating system management tasks. 1 … … … 2 … … … 3 … … … [6]

3 9608/12/O/N/17 © UCLES 2017 [Turn over 2 (a) The diagram shows three items of software that translate program code. Draw one line from each context to the correct item of translation software. Assembler Interpreter Compiler Context Item of translation software The source code is written in a high-level language. An executable file is produced. The source code uses instructions from the processor’s instruction set. The source code and translation software must both be in main memory at execution time. A web page contains some JavaScript code. [4] (b) A programmer is developing software and has both a compiler and interpreter for the high-level language used. Describe two benefits of using each form of translation software. (i) Benefits of a compiler 1 … … 2 … … [2] (ii) Benefits of an interpreter 1 … … 2 … … [2]

4 9608/12/O/N/17 © UCLES 2017 3 A Local Area Network is used by school staff who access data stored in a Database Management System (DBMS). (a) (i) Explain the difference between security and privacy of data. … … … … … …[3] (ii) Give an example for this application where privacy of data is a key concern. … …[1] (b) Name and describe two security measures the Network Manager has in place to protect the security of the data held in the DBMS. 1 … … … … 2 … … … … [4] (c) A task for staff at the start of the school year is to key in new pupil data from a paper document. The data is entered to a screen form and includes the data verification of some fields. Describe what is meant by verification. … … … …[2]

5 9608/12/O/N/17 © UCLES 2017 [Turn over 4 The following diagram shows the components and buses found inside a typical personal computer (PC). A B C Control unit Main memory F E D (a) Some components and buses only have labels A to F to identify them. For each label, choose the appropriate title from the following list. The title for label D is already given. • Control bus • Address bus • Arithmetic Logic Unit (ALU) • General purpose registers • Secondary storage • System clock A … B … C … D Data bus E … F … [5] (b) Clock speed is a factor that affects the performance of a PC. Explain this statement. … … …[2]

6 9608/12/O/N/17 © UCLES 2017 (c) An assembly language program can contain both macros and directives. (i) Explain what is meant by these terms. Macro … … … Directive … … … [3] (ii) Give an example of the use of a directive. … …[1] (d) 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 (mnemonic) Operand LDD <address> Direct addressing. Load the contents of the given address to ACC. LDV #n Relative addressing. Move to the address n locations from the address of the current instruction. Load the contents of this address to ACC. STO <address> Store the contents of ACC at the given address. INC Increment the contents of ACC. OUTCH Output the character corresponding to the ASCII character code in ACC. JPE <address> Following a compare instruction, jump to <address> if the compare was True. JMP <address> Jump to the given address. CMP #n Compare the contents of ACC with number n.

7 9608/12/O/N/17 © UCLES 2017 [Turn over Complete the trace table for the following assembly language program. Label Instruction StartProg: LDV #Offset ASCII code table (selected codes only) <Space> 2 A B Y 32 50 65 66 89 CMP Value JPE EndProg OUTCH LDD Offset INC STO Offset JMP StartProg EndProg: END Offset: 10 50 65 89 32 Value: 32 Trace table: ACC Offset OUTPUT 10 50 2 10 [5]

8 9608/12/O/N/17 © UCLES 2017 (e) The program given in part (d) is to be translated using a two-pass assembler. The program has been copied here for you. Label Instruction StartProg: LDV #Offset CMP Value JPE EndProg OUTCH LDD Offset INC STO Offset JMP StartProg EndProg: END Offset: 10 50 65 89 32 Value: 32 On the first pass, the assembly process adds entries to a symbol table. The following symbol table shows the first five entries, part way through the first pass. The circular labels show the order in which the assembler made the entries to the symbol table. Complete the symbol table. Use circular labels to show the order in which the assembler makes the entries. Symbol table Symbolic address Relative address StartProg 1 0 2 Offset 3 UNKNOWN 4 Value 5 [6]

9 9608/12/O/N/17 © UCLES 2017 [Turn over 5 The IEEE Software Engineering Code of Ethics uses eight key principles shown in the right-hand column of the following diagram. Tom is employed as a tester with a software company. He is keen to become a trainee programmer. The middle column in the diagram labels six incidents which have happened to Tom this week. The table that follows the diagram describes each incident. Public Client and Employer Product Judgement Management Profession Colleagues Self Incident A Incident B Incident C Incident D Incident E Incident F Ethical behaviour Unethical behaviour IEEE category Incident Description A Tom has received some phishing emails. He reported this to the bank they were supposed to have come from. B Tom has asked his manager if they will pay for him to attend a programming course. C Tom is testing beta versions of new games software at work. He copies the software on to CD-Rs and sells them to his friends. D Tom has completed the application forms to join the Chartered Institute for IT. E Tom finds it difficult to work with one of his colleagues. His way of dealing with this has been to refuse to speak with the colleague. F Tom’s manager had considered the testing of a new game was completed. Tom reported to his manager that he thought there were still bugs which needed to be rectified. (a) Draw a line on the diagram to link each of the six incidents to either ethical behaviour or unethical behaviour. [2] (b) Consider each incident you have identified as ethical behaviour. Draw a line from each incident to indicate the IEEE category it maps to. [4]

10 9608/12/O/N/17 © UCLES 2017 6 (a) A personal computer (PC) is extensively used for a wide range of applications, including the three shown in the following table. Write in the table, a suitable input device, output device, or both needed for each application. Do not give a monitor, keyboard or mouse in your answers. Application Input device Output device Capture the text from a paper document, in order that the text can be word processed Producing a replica of a small plastic component from a washing machine A museum has interactive information facilities throughout the building [3] (b) Explain the basic internal operation of a hard disk drive. … … … … … … … … … … … … … … …[4]

11 9608/12/O/N/17 © UCLES 2017 [Turn over 7 A company takes customer service for its clients very seriously. The client • The client names are unique. A visit • The company arranges a date for a visit to gather feedback from a client. • A visit to a client never takes more than one day. • Over time, the client receives many visits. Staff (Interviewers) • One or more staff attend the visit. • If there is more than one staff member visiting, each performs a separate interview. Interviews • Each interview is classified as either ‘general’ or by some specialism, for example, marketing, customer service or sales. • A report is produced for each interview, InterviewText. • Each interview is conducted by a single staff member. The client, visit, staff and interview data will be stored in a relational database. (a) (i) Underline the primary key for each table in the following suggested table designs. STAFF(StaffID, StaffName, Department) CLIENT(ClientName, Address, Town) VISIT(ClientName, VisitDate) INTERVIEW(ClientName, VisitDate, StaffID, SpecialistFocus, InterviewText) [3] (ii) For each of the pairs of entities, A, B and C, draw the relationship between the two entities. A CLIENT VISIT B VISIT INTERVIEW C INTERVIEW STAFF [3]

12 9608/12/O/N/17 © UCLES 2017 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. (b) The company decides to produce a visit report, VisitReportText, for each visit made. This text will be produced from the one or more interview texts obtained at the visit. State how one or more of the given table designs can be changed to add this attribute. … …[1] (c) Client ABC Holdings are now trading under the name of Albright Holdings. (i) Write an SQL script to update this client’s record in the database. UPDATE … SET … WHERE … [3] (ii) Describe why this update could cause problems with the existing data stored. … … …[2] (d) Write an SQL script to display the Staff ID of each member of staff who performed an interview when they visited New Age Toys on 13/10/2016. … … …[3] (e) At present, all interviews are performed in the UK. Many clients now operate in other countries in Europe. The company wants to perform interviews with the client’s staff in other countries. Not all interview staff are willing to travel outside of the UK. State how one or more of the table designs should be revised to store this information. … …[1]

® IGCSE is a registered trademark. This document consists of 12 printed pages. © UCLES 2017 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/12 Paper 1 Written Paper October/November 2017 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 2017 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 2 of 12 Question Answer Marks 1 1 Mark for stating the management task 1 Mark for a corresponding description Maximum 2 marks for each task Maximum 3 tasks Process / Task Management • Allocation of processor time • Scheduling of processes or tasks / multi-tasking / multi-programming etc. • By example – e.g. round-robin, shortest remaining time first etc. • Resolution of conflict when two or more processes require the same resource Secondary Storage management • Storage space divided into file allocation units • Space allocated to particular files • OS maintains a file directory and FAT • Provides file naming conventions • Controls access. Peripheral / Hardware / Device / Input/output Management • Installation of appropriate driver software • Controls access to data being sent to/from hardware/peripherals • Controls access to hardware/peripherals • Manages communication between devices / hardware and software Provision of a User interface • Allows user interaction with the computer system// Facilitates human computer communication • Hides the complexity of the hardware from the user • Or by example – e.g. GUI, command line etc. Interrupt Handling • Halts the execution of the current process • Stores the values of the current process on the stack • Loads and executes the appropriate ISR code • Use of priorities for handling simultaneous interrupts • Saves data on power outage Security Management • Makes provision for recovery when data is lost • Provides usernames and passwords / encryption / user accounts • Prevents unauthorised access • Ensures privacy of data Provision of a software platform / environment • On which other programs / applications can be run 6

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 3 of 12 Question Answer Marks 2(a) 1 Mark for each correct connection 4 2(b)(i) 1 Mark per bullet, max 2 • Once translated the compiler software is not needed to run the program • Compiled code should execute faster • Compiler produces an executable file • The executable file produced by a compiler can be distributed without users having sight of the source code // source code is kept secure // users are unable to make changes to the program • Cross-compilation is possible 2 2(b)(ii) 1 Mark per bullet, max 2 • Easier de-bugging • The interpreter stops when error encountered • error can be corrected in real time • The interpreter translates a statement then executes it immediately • Parts of the program can be tested, without all the program code being available. 2

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 4 of 12 Question Answer Marks 3(a)(i) 1 Mark per bullet, max 3 • Security is keeping the data safe • From accidental / malicious damage /loss • By example of need for security • Privacy is the need to restrict access to personal data • To avoid it being seen by unauthorised people • By example of need for privacy 3 3(a)(ii) 1 Mark for a suitable example For example: Personal data of students / staff 1 3(b) 1 Mark for stating the security measure 1 Mark for a corresponding description Maximum 2 marks for each measure Maximum 2 measures Physical measures • Locked doors/keyboards etc. • Secure methods of access, keypads/ biometric scans etc. Backup of data • Regular copies of the data are made • If the data is corrupted it can be restored Disk-mirroring • All activity is duplicated to a second disk in real time so that if the first disk fails there is a complete copy available Access rights • Different access rights for individuals/groups of users • To stop users editing data they are not permitted to access • By example Encryption • If accessed, data cannot be understood by unauthorised personnel • Accessed only by those with the decryption key Firewall • To stop unauthorised access/hackers gaining access to the computer network Use authentication methods such as passwords and usernames • Passwords should be strong / biometrics • To prevent unauthorised access to data Anti-malware program • To detect / remove / quarantine viruses / key-loggers etc. • Carrying out regular scans Concurrent Access Controls // Record locking • Closes a record to second user until first update complete • To prevent simultaneous updates being lost 4

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 5 of 12 Question Answer Marks 3(c) 1 Mark per bullet, max 2 • Checking that the data entered matches / is consistent with that of the source. • Comparison of two versions of the data • Examples include double entry, visual checking, proof reading etc... • In the event of a mismatch – the user is forced to re-enter the data • By example, e.g. creation of a password • Does not check data is sensible/acceptable 2

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 6 of 12 Question Answer Marks 4(a) 1 Mark for each correct answer A – General purpose registers B – System clock C – ALU E – Control bus F – Address bus 5 4(b) 1 Mark per bullet, max 2 • The clock sends out a number of pulses in a given time interval (clock speed) • Each processor instruction takes a certain number of clock cycles to execute • The higher the clock frequency, the shorter the execution time for the instruction // Increasing the clock frequency improves performance 2 4(c)(i) 1 Mark per bullet Maximum 2 for Macro Maximum 2 for Directive Maximum 3 in total Macro • A group of instructions given a name // subroutine • A group of instructions that need to be executed several times within the same program • The statements are written once and called using the name whenever they need to be executed • Macro code is inserted into the source file at each place it is called • By example Directive • An instruction that directs the assembler to do something • A directive is not a program instruction • It is information for the assembler • By example 3 4(c)(ii) 1 Mark for a suitable example For example: State the start address for the program //tell the assembler to set aside space for variables // include an external file etc. 1

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 7 of 12 Question Answer Marks 4(d) Mark as shown ACC Offset OUTPUT 10 50 2 10 11 11 1 Mark for these two values, as first instructions 65 1 Mark for this value, in any row A 1 Mark for this value, in any row 11 1 Mark for this value, after 65, nothing in between 12 12 1 Mark for the rest 89 Y 12 13 13 32 5

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 8 of 12 Question Answer Marks 4(e) Mark as follows: Table entries: 1 Mark per bullet, max 4 • EndProg • 2 × Unknown • 9 • 14 • 8 Numbering: 1 Mark per bullet, max 2 • Relative address of Value is numbered 6 • Number given for EndProg is next number in sequence to relative address of Value • All numbers correct – award 2 marks 6 1 7 6 8 1 9

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 9 of 12 Question Answer Marks 5 5(a) Mark as follows: Unethical: C and E 1 Mark Ethical: A,B, D and F 1 Mark 2 5(b) Mark as follows: A – Public interest 1 Mark B – Self 1 Mark D – Profession 1 Mark F – Product 1 Mark 4 Public Incident A Client & Employer Incident B Product Incident C Judgement Incident D Management Incident E Profession Incident F Colleagues Self Ethical Unethical

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 10 of 12 Question Answer Marks 6(a) 1 mark for each correct row Application Input device Output device Capture the text from a paper document, in order that the text can be word-processed Flatbed scanner / Digital camera Producing a replica of a small plastic component from a washing machine 3D Printer A museum has interactive information facilities throughout the building Touch screen / touch pad / microphone etc. Touch screen / speakers etc. 3 6(b) 1 Mark per bullet to max 4 • The hard disk has one or more platters made of aluminium or glass • Each surface of the platter/disk is ferrous-oxide which is capable of being magnetised • The platters/disks are mounted on a central spindle • The disks are rotated at high-speed • Each surface of the disk has a read/write head mounted on an arm positioned just above the surface • Electronic circuits control the movement of the arm and hence the heads • The surface of the platter/disk is divided into concentric tracks and sectors • One track in one sector is the basic unit of storage called a block • The data is encoded as a magnetic pattern for each block • When writing to disk, a variation in the current in the head produces a variation in magnetic field on the disk • When reading from disk, a variation in magnetic field produces a variation in current through the head 4

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 11 of 12 Question Answer Marks 7(a)(i) 1 Mark for correct primary key identified in both STAFF and CLIENT STAFF(StaffID, StaffName, Department) CLIENT(ClientName, Address, Town) 1 Mark for correct primary key identified in VISIT VISIT(ClientName, VisitDate) 1 Mark for correct primary key identified in INTERVIEW INTERVIEW(ClientName, VisitDate, StaffID, SpecialistFocus, InterviewText) 3 7(a)(ii) 1 Mark for each correct relationship CLIENT VISIT VISIT INTERVIEW INTERVIEW STAFF 3 7(b) 1 Mark for correct answer Add attribute VisitReportText to table VISIT 1 7(c)(i) 1 Mark for each correct line UPDATE CLIENT SET ClientName = 'Albright Holdings' WHERE ClientName = 'ABC Holdings'; 3 7(c)(ii) 1 Mark per bullet, max 2 • Referential integrity should be maintained // Referential integrity could be violated • Data becomes inconsistent • There may be records in the VISIT and INTERVIEW tables / other tables with client name ABC Holdings • The ClientName in the VISIT and INTERVIEW tables / other tables might not be automatically updated • Records in the VISIT and INTERVIEW tables / other tables will become orphaned 2

9608/12 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2017 © UCLES 2017 Page 12 of 12 Question Answer Marks 7(d) 1 Mark for each correct line SELECT StaffID FROM INTERVIEW WHERE ClientName = 'New Age Toys' AND VisitDate = '13/10/2016'; (Accept clauses other way round) 3 7(e) 1 Mark for a correct answer Add a suitable attribute, for example, EuropeTraveller to the STAFF table // Add a suitable attribute, for example, Country to the CLIENT table 1