Cambridge A Level Computer Science 9608 — 2016 Oct/Nov Paper 1 · Variant 2

This document consists of 12 printed pages. DC (KN) 122134/3 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 4 2 0 4 5 4 4 6 8 6 * COMPUTER SCIENCE 9608/12 Paper 1 Theory Fundamentals October/November 2016 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/16 © UCLES 2016 1 (a) A student writes the following logic expression: X is 1 IF (B is NOT 1 AND S is NOT 1) OR (P is NOT 1 AND S is 1) Draw a logic circuit to represent this logic expression. Do not attempt to simplify the logic expression. B S X P [6] (b) Complete the truth table for the logic expression given in part (a). B S P 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]

3 9608/12/O/N/16 © UCLES 2016 [Turn over 2 (a) When recording a video, state what is meant by frame rate. … …[1] (b) Video streaming can use either interlaced encoding or progressive encoding. Describe what is meant by the following terms. Interlaced encoding … … … … Progressive encoding … … … …[4] (c) (i) Name the video terms described below: Description Term Pixels in two video frames have the same value in the same location. There is duplication of data between frames. … A sequence of pixels in a single video frame have the same value. … [2] (ii) Give one file technique that could be applied when either of the two features, described in part (c)(i), are present. … …[1]

4 9608/12/O/N/16 © UCLES 2016 3 When an application program requests a file stored on a hard disk, the computer system reads the file. Use the statement labels A to H to complete the sequence of steps that describe how this happens. Label Statement A When the hard disk drive has read the file, it generates an interrupt. B While the file continues, the head reads successive clusters of sectors from the disk and writes data into the disk buffer. C The head reads the first cluster of sectors from disk and writes data into the disk buffer. D The head moves to the correct track. E The operating system transfers the contents of the disk buffer to the application program’s data memory. F In the relevant directory file, the operating system looks up the track and sector where the file begins. G Application program passes file read request to the operating system. H The hard disk drive waits for the correct sector to arrive under the head. 1. The application program executes a statement to read a file. 2. … 3. The operating system begins to spin the hard disk, if it is not currently spinning. 4. … 5. … 6. … 7. … 8. … 9. … 10. … [8]

5 9608/12/O/N/16 © UCLES 2016 [Turn over 4 Hexadecimal, Binary Coded Decimal (BCD) and binary values are shown below. Draw a line to link each value to its correct denary value. Hexadecimal, BCD, binary Denary 93 –65 58 –63 73 49 –93 Hexadecimal: 3A BCD representation: 0100 1001 Binary integer: 01011101 Two’s complement binary integer: 11000001 [4]

6 9608/12/O/N/16 © UCLES 2016 5 The table shows assembly language instructions for a processor that 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 given address to ACC. LDX <address> Index addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC. LDI <address> Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC. STO <address> Store the contents of ACC at the given address. INC <register> Add 1 to contents of the register (ACC or IX). ADD <address> Add the contents of the given address to the ACC. END Return control to the operating system. The diagram shows the contents of a section of main memory: Main memory 100 0000 0010 101 1001 0011 102 0111 0011 103 0110 1011 104 0111 1110 105 1011 0001 106 0110 1000 107 0100 1011 … 200 1001 1110

7 9608/12/O/N/16 © UCLES 2016 [Turn over (a) (i) Show the contents of the Accumulator after the execution of the instruction: LDD 102 ACC: [1] (ii) Show the contents of the Accumulator after the execution of the instruction: LDX 101 IX: 0 0 0 0 0 1 0 0 ACC: Explain how you arrived at your answer. … … … …[2] (iii) Show the contents of the Accumulator after the execution of the instruction: LDI 103 ACC: Explain how you arrived at your answer. … … … … … …[3]

8 9608/12/O/N/16 © UCLES 2016 (b) Complete the trace table below for the following assembly language program. 800 LDD 810 801 INC ACC 802 STO 812 803 LDD 811 804 ADD 812 805 STO 813 806 END … 810 28 811 41 812 0 813 0 Trace table: ACC Memory address 810 811 812 813 28 41 0 0 [6]

9 9608/12/O/N/16 © UCLES 2016 [Turn over 6 (a) Describe two differences between RAM and ROM. 1 … … 2 … …[2] (b) State three differences between Dynamic RAM (DRAM) and Static RAM (SRAM). 1 … … 2 … … 3 … …[3] 7 One management task carried out by an operating system is to provide a user interface. Describe two more of these management tasks. 1 … … … … 2 … … … …[4]

10 9608/12/O/N/16 © UCLES 2016 8 A programmer is writing a program that includes code from a program library. (a) Describe two benefits to the programmer of using one or more library routines. 1 … … … … 2 … … … …[4] (b) The programmer decides to use a Dynamic Link Library (DLL) file. (i) Describe two benefits of using DLL files. 1 … … … … 2 … … … …[4] (ii) State one drawback of using DLL files. … … …[2]

11 9608/12/O/N/16 © UCLES 2016 [Turn over 9 A health club offers classes to its members. A member needs to book into each class in advance. (a) The health club employs a programmer to update the class booking system. The programmer has to decide how to store the records. The choice is between using a relational database or a file-based approach. Give three reasons why the programmer should use a relational database. 1 … … … … 2 … … … … 3 … … … …[6] (b) The programmer decides to use three tables: MEMBER, BOOKING and CLASS. Complete the Entity-Relationship (E-R) diagram to show the relationships between these tables. MEMBER CLASS BOOKING [2]

12 9608/12/O/N/16 © UCLES 2016 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. (c) The CLASS table has primary key ClassID and stores the following data: ClassID Description StartDate ClassTime NoOfSessions AdultsOnly DAY01 Yoga beginners 12/01/2016 11:00 5 TRUE EVE02 Yoga beginners 12/01/2016 19:00 5 FALSE DAY16 Circuits 30/06/2016 10:30 4 FALSE Write an SQL script to create the CLASS table. … … … … … … … … … …[6]

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 11 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/12 Paper 1 Written Paper October/November 2016 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 will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the October/November 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 1 (a) ONE mark for each correct gate. [6] (b) ONE mark for each pair of rows. B S P 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 1 1 1 1 0 [4]

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 2 (a) The number of images / frames recorded per second / unit time. // The frequency with which the images/frames are recorded. [1] (b) ONE mark per bullet point below. MAX THREE marks per type of encoding. Interlaced encoding • 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). • Originally used in television broadcasting and adapted for video recordings. • Produces what appears to the eye to be a high refresh rate. • Halves the transmission bandwidth requirements. Progressive encoding • Stores the data for an entire frame and displays all the frame data at the same time. • The rate of picture display is the same as the frame rate. • Used by traditional film / video digitised from a film camera / computer displays progressive encoding. • High bandwidth requirements. [4] (c) (i) ONE mark per term. Description Term Pixels in two video frames have the same value in the same location. There is duplication of data between frames. Temporal redundancy A sequence of pixels in a single video frame have the same value. Spatial redundancy [2] (ii) (File) compression [1]

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 3 ONE mark for each letter in the correct place. Then ONE mark for any pair of letters in the correct order, but not in the correct place 1 The application program executes a statement to read a file. 2 G 3 The operating system begins to spin the hard disk, if it is not currently spinning. 4 F 5 D 6 H 7 C 8 B 9 A 10 E [8]

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 4 ONE mark for each correct line. Extra lines from left hand box, no mark for that box. [4] 93 - 65 58 - 63 73 49 - 93 Hexadecimal: 3A BCD representation: 0100 1001 Binary integer: 01011101 Two’s complement binary integer: 11000001

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 5 (a) (i) 0 1 1 1 0 0 1 1 [1] (ii) ONE mark for Accumulator contents, ONE mark for the explanation. 1 0 1 1 0 0 0 1 • Index Register holds the value 4; 101 + 4 = 105 so load data from address 105 [2] (iii) ONE mark for Accumulator contents, TWO marks for the explanation. 0 1 0 0 1 0 1 1 • Memory address 103 contains the value 107 • So address 107 is the address from which to load the data [3] (b) ONE mark for each correct row. Memory address ACC 810 811 812 813 28 41 0 0 28 29 29 41 70 70 [6]

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 6 (a) ONE mark for each difference from the bullet points below. • RAM loses content when power turned off / volatile memory / temporary memory ROM does not lose content when power turned off / non-volatile memory / permanent memory • Data in RAM can be altered / deleted / read from and written to ROM is read only / cannot be changed / altered / deleted • RAM stores files / data / operating system currently in use ROM is used to store BIOS / bootstrap / pre-set instructions [2] (b) THREE from: • DRAM has to be refreshed / charged // SRAM does not request a refresh • DRAM uses a single transistor and capacitor // SRAM uses more than one transistor to form a memory cell // SRAM has more complex circuitry • DRAM stores each bit as a charge // SRAM each bit is stored using a flip-flop/latch • DRAM uses higher power (because it requires more circuitry for refreshing) //SRAM uses less power (no need to refresh) • DRAM less expensive (to purchase / requires fewer transistors) // SRAM is more expensive (to buy as it requires more transistors) • DRAM has slower access time / speed (because it needs to be refreshed) // SRAM has faster access times • DRAM can have higher storage / bit / data density // SRAM has lower storage / bit / data density • DRAM used in main memory // SRAM used in cache memory [3]

Page 8 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 7 ONE mark per bullet point, MAX TWO marks per task. • Process / resource management • Scheduling of processes / multi-tasking / multi-programming etc. • Resolution of conflicts when two or more processes require the same resource • Main memory management • Memory protection to ensure that two programs do not try to use the same space • Use of virtual memory • Deciding which processes need to be in main memory at any one time • Location of processes within the memory • By example, e.g. when process terminates, memory is made available • Peripheral / hardware / device 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 • File / secondary storage management • Maintains directory structures • Provides file naming conventions • Controls access • 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 can be run • Interrupt handling • Identifies priorities of interrupts • Save current memory / process values / saves data on power outage • Loads appropriate Interrupt Service Routine (ISR) • Any relevant example [4]

Page 9 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 8 (a) ONE mark for each bullet point from MAX TWO groups. • The code is already written • (So the programmer is not starting over again) which saves time • The code will have been used by many people • So it should be already thoroughly tested // relatively error-free • The programmer can use, e.g. mathematical / graphics functions, etc. (may not know how to code) • Can be sure that the function will perform as it should // simplifies the program. • The code should conform to industry standards • And therefore contribute towards a more robust program [4] (b) (i) ONE mark for each benefit, and ONE mark for a further expansion. • The executable file is smaller / the executable does not contain all the library routines … • … DLL files are only loaded into memory when required. • Changes / improvements / error correction to the DLL file code are done independently of the main program... • … So there is no need to recompile the main program • … All programs using it will benefit • A single DLL file can be made available to several application programs... • … Saving space in memory / easing the pressure on memory [4] (ii) ONE mark for each bullet point from MAX ONE group. • The executable code is not self-contained … • … the DLL file(s) needed to be included at run time. • Appropriate (linking) software must be available at run-time … • … to link / include / import the DLL files. • The DLL file must be present … • … otherwise (unable to find X.dll) errors • Unexpected changes to the DLL file / corrupted DLL file … • … could mean the program stops working as expected • Malicious changes to the DLL file … • … could install a virus on the user’s computer / related files could be corrupted [2]

Page 10 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 9 (a) ONE mark for each reason and ONE mark for a further explanation. MAX THREE reasons. • Reduced data redundancy / data duplication • Data is stored in (separate) linked tables • The database (generally) stores data only once / data need only be updated once • Improved data consistency / integrity / associated data will be automatically updated / easier to maintain the data / elimination of unproductive maintenance • Complex queries can be more easily written • To search / find specific data // specific example related to the Health Club • Fields can be more easily added to or removed from tables • Without affecting existing applications (that do not use these fields) • Program-data dependence is overcome • Changes to the data (design) do not require changes to programs // changes to programs do not require changes to data // the data can be accessed by any appropriate program • Security is improved • Each application only has access to the fields it needs // different users can be given different access rights • Different users can be given different views of the data / data privacy is maintained • So they do not see confidential information • Allows concurrent access • Record locking prevents two users updating the same record at the same time // record locking assures data consistency [6]

Page 11 Mark Scheme Syllabus Paper Cambridge International AS/A Level – October/November 2016 9608 12 © UCLES 2016 (b) ONE mark for each correct relationship as shown. [2] (c) An example of a script is shown, but different syntax may be used. CREATE TABLE CLASS ( ClassID VARCHAR(5), Description VARCHAR(30), StartDate DATE, ClassTime TIME, NoOfSessions INT, AdultsOnly BIT, PRIMARY KEY(ClassID) ); Mark as follows: 1 mark for CREATE TABLE CLASS and (); 1 mark for PRIMARY KEY(ClassID) 1 mark for both ClassID VARCHAR(5),and Description VARCHAR(30), 1 mark for both StartDate DATE, and ClassTime TIME, 1 mark for NoOfSessions INT, 1 mark for AdultsOnly BIT, [6]