2. This Question Booklet contains nine questions. Answer any SIX questions.

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1 PROGRESSIVE COMPREHENSIVE HIGH SCHOOL (PCHS) MANKON, BAMENDA APRIL 2014 Subject/Code: Computer Science 795 Paper N Paper 2 Examiner DZEUGANG Placide ADVANCED LEVEL TIME ALLOWED: 2 hours INSTRUCTIONS 1. This Question Booklet is your question paper. Do not write anything therein apart from your name and candidate number 2. This Question Booklet contains nine questions. Answer any SIX questions. 3. All questions carry 20 marks each. For your guidance, the approximate mark for each part of a question is indicated in brackets. 4. You are reminded of the necessity for good English and orderly presentation in your answer. 5. In calculations, you are advised to show all the steps in your working, giving your answer at each stage. 6. Clip board, log tables, slide rules, programmable calculator, cellular phone, pager and electronic gadgets in any form are not allowed. 7. Noiseless and cordless electronic calculators may be used. 8. The Answer Sheet must be handed over to the invigilator before leaving the examination hall. TURN OVER PCHS mock April 2014/ Computer Science Paper 2 Page 1 of 6

2 Question 1 1- Determine the value of X in this equation X = Suppose you have to write an assembly program that performs the following calculation: y = x 2 30x The input x is an UNSIGNED five-bit binary number. (a) What is the decimal range for input x? (b) What is the maximum positive value for y? (c) What is the maximum negative value for y? (d) How many bits will you need to allocate for the SIGNED result y? (e) Convert your decimal answers for parts b) and c) to SIGNED 2 s complement binary. 3- In a certain coding scheme, each character occupies 7 bits. Letters of the alphabet are assigned consecutive codes. If letter N is represented by ; What is the representation of letter A in this coding scheme? 4- The diagram shows a cabinet designed to house machinery. Sliding panels allow easy access. The output Q of an electronic warning system triggers an alarm if the enable switch A is turned on, when either panel is open, or both are open. Each sliding panel closes a microswitch, when in place. The microswitches, B and C, output a logic 0 signal when closed. The enable switch A sends a microswitch B logic 1 signal to the electronic system when turned on. The system outputs a logic 1 to trigger the alarm. enable switch A (a)draw the truth table for the logic system. (b)write a Boolean expression for the output Q in terms of inputs A, B and C, and simplify it using Karnaugh map. (c) Design a circuit of logic gates for the alarm system 5- A double sided disk contains 40 tracks on each side. The tracks are divided into 9 sectors of 512 bytes each. What is the total capacity of the disk in megabytes? ( 2mks) Question 2 1- The following information was seen in one of the local daily newspaper. Satellite L350 22V Intel Duo Core 2.1 GHz, Genuine Windows Vista Home Premium, 3072MB, 320GB HDD, DVD Super Multi(Double layer) drive, 17.0 TruBrite WXGA + TFT High Brightness, Web Cam, Wi Fi (a) From the above advert identify the following items: i. Type of processor ii. Memory capacity of the computer. iii. Type of monitor (b) Which characteristics of the computer above make it a multimedia computer (c) Explain any three hardware considerations before purchasing a computer. microswitch C PCHS mock April 2014/ Computer Science Paper 2 Page 2 of 6

3 2- Study the diagram below and answer questions that follow: (a) Identify the port shown in the diagram. (1mk) (b) Give TWO reasons why the identified port in 2(a) above finds widespread use in computer systems. 3- A computer must go through the process of booting/ initialization before use (a) Briefly explain the term computer booting. (b) Explain what happens in the computer during the booting process (c) Explain and give the difference between the following types of booting (i) Cold booting: (ii) Warm Booting (d) What is BIOS? What is its role in the computer? If you have a bootable CD-ROM containing the original system setup, what BIOS option do you adjust if you need to restore the system with its original software? Question 3 1- (a). The following are some of the phases in the system development life cycle (SDLC): system analysis, system design, system implementation, system review and maintenance. Give a brief description of any two phases. (4 mks) (b) Despite rigorous testing, it is sometimes necessary for software developers to maintain the systems they have produced. Explain why this situation might arise and describe, using suitable examples, two types of maintenance that might have to be undertaken. (c) State two methods of gathering information during system analysis stage. (d) State two reasons why an organizations may use other strategies of software acquisition other than developing their own. (e) Name three functions that the systems analyst perform during the Systems Development Life Cycle (SDLC) 2- Develop the network activity as a Gantt chart or PERT chart and identify the critical path for a project based on the following information. (6 mks) Activity A B C D E F G H I J Expected duration Predecessors (in days) -- A A A B, C D, E F G F H, I Question 4 1- What is the difference between kernel mode and user mode as far as operating system is concerned? 2- How does the distinction between kernel mode and user mode function as a rudimentary form of protection (security) system? 3- Which of the following instructions should be privileged? (4 mks) a. Set value of timer. e. Turn off interrupts. b. Read the clock. f. Modify entries in device-status table. c. Clear memory. g. Switch from user to kernel mode. d. Issue a trap instruction. h. Access I/O device. 4- What is the purpose of system calls? PCHS mock April 2014/ Computer Science Paper 2 Page 3 of 6

4 5- Consider a system with a total of 150 units of memory, allocated to three processes as shown Process Max Hold Apply banker s algorithm to determine it would be safe to grant each of the following request. If yes, indicate a sequence of terminations that could be guaranteed possible. If no, show the reduction of the resulting allocation table. (6 mark) a) A fourth process arrives with maximum memory need of 60 and initial need of 25 units. b) A fourth process arrives with maximum memory need of 60 and initial need of 35 units. 6- What is a file system? Show the difference between NTFS and FAT 32 file systems (4 marks) Question 5 1- What is a memory hierarchy? Describe the problem a memory hierarchy solves and explain why it works so well. 2- A printer fails to work as expected when a document is sent to be printed. The user has checked that the on-line light of the printer is on and the printing paper is correctly inserted. Give TWO other possible reasons why the printing process failed. 3- With reference to disk management explain what is meant by the terms below. i) Formatting ii) Defragmentation iii) Disk partitioning 4- What is a mass memory device? Name and explain any two mass memory device 5- (a) What is the difference between interrupt and pooling? (b) What is Non-Maskable Interrupt? Give an example 6- What is the von Neumann bottle neck? Explain how the problem is solve while using a system bus architecture 7- Explain any of the following input technology: OCR, OMR, MICR Question 6 1- What is data validation? If some data passes a validation check does this mean that the data is correct? Explain. 2- Some data is being entered into a database. Suggest the most appropriate validation checks that could be used for each of these fields : a) Month of the Year b) Gender c) Postcode 3- What is Dual input verification? Give an example of situation where it is used. If some data passes the Dual Input verification test does that mean that it has definitely been entered correctly? Why? 4- Explain the concept of distributed database and give two advantages. 5- Study all the functional dependencies and normalise the following data taken from a student assessment form, bearing in mind that students will take a number of modules: Student Number, Student Name, Student Address, Module Code, Module Name, Module Mark, Module Grade (6 mks) 6- It is advisable to enforce referential integrity when creating a relationship. When creating a relationship, what do you understand by the term referential integrity? PCHS mock April 2014/ Computer Science Paper 2 Page 4 of 6

5 Question 7 1- Let s a and b denote positive integers. Suppose a function Q is defined recursively as follow: Q(a,b) = 0 if a < b Q a b, b + 1 if b a (a) Find the value of Q(2, 3) and Q(14,3) showing the intermediate steps to your answer (6 mks) (b) What does this function do? (c) Write a recursive function which calculate F(n) 2- (a) What is an abstract data type? (b) Choose two of the following ADTs, Explain their functioning, state and explain two operations used and their signature: Queue, Stack, Vector, Link list (6 mks) 3- Explain overflow and underflow conditions of a stack with examples. Question 8 1- Write down the output what would be generated by the following program segment. sentinel 1 repeat Sentinel sentinel + 1; Write (sentinel); Until (sentinel = 9); 2- What would happen to the programs execution if the statement sentinel sentinel + 1; was changed to Sentinel sentinel 1? 3- Draw a program flowchart from the above algorithm segment 4- Define and differentiate the following concepts (6 mks) a) Procedural programming and modular programming b) Top-down design and bottom-up design c) Call by value and call by reference 5- Define the term reusability and portability and explain how each is considered as an advantage of modular programming (4 mks) 6- Explain the principle of binary search. Formulate the sequence of steps of that will be followed to pick the value 80 from the following sequence using the binary search technique (4 mks) Question 9: 1- (a) Give the name of the communication media depicted in the diagram below. (b) Give names to the parts indicated by A,B,C,and D (1mk) (4mks) (c) List two advantages of the communication media above. 2- Explain the role of the following on a network. i) A router ii) A gateway PCHS mock April 2014/ Computer Science Paper 2 Page 5 of 6

6 3- What is meant by collision in LAN? Explain how collision is handle in a CSMA/CA Technology 4- What are the advantages of FDDI over a basic Token Ring in term of robustness? 5- Your principal is intending to install a simple Internet connection in the school. List down and explain three equipment/ services that he ll require to achieve this 6- Explain how each of the following internet services is carried out and give and example of tool used in each case. i) Internet relay chat ii) VoIP iii) research Your success is in Jesus-Christ!!! PCHS mock April 2014/ Computer Science Paper 2 Page 6 of 6

2. This Question Booklet contains nine questions. Answer any SIX questions.

2. This Question Booklet contains nine questions. Answer any SIX questions. PROGRESSIVE COMPREHENSIVE HIGH SCHOOL (PCHS) MANKON, BAMENDA 14 FEBRUARY 2014 ADVANCED LEVEL Subject/Code: Computer Science 795 Paper N Paper 2 Examiner DZEUGANG Placide TIME ALLOWED: 2 hours INSTRUCTIONS