ZHSS 2019 P1

Setter: Mr. Calvin Heng Vetter: Mr. Low Kee Ley This question paper consists of 15 printed pages including this cover page. ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2019 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number COMPUTING 7155/01 Paper 1 19 September 2019 2 hours Additional Materials: NIL READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all the questions. Write your answers in this question booklet. Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place in the case of angles in degrees, unless a different level of accuracy is specified in the question. The use of a scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. At the end of the presentation, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 80. For Examiner’s Use:

2 1 The following is a simplified computer architecture diagram. Complete the Table: Label Name of Device Purpose of Device A B C D E [2] [2] [2] [2] [2]

3 2 (a) Describe one difference between a LAN and a WAN. [2] ___________________________________________________ ___________________________________________________ ___________________________________________________ (b) Topology describes the physical layout of a computer network. Name each of the topologies shown below. (i) [1] (ii) [1] (c) With respect to cabling, describe one advantage and one disadvantage in a Star Topology network. (i) Advantage [1] (ii) Disadvantage [1]

4 (d) Explain the concept of the Parity Check. [2] ___________________________________________________ ___________________________________________________ ___________________________________________________ (e) Using the example of the bit string below, indicate what the parity bit should be, based on the system of odd parity. [1] (f) What is a shortcoming of the parity check? [1] ___________________________________________________ ___________________________________________________ Parity Bit Original data bits

5 3 Study the flow chart and answer the questions. START INPUT h INPUT d h >= 1 ? h is odd ? answer = answer + d h = h // 2 d = d * 2 OUTPUT answer STOP Y N N Y answer = 0

6 (a) Complete the Trace Table for 2 runs: h=11, d=8 and h=5, d=12 h d answer h >= 1? h is odd? output [6]

7 (b) What does the algorithm do? [1] __________________________________________________ __________________________________________________ (c) Based on the algorithm described by the flowchart, write a python function that will return the result as computed by the algorithm. The starting statement has been given. def function_m(h, d): [5]

8 4 When conducting Program Testing, a good programmer will consider the following Types of Conditions: Normal Conditions Boundary Conditions Error Conditions Consider the following Python Program: Complete the table for Test Conditions to test the above Python Program. Test Condition Type Sample Input Data Expected Output [1] [1] [1] [1] [1] [1]

9 5 All the sheep belonging to Farmer Miles have escaped from his farm to a nearby hillside, where they have joined other sheep. Farmer Miles wishes to recover all his sheep and knows the following: — Not one of his sheep is black as he believes these to be unlucky. — All his sheep are branded ‘G’, or have a collar. Use the following: B = black sheep G = branded ‘G’ C = has a collar F = belongs to Farmer Miles (a) Draw a Truth Table from these conditions to show those sheep owned by Farmer Miles. Truth Table: B G C F [4] (b) From your Truth Table, produce a Boolean expression to represent those sheep owned by Farmer Miles. F = [2]

10 (c) Using only NAND gates, draw a logic circuit diagram capable of carrying out the Boolean expression. [4] 6 (a) Denary numbers are represented as binary numbers inside a computer. Note: all workings must be clearly shown. (i) Convert the denary number (123)10 into 8-bit binary. [2] _______________________________________________ (ii) Convert the positive whole binary number (10001010)2 into a Hexadecimal number. [2] _______________________________________________