XMSS 2018 P1

2 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 1 Insert five of the following words about computer architecture in the correct place in the text below. memory data bus computer program input device address bus output device computer processor A ………………..…………………… carries out the instructions in a ………………..…………………… . The ………………..…………………… is where data and instructions are stored ready to be processed. The ………………..…………………… identifies the location of data. The ………………..…………………… transports the data from one location to another. [5] 2 Give an example for each type of data storage. Volatile data storage ………………………………………………………..…………...... Non-volatile data storage ………………………………………………...……………….. [2] 3 A school wants to use a computer program to find out which student has achieved the lowest score in a Physics class. There are 24 students in the class and all the students’ scores are different. State the inputs, the outputs and the processes required to find the name and the score of the student with the lowest score. Inputs ………………………………………………………………………………………. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. Outputs …………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. Processes required ……………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. [6]

3 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 4 The problem of calculating the remainder when a number is divided by 4 can be defined as follows: Input Output • Number: a positive whole number • Remainder when Number is divided by 4 A possible solution to this problem is as follows: Step 1: If Number is less than 4, proceed to Step 3. Otherwise, proceed to Step 2. Step 2: Subtract 4 from Number and then proceed to Step 1. Step 3: Output Number as the final answer. A similar problem is as follows: Input Output • Number: a positive whole number • Divisor: a positive whole number • Remainder when Number is divided by Divisor. Write down the solution to the second problem by generalising the first solution. ………………………………………………………………………..………………………. ………………………………………………………………………………..………………. ……………………………………………………………………………………..…………. …………………………………………………………………………………..……………. ………………………………………………………………………………..………………. ………………………………………………………………………………..………………. ………………………………………………………………………………..………………. [3]

4 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 5 Fig. 5 shows a flowchart of an algorithm Fig. 5 START rem = n MOD 10 Is num = sum? OUTPUT TRUE END Yes No INPUT num sum = 0 n = num Is n >= 1? Yes sum = sum + (rem*rem*rem) n = n//10 OUTPUT FALSE No

5 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use Complete the trace table for the following set of data. 371 Trace table num sum n rem OUTPUT [5] 6 Constants, variables and arrays are used in programming. Describe what is meant by: a constant ………………………………………………………………………………….. ……………………………………………………………………………………………….. a variable …………………………………………………………………………………… ……………………………………………………………………………………………….. an array ……………………………………………………………………………………... ……………………………………………………………………………………………….. [3]

6 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 7 Write a program using Python that asks the user to input 2 positive integers and output their sum to the screen. However, if the 2 integers are the same, output twice their sum to the screen. Input verification is not required. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. [9] 8 Length check and range check are common checks that are performed in data validation. Describe what is meant by: length check …………………………………………………………………………….…. ……………………………………………………………………………………………….. range check ………………………………………………………………………………… ……………………………………………………………………………………………….. [2]

7 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 9 An algorithm is required to find the average of 10 numbers stored in an array. The input is provided in an array called “Number” and the output is provided through a variable named “Average”. Study the following pseudo-code. Total = 500 Counter = 1 WHILE Counter > 11 DO Total = Total – Number[Counter] Counter = Counter + 1 ENDWHILE Average = Total / Counter There are four errors in this pseudo-code. Locate the errors and state the correct pseudo-code. Error 1 ………………………………………………………………………………………. Correction …………………………………………………………………………………... ……………………………………………………………………………………………….. Error 2 ………………………………………………………………………………………. Correction …………………………………………………………………………………... ……………………………………………………………………………………………….. Error 3 ………………………………………………………………………………………. Correction …………………………………………………………………………………... ……………………………………………………………………………………………….. Error 4 ………………………………………………………………………………………. Correction …………………………………………………………………………………... ……………………………………………………………………………………………….. [8]

8 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 10 Five descriptions and five security issues are shown below. Draw a line to connect each description to the correct security issue. Description Security issue malicious code installed on the hard drive of a user’s computer or on the web server; this code will re-direct user to a fake web site without their consent hacking software that gathers information by monitoring key presses on a user’s computer and relays the information back to the person who sent the software pharming program or code that replicates itself and is designed to amend, delete or copy data and files on a user’s computer without their consent phishing the act of gaining illegal access to a computer system without the owner’s consent spyware creator of code sends out a legitimate-looking email in the hope of gathering personal and financial data; it requires the recipient to follow a link in the email or open an attachment virus [5]

9 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 11 (a) Convert the hexadecimal number BC into a binary number. Show your working. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. [2] (b) Convert the denary number 401 into a binary number. Show your working. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. [2] (c) Convert the denary number 11001 into a hexadecimal number. Show your working. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. [2]

10 7155/01/Computing/XMSS 2018 Preliminary Exam For Examiner’s Use 12 An alarm sounds when a car fuel injection system gives certain fault co