2018 SRSS P1

This question paper consists of 12 printed pages. Name__________________________________ ( ) Class: Sec _________ SERANGOON SECONDARY SCHOOL PRELIMINARY EXAMINATION 2018 SECONDARY 4 EXPRESS COMPUTING 7155/01 PAPER 1 24 Aug 2018 Name of Setter: 2 hours READ THESE INSTRUCTIONS FIRST Do not open the question papers until you are told to do so. Write in dark blue or black pen in the spaces provided on the Question Paper. You may use a soft pencil for any diagrams, graphs, music or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. 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. FOR EXAMINER’S USE 80

2 1 Draw a line between the description and the correct spreadsheet function. Description Function [3] 2 (a) Convert the binary number 10110101 into a denary number. Show your workings. ………………………………………………………………………………………………… …………………………………………………………………………………….................. …………………………………………………………………………………………….. [2] (b) Convert the hexadecimal number F8 into a binary number. Show your workings. ………………………………………………………………………………………………… …………………………………………………………………………………….................. …………………………………………………………………………………………….. [2] (c) Convert the denary number 250 into a hexadecimal number. Show your workings. ………………………………………………………………………………………………… …………………………………………………………………………………….................. …………………………………………………………………………………………….. [2] Returns number rounded up to a given multiple MODE SMALL ROUND Returns the most repeated number in a set of numbers Use to retrieve the nth lowest number from a set of numbers CEILING

3 3 (a) A bank needs to keep its customers’ data safe and secure. Unauthorised access can happen due to poor authentication, access control and privacy policy. For each cause of unauthorised access, give: (i) a description of the cause (ii) how it can be prevented (iii) explain how the cause can affect the integrity of data Authentication (i) Description: ……………………………………………………………………………... …………………………………………………………………………………………………. (ii) Prevention: ……………………………………………………………………………… …………………………………………………………………………………………………. (iii) Integrity of data: ………………………………………………………………………... …………………………………………………………………………………………………. Access control (i) Description: ……………………………………………………………………………... …………………………………………………………………………………………………. (ii) Prevention: ……………………………………………………………………………… …………………………………………………………………………………………………. (iii) Integrity of data: ………………………………………………………………………... …………………………………………………………………………………………………. Privacy policy (i) Description: ……………………………………………………………………………... …………………………………………………………………………………………………. (ii) Prevention: ……………………………………………………………………………… …………………………………………………………………………………………………. (iii) Integrity of data: ………………………………………………………………………... …………………………………………………………………………………………………. [9]

4 4 Five statements about interpreters and compilers are shown in the table below. Study each statement. Tick (ü) to show whether the statement refers to an interpreter or to a compiler. [5] 5 Insert three of the following words about computer architecture in the correct place in the text below. A ……………….. is used to transfer bits of data between the different components found on the …………….. One such component is the ………………… , which stores the instructions to start-up the computer. [3] Statement Interpreter Compiler takes one statement at a time and executes it generate an error report at the end of translation of the whole program stops the translation process as soon as the first error is encountered slow speed of execution of program loops translates the entire program in one go processor motherboard ROM CPU bus input Hard disk RAM

5 6 Identify a different network device other than a hub, for each of the scenario below. In each case explain the function of the device. (a) A hub is used to connect three computers in a network at home. The network does not need access to the internet. Device 1………………………………………………………………………………………. Function ……………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… (b) A local area network of thirty computers in a building which does not need access to the internet. Device 2………………………………………………………………………………………. Function ……………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… (c) A local area network which needs to access the internet. Device 3………………………………………………………………………………………. Function ……………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… [9] 7 (a) Describe three differences between an IP address and a MAC address. 1 ………………………………………………………………………………………………….. ……………………………………………………………………………………………………. 2 ………………………………………………………………………………………………….. ……………………………………………………………………………………………………. 3 ………………………………………………………………………………………………….. …………………………………………………………………………………………………. [3]

6 (b) Odd parity bit is used in the following data transfer between the sender and receiver. The 8th bit is the parity bit. Sender 1 2 3 4 5 6 7 8 0 1 1 0 1 0 1 1 Receiver 1 2 3 4 5 6 7 8 0 0 1 0 1 0 1 1 State the function of the parity bit. ………………………………………………………………………………………………… ……………………………………………………………………………………………… [1] (c) What has happened in the above data transfer? ………………………………………………………………………………………………... ………………………………………………………………………………………………... ……………………………………………………………………………………………… [2] (d) Give one limitation of the parity bit used in the above data transfer. ………………………………………………………………………………………………… ……………………………………………………………………………………………… [1]

7 8 Audrey wants to purchase a particular mobile phone model, which is sold at three different shops. Each shop is offering the phone at different selling prices and different discounted rates. State the inputs, the outputs and the processes required to find the shop that sells the phone at the lowest cost. Inputs ……………………………………………………………………………………………... ……………………………………………………………………………………………………... Outputs …………………………………………………………………………………………… ……………………………………………………………………………………………………... Processes required ……………………………………………………………………………… ……………………………………………………………………………………………………... …………………………………………………………………………………………………. [6] 9 (a) An algorithm input thirty positive numbers and then output the smallest number input. 1 Small = 0 2 Counter = 0 3 REPEAT 4 INPUT Num 5 IF Num < Small THEN Num = Small 6 Counter = Counter + 1 7 PRINT Small 8 UNTIL Counter < 30 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 (b) The thirty positive numbers are to be printed in the reverse order that it was input. (i) State by providing a reason, what needs to be done to the input variable Num in order to do this. ……………………………………………………………………………………………...... …………………………………………………………………………………………….. [2] (ii) Show how the input statement at line 4 would be modified to do this. ……………………………………………………………………………………………. [2] 10 An alarm, Y, sends a signal when certain fault conditions in a chemical process are detected. The inputs are: Input Binary value Condition A 1 acidity > 5 0 acidity