JYSS 4E_COM_Prelim_P1_QP

JUNYUAN SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 SECONDARY FOUR EXPRESS CANDIDATE NAME CLASS INDEX NUMBER COMPUTING 7155/01 Paper 1 Written 26 Aug 2022 Candidates answer on the Question Paper. 2 hours No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number 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 or graphs. Do not use staples, paper clips, glue or correction fluid. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total number of marks for this paper is 80. This document consists of 14 printed pages and 2 blank pages. [Turn over For Examiner’s use 80

2 1 (a) The computer uses a complex circuit made of many components called the central processing unit (CPU). Two of these components are the ALU and CU. (i) State what ALU is and describe its function. [2] (ii) State what CU is and describe its function. [2] (b) Computers represent data using numbers that are express in different number systems. Show your working for the following questions. (i) Convert 12410 to a hexadecimal number. [2] (ii) Convert 11012 to a hexadecimal number. [2] (iii) Convert 17716 to a denary number. [2]

3 4E Computing P1 2022 Prelim [Turn over 2 Five terms of network systems and communications , and eight descriptions are given. Draw one line from each item to its appropriate description. Term Description Device that connects multiple LANs that uses the same protocol Media Access Control (MAC) address A 32-byte string that identifies a wireless access point (WAP) and all the devices connected to it. Server Used together with an Internet Protocol (IP) address to identify a program running on a network Port number Hardware interface to enable the transfer of data between a device and network Ethernet Computer that shares resources with and responds to requests on the network Network Interface Controller Sequence of bytes (usually permanent in nature) that is used to identify a particular physical network device. The most commonly used wired network protocol for local and metropolitan area networks. [5]

4 3 (a) In data transmission, packets are checked for errors using two different methods. One method is the parity check. (i) The data shown below uses an even parity system where the first digit is the parity bit. Fill in the missing bit. 0 1 1 1 0 1 1 [1] (ii) A checksum is a second error-checking method. Explain how a checksum detects errors.