ACSBR 2020 Computing P1 with solution

This paper has 13 pages, inclusive of the cover page. Name: Class: 4S3 Index Number: Anglo-Chinese School (Barker Road) PRELIMINARY EXAMINATION 2020 SECONDARY FOUR EXPRESS COMPUTING PAPER 1 7155/01 2 HOURS INSTRUCTIONS TO CANDIDATES: Do not open this booklet until you are told to do so. Write your name and index number clearly in the spaces at the top of this page. Write in dark blue or black pen. You may use soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, 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 of question. You should show all your working. The total mark for this paper is 80. TOTAL 80

Anglo-Chinese School (Barker Road) Preliminary Examination 2020 2 Secondary 4 Express Computing 7155/01

Anglo-Chinese School (Barker Road) Preliminary Examination 2020 3 Secondary 4 Express Computing 7155/01 1 The diagram show four types of computer or network identifiers and six types of representation on the right. Draw one line between each identifier to its correct representation. Identifiers Representation • sequence of six hexadecimal numbers, one for each byte of the address, separated by hyphens or colons IPv4 • • two byte number assigned in a range from 0 to 65,535. Media Access Control (MAC) • • sequence of four denary numbers, one for each byte of the address, separated by dots. Port • • sequence of three bytes, one for each component SSID • • thirty-two byte string • sequence of sixteen hexadecimal digits, one for each byte of the address, separated by dots. [4]

Anglo-Chinese School (Barker Road) Preliminary Examination 2020 4 Secondary 4 Express Computing 7155/01 2 (a) Convert the binary number 1011 1101 into a positive whole denary number. [1] (b) In a signed byte, the leftmost bit in one byte of data can be used as a sign bit, i.e. 0 or 1 to represent positive or negative numbers respectively. State the biggest positive whole denary number that can be represented by one signed byte of data. [1] 3 Memory addresses can be represented in hexadecimal codes. (a) 6EF50A50 is an example of a hexadecimal memory address. Complete the table below to convert each unique hexadecimal digit to its binary value. Hexadecimal 6 E F 5 0 A Binary ………… ………… ………… ………… ………… ………… [3] (b) Convert the denary number 1258 into hexadecimal number. Show your working. [2] (c) Explain why hexadecimal numbers are commonly used to represent binary numbers. [1]

Anglo-Chinese School (Barker Road) Preliminary Examination 2020 5 Secondary 4 Express Computing 7155/01 4 (a) Draw the logic circuit to represent the following Boolean statement. Do not simplify the statement. X = NOT A OR (B NOR C) NAND (A OR C) A B C X [4] (b) Complete the truth table for the Bo