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© UCLES 2015 0478/11/M/J/
9 Draw a line to connect each question to the correct answer. Question Answer What is the denary (base 10) equivalent to the hexadecimal
digit E?^8
If 1 GB = 2value of X? x then what is the 12
How many bits are there in one
byte?^14
If the broadband data download rate is 40 megabits per second, how many seconds will it take to download a 60 MB file?
What is the denary (base 10) value of the binary number
What hexadecimal value is obtained when the two hexadecimal digits C and D are added together?
[5]
QUESTION 1.
© UCLES 2016 0478/12/M/J/
(d) Describe three tasks carried out by a firewall. 1 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... 3 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [3]
9 In the following barcode, each binary number is made up of seven bars. Each bar is black or grey. A black bar is interpreted as a “1” and a grey bar is interpreted as a “0”. (a) Write the binary numbers that would be produced from this barcode:
%LQDU\QXPEHU$ %LQDU\QXPEHU%
Binary number A:
Binary number B: [2] (b) This barcode system uses odd parity. Write the parity bit for each of the binary numbers in part (a) : Parity bit Binary number A: Binary number B: [2]
QUESTION 2.
©UCLES 2018 0478/11/M/J/18 [Turn over
3 The three binary numbers in the registers A, B and C have been transmitted from one computer to another. Parity bit Register A 1 0 0 1 1 0 0 0
Register B 0 1 1 0 0 1 1 1
Register C 1 0 0 1 1 0 0 1 One binary number has been transmitted incorrectly. This is identified through the use of a parity bit. Identify which register contains the binary number that has been transmitted incorrectly. Explain the reason for your choice. The binary number that has been transmitted incorrectly is in Register .......................................... Explanation ...................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... [4]
QUESTION 4.
©UCLES 2018 0478/13/M/J/
5 (a) Convert the denary number 107 to binary.
.............................................................................................................................................. [1] (b) Represent the denary number 300 as it would be stored in a 12-bit binary register.
.............................................................................................................................................. [2] (c) Convert the denary number 179 to hexadecimal.
.............................................................................................................................................. [2]
6 One of the roles of an operating system is to deal with interrupts. (a) Explain the term interrupt. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (b) Identify three devices that make use of interrupts. Device 1 .................................................................................................................................... Device 2 .................................................................................................................................... Device 3 .................................................................................................................................... [3]
QUESTION 5.
©UCLES 2020 0478/13/M/J/
1 Pradeep is reading hexadecimal values for a project he is working on. (a) The first three hexadecimal values he reads are 15 , 102 and A. Give the denary values for the three hexadecimal values. 15 .............................................................................................................................................. 102 ............................................................................................................................................ A ............................................................................................................................................. [3] Working space ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... (b) Pradeep has two 8-bit binary values that he needs to convert to hexadecimal values for his project. Give the hexadecimal values for the two 8-bit binary values. 01010000 .................................................................................................................................. 00111101 .................................................................................................................................. [4]
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QUESTION 7.
© UCLES 2015 0478/11/O/N/
10 Characters can be represented in a computer by a numerical code. The following list shows 16 characters with their numerical codes in denary: a = 97 e = 101 k = 107 t = 116 b = 98 g = 103 m = 109 u = 117 c = 99 h = 104 o = 111 w = 119 d = 100 i = 105 r = 114
. = 46 (code for the full stop) Web addresses can be written using hexadecimal rather than denary. Hexadecimal codes are preceded by a % sign. For example, the word “ c a g e ” is written as: either 99 97 103 101 (in denary) or %63 %61 %67 %65 (in hexadecimal) (a) Complete the conversion of the following web address into hexadecimal: w w w. c i e. o r g. u k %77 %77 % [3] (b) Complete the web address from the given hexadecimal codes: %77 %77 %77 %2E %72 %6F %63 %6B %69 %63 %74 %2E %63 %6F %6D
W W W [3]
11 A passenger logs onto an airline website and types in the reference number for their flight. Once the passenger accesses their account they can choose their seat and also print out a boarding pass which contains a unique barcode. This barcode is scanned at the airport check-in desk. Name one input and one output device found at the check-in desk and give a reason for your choice. Input device ...................................................................................................................................... Reason ............................................................................................................................................. .......................................................................................................................................................... Output device ................................................................................................................................... Reason ............................................................................................................................................. .......................................................................................................................................................... [4]
QUESTION 8.
©UCLES 2018 0478/11/O/N/
2 (a) Six binary or hexadecimal numbers and six denary conversions are given. Draw a line to connect each binary or hexadecimal number to the correct denary conversion.
Binary or hexadecimal Denary
4E
A
[5]
(b) Hexadecimal is often used by computer programmers to represent binary values. Explain why computer programmers may choose to use hexadecimal. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2]
QUESTION 10.
©UCLES 2018 0478/12/O/N/
1 Computers use a character set to convert text into binary. One character set that can be used is ASCII. Each letter in ASCII can also be represented as a denary value. (a) The word BUS has the denary values: B U S 66 85 83 Convert the denary values into 8-bit binary. 66
85
83 [3] (b) Each letter in ASCII can also be represented as a hexadecimal value. The word KEY has the 8-bit binary values: K E Y 01001011 01000101 01011001 (i) Convert the three 8-bit binary values into hexadecimal. 01001011 ............................................... 01000101 ............................................... 01011001 ............................................... [3]
QUESTION 11.
©UCLES 2019 0478/11/O/N/19 [Turn over
2 An electronic guessing game compares denary integer values input by a user with pre-stored values. The pre-stored values are held in 10-bit binary format. (a) Convert the binary values in the table to denary. Binary Denary 0001001110 0110110111 1000000001 [3]
(b) When planning the game, the designer decided to use hexadecimal notation to represent the binary values. Explain why the designer used hexadecimal notation. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (c) State the hexadecimal equivalent of the binary value 1010110101 ............................................................................................................................................. [3] 3 A company has several offices. It uses the Internet to transfer data between offices. The company also makes payments to staff and suppliers using online banking. The company are concerned about spyware and other security aspects of using the Internet. (a) Explain what is meant by spyware and how it is used to obtain data. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [3]
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QUESTION 12.
©UCLES 2019 0478/12/O/N/19 [Turn over
4 An 8-bit binary register contains the value: 0 0 1 1 0 1 0 0 (a) Convert the binary value to denary. ................................................................................................................................................... ............................................................................................................................................. [1] (b) The contents of the register shifted one place to the right would give the result: 0 0 0 1 1 0 1 0 The contents of the register shown at the start of question 4 are shifted two places to the left. Show the contents of the register after this shift has taken place.
[1]
(c) State the effect this shift has on the denary value in part (a). ................................................................................................................................................... ............................................................................................................................................. [1] 5 Audrey wants to send a sound file to Nico using email. The file is too large to attach to an email so Audrey decides to compress the file. She uses lossy compression to reduce the size of the sound file. (a) Describe how lossy compression reduces the size of the sound file. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]
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QUESTION 13.
