9608_w18_qp_13
A paper of Computer Science, 9608
Questions:
8
Year:
2018
Paper:
1
Variant:
3
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1
A product designer is creating a poster. The designer creates a 6-colour bitmap image for the poster as shown. Each colour is represented by a letter, for example, R = red, B = blue. R R P P P G B R R P G G B W B B O O B W W P P O B B R P G O B R R P G O State the minimum number of bits needed to represent each pixel in the image in part . Calculate the minimum file size of the image shown in part . Show your working. Working File size The designer takes a photograph to put on the poster. The photograph has a resolution of 50 000 pixels by 50 000 pixels. The colours are represented using 4 bytes per pixel. Estimate the file size of the photograph in gigabytes. Show your working. Working Estimated file size The photograph needs to be sent by email but the file size is too big. It needs to be compressed. The table lists several methods of making an image file size smaller. Tick (✓) one box on each row to indicate whether each method is lossy or lossless. Compression method Lossy Lossless Cropping the image Reducing the resolution of the image Using run-length encoding (RLE) Reducing the colour depth of the image Explain how run-length encoding would compress the image in part .
1. Theory Fundamentals  →  1.1. Information representation
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2
The following table shows assembly language instructions for a processor which has one general purpose register, the Accumulator (ACC) and an Index Register (. Instruction Explanation Op code Operand LDD Direct addressing. Load the contents of the location at the given address to ACC. LDX Indexed addressing. Form the address from + the contents of the Index Register. Copy the contents of this calculated address to ACC. LDR #n Immediate addressing. Load the number n to IX. STO Store contents of ACC at the given address. ADD Add the contents of the given address to ACC. INC Add 1 to the contents of the register (ACC or . DEC Subtract 1 from the contents of the register (ACC or . CMP Compare contents of ACC with contents of . JPE Following compare instruction, jump to if the compare was True. JPN Following compare instruction, jump to if the compare was False. JMP Jump to the given address. OUT Output to the screen the character whose ASCII value is stored in ACC. END Return control to the operating system. State what is meant by relative addressing and indexed addressing. Relative addressing Indexed addressing The current contents of a general purpose register (are: X The contents of X represent an unsigned binary integer. Convert the value in X into denary. The contents of X represent an unsigned binary integer. Convert the value in X into hexadecimal. The contents of X represent a two’s complement binary integer. Convert the value in X into denary. Show the result on the general purpose register (after the following instruction is run. INC X The current contents of the main memory, Index Register (and selected values from the ASCII character set are provided with a copy of the instruction set. Instruction set Instruction Explanation Op code Operand LDD Direct addressing. Load the contents of the location at the given address to ACC. LDX Indexed addressing. Form the address from + the contents of the Index Register. Copy the contents of this calculated address to ACC. LDR #n Immediate addressing. Load the number n to IX. STO Store contents of ACC at the given address. ADD Add the contents of the given address to ACC. INC Add 1 to the contents of the register (ACC or . DEC Subtract 1 from the contents of the register (ACC or . CMP Compare contents of ACC with contents of . JPE Following a compare instruction, jump to if the compare was True. JPN Following a compare instruction, jump to if the compare was False. JMP Jump to the given address. OUT Output to the screen the character whose ASCII value is stored in ACC. END Return control to the operating system. Address Instruction LDD 96 CMP 97 JPE 32 LDX 86 CMP 98 JPN 27 OUT LDD 96 INC ACC STO 96 INC IX JMP 21 END … IX ASCII code table (selected codes only) ASCII code Character = & ( )
1. Theory Fundamentals  →  1.4. Processor fundamentals
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3
This question presents three scenarios. Tick (✓) one box for each scenario to indicate whether you think the person’s behaviour is ethical or unethical. Justify your choice. Mason is using his work computer to book a holiday whilst at work. Ethical Unethical Justification Ethan is supervising a trainee. The trainee asks Ethan for a reference for another job. Ethan does not want to lose the trainee, so refuses to give him a reference. Ethical Unethical Justification Margarita finds that one of her team members has produced some inventive code. She presents this to her manager, praising the individual by name. Ethical Unethical Justification
1. Theory Fundamentals  →  1.7. Ethics and ownership
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4
Ava needs to view a website and she knows the Uniform Resource Locator (URL). Complete the series of steps that take place. Write the letter of the appropriate statement in each space. A DNS finds corresponding IP B DNS looks up URL in table C Ava types the URL into a web browser Web browser sends URL to Domain Name Service (DNS) DNS returns IP address to web browser An IPv4 address has been entered as 12.258.3 Give two reasons why this IP address is invalid. An IPv6 address has been entered as 15EF:5L63::2014:BB::60AA Give two reasons why this IP address is invalid. The table shows four descriptions of IP addresses. Tick (✓) one box in each row to identify whether each description applies to a public or private IP address. Description Public Private The address can be reached over the Internet. The address is more secure. The address can only be accessed through the same LAN. The address can be duplicated in different networks.
1. Theory Fundamentals  →  1.2. Communication and Internet technologies
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5
Arnold is a software developer. He has created a computer game for people to download over the Internet. Arnold is considering releasing the game as a piece of commercial software. Describe what is meant by a commercial licence. Name and describe one other type of licence that Arnold can consider using. Licence type Description Users need to enter their name and email address to create an account. The information is stored in a database on Arnold’s computer. Give three ways that Arnold can ensure users’ details are kept secure.
1. Theory Fundamentals  →  1.7. Ethics and ownership
1. Theory Fundamentals  →  1.6. Security, privacy and data integrity
Open
6
The fetch-execute (FE) cycle uses special purpose registers. The stages in the FE cycle are shown in register transfer notation. MAR [ ] PC PC + 1 [ [MAR] ] [MDR] The steps shown in part are incomplete. Write the missing register names in the spaces in part . The third instruction [ [MAR] ] has double brackets. State the purpose of the double brackets. One stage of the FE cycle includes checking for interrupts. State what is meant by an interrupt. There are two types of RAM: dynamic RAM (DRAM) and static RAM (SRAM). The following table shows five statements about DRAM and SRAM. Tick (✓) one box in each row to indicate whether the statement applies to DRAM or SRAM. Statement DRAM SRAM Does not need to be refreshed as the circuit holds the data while the power supply is on Mainly used in cache memory of processors where speed is important Has less complex circuitry Requires higher power consumption under low levels of access, which is significant when used in battery-powered devices Requires data to be refreshed occasionally so it retains the data
1. Theory Fundamentals  →  1.4. Processor fundamentals
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