9608_w20_qp_13
A paper of Computer Science, 9608
Questions:
8
Year:
2020
Paper:
1
Variant:
3
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2
Four terms about videos are given with six descriptions. Draw one line from each term relating to videos to its correct description. The number of images that are displayed per second The number of pixels per unit of measurement e.g. per inch Each frame is split into two fields: the first field contains only the odd lines, the second field contains the even lines Only the pixels that have changed are transmitted The complete frame is reproduced in each scan of the image The number of pixels in the image Description Progressive encoding Frame rate Interlaced encoding Image resolution Term
1. Theory Fundamentals  →  1.1. Information representation
Open
3
Hannah is writing a computer program using a high-level language. She uses both a compiler and an interpreter. Describe the ways in which Hannah will use an interpreter while writing the program. Explain the reasons why Hannah uses a compiler when she has finished writing the program. Some high-level languages are partially compiled and partially interpreted. Give one benefit and one drawback of using a language that is partially compiled and partially interpreted. Benefit Drawback
1. Theory Fundamentals  →  1.5. System software
Open
4
A laptop on a home network connects to the Internet through a router. The laptop has an IP address. Give the reasons why the laptop has an IP address. The laptop’s IP address is private. Give the reasons why the laptop does not have a public IP address. The router has an IPv4 address. Give three differences between the format of an IPv4 address and an IPv6 address. A Public Switched Telephone Network (PSTN) is one example of a communication system that can be used to support the Internet. Identify and describe two other communication systems that can be used to support the Internet. System 1 Description System 2 Description A web page contains PHP code. Complete the following table by writing a description of the function of each line of PHP code. PHP code Description echo "Hello World"; $number1 = 22; $newValue = $_GET["number"]; print "Hello " . $name . ""; PHP is a server-side scripting language. Give an example of a client-side scripting language. The laptop includes a parity bit in each byte it transmits. Explain how parity checks protect the integrity of the data.
1. Theory Fundamentals  →  1.2. Communication and Internet technologies
Open
5
The fetch-execute cycle is used when a computer processor runs a program. Complete the table by writing the register transfer notation for each of the descriptions. Letter Description Register transfer notation A The Memory Address Register (MAR) stores an address. The contents of this stored address are copied to the Memory Data Register (MDR). B The contents of the Program Counter (PC) are copied to the Memory Address Register (MAR). C The contents of the Memory Data Register (MDR) are copied to the Current Instruction Register (CIR). D The contents of the Program Counter (PC) are incremented. Write one of the letters A, B, C or D (from the table above) on each row (1 to 4), to show the correct order of the fetch-execute cycle. Buses are used to transfer data between various components of the computer system. Tick (✓) one or more boxes on each row to identify the buseach statement describes. Statement Address bus Control bus Data bus Receives data from the MAR Carries an address or an instruction or a value Transmits timing signals to components Bidirectional The following table shows assembly language instructions for a processor that has one general purpose register, the Accumulator (ACC). Instruction Explanation Op code Operand INV Input a denary value from the keyboard and store it in ACC. LDD Direct addressing. Load the contents of the location at the given address to ACC. LDM #n Immediate addressing. Load the denary number n to ACC. LDI Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC. ADD Add the contents of the given address to ACC. OUT Output to screen the character whose ASCII value is stored in ACC. INC Add 1 to the contents of the register (ACC or . CMP Compare the contents of ACC with the 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. STO Store contents of ACC at the given address. END Return control to the operating system. The assembly language instructions are grouped according to their function. Write one example of an op code from the table of instructions for each of the following groups. Arithmetic Data movement The current contents of the main memory are: Address Instruction INV STO 901 INV STO 900 ADD 902 STO 902 LDD 903 INC ACC STO 903 CMP 901 JPN 502 END … The current contents of a general-purpose register X are: X The contents of X represent an unsigned binary integer. Convert the contents of X into denary. The contents of X represent a two’s complement binary integer. Convert the contents of X into denary. State why the binary number in X cannot represent a Binary Coded Decimal (BCD).
1. Theory Fundamentals  →  1.4. Processor fundamentals
Open
6
Lara is managing a team of software developers who are writing a computer program. Benedict is one of the developers. He is struggling to keep up with his workload. Describe the ways in which Lara can ethically support Benedict. Lara has identified that when a specific sequence of actions is performed in the program, a run-time error causes the program to crash. She has decided there is not enough time to debug the code because the client needs the system urgently, and there is a possibility that the client may never perform this sequence of actions. Explain the reasons why Lara is not acting ethically. The client wants to copyright the final program so that no one else can copy or amend it. State the purpose of copyrighting the computer program. Identify two software licences that would be appropriate for the program. Licence 1 Licence 2 Identify one software licence that would not be appropriate for the program. Justify your choice. Software licence Justification
1. Theory Fundamentals  →  1.7. Ethics and ownership
Open
7
Wilbur uses vector graphics to create a logo for his company. Wilbur Designs Describe how the logo is represented and encoded by the computer. Wilbur scans a hand drawn image. The scanned image uses 8 bits to store the colour for each pixel. The image is 2048 pixels wide by 1024 pixels high. Calculate an estimate of the file size of the scanned image. Give your answer rounded to the nearest MB. Show your working. Answer MB Wilbur wants to compress the scanned image before emailing it to his colleague. Describe one lossy compression technique that Wilbur can use to compress this image.
1. Theory Fundamentals  →  1.1. Information representation
Open