0478_s15_qp_13
A paper of Computer Science, 0478
Questions:
10
Year:
2015
Paper:
1
Variant:
3
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4
Choose six correct terms from the following list to complete the spaces in the paragraphs below: • encryption • file name • firewall • HTML tags/text • IP address • protocol • proxy server • SSL certificate • web server name A user enters a URL. The web browser breaks up the URL into three components: The web server returns the selected web page. The web browser reads the from the selected page and shows the correctly formatted page on the user’s screen. A is used between the user’s computer and the network to examine the data traffic to make sure it meets certain criteria. To speed up the access to the web pages next time, a is used between the computer and web server; this device uses a cache to store the website home page after it has been accessed for the first time.
5. The internet and its uses  →  5.1. The internet and the world wide web
Open
5
Five storage devices are described in the table below. In column 2, name the storage device being described. In columns 3, 4, or 5, tick () to show the appropriate category of storage. Description of storage device Name of storage device Category of storage Primary Secondary Off-line optical media which use one spiral track; red lasers are used to read and write data on the media surface; makes use of dual-layering technology to increase the storage capacity non-volatile memory chip; contents of the chip cannot be altered; it is often used to store the start up routines in a computer (e.g. the BIOS) optical media which use concentric tracks to store the data; this allows read and write operations to be carried out at the same time non-volatile memory device which uses NAND flash memories (which consist of millions of transistors wired in series on single circuit boards) optical media which use blue laser technology to read and write data on the media surface; it uses a single 1.1 mm polycarbonate disc
3. Hardware  →  3.3. Data storage
Open
6
Viruses, pharming and phishing are all examples of potential Internet security issues. Explain what is meant by each of these three terms. Virus Pharming Phishing An online bank requires a client to supply an 8-digit code each time they wish to access their account on the bank’s website. Rather than ask the client to use a keyboard, they are requested to use an on-screen keypad (shown on the right) to input the 8-digit code. The position of the digits on the keypad can change each time the website is visited. 2 5 1 6 8 3 9 0 4 The client uses a mouse or touch screen to select each of the 8 digits. Explain why the bank has chosen to use this method of entering the 8 digits. Name and describe another measure that the bank could introduce to improve the security of their website. Name Description
5. The internet and its uses  →  5.3. Cyber security
Open
7
One of the key features of von Neumann computer architecture is the use of buses. Three buses and three descriptions are shown below. Draw a line to connect each bus to its correct description. Bus Description address bus this bus carries signals used to coordinate the computer’s activities control bus this bi-directional bus is used to exchange data between processor, memory and input/ output devices data bus this uni-directional bus carries signals relating to memory addresses between processor and memory The seven stages in a von Neumann fetch-execute cycle are shown in the table below. Put each stage in the correct sequence by writing the numbers 1 to 7 in the right hand column. The first one has been done for you. Stage Sequence number the instruction is then copied from the memory location contained in the MAR (memory address register) and is placed in the MDR (memory data register) the instruction is finally decoded and is then executed the PC (program counter) contains the address of the next instruction to be fetched the entire instruction is then copied from the MDR (memory data register) and placed in the CIR (current instruction register) the address contained in the PC (program counter) is copied to the MAR (memory address register) via the address bus the address part of the instruction, if any, is placed in the MAR (memory address register) the value in the PC (program counter) is then incremented so that it points to the next instruction to be fetched
3. Hardware  →  3.1. Computer architecture
Open
8
An alarm clock is controlled by a microprocessor. It uses the 24 hour clock. The hour is represented by an 8-bit register, A, and the number of minutes is represented by another 8-bit register, B. Identify what time is represented by the following two 8-bit registers. A B : Hours Minutes An alarm has been set for 07:30. Two 8-bit registers, C and D, are used to represent the hours and minutes of the alarm time. Show how 07:30 would be represented by these two registers: C D : Hours Minutes Describe how the microprocessor can determine when to sound the clock alarm. The LCD (liquid crystal display) on the clock face is back-lit using blue LEDs (light emitting diodes). The brightness of the clock face is determined by the level of light in the room. The amount of light given out by the LEDs is controlled by a control circuit. Describe how the sensor, microprocessor and LEDs are used to maintain the correct brightness of the clock face. Modern LCD monitors and televisions use LED back-lit technology. Give two advantages of using this new technology compared to the older cold cathode fluorescent lamp (CCFL) method.
3. Hardware  →  3.1. Computer architecture
1. Data representation  →  1.1. Number systems
Open
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? If 1 GB = 2x then what is the value of X? How many bits are there in one byte? 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 0 0 1 0 0 1 0 0 ? What hexadecimal value is obtained when the two hexadecimal digits C and D are added together?
1. Data representation  →  1.1. Number systems
Open
10
Five statements about interpreters and compilers are shown in the table below. Study each statement. Tick () to show whether the statement refers to an interpreter or to a compiler. Statement Interpreter Compiler takes one statement at a time and executes it generates an error report at the end of translation of the whole program stops the translation process as soon as the first error is encountered slow speed of execution of program loops translates the entire program in one go
4. Software  →  4.2. Types of programming language, translators and integrated development environments (IDEs)
Open