9608_w15_qp_12
A paper of Computer Science, 9608
Questions:
8
Year:
2015
Paper:
1
Variant:
2
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2
Describe how a laser mouse operates. The following table shows a list of five statements which describe the stages when a page is printed using an inkjet printer. Put each statement in the correct sequence by writing the numbers 1 to 5 in the right-hand column. Statement Sequence number Paper feed stepper motor activated; sheet of paper fed from paper tray Printer driver translates data into a suitable format for the printer The print head moves across the page; ink is sprayed each time the print head pauses for a fraction of a second Paper feed stepper motor advances paper a fraction of a cm after each complete head pass Printer receives data from the computer and stores the data in the printer’s buffer
1. Theory Fundamentals  →  1.3. Hardware
1. Theory Fundamentals  →  1.4. Processor fundamentals
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3
A touch screen has three squares where a selection can be made: T S U The x-coordinate of the centre of the three squares is held in three memory locations: Address Memory contents S 0000 1011 0100 T 0010 0101 0100 U 0100 0110 1100 Give the hexadecimal value of the memory contents for U. Convert the denary number 40 into binary. Bitmap graphics are used to represent squares S, T and U. These can be saved in a number of different image resolutions. Give the number of bits required to store each pixel for a black and white bitmap. Identify how many bits are required to store each pixel for a 256-colour bitmap. Explain your answer. Images can be compressed to reduce file size. Describe how lossless compression techniques work. Describe how lossy compression techniques work.
1. Theory Fundamentals  →  1.1. Information representation
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4
Sound can be represented digitally in a computer. Explain the terms sampling resolution and sampling rate. Sampling resolution Sampling rate The following information refers to a music track being recorded on a CD: • music is sampled 44 100 times per second • each sample is 16 bits • each track requires sampling for left and right speakers Calculate the number of bytes required to store one second of sampled music. Show your working. A particular track is four minutes long. Describe how you would calculate the number of megabytes required to store this track. When storing music tracks in a computer, the MP3 format is often used. This reduces file size by about 90%. Explain how the music quality is apparently retained.
1. Theory Fundamentals  →  1.1. Information representation
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5
Bobby is a senior programmer at a software house which produces intruder detection software. He also runs his own software company which develops and sells various computer applications. The following table shows seven activities which Bobby carries out. Put a tick (✓) in the appropriate column to identify if the activity is ethical or unethical. Activity Ethical Unethical gives away passwords used in the intruder detection software uses source code developed at the software house for the software he develops for his own company insists that staff work to deadlines turns down training opportunities offered by his employer writes and sells software that reads confidential data from client computers fakes test results of safety-critical software has the software applications developed overseas for sale in his own country
1. Theory Fundamentals  →  1.7. Ethics and ownership
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7
The string of characters, “BINARY CODE”, was transmitted using 11 bytes of data. An additional byte, called the parity byte, was also transmitted. Parity bytes can be used to identify exactly which bit has been transmitted incorrectly. The table shows bit patterns for all 12 bytes after transmission. Even parity was used and the first bit is the parity bit. character bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 8 byte 1 B byte 2 I byte 3 N byte 4 A byte 5 R byte 6 Y byte 7 byte 8 C byte 9 O byte 10 D byte 11 E parity byte There is one error in the transmission. Indicate the byte number and bit number of the bit which has been incorrectly transmitted. Byte number Bit number Explain your answer to part . Verification and validation can be applied during data entry. Describe what is meant by these terms. For each method, explain why it is needed. Verification Validation
3. Advanced Theory  →  3.6. Monitoring and control systems
1. Theory Fundamentals  →  1.2. Communication and Internet technologies
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8
The table shows assembly language instructions for a processor which has one general purpose register – the Accumulator (ACC). Instruction Explanation Op code Operand LDD Direct addressing. Load the contents of the given address to ACC LDX Index addressing. Form the address from + the contents of the index register. Copy the contents of this calculated address to ACC LDI Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC STO Store the contents of ACC at the given address INC Add 1 to contents of the register (ACC or ADD Add the contents of the given address to the ACC END Return control to the operating system The diagram shows the contents of the memory: 0 0 0 0 0 0 1 0 1 0 0 1 0 0 1 1 0 1 1 1 0 0 1 1 0 1 1 0 1 0 1 1 0 1 1 1 1 1 1 0 1 0 1 1 0 0 0 1 0 1 1 0 1 0 0 0 0 1 0 0 1 0 1 1 main memory 1 0 0 1 1 1 1 0 Show the contents of the Accumulator after execution of the instruction: LDD 102 Accumulator: Show the contents of the Accumulator after execution of the instruction: LDX 101 Index register: Accumulator: Explain how you arrived at your answer. Show the contents of the Accumulator after execution of the instruction: LDI 103 Accumulator: Explain how you arrived at your answer. Trace the assembly language program using the trace table. LDD INC STO LDD ADD STO END Trace table: Accumulator Memory address
1. Theory Fundamentals  →  1.4. Processor fundamentals
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