9618/11 Oct/Nov 2022

One similarity and two differences between ASCII and Unicode.

Similarity (1 mark):

• Both use unique codes to represent characters .
  Differences (max 2):

• Unicode can use up to 32 bits per character, whereas ASCII uses 7 or 8.

• Unicode supports multiple languages, unlike ASCII which is limited to English.

Explain the effect of increasing sampling resolution.

• Increases number of bits per sample.

• Increases file size.

• More accurate sound representation / closer to analogue waveform.

• Smaller quantisation error.

Match each security feature to its description

• Firewall:

• Pharming:

• Anti-virus software:

• Encryption: .

• Firewall: Accepts/rejects packets based on criteria

• Pharming: Redirects user to fake website

• Anti-virus software: Scans files for malicious software

• Encryption: Converts data to alternative form

Give the features of 3NF

• No repeating groups of attributes (data is atomic)

• No partial key dependencies

• No non-key dependencies (no transitive dependencies)

What is meant by the von Neumann architecture?

Instructions and data are stored in the same memory space / in main memory

Index Register (IX):

Stores value to add to address

Tick the correct bus used by each component.
A:

• System clock:

• Memory Address Register (MAR):

• System clock: Control bus

• Memory Address Register (MAR): Address bus

Describe the role of the Control Unit (CU).

• Coordinates actions of CPU components

• Sends/receives control signals via control bus

• Manages instruction execution sequence

• Controls communication between CPU components

What is the purpose of an interrupt?

• To send a signal from a device or process

• To seek attention of the processor

Give two examples of events that could cause an interrupt.

• Division by zero / runtime error

• Invalid memory access

• Array index out of bounds

• Stack overflow

Match each assembler task to the correct pass.

• Remove comments:

• Read program one line at a time:

• Generate object code:

• Check opcode is in instruction set:

• Remove comments: First pass

• Read program one line at a time: Both passes

• Generate object code: Second pass

• Check opcode is in instruction set: First pass

Give two benefits of using dynamic link libraries (DLLs).

• Reduces main memory usage — DLL loaded only when required

• Executable file size is smaller

• Main program doesn’t need recompilation when DLL changes

• DLL maintenance is separate — handled by third party or OS

Describe how memory is managed by the OS. (BARPS)

• RAM is divided into blocks

• Allocates blocks dynamically to processes

• Reclaims unused blocks

• Prevents overlap between programs

• Supports paging, segmentation, and virtual memory

Explain how cache memory improves CPU performance. (FSRM)

• Fast memory close to the CPU

• Stores frequently used instructions/data

• Reduces CPU waiting time

• More cache = fewer accesses to slower ram

Identify suitable ports for the following devices:

• 3D printer:

• Monitor:

• 3D printer: USB port

• Monitor: HDMI

Explain how CSMA/CD handles collisions on a bus network. (The IFs)

• Device listens to channel before transmitting

• If channel is busy, it waits

• If channel is free, data is sent

• If two devices transmit at once, a collision occurs

• Devices detect collision, stop, send jamming signal

• Both wait random time, then retry

Give two advantages of using EEPROM to store firmware. (Never Ending Updates (NEU)

• No extra tools needed to update (user can update themselves)

• Can be erased and reprogrammed multiple times

• Updates possible without removing chip