9618/11 Paper 1 – May/June 2024

Identify two characteristics of an embedded system.

• Only performs specific tasks (motion detection, video recording, ringing).

• CPU, memory, storage, and software are dedicated to just this task.
  (Also acceptable: Built-in motion sensor and camera; uses a microprocessor for limited tasks.)

Complete the table about solid state memory (flash):

• Logic gates:

• Transistors per cell:

• Gate that retains charge without power:

• Gate that allows/stops current:

• Logic gates: NAND, NOR

• Transistors per cell: 2

• Gate that retains charge without power: floating

• Gate that allows/stops current: control

How does the buffer help in the video doorbell?

• Stores data (e.g., video) before sending to smartphone or saving.

• Holds motion sensor readings until processor is ready.

• Used to rewind recent video or manage temporary data flow.

How does increasing the sampling rate affect performance?

• More data to transmit = slower delivery to smartphone.

• Storage fills up faster = fewer videos can be stored.

• Videos may be overwritten more frequently.

What is meant by bit streaming?

Continuous, ordered flow of bits over a communication path.

Give two differences between real-time and on-demand bit streaming.

• Real-time = live/direct from source; on-demand = pre-recorded.

• Real-time = cannot pause/replay; on-demand = can pause, rewind, and play later.

Why is an interpreter better for debugging than a compiler?

• Interpreter stops at each error.

• Errors can be fixed one at a time, and results seen instantly.

Why is a compiler better for releasing the finished program?

• Compiled code runs without source, so it cannot be edited/stolen.

• No need for end users to install a translator.

• Faster execution without re-translation.

In a client-server model, describe the roles of the client and server devices.

• Server: Receives and processes client requests.

• Client: Sends requests to the server, waits for the server to respond, and outputs the response.

Describe how a parity check can be used to verify data transmitted from one computer to another.

• Both systems agree on odd or even parity.

• Data is split into 7-bit groups.

• If using odd parity and a group has an even number of 1s, a parity bit of 1 is added (else 0).

• A block check counts the number of 1s in each bit column.

• A parity byte is added to ensure each column matches the agreed parity.

Explain how a firewall can help protect a network.

• Monitors all incoming and outgoing transmissions.

• Compares them against set rules, whitelists, or blacklists.

• Blocks data not meeting the rules, including data from specific ports or unauthorised software.

How is artificial intelligence used in facial recognition for biometric authentication?

• Captures an image of the user’s face.

• Uses image recognition trained on many samples.

• Identifies facial features in the image.

• Analyses the image and compares with stored patterns using probability of a match

Define the following DBMS features: Data dictionary and Logical schema

Data dictionary: Metadata about the database, e.g., field names, data types, validation rules, keys, relationships.

Logical schema: Conceptual overview of the database structure; database-independent; defines entities and relationships.

Why does a router connecting to the internet need a public IP address?

So that it is visible and accessible by other devices on the internet.

Enter the topology/ies for each network statement:

All devices connect to one central device

All devices connect to a central cable

Multiple paths for the packets to travel

Robust against line failure

Most likely to lose data through collisions

Bus : All devices connect to a central cable

Star: All devices connect to one central device, Robust against line failure

Mesh: Multiple paths for the packets to travel, Robust against line failure

Identify two other differences between IPv4 and IPv6 (besides separators).

IPv4 has 4 groups of digits whilst IPv6 has 8 groups

IPv4 is usually represented in denary whilst IPv6 is usually represented in hexadecimal

IPv4 groups are between 0 and 255 whilst IPv6 is between 0 and FFFF

IPv4 is 32 bits whilst IPv6 is 128 bits

What is lossy compression, and give one method used to achieve it?

• Lossy compression permanently removes unnecessary or less important data to reduce file size.

• Original file cannot be fully restored after compression.

• Commonly used for multimedia files (e.g. images, audio, video).

Method:

• Perceptual coding: Removes sounds or image details that are unlikely to be noticed by the human ear or eye.
  Example: MP3 audio compression removes frequencies outside human hearing range.

Explain how JPEG compression reduces the file size of an image

• JPEG uses lossy compression.

• It removes data that is less important to human perception.

• Similar colours in neighbouring pixels are stored as a single colour.

• Fine detail may be lost when colours or edges are simplified.

• Reduces the number of bits used to store the image.