Data Representation and Storage Basics

2.1.2: Binary Representation

• Computers use binary (0s and 1s) to represent data.
• Binary numbers can be converted to denary (decimal) numbers.
• Two's complement is a method for representing negative numbers in binary.
• The number of different states represented by a binary pattern of length n is 2ⁿ.

2.2.2: Data Representation

• ASCII (American Standard Code for Information Interchange) uses 7 bits to represent characters.
• Bitmap images are made up of pixels, each with a binary value.
• Image quality is determined by resolution and color depth.
• Analog sound is represented in binary through sampling and bit depth.

2.3.1: Data Storage and Compression

• Data storage units include bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and tebibytes.
• File sizes are calculated based on storage units and data.
• Lossless compression reduces file sizes without losing data.
• Lossy compression discards some data to reduce file sizes.

3.1.1: Hardware (Von Neumann Architecture)

• The Von Neumann architecture is a common computer structure.
• It includes a CPU (with control unit and ALU), memory, and input/output devices.
• The CPU processes instructions through the fetch-decode-execute cycle.

3.1.3: The Internet

• The internet is a global network that links devices.
• Each device is identified by a unique IP address.
• DNS translates human-readable domain names (like www.google.com) to IP addresses.

3.2.1: Network Protocols

• TCP/IP handles communication over the internet.
• HTTP/HTTPS transfer web pages. HTTPS is secured.
• FTP is used for transferring files.

3.2.3: Network Security

• Malware (viruses, worms, Trojans, ransomware) harms digital systems.
• Firewalls block unauthorized access.
• Encryption prevents unauthorized access.

5.1.1: Environmental Issues

• Digital devices consume energy.
• E-waste (discarded devices) has environmental impacts.
• Device manufacturing and disposal contribute to pollution.

5.2.1: Ethical and Legal Issues - Personal Data

• Privacy is the right to control personal data.
• Laws like GDPR regulate personal data.
• Users should own their data and consent to its use.
• Data misuse can lead to problems like identity theft.

5.2.2: Ethical and Legal Issues - AI and Robotics

• AI accountability is important for responsible decisions.
• AI algorithms can have biases from training data.
• Ensuring the safety of AI systems is crucial.
• Legal liability is a consideration when AI causes harm.

5.2.3: Ethical and Legal Issues - Intellectual Property

• Copyright protects original works.
• Patents protect inventions.
• Trademarks protect symbols and names.
• Licensing allows legal use of intellectual property.

5.3.1: Cybersecurity Threats (Malware)

• Malware (viruses, worms, Trojans, ransomware) damages systems.
• Viruses attach to files and spread.
• Worms self-replicate across networks.
• Trojans are disguised and cause harm.
• Ransomware locks files and demands payment.

5.3.2: Cybersecurity Protection

• Anti-malware software detects and removes malware.
• Encryption protects data from unauthorized access.
• Backups help recover from data loss.
• Acceptable use policies govern system use.