Summary of Material for The Grade 8G Digital Technology (TryOuT)

 Summary of Key Concepts

• Binary System (Base-2): Computers process and store all data using binary numbers, which consist of only two digits: 0 and 1.

• Transistors & Microprocessors: A microprocessor serves as the brain of the computer (CPU) and contains billions of tiny electronic switches called transistors. Transistors represent binary states where ON = 1 and OFF = 0.

• Decimal vs. Binary: The decimal system (Base-10) uses digits 0 through 9. The binary system (Base-2) uses place values that increase from right to left as powers of 2 (1, 2, 4, 8, 16...).

• Number Conversion: Decimal numbers can be converted into binary by subtracting the largest matching power of 2 or using repeated division by 2. Binary numbers are converted back to decimal by adding up the place values where a 1 appears.

• Bits and Bytes: A bit (lowercase b) is the single smallest unit of data (0 or 1). A byte (uppercase B) is a group of $8\text{ bits}$, which stores a single character or letter.

• Data Units Scale: Storage sizes scale up by approximately 1,024 times per level: Byte -> Kilobyte (KB) -> Megabyte (MB) -> Gigabyte (GB) -> Terabyte (TB). Internet speed is measured in bits per second (bps/Mbps), while file sizes are measured in Bytes.

• Text Encoding: Computers convert characters into binary numbers so they can process and store text.

• ASCII Standard: An early text encoding system using 7 or 8 bits that represents up to 128–256 characters, limited mainly to English letters, basic numbers, and symbols.

• Unicode Standard: A modern encoding standard (such as UTF-8) supporting over 150,000 characters across global languages, scripts, and emojis.

• Digital Audio & Sampling Rate: Sound is digitized when a microphone turns air vibrations into voltage, which an Analog-to-Digital Converter (ADC) measures thousands of times per second into binary code. The audio sampling rate (measured in kHz) determines how many times per second sound is measured. Higher sampling rates improve audio quality but increase overall file size.

• Digital Video: Video works by rapidly playing a sequence of still image frames made of pixels converted into binary data.

• Logic Gates: Hardware building blocks inside the CPU that combine binary signals to make decisions:

  • AND Gate: Outputs 1 only when all inputs are 1.

  • OR Gate: Outputs 1 if at least one input is 1.

  • NOT Gate: Reverses the input signal (a 1 becomes a 0, and a 0 becomes a 1).

• Personal Data Protection: Personal data includes identifiable details like your full name, location, and phone number, which must be protected online to maintain privacy.

• Digital Footprint: The trail of digital data you leave behind whenever you browse, post, or interact online, which can be permanent and difficult to delete.

• Data Collection & Targeted Ads: Free websites and apps collect behavioral data (clicks, location, search history) to build profiles and show targeted advertising to users.

• AI Algorithm Bias: AI systems learn from historical data; if the training data contains human biases, the AI can replicate unfair decisions or misidentify certain groups of people.

• Cybersecurity Practices: Protect personal data online by using long passphrases with Two-Factor Authentication (2FA), enabling a Virtual Private Network (VPN) on public Wi-Fi networks, and recognizing phishing emails.