Information and Communication Technology Study Notes

UNIT 1: DIGITAL DEVICES

Chapter 1: Digital Devices

Types of Digital Devices

  • Mainframe Computers: Large, powerful systems used by major organisations for complex processing tasks like statistical analysis and bulk data processing. They can handle complicated jobs quickly and be used by many people simultaneously.

  • Microprocessors: Embedded devices that control products such as washing machines, televisions, and cameras. They take data input, process it, and provide output.

Personal Computers (PCs)

  • Desktops: Have more space for components and are easy to upgrade. Usually require external peripheral devices like monitors, mice, and keyboards.

  • All-in-One Desktops: Combine the monitor and PC hardware into a single unit.

  • Laptops: Portable computers with integrated screens, keyboards, trackpads, and rechargeable batteries.

  • Desktop Replacements: Large laptops with high performance and high-quality screens, designed to replace permanent desktop setups.

Single-Board Computers (SBCs)

  • Affordable, compact computers like the Raspberry Pi Zero used for education, embedded computing, and physical computing projects.

Mobile Devices

  • Mobile Phones: Use a SIM (Subscriber Identity Module) card to connect to cellular networks.

  • Smartphones: Small computers with advanced operating systems, Wi-Fi, and apps. They function as multifunctional devices (camera, media player, navigation). They consume more power, leading to shorter battery life.

  • Specialist Phones: Designed for specific needs, such as the Alto 2 'talking phone' for the visually impaired or phones with emergency buttons for the elderly.

  • Tablets: Larger than smartphones but with similar features (touch screens, apps, Wi-Fi). Some include SIM slots for mobile data.

Media and Entertainment Devices

  • Cameras and Camorders: Capture images/video using light sensors. Quality depends on the lens, image processor, and sensor resolution (width×height\text{width} \times \text{height}, measured in pixels).

  • Home Entertainment Systems:

    • Televisions: Features range from standard HD (1280×7201280 \times 720 or 1920×10801920 \times 1080) to 4K (4096×21604096 \times 2160) and 8K. Smart TVs can stream content via apps.

    • Sound Systems: High-quality speakers and amplifiers. Connectivity includes Bluetooth, USB, and Wi-Fi.

    • Blu-ray/DVD Players: Devices for optical media playback. Blu-ray supports HD/4K content.

    • Personal Video Recorders (PVR): Record broadcast content for later viewing.

    • Games Consoles: Designed for gaming on screens. Features include motion sensors, wireless controllers, and virtual reality (VR). Handheld versions offer mobile gaming with lower storage and image quality.

    • Media Players: Stream or play digital audio/video. Personal media players often use solid-state flash memory for durability during movement.

Navigation Aids and Smart Technology

  • GPS (Global Positioning System): Uses satellite signals (24 satellites orbit Earth) to determine exact location and orientation with accuracy within 5 metres.

  • Home Automation: Connects digital devices to control functions like temperature and lighting (Smart Homes).

Multifunctional Devices and Convergence

  • Multifunctional: A single device (e.g., smartphone) performing various functions like photography, navigation, and gaming.

  • Convergence: When designs of different devices become similar (e.g., phablets blurring the line between smartphones and tablets).

Features of Digital Devices

  • Portability: Related to size and weight.

  • Performance: Determined by processor (CPU) speed and RAM capacity. Inefficient software can degrade performance.

  • Storage: Space available for programs and files. Faster storage improves loading times.

  • User Interface (UI):

    • Command Line (CLI): Text-based, low memory usage.

    • Menu-driven: Easy for tasks like ATMs or older phones.

    • Graphical (GUI): Uses WIMP (Windows, Icons, Menus, Pointers).

    • Voice: Spoken commands; requires internet-based word libraries.

    • Gesture: Swiping/pinching on touch screens.

  • Connectivity: Wired (USB, Ethernet) or Wireless (Wi-Fi, Bluetooth).

  • Energy Consumption: Lower consumption increases battery life and reduces environmental impact.

  • Expansion Capability: Slots for SD cards or USB ports for peripherals.

  • Security Features:

    • Software: Passwords, PINs (6-digit PIN has 1×1061 \times 10^6 combinations), biometric scanners (FaceID, TouchID).

    • Physical: Locks and security slots (Kensington locks).

Chapter 2: Software

System Software

  • Utility Software: Configuration and maintenance tools.

    • Backup: Creates copies of files automatically.

    • Defragmentation: Reorganises fragmented data on hard disks to improve speed.

    • Compression: Reduces file size by removing repeated patterns (e.g., Run Length Encoding).

    • Formatting: Prepares storage media for first use.

  • Operating Systems (OS): Manages hardware and software interactions.

    • Memory Management: Allocates RAM and handles virtual memory.

    • Resource Management: Queues hardware requests (e.g., for printers).

    • Print Spooling: Queues print jobs.

    • Security/Authentication: Manages user logins and firewalls.

Application Software

  • Office Productivity: Word processing, spreadsheets (modeling financial scenarios), databases (DBMS), and desktop publishing (DTP).

  • Web Authoring: WYSIWYG editors or HTML coding for creating web pages.

  • Editing Software: Graphics editors (vector), photo editors (bitmap/cropping), and sound editors (joining tracks, normalisation).

  • Control Applications: Use sensor input to automate mechanisms like lift doors or heating systems (Internet of Things).

  • Project Management: Track tasks via timelines/milestones (Gantt charts) and identify the 'critical path'.

  • Communication Software: Web browsers, email (SMTP/IMAP), SMS (160 characters), MMS, and instant messaging.

Software Licensing and Updates

  • Free/Open-Source: Users can modify and distribute source code.

  • Proprietary: Marketed under a brand name; source code is not available. Includes 'freeware'.

  • Updates: Fix bugs, improve usability, or increase security. Important to backup before updating.

Chapter 3: Memory and Processors

Memory Types

  • RAM (Random Access Memory): Volatile main memory used to store active instructions. More RAM allows more programs to run simultaneously.

  • Virtual Memory: Secondary storage space used as an overflow when RAM is full (slower access).

  • ROM (Read Only Memory): Non-volatile, used for booting systems and storage of firmware.

    • PROM: Programmable once.

    • EPROM: Erasable via UV light.

    • EEPROM: Electrically erasable (precursor to flash memory).

  • Flash Memory: Non-volatile EEPROM with no moving parts; fast and energy-efficient.

Processors (CPUs)

  • Cores: Multi-core processors (e.g., Quad-core) do more work per cycle at lower temperatures.

  • Speed: Measured in Clock Cycles Per Second (Hertz).

    • 1 kHz=1,000 cycles/sec1\,\text{kHz} = 1,000\,\text{cycles/sec}

    • 1 MHz=1,000,000 cycles/sec1\,\text{MHz} = 1,000,000\,\text{cycles/sec}

    • 1 GHz=1,000,000,000 cycles/sec1\,\text{GHz} = 1,000,000,000\,\text{cycles/sec}

UNIT 2: CONNECTIVITY

Chapter 4: Digital Communication

Bandwidth and Latency

  • Bandwidth: Number of bits carried per second (Mbit/s\text{Mbit/s} or Gbit/s\text{Gbit/s}). Impact: Higher bandwidth enables HD streaming.

  • Latency: Delay in sending data between devices. Measured by 'pinging'. Impact: High latency causes 'lag' in online gaming.

Networks

  • LAN (Local Area Network): Small geographical area (e.g., a home or office).

  • WAN (Wide Area Network): Large geographical area (e.g., the internet or international business networks).

  • PAN (Personal Area Network): Connects a user's personal devices (e.g., smartwatch to phone).

  • Tethering: Sharing a mobile phone's broadband connection with other devices.

Communication Methods

  • Satellite: Used for GPS, satellite TV (DVB-S), and satellite phones in remote areas. Signal can be affected by weather/objects.

  • Broadcast: Analogue/Digital (DVB-T) television and radio (DAB).

  • Wired: Faster and more secure. Types include HDMI, USB, and Ethernet (up to 100 m100\,\text{m} range).

  • Wireless:

    • Wi-Fi: Uses IEEE 802.11 standards. Longer range than Bluetooth.

    • Bluetooth: Short-range, used for pairing peripherals (mice, headphones).

    • Mobile Broadband: 3G and 4G (and future 5G) cellular networks.

    • Infra-red (IR): Short range, line-of-sight (e.g., remote controls).

    • NFC (Near-Field Communication): Very short-range (payment cards, travel cards).

UNIT 3: OPERATING ONLINE

Chapter 6: Risks to Data and Personal Information

Specific Risks

  • Malware: Malicious software including viruses (spread via networks), ransomware (threatens file deletion for money), adware, and spyware (keyloggers).

  • Phishing: Emails/messages pretending to be from legitimate organisations to steal login details.

  • Pharming: Redirecting users from legitimate websites to fake ones via domain name server alteration.

  • Botnets: Groups of computers hijacked to spread malware.

Security Measures

  • Firewalls: Control incoming/outgoing network traffic based on rules.

  • Encryption: Symmetric (one key) or Public Key (mathematically related key pair).

  • CAPTCHA: Distinguishes humans from automated bots.

  • HTTPS: Secure protocol using SSL/TLS for encryption (indicated by a green padlock).

  • Backups: Full, differential, or incremental copies stored in safe locations or the cloud.

Chapter 8: Online Communities

Features and Functions

  • Social Networking: Profiles, status updates, targeted marketing (selling user data to advertisers), groups, circles, and analytics.

  • VLE (Virtual Learning Environments): Teaching/assessment tools, gradebooks, and document editors.

  • User-Generated Content: Wikis (Collaborative editing), Blogs (online diaries), and Social Bookmarking (categorising URLs with tags).

UNIT 4-6: SOFTWARE AND APPLICATION SKILLS

Storage Units

  • 1 Kilobyte (KB)=1,000 Bytes1\,\text{Kilobyte (KB)} = 1,000\,\text{Bytes}

  • 1 Megabyte (MB)=1,000,000 Bytes1\,\text{Megabyte (MB)} = 1,000,000\,\text{Bytes}

  • 1 Gigabyte (GB)=1,000,000,000 Bytes1\,\text{Gigabyte (GB)} = 1,000,000,000\,\text{Bytes}

  • 1 Terabyte (TB)=1,000,000,000,000 Bytes1\,\text{Terabyte (TB)} = 1,000,000,000,000\,\text{Bytes}

Database Structure

  • Tables: Made of records (rows) and fields (columns).

  • Fields: Have specific data types: Alphanumeric/Text, Numeric, Date, Logical/Boolean, and Currency.

  • Primary Key: A unique identifier for a record.

  • Foreign Key: A primary key from one table used in another to create a relationship.

  • Validation Checks: Presence, Type, Length, and Range checks.

Spreadsheet Skills

  • Formulae: Start with == and use arithmetic operators (++, −-, ∗*, //).

  • Referencing: Relative (basic) vs. Absolute (using \ to fix cells).

  • Functions: SUM, AVERAGE, MIN, MAX, COUNT, IF, VLOOKUP.

  • Charts: Pie (proportions), Bar/Column (comparisons), Line (trends), and Scattergrams (correlations).