Textbook Revision Notes (CH1-CH6)

CH1 – WHAT IS A COMPUTER?

• A computer is a device that receives data, processes it, and shows the results.
• It follows instructions to do different tasks, like solving problems, showing information, or running programs.

INPUT-PROCESS-OUTPUT CYCLE

• A computer works in three main steps: input, process, and output.
  • Input: The user gives data or instructions (e.g., typing on a keyboard, clicking a mouse).
  • Process: The computer works on the data (e.g., doing calculations).
  • Output: The computer shows the results (e.g., showing text on a screen, printing, playing sound).

EXAMPLES OF COMPUTERS

• Desktop Computer
  • Housed in a big case with components like the processor and storage.
  • Connected to external devices like a monitor, keyboard, and mouse.
  • Higher computing power and storage capacity than laptops or tablets due to size and stable power supply.
  • Less portable.
  • Ideal for video editing, gaming, and running many programs at once.
  • Often used in school computer labs and offices.
• Laptop Computer
  • Portable personal computer.
  • Built-in screen, keyboard, and battery.
  • Can be used without plugging into a power source for a few hours.
  • Used for similar tasks as desktop computers but more convenient for users who need to work on the go.
  • Many students use laptops for online learning, typing assignments, and browsing the web.
• Tablet
  • Lightweight, portable computer with a touchscreen.
  • Controlled by tapping on the screen using a virtual keyboard.
  • Great for browsing the internet, reading e-books, watching videos, and playing games.
  • Examples: iPad, Samsung Galaxy Tab.
• Smartphone
  • Handheld device that combines the features of a mobile phone and a computer.
  • Touchscreens and can run various apps.
  • Examples: iPhones and Android phones.
• Game Console
  • Special computer designed mainly for playing video games.
  • Connected to a TV for a larger display.
  • Specialized in graphic rendering.
  • Popular consoles: PlayStation, Xbox, and Nintendo Switch.
• POS Terminal
  • Used in stores to process sales transactions.
  • Includes a cash register, barcode scanner, and receipt printer.
  • Used to scan items and accept payments.
• Automated Teller Machine (ATM)
  • Computer used for banking services.
  • Allows people to withdraw cash, check account balances, or transfer money.
  • Found outside banks, in shopping malls, and at convenience stores.
• Self-Service Kiosk
  • Touch-screen computer that allows people to perform tasks on their own.
  • Examples: buying tickets, checking in for flights, or ordering food.
  • Often found in fast-food restaurants, airports, and movie theaters.

DEVELOPMENT OF COMPUTERS

• Evolved significantly from the 1930s to today.
• Alan Turing’s Turing machine in 1936.
• Integrated circuit in 1958.
• First personal computers in the 1980s.
• 2000s: Rise of mobile computing (iPad) and touchscreen tablets.
• Recent advancements: Virtual Reality (VR), Augmented Reality (AR), and specialized systems for AI research.
• Future: Quantum computing and advanced AI models like GPT-4.
• Wearable Technology
  • Electronic devices worn on the body, often incorporated into clothing or accessories.
  • SmartWatch
    • Computerized wristwatch with advanced features (playing music, taking photos, monitoring heart rate).
    • Connects with smartphones for notifications and health data.
  • SmartGlass
    • Wearable computer in the form of glasses.
    • Uses augmented reality (AR) to overlay digital information onto the real world.
    • Allows users to see both real-life images and digital content simultaneously.
• Virtual Reality (VR)
  • Completely immersive experience.
  • Creates a fully virtual environment, blocking out the real world.
  • Users interact with special headsets like the Oculus Rift.
  • VR games place players entirely inside a virtual 3D world (e.g., racing game, flight simulator).
• Microcontroller
  • Small, programmable circuit board, like a minicomputer.
  • Multiple pins for connecting components.
  • Users can create custom machines, such as remote controls or weather monitoring stations.
• Maker Culture
  • Movement that encourages creativity and innovation by designing and building gadgets.
  • Emphasizes a DIY (Do-It-Yourself) approach.
  • Microcontrollers play a key role, acting as a bridge between software and hardware.
  • Enables makers to turn ideas into functional devices, such as robots, sensors, and other electronic projects.

CH2 – INPUT AND OUTPUT (I/O) DEVICES

• Input and output (I/O) devices provide an interface for users to interact with the computer.

INPUT DEVICES

• An input device is hardware that collects data from users for further processing.
• Examples: keyboards, pointing devices, and sensors.
• Keyboard
  • Used to input characters and symbols into the computer.
  • Most keyboards have a QWERTY-based layout.
• Pointing Devices
  • Used to control the cursor.
  • Mouse
    • Can be connected in wired (USB cable) or wireless forms.
    • Wireless mouse connects via a USB receiver (dongle) or Bluetooth.
  • Touchpad
    • Also known as a trackpad.
    • Found on notebook computers.
    • Users move their fingers to move the cursor.
  • Trackball
    • Controls the cursor by rolling the ball in any direction.
    • Requires less space than a mouse.
  • Joystick and Racing Wheel
    • Commonly used for video game control movements.
• Touchscreen
  • Functions as both an input and output device.
  • Senses and responds to touches from fingers, styluses, or other touch-sensitive tools.
  • Users can tap, swipe, or drag on the screen to interact.
  • Provides real-time feedback by visually responding to user inputs.
• Microphone
  • Captures sound waves and converts them into electrical signals.
  • These signals can be transformed into digital audio files through a computer’s sound card.
• Image Scanner
  • Uses optical technology to input data directly from paper documents and images.
  • Scanned file is normally saved as an image format.
  • With optical character recognition (OCR) software, the text document can be converted into an editable computer file.
• 3D Scanner
  • Captures the shape, size, and appearance of real-world objects.
  • Analyzes the object’s surface and creates a digital 3D model.
  • This model can be processed, modified, or printed using a 3D printer.
• Webcam
  • Used for capturing images and videos.
  • Often used for video chats or conferences.
  • Most laptops have a built-in webcam.
• Sensor
  • Captures certain physical quantities from the surroundings.
  • Commonly found in smartphones, tablet computers, and video game consoles.
  • Light Sensor
    • Measures: Brightness
    • Applications: Adjusts screen brightness on mobile phones automatically, activates automatic lighting systems.
  • Ultrasonic Sensor
    • Measures: Distance
    • Applications: Used in automatic hand washers, helps with vehicle parking.
  • Compass
    • Measures: Direction
    • Applications: Used in navigation systems.
  • Temperature and Humidity Sensor
    • Measures: Temperature and humidity levels
    • Applications: Used in air conditioning systems.
  • Gyroscope
    • Measures: Orientation
    • Applications: Helps change the orientation of mobile phone screens when the device is rotated.

OUTPUT DEVICES

• An output device delivers information to users.
• Output devices can be wired or wireless.
• Wired visual output devices (monitors) typically connect through VGA or HDMI ports.
• Wired audio output devices (speakers, headphones) commonly use a 3.5 mm jack.
• Monitor
  • Displays the user interface and the results of information processing.
  • Types: LCD, LED, and OLED.
    • LCD (Liquid Crystal Display): Uses liquid crystals, generally more affordable but has lower contrast and brightness consistency.
    • LED (Light Emitting Diode): Enhanced versions of LCDs, using LED backlighting for better brightness and energy efficiency.
    • OLED (Organic Light Emitting Diode): Offers higher contrast ratio, deeper blacks, brighter whites, better brightness consistency, wider viewing angles, and are lighter and thinner.
• Projector
  • Projects images, videos, or data onto a large surface.
  • Used in classrooms, offices, home theaters, and presentations.
• Speaker
  • Outputs sound waves that humans can hear.
  • Connected to a sound card for conversion between digital signals and analog sound waves.
• Printer
  • Delivers information in printed form.
  • Inkjet Printer: Best for high-quality photo printing and occasional home use, lower initial cost but higher ongoing ink costs.
  • Laser Printer: Ideal for frequent, high-volume printing of text-heavy documents in offices, faster speeds and lower cost per page.
  • Thermal Printer: Uses heat to print on heat-sensitive paper, common for receipts in POS systems, ATMs, and shipping labels, low maintenance but printed material can fade over time and only prints in black and white.
  • Dot-Matrix Printer: Uses pins to strike an ink ribbon, creating dots on paper, slower print speed, lower resolution, and more noise, but ideal for printing multi-part forms like carbon copies.
  • 3D Printer: Builds objects layer by layer using materials like plastic, metal, or resin based on a digital 3D model.

SOFTCOPY VS. HARDCOPY

• Softcopy (screen output): More environmentally friendly, can include interactive elements, prone to technical issues, virus attacks, and relies on electronic devices.
• Hardcopy (printer output): Consumes significant paper, limited to static content, useful for disaster recovery, can be viewed without electricity.

CH3 – SYSTEM UNIT

• The system unit houses essential components of a computer system: the motherboard, processors, storage devices, interface cards, and the power supply unit.
• Together, these components allow the computer to process data, store information, and communicate with external devices.

INSIDE VIEW OF A SYSTEM UNIT

• The motherboard connects all components.
• The processor (CPU) handles the processing of data and instructions.
• Main memory (primary storage): RAM (temporary storage) and ROM (firmware).
• Secondary storage: Long-term data storage.
• Power supply unit: Provides power for the computer to operate.

COMPONENTS OF A SYSTEM UNIT

• Motherboard
  • A circuit board that acts as the main platform for connecting various electrical components and devices.
  • It contains slots and ports that allow components like the central processing unit (CPU), random access memory (RAM), graphics processing unit (GPU) as well as peripherals like the mouse and monitor, to be connected and communicate with each other.
• Central Processing Unit (CPU)
  • Acts as the brain of the computer, responsible for processing all instructions and performing logical operations.
  • Multiple electronic and logic circuits that execute tasks and manage data flow within the system.
  • Major manufacturers: Intel and AMD.
  • Generates heat during operation.
  • Cooling system required to keep the temperature within a desired range.
    • Air cooling: Uses cooling fans and a heat sink to drive heat away, low setup cost but creates more noise.
    • Liquid cooling: Uses coolant and liquid sink, more effective than air cooling, generates less noise, but has high installation and maintenance cost, and risk of spillage.
• Graphics Processing Unit (GPU)
  • Can be integrated into the motherboard or located on a dedicated display card (graphics card).
    • Integrated GPU: Integrated into the CPU, shares the system's main memory (RAM), less powerful, used for basic tasks.
    • Dedicated GPU: Located on a separate graphics card, has its own video memory (VRAM), designed for demanding tasks like gaming, video editing, and 3D rendering, plugged into the motherboard through a PCIe slot (Peripheral Component Interconnect Express).
• CPU vs. GPU
  • CPU: General-purpose processor designed to handle a wide range of tasks.
  • GPU: Specialized for graphic rendering and parallel processing, has thousands of smaller cores (more cores than CPU), efficient at performing many simple, repetitive tasks simultaneously, excels at parallel workloads for graphic rendering, AI, and machine learning.
• Power Supply
  • An electrical device that provides different voltage power to the motherboard, CPU, and storage devices.
  • Generates a lot of heat during operation and there is often a fan attached for cooling.
• Storage Device
  • Used for keeping data for both short-term and long-term storage.
  • Different types of storage devices, such as hard disk (HDD), solid-state drive (SSD) and RAM.

CH4 – CENTRAL PROCESSING UNIT (CPU)

• A CPU (Central Processing Unit) is the main processor of a computer, responsible for executing instructions and performing data processing.

COMPONENTS OF CPU

• Arithmetic and Logic Unit (ALU)
  • Performs arithmetic and logical operations.
    • Arithmetic operations: addition ($+), subtraction ($-), multiplication ($\times$), and division ($\div$).
    • Logical operations: equals ($=), not equals ($\neq$), less than ($
• Control Unit (CU)
  • Manages the computer.
  • Controls how the ALU and other devices react to instructions.
  • Manages the flow of data between the CPU and other parts of the computer.
  • Number of cores.
  • Clock rate.
  • Word length.
• Registers
  • Small, fast storage spaces inside the CPU.
  • Used to hold data or addresses that the ALU or Control Unit (CU) need to use for processing.
  • Allow quick data access but have small storage capacity.

PROCESSING CAPACITY

• The processing capacity of CPUs depends on the following factors:
  • Number of Cores
    • A CPU with more processing cores generally works faster because it can divide the workload between the different cores, allowing for better multitasking.
    • A quad-core CPU (four cores) usually performs better than a dual-core CPU (two cores), assuming both have the same clock rate.
  • Clock Rate
    • Refers to the processing speed of a CPU.
    • Measured in megahertz (MHz) or gigahertz (GHz).
    • A CPU with a higher clock rate can process more instructions than a CPU with a lower clock rate and has higher energy consumption.
  • Word Length
    • Refers to the amount of data a CPU can process at one time, and it is measured in bits.
    • Personal computers today have a word length of either 32-bit or 64-bit.
    • A CPU with a longer word length can handle more data at once.
    • 32-bit CPUs is known as x86 processors.

OVERCLOCKING

• Overclocking increases a CPU's performance by forcing it to operate at a clock rate higher than its default speed.
• Causes the CPU to consume more power and generate more heat, which increases the risk of hardware failure.
• Many manufacturers void warranties on devices that have been overclocked, as it can shorten the lifespan of the CPU and other components.

CH5 – STORAGE DEVICES

• File size is typically measured in units of data like bytes, KB (kilobytes), MB (megabytes), or GB (gigabytes).
• Machines operate in the binary system (based on 2) because computers process data using bits (binary digits), which are either 0 or 1.
• These binary calculations are the foundation of how data is stored and measured in digital devices.

PRIMARY STORAGE DEVICES

• Primary storage, or main memory, is directly connected to the CPU for rapid data access.

• Primary storage includes Random Access Memory (RAM), and Read-only Memory (ROM).

• Random Access Memory (RAM)

  • Temporarily stores data while a computer is running, allowing quick access for active programs and processes.
  • Volatile, meaning that all data in RAM is lost when the computer is turned off.
  • A computer with more RAM performs better, as it can handle more tasks simultaneously.
  • To increase a computer’s RAM, you can either add more RAM sticks or replace existing ones on the motherboard.

• Read-only Memory (ROM)

  • Non-volatile memory that retains its data even when the computer is turned off.
  • Typically read-only, meaning that its data usually cannot be rewritten or modified.
  • Stores firmware, which consists of essential instructions needed to boot up the system.
  • This firmware is often referred to as the Basic Input/Output System (BIOS), which helps the computer start and manage communication between the hardware and the operating system.

SECONDARY STORAGE DEVICES

• Secondary storage, or back-up storage, refers to internal or external storage devices used for long-term data storage.

• Unlike RAM, it is non-volatile, meaning it retains data even when the computer is turned off.

• Some common examples of secondary storage devices include hard disks, USB flash drives, and CD-ROMs.

• Hard Disk

  • In a traditional hard disk drive (HDD), data is stored on a spinning disk called the platter.
  • During operation, the platter rotates quickly, and the read/write head moves across the surface to read or write data.

• Solid-date drive (SSD)

  • A Solid-State Drive (SSD) is composed of flash memory and a controller.
  • Flash memory allows for the fast reading and writing of data using electricity, while the controller manages these processes.
  • Unlike traditional hard disks (HDDs), an SSD has no moving parts, which makes it more durable, portable, and energy-efficient.
  • SSDs are typically more expensive than hard disks, as they have a higher cost per storage capacity.

• Both hard disks (HDDs) and solid-state drives (SSDs) can be used as either internal or external storage devices.

  • Internal storage devices are installed inside the system unit and are typically used to store the operating system, software, and active files.
  • External storage devices are portable and removable, often used for storing backup data or transferring files between computers.

• Comparison between a hard disk and a solid-state drive:

• Memory Card
  • Also made of flash memory and is designed to be compact for use in mobile devices such as smartphones and digital cameras.
  • Its small size makes it ideal for portable devices.
  • One common format of memory cards is Secure Digital (SD), which comes in various sizes, including standard SD, miniSD, and microSD, to fit different devices and storage needs.
• USB Flash Drive
  • Built using flash memory and features an integrated USB interface, which gives it its small size and high portability.
  • Commonly used for backing up data and transferring files between different devices, making it a convenient tool for portable and easy data storage.
  • Connected to a device through a USB port.
    • USB Type-A: The most common, rectangular port found on most computers.
    • USB Type-B: Typically used for larger devices like printers.
    • USB Type-C: A newer, smaller, reversible connector that supports faster data transfer and charging.
• Optical Disc
  • Lower cost per storage unit.
  • Uses the property of light to store data.
• Cloud Storage
  • A type of web-based storage where data is saved on remote servers.
  • Commonly used for data storage and backup.
  • Major service providers include Dropbox, Google Drive, and others.
  • Some services are free, while others charge extra for increased storage capacity.
    • Advantage:
      • Users can access data from anywhere via the Internet using their own devices.
      • Cloud storage space is flexible, allowing users to adjust it to meet their needs.
      • There's no setup cost, as no additional hardware is needed.
      • Service providers often offer automatic backups of files.
    • Disadvantage:
      • Users cannot access their data without an Internet connection.
      • Data stored on remote servers could face security risks and privacy concerns.
      • When the cloud server is busy, users may take longer time to access data.
• Memory Hierarchy
  • Computer storage can be organized into a hierarchy based on factors like data access rate, storage size, and unit price per capacity.
  • As we move up the storage hierarchy:
    • The data access rate (how quickly data can be accessed) increases.
    • The average storage size (how much data can be stored) decreases.
    • The unit price per capacity (cost per unit of storage) increases.

DATA FLOW BETWEEN COMPUTER COMPONENTS

BINARY NUMBERS

• A decimal number is a number in base 10, which uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
• A binary number is a number in base 2, which uses only two digits: 0 and 1.
• To distinguish between numbers in base 10 and base 2, we can write them with subscripts, such as 1011{10}$for decimal and$10112 for binary.
  • 1011_{10} means the number 1011 in decimal.
  • 1011_2 means the number 1011 in binary.

THE CONVERSION OF BINARY NUMBERS TO DECIMAL NUMBERS

• Each digit is represented by an increasing power of 2
• Add up the power of 2 where there is a 1
• Question: Convert 1011_2 into a decimal number

• 10112 = 1 \times 2^3 + 0 \times 2^2 + 1 \times 2^1 + 1 \times 2^0 = 11{10}

THE CONVERSION OF DECIMAL NUMBERS TO BINARY NUMBERS

• Use short division to repeatedly divide the decimal number by 2
• Take the remainders of each division from bottom to top
• Question: Convert 37_{10} into a binary number
• Therefore, 37{10} = 1001012$$

CH6 – SOFTWARE

• Software refers to the non-physical parts of a computer system and is designed to help the computer perform tasks.

• Unlike hardware, which includes the physical components of a computer, software consists of programs and applications that tell the computer what to do and how to do it.

• There are two types of software:

  • System Software: Manages and controls the hardware and provides a platform for running application software. Examples include Microsoft Windows, macOS, iOS, and Android.
  • Application Software: Designed to help users perform specific tasks, such as word processing, graphic design, or playing games. Examples include Microsoft Word and Adobe Photoshop.

• User interacts with application software (e.g., Microsoft Excel, Adobe Illustrator).

• Application software operates on a platform provided by system software (e.g., Microsoft Windows, macOS).

• The system software controls the underlying hardware (e.g., CPU, monitor).

SYSTEM SOFTWARE

• System software is responsible for controlling the operations of both computer hardware and application software.

• There are three types of system software:

  • Operating systems
  • Drivers
  • Utility programs

• Operating systems manage the hardware of a computer and provide a platform for running application software (e.g., Windows, macOS).

• List of functions of an operating system:

• Types of operating systems:

• Drivers enable communication between the operating system and hardware devices (e.g., printer drivers, speaker drivers).

  • Driver programs control devices like mice, keyboards, and speakers connected to the computer.
  • They act as a translator, converting user requests into machine-level commands that the hardware can understand.
  • Each driver is specifically designed for a particular operating system and device to ensure proper communication and functionality.
  • Some drivers support hot swapping, which allows users to plug in or swap devices while the computer is still operating without needing to reboot the system.

• Utility Programs perform maintenance tasks, help optimize the performance of a computer and provide extra functions to the operating system.

APPLICATION SOFTWARE

• Application software refers to programs designed to carry out specific tasks for users.

• There are three main types:

  • Productivity Software: Helps users perform tasks efficiently, such as word processing (e.g., Microsoft Word) and spreadsheets (e.g., Microsoft Excel).

  • Multimedia Software: Allows users to create or view multimedia content, such as photo editing (e.g., Adobe Photoshop) and video playback (e.g., VLC Media Player).

  • Communication Software: Facilitates communication between users, such as email clients (e.g., Gmail) and instant messaging tools (e.g., WhatsApp).

• Each type of application software serves a distinct purpose, making computers more useful for a wide range of activities.