Here is a long, detailed note (about 3000 words) on Computer Hardware, written in simple, clear language so you can use it to study yourself and also teach Grade 1–6 students. You can shorten it later for lower grades. --- COMPUTER HARDWARE (Full Note – About 3000 Words) 1. Introduction to Computer Hardware A computer is an electronic machine that works with data and information. It can take input, process it, store it, and give output. But a computer cannot work without its physical parts. These physical parts of a computer are called computer hardware. Computer hardware means all the parts of a computer that we can see and touch. Hardware is the body of the computer. Without hardware, a computer cannot work. For example: You can touch the keyboard You can touch the mouse You can touch the monitor You can touch the system unit (CPU) All of these are hardware parts. Hardware = Physical parts of a computer that can be seen and touched. Just like the human body has hands, eyes, brain, and heart, a computer also has different parts that work together to make it work properly. --- 2. Main Parts of Computer Hardware Computer hardware is divided into four main groups: 1. Input Devices 2. Output Devices 3. Processing Device 4. Storage Devices Each group has an important job to do. Let us learn them one by one in detail. --- 3. Input Devices Input devices are the parts of the computer that are used to enter information into the computer. They send data and instructions to the computer. Input = Give information to the computer Examples of Input Devices: a) Keyboard The keyboard is used to type letters, numbers, and symbols into the computer. It looks like a typewriter. You can use the keyboard to: Type your name Write a story Do calculations Write a letter The keyboard has: Alphabet keys (A–Z) Number keys (0–9) Special keys like Enter, Shift, Spacebar, Backspace Without a keyboard, you cannot type words into a computer. b) Mouse The mouse is a small device used to move the pointer on the computer screen. It is used to: Click Select Drag Open files and folders The mouse usually has two buttons: Left button Right button Some mice also have a scroll wheel in the middle. A mouse helps us control the computer easily. c) Microphone A microphone is used to record sound or speak into the computer. You can use a microphone to: Record your voice Talk to people online Give voice commands d) Scanner A scanner is a device that can copy pictures or text into the computer. For example, if you have a picture on paper, you can use a scanner to put that picture into the computer. e) Webcam A webcam is used to take pictures or videos using the computer. It is mostly used for: Online classes Video calls Taking pictures These devices send information into the computer. That is why they are called Input Devices. --- 4. Output Devices Output devices are the parts of the computer that show

1. CHAPTER-TWO
COMPUTER HARDWARE

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INTRODUCTION
 Computer hardware refers to the physical parts of a computer and its related devices.
 Internal hardware devices are usually called components
 External hardware devices are usually called peripherals
 Hardware can be categorized as:
 Input devices
 Output devices
 System Unit
 Storage devices
 Communication devices

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INPUT DEVICES
 This is any peripheral used to input data into the computer.
 Examples
 Keyboard
 Mouse
 Touchpad
 Scanner
 Digital Camera
 Microphone
 Joystick
 Graphic Tablet
 Light pen

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KEYBOARD
 What is the name of the area where the numbers 1-9 and letters A-Z are located?

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INPUT DEVICES (POINTING DEVICES)
 These are devices used to control the position of the pointer on the screen.
 These include the mouse and its variants, touchscreen, pen inputs etc.

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OUTPUT DEVICES
 These are devices used to communicate results of the data processing carried out by an information
processing system such as a computer to a user.
 Output is data that has been processed into a useful from called information.
 Output can be in the form of text, graphics, audio, and video.

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DISPLAY SCREENS/ MONITORS
 The monitor is a device that displays visual output from your computer as generated from your video card.
 Some technologies used in monitors are:
 CRT – Cathode Ray Tube
 LED – Light Emitting Diode
 LCD – Liquid Crystal Display
 Projectors are also capable of displaying output.
 It is used mostly for a large audience

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PRINTERS
 A printer is a device that can print characters, symbols and graphics on paper or other hardcopy media.
 Impact printers
 Dot-matrix printer
 Non-impact printers
 LaserJet
 InkJet
 Plotter
 Photo
 Some special printers combine many functions and are usually called All-in-One printer (printer, scanner, copier, fax)

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PRINTERS
Plotter
Dot matrix printer Photo printer
LaserJet printer
InkJet printer
All-in-One printer

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SYSTEM UNIT
 The system unit is the case that houses all the components in the computer system.
 Some of these components are:
 Motherboard
 Processor
 Power Supply Unit (PSU)
 Random Access Memory (RAM)
 Read Only Memory (ROM)

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SYSTEM UNIT

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SYSTEM UNIT - MOTHERBOARD
 It is the main circuit board in the computer to
which everything else (processor, keyboard,
mouse, RAM, ROM, HDD, monitor, etc.) connects
in order to function
 There are ports for keyboard, mouse etc. and
expansion slots for extending functionality (video,
sound, network etc.)

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SYSTEM UNIT - PROCESSOR
 Also called Central Processing Unit (CPU) works directly with the main memory to process data.
 It is made up of 2 parts
 Control Unit (CU)
 Arithmetic and Logic Unit (ALU)

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CONTROL UNIT (CU)
 It is a component of a computer's central processing unit (CPU) that directs the operation of the processor.
 It tells the computer's memory, arithmetic and logic unit and input and output devices how to respond to the
instructions that have been sent to the processor.
 It regulates and integrates the operations of the computer.

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ARITHMETIC AND LOGIC UNIT (ALU)
 ALU is the part of a CPU that carries out arithmetic and logic operations.
 Arithmetic operations include addition, subtraction, multiplication, and division
 Logic operations include AND, OR, and NOT operations.

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CENTRAL PROCESSING UNIT
CPU Architecture

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MEMORY
 Computer memory is any physical device capable of storing information temporarily, like RAM or permanently,
like ROM.
 Memory is important to fast operation of a computer
 Each device in a computer operates at a different speed which slower than the processor.
 It is memory that provides a place for quick access of data.
 The types of memory are RAM and ROM

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MEMORY - RAM
 It is a form of computer memory that can be read and changed in any order.
 RAM is the main memory in a computer.
 Like a human being's short-term memory, RAM only stores data that the
processor needs to work on immediately
 RAM comes in two primary forms – SRAM and DRAM (Static and Dynamic)
 DRAM - it needs continuous power to retain stored data and must be
refreshed constantly
 SRAM – same power requirements as DRAM but does NOT need to be
refreshed constantly to retain stored data.
 Variants include SDRAM, DDR-SDRAM

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MEMORY - ROM
 Data on the ROM cannot be erased by the computer without special equipment.
 ROM chips contain fixed startup instructions and data that does not change often sometimes called firmware.
 They are non-volatile, i.e. their contents are not lost when power is turned off.
 Programmable ROM (PROM) is a ROM chip that allows the user to load read-only programs and data only once.

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PORTS AND CONNECTORS
 A port/connector is a physical docking point through which an external device can be connected to the computer.
 A port has the following characteristics −
 External devices are connected to a computer using cables and ports.
 Ports are slots on the motherboard into which a cable of external device is
plugged in.
 Examples of external devices attached via ports are the mouse, keyboard,
monitor, microphone, speakers, etc.
 Some ports are Serial, Parallel, PS/2, Universal Serial Bus (USB),VGA, Power Connector, Firewire, Modem, Ethernet, Game,
DVI, Bluetooth

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EXPANSION SLOTS
 This is a connection or port inside a computer on the
motherboard.
 It provides an installation point for a hardware expansion
card to be connected.
 For example, if you wanted to install a new video card in the
computer, you must purchase a video expansion card and
install that card into the compatible expansion slot.

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STORAGE DEVICES
 This is any hardware that stores data.
 There are 2 types of storage devices namely Primary & Secondary
 Primary or main storage is the one directly accessible by the CPU
 Secondary storage a.k.a external memory or auxiliary storage is NOT directly accessible by the CPU
 Examples of secondary storage are HDD, Optical discs, Flash disks (pen drives), flash memory (memory cards)
etc.
 Optical discs include CD-R,CD-RW, DVD-R, DVD-RW, BluRay

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STORAGE DEVICES

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COMMUNICATION DEVICES
 These help the computer to transmit data or information using a
communication channel.
 Modem (Modulator – Demodulator) is a device that converts data from a
digital format into one suitable for a transmission medium such as telephone
lines or radio signals.
 Modems are referred to as an asynchronous device, meaning that the
device transmits data in an intermittent stream of small packets.
 Once received, the receiving system then takes the data in the packets and
reassembles it into a form the computer can use.

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OPERATION OF A MODEM

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NETWORK INTERFACE CARD (NIC)
 This is a hardware component without which a computer cannot be
connected over a network.
 It is a circuit board installed in a computer that provides a dedicated
network connection to the computer.
 It is also called network interface controller, network adapter or LAN
adapter.
 It can either be Internal or External

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INTERNAL COMPUTER HW COMPONENTS
.
Component Function
Motherboard The main circuit board that connects and allows communication between all
components.
CPU (Central Processing Unit) Executes instructions and performs calculations; the brain of the computer.
RAM (Random Access Memory) Temporarily stores data and instructions for quick access by the CPU.
Power Supply Unit (PSU) Converts electrical power to usable voltage levels for internal components.
Hard Drive / SSD Stores data permanently, including OS, software, and user files.
.
CMOS Battery Powers the BIOS/UEFI chip to retain system settings and time.
BIOS/UEFI Chip A firmware interface that initializes hardware during startup.
Cooling Fans / Heat Sinks Keep internal components, especially CPU and GPU, from overheating.
Optical Drive (if present) Reads/writes CDs, DVDs, or Blu-ray discs. (Becoming less common)
Expansion Cards Additional cards like sound cards, network cards, or TV tuners.
Internal Cables Transfer power and data between internal components (e.g., SATA, power cables).

28. EXTERNAL COMPUTER HW COMPONENTS
Computer Hardware Components
External Components Function
Monitor Displays the visual output from the computer.
Keyboard Allows user to input text and commands.
Mouse Controls cursor and GUI interaction.
Printer Prints digital documents to paper.
External Storage Devices Stores and transfers data externally (e.g., USB
drives).

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