Hardware refers to the physical parts of a computer system that enable input, processing, storage, and output.
1. Input Devices
Definition: Hardware used to enter data/commands into a computer.
Types of Input Devices
| Device | Function | Examples |
|---|
| Keyboard | Enters text/commands | QWERTY, ergonomic, virtual |
| Mouse | Controls cursor movement | Optical, wireless, trackball |
| Touchscreen | Direct touch interaction | Smartphones, ATMs, kiosks |
| Scanner | Converts physical documents to digital | Flatbed, handheld, barcode |
| Microphone | Captures audio input | USB mics, headsets |
| Webcam | Records video | Built-in (laptops), external |
| Biometric | Authenticates via body features | Fingerprint, facial recognition |
Specialized Input Devices
- Graphics Tablet: For digital drawing (e.g., Wacom).
- Joystick/Gamepad: For gaming.
- OMR/OCR Scanners: Reads marked forms (e.g., exam sheets).
2. Output Devices
Definition: Hardware that displays/processes data from the computer.
Types of Output Devices
| Device | Function | Examples |
|---|
| Monitor | Displays visual output (soft copy) | LCD, LED, OLED, 4K screens |
| Printer | Produces hard copy output | Inkjet, Laser, 3D printers |
| Speakers | Outputs audio | Stereo, surround sound, headphones |
| Projector | Projects images onto a screen | DLP, LCD projectors |
| Plotter | Prints large-scale designs | Used in engineering/architecture |
Comparison: Printers
| Type | How It Works | Best For | Speed/Quality |
|---|
| Inkjet | Sprays liquid ink | Photos, home use | Slow, high-quality |
| Laser | Uses toner powder & heat | Office documents | Fast, sharp text |
| 3D | Layers melted plastic | Prototypes, models | Very slow |
3. Central Processing Unit (CPU)
Definition: The “brain” of the computer that executes instructions.
CPU Components
- Control Unit (CU): Manages instruction execution.
- Arithmetic Logic Unit (ALU): Performs calculations/logic operations.
- Registers: Small, fast storage for immediate data.
- Cache: High-speed memory for frequent data access (L1, L2, L3).
Key CPU Terms
- Clock Speed: Measured in GHz (higher = faster processing).
- Cores: Multiple cores allow parallel processing (e.g., quad-core).
- Threads: Virtual cores (e.g., Intel Hyper-Threading).
Popular CPU Brands
- Intel: Core i3/i5/i7/i9, Xeon (servers).
- AMD: Ryzen 3/5/7/9, Threadripper (workstations).
4. Memory (Primary Storage)
Definition: Temporary storage for active data and programs.
Types of Memory
| Type | Volatile? | Speed | Purpose |
|---|
| RAM | Yes (loses data when powered off) | Fast | Stores running apps & OS |
| ROM | No (permanent) | Slow | Stores firmware (e.g., BIOS) |
| Cache | Yes | Very Fast | Speeds up CPU operations |
RAM vs. ROM
| Feature | RAM | ROM |
|---|
| Volatility | Volatile | Non-volatile |
| Speed | Faster | Slower |
| Usage | Temporary data | Permanent instructions |
| Upgradability | Expandable (e.g., 8GB → 16GB) | Fixed (cannot be modified) |
5. Storage Devices (Secondary Storage)
Definition: Long-term storage for files and programs.
Types of Storage
| Type | Description | Capacity | Speed | Examples |
|---|
| HDD | Magnetic disks | 500GB–10TB+ | Slow | Seagate, WD |
| SSD | Flash memory (no moving parts) | 128GB–4TB | Very Fast | Samsung 970 EVO |
| USB Drive | Portable flash storage | 8GB–2TB | Moderate | SanDisk, Kingston |
| Cloud | Remote storage (Internet) | Unlimited (paid) | Varies | Google Drive, Dropbox |
HDD vs. SSD
| Feature | HDD | SSD |
|---|
| Speed | Slower (mechanical parts) | Faster (no moving parts) |
| Durability | Prone to damage | More shock-resistant |
| Cost | Cheaper per GB | More expensive |
| Lifespan | Shorter (moving parts wear) | Longer (limited write cycles) |
