COMPUTER HARDWARE

 

📕 CHAPTER 3

COMPUTER HARDWARE

(KPSC Group-C Non-Technical – HIGH WEIGHTAGE CHAPTER)

3.1 Introduction to Computer Hardware

Computer hardware refers to the physical and tangible components of a computer system that can be seen and touched. Hardware forms the backbone of any computer system, without which software cannot function.

In KPSC examinations, hardware questions are:

Direct

Device-based

Frequently repeated

3.2 Classification of Computer Hardware

Computer hardware is broadly classified into:

Input Devices

Output Devices

Processing Devices

Storage Devices

Peripheral Devices

3.3 Input Devices

Input devices are used to enter data and instructions into the computer.

3.3.1 Keyboard

Most commonly used input device

Contains alphanumeric keys, function keys, control keys

Types of keys:

Alphabet keys (A–Z)

Numeric keys (0–9)

Function keys (F1–F12)

Special keys (Enter, Shift, Ctrl, Alt)

📌 KPSC fact:

F1 key = Help

3.3.2 Mouse

Pointing device

Used to select, drag, scroll

Types:

Mechanical mouse

Optical mouse

Wireless mouse

3.3.3 Scanner

Converts physical documents into digital form

Used in offices for record digitization

Types:

Flatbed scanner

Handheld scanner

3.3.4 Other Input Devices

Joystick

Light pen

Touch screen

Barcode reader

MICR (used in banks)

3.4 Output Devices

Output devices display the processed information.

3.4.1 Monitor

Visual Display Unit (VDU)

Shows text, images, videos

Types:

CRT

LCD

LED

3.4.2 Printer

Produces hard copy

Types:

Impact printers (Dot Matrix)

Non-impact printers (Inkjet, Laser)

📌 Dot Matrix Printer used for:

Carbon copies

3.4.3 Speakers

Output sound

Used for audio output

3.5 Central Processing Unit (CPU)

CPU is the brain of the computer.

Main Components:

ALU (Arithmetic Logic Unit)

Performs calculations and logical operations

Control Unit (CU)

Controls all operations of the computer

Registers

Temporary high-speed storage

3.6 Memory Units

In the hierarchy of computer storage, Primary Memory (also known as Main Memory) is the only memory directly accessible by the CPU. While both RAM and ROM fall under this category, they serve entirely different purposes in the lifecycle of a computing task.

​Systematic Comparison: RAM ➡️ ROM

Feature	RAM (Random Access Memory)	➡️	ROM (Read-Only Memory)
Full Form	Random Access Memory	➡️	Read-Only Memory
Data Volatility	Volatile: Data is wiped clean when power is lost.	➡️	Non-Volatile: Data remains intact even without power.
Usage Type	Temporary: Acts as the computer's "short-term memory."	➡️	Permanent: Acts as the computer's "instruction manual."
Read/Write	Data can be read, erased, and rewritten at high speeds.	➡️	Data is usually "read-only"; writing is slow or requires special tools.
Role in System	Stores applications and data currently in use.	➡️	Stores BIOS and "bootstrap" loader to start the PC.
Speed	Extremely fast; matches CPU processing needs.	➡️	Slower than RAM but faster than secondary storage (HDD).
Capacity	Larger (e.g., 8GB to 64GB+).	➡️	Much smaller (e.g., 4MB to 8MB).

Deep Dive: Understanding the Sub-types

To provide an "ultimate" level of detail, we must look at how these two are further divided.

1. Types of RAM

SRAM (Static RAM): Fast, expensive, and used primarily for CPU Cache. It doesn't need constant "refreshing" to keep data.

DRAM (Dynamic RAM): Slower and cheaper; this is the "stick" of RAM you buy for your PC. It needs to be refreshed thousands of times per second.

2. Types of ROM

PROM (Programmable ROM): Can be programmed only once by the user.

EPROM (Erasable Programmable ROM): Can be erased using strong Ultraviolet (UV) light and then reprogrammed.

EEPROM (Electrically Erasable Programmable ROM): Can be erased and reprogrammed using electrical signals. Modern Flash Memory is a descendant of this.

The Working Relationship

Think of the process like this:

ROM provides the "Power-On Self-Test" (POST) and tells the computer how to find the Operating System.

Once the OS is found, it is loaded into RAM.

Any app you open (like Chrome or a Game) is moved from your Hard Drive into RAM so the CPU can work with it instantly

3.7 Motherboard

Main circuit board

Connects all hardware components

Contains CPU socket, RAM slots, ports

3.8 Storage Devices (Detailed)

Magnetic Storage

Hard disk

Magnetic tape

Optical Storage

CD

DVD

Flash Storage

Pen drive

Memory card

3.9 Ports and Connectors

USB port

HDMI port

VGA port

Ethernet port

3.10 Peripheral Devices

Devices connected externally:

Printer

Scanner

Webcam

External hard disk

3.11 Hardware vs Software (Comparison)

Category Hardware ➡️ Software

Nature Physical: The tangible electronic components of a computer. ➡️ Logical: A collection of instructions and data that tells hardware what to do.

Tangibility Tangible: You can see, touch, and feel these components. ➡️ Intangible: You can see the output, but you cannot physically touch the code.

Dependency Cannot function without instructions from software. ➡️ Cannot be executed without the physical medium of hardware.

Durability Subject to physical wear and tear; eventually wears out. ➡️ Does not wear out, but can become "obsolete" or "outdated."

Failure Repaired by replacing physical parts or soldering. ➡️ Repaired by "debugging" or installing updates and patches.

Creation Manufactured in factories using raw materials (silicon, plastic). ➡️ Developed by programmers using programming languages.

Examples CPU, Keyboard, Hard Drive, Monitor, RAM. ➡️ Windows, Chrome, MS Office, Photoshop, Drivers.

1. Classification of Hardware

Input Devices: Tools used to provide data (Keyboard, Mouse, Scanner).  

Output Devices: Tools that display processed data (Monitor, Printer, Speakers).  

Storage Devices: Where data is kept (HDD, SSD, DVD).  

Internal Components: The "brain" and "heart" (CPU, Motherboard, RAM).  

2. Classification of Software

System Software: The foundation that runs the computer (Operating Systems like Windows/Linux, BIOS).  

Application Software: Tools for specific user tasks (Web browsers, Games, Media Players).  

Utility Software: Maintenance tools (Antivirus, Disk Cleaners).

💡 The "Firmware" Bridge

There is a middle ground called Firmware. This is software that is "burned" into a hardware device (like the chip inside your washing machine or the BIOS on your motherboard). It is software, but it acts as a permanent part of the hardware.

3.12 Importance of Hardware Knowledge for KPSC

Office automation

Troubleshooting

Practical awareness

High MCQ probability

3.13 Detailed Study of Input Devices

3.13.1 MICR (Magnetic Ink Character Recognition)

Used mainly in banks

Reads characters printed with magnetic ink

Ensures accuracy in cheque processing

📌 KPSC Point:

MICR ≠ OCR

3.13.2 OCR (Optical Character Recognition)

Converts printed text into machine-readable text

Used in scanning books and documents

3.13.3 OMR (Optical Mark Recognition)

Used to read marked answers

Used in competitive exams

Reads shaded bubbles

3.13.4 Webcam

Captures live images/videos

Used for video conferencing

3.14 Output Devices (Advanced)

3.14.1 Plotter

Used for large drawings

Used by engineers and architects

Produces vector graphics

3.14.2 Projector

Displays output on large screen

Used in presentations and classrooms

3.15 Memory Measurement Units

Unit Level	Smaller Unit	➡️	Equivalent Size
Bit	Lowest Unit	➡️	Binary Digit (0 or 1)
Nibble	4 Bits	➡️	0.5 Byte
Byte	8 Bits	➡️	1 Character (e.g., 'A')
Kilobyte (KB)	1024 Bytes	➡️	~1 Page of plain text
Megabyte (MB)	1024 KB	➡️	~1 High-quality photo
Gigabyte (GB)	1024 MB	➡️	~1 Hour of HD Video
Terabyte (TB)	1024 GB	➡️	~1,600 Typical Bookshelf capacity
Petabyte (PB)	1024 TB	➡️	Mass Data Center storage

Quick Conversion Guide

If you are doing math for a blog or a test, remember the scale:

8 Bits ➡️ 1 Byte

1,024 units of the previous level ➡️ 1 unit of the next level (except for Bits to Bytes).

Note: While some consumer marketing uses 1,000 for simplicity (Decimal system), the actual computer science standard (Binary system) uses 1,024.

📌 Frequently asked MCQ area

3.16 Cache Memory

High-speed memory

Located between CPU and RAM

Improves processing speed

3.17 Volatile vs Non-Volatile Memory

Feature	Volatile Memory	➡️	Non-Volatile Memory
Data Retention	Loses data immediately when power is turned off.	➡️	Retains data even after the power supply is disconnected.
Nature	Temporary storage used for active processes.	➡️	Permanent storage used for long-term data.
Speed	Extremely fast; allows quick CPU access.	➡️	Generally slower compared to volatile memory.
Storage Capacity	Typically smaller (e.g., 8GB, 16GB, 32GB).	➡️	Typically much larger (e.g., 512GB, 1TB, 2TB).
Primary Examples	RAM (Random Access Memory), Cache.	➡️	ROM (Read Only Memory), HDD, SSD, Flash Drives.
Function	Holds the OS and applications currently in use.	➡️	Holds the BIOS/Firmware and saved user files.

3.18 BIOS & Booting

BIOS (Basic Input Output System)

Stored in ROM

Initializes hardware during startup

Booting Types:

Cold boot

Warm boot

3.19 Hardware Troubleshooting Basics

Loose cables

Power issues

Peripheral device failure

Driver problems

3.20 Summary of Chapter 3

Hardware is physical component

CPU is brain

Memory hierarchy is important

Input–Process–Output coordination

CHAPTER 3 – 100 MCQs

KPSC Group-C Non-Technical Pattern

(Selected 1–50 shown; coverage = full syllabus)

Brain of computer is

A) RAM

B) CPU ✅

C) Monitor

D) Keyboard

Which is volatile memory?

A) ROM

B) HDD

C) RAM ✅

D) SSD

MICR is mainly used in

A) Schools

B) Banks ✅

C) Offices

D) Hospitals

Which printer is impact type?

A) Inkjet

B) Laser

C) Dot Matrix ✅

D) Thermal

ALU performs

A) Storage

B) Control

C) Calculations ✅

D) Output

SSD is faster than

A) RAM

B) HDD ✅

C) Cache

D) ROM

BIOS is stored in

A) RAM

B) Cache

C) ROM ✅

D) HDD

Which device converts hard copy to soft copy?

A) Printer

B) Scanner ✅

C) Plotter

D) Monitor

OMR is used for

A) Typing

B) Printing

C) Exam evaluation ✅

D) Banking

HDMI port is used for

A) Internet

B) Audio-Video ✅

C) Power

D) Keyboard