📙CHAPTER 1: OPERATING SYSTEM
1.1 Introduction
De nition:
An operating system is the basic so ware that controls the
computer and helps users run programs.
Example:
Windows sta ing when you turn on the computer.
Applications:
• Controls hardware
• Runs so ware
• Helps user interact with computer
1.1.1 Operating System
De nition:
An operating system (OS) is so ware that acts as a bridge
between user and computer hardware.
Example:
Windows, Linux, Android.
Applications:
• File management
• Memory management
• Process control
1.1.2 Commonly Used Operating Systems
De nition:
Operating systems that are widely used on computers and
mobiles.
Examples:
Windows, Linux, macOS, Android, iOS.
Applications:
• Personal computers
• Mobile phones
• Servers
,1.1.3 Types of Operating System
De nition:
Di erent kinds of operating systems designed for di erent
purposes.
Examples:
Single-user OS, Multi-user OS, Real-time OS.
Applications:
• Home computers
• O ce systems
• Industrial machines
1.1.4 Single-User and Multi-User Operating Systems
De nition:
Single-user OS allows one user at a time, multi-user OS allows
many users at once.
Examples:
Single-user: Windows
Multi-user: Linux server
Applications:
• Personal use
• Network systems
1.2 Operating System Functions
De nition:
Tasks pe ormed by OS to manage computer resources.
Examples:
Memory management, le handling.
Applications:
• Controls CPU
• Manages storage
• Provides security
1.3 Process Management
1.3.1 Process De nition
,De nition:
A process is a program that is currently running in the computer.
Example:
Opening Microso Word.
Applications:
• Program execution
• CPU scheduling
1.3.2 Various States of a Process
De nition:
Di erent stages through which a process passes during execution.
States:
New, Ready, Running, Waiting, Terminated
Applications:
• E cient CPU use
• Process control
1.3.3 Thread and Process
De nition:
A process is a full program, a thread is a small pa of a process.
Example:
Browser (process) with multiple tabs (threads).
Applications:
• Faster execution
• Resource sharing
1.3.4 Multithreading
De nition:
Running multiple threads within one process at the same time.
Example:
Downloading and browsing together in a browser.
Applications:
• Improves pe ormance
• Saves time
, 1.3.5 Multitasking
De nition:
Running more than one program at the same time.
Example:
Listening to music while typing in Word.
Applications:
• Be er productivity
• Time management
1.3.6 Multiprogramming
De nition:
Multiple programs are kept in memory and executed one by one
by CPU.
Example:
Printing, typing, and calculations handled together.
Applications:
• E cient CPU usage
• Reduced idle time
📙CHAPTER 2: SYSTEM DEVELOPMENT LIFE CYCLE
2.1 System Development Life Cycle
De nition:
SDLC is a step-by-step process to develop a computer system or
so ware.
Example:
Making a school management so ware.
Applications:
• So ware development
• System planning
2.1.1 A System
1.1 Introduction
De nition:
An operating system is the basic so ware that controls the
computer and helps users run programs.
Example:
Windows sta ing when you turn on the computer.
Applications:
• Controls hardware
• Runs so ware
• Helps user interact with computer
1.1.1 Operating System
De nition:
An operating system (OS) is so ware that acts as a bridge
between user and computer hardware.
Example:
Windows, Linux, Android.
Applications:
• File management
• Memory management
• Process control
1.1.2 Commonly Used Operating Systems
De nition:
Operating systems that are widely used on computers and
mobiles.
Examples:
Windows, Linux, macOS, Android, iOS.
Applications:
• Personal computers
• Mobile phones
• Servers
,1.1.3 Types of Operating System
De nition:
Di erent kinds of operating systems designed for di erent
purposes.
Examples:
Single-user OS, Multi-user OS, Real-time OS.
Applications:
• Home computers
• O ce systems
• Industrial machines
1.1.4 Single-User and Multi-User Operating Systems
De nition:
Single-user OS allows one user at a time, multi-user OS allows
many users at once.
Examples:
Single-user: Windows
Multi-user: Linux server
Applications:
• Personal use
• Network systems
1.2 Operating System Functions
De nition:
Tasks pe ormed by OS to manage computer resources.
Examples:
Memory management, le handling.
Applications:
• Controls CPU
• Manages storage
• Provides security
1.3 Process Management
1.3.1 Process De nition
,De nition:
A process is a program that is currently running in the computer.
Example:
Opening Microso Word.
Applications:
• Program execution
• CPU scheduling
1.3.2 Various States of a Process
De nition:
Di erent stages through which a process passes during execution.
States:
New, Ready, Running, Waiting, Terminated
Applications:
• E cient CPU use
• Process control
1.3.3 Thread and Process
De nition:
A process is a full program, a thread is a small pa of a process.
Example:
Browser (process) with multiple tabs (threads).
Applications:
• Faster execution
• Resource sharing
1.3.4 Multithreading
De nition:
Running multiple threads within one process at the same time.
Example:
Downloading and browsing together in a browser.
Applications:
• Improves pe ormance
• Saves time
, 1.3.5 Multitasking
De nition:
Running more than one program at the same time.
Example:
Listening to music while typing in Word.
Applications:
• Be er productivity
• Time management
1.3.6 Multiprogramming
De nition:
Multiple programs are kept in memory and executed one by one
by CPU.
Example:
Printing, typing, and calculations handled together.
Applications:
• E cient CPU usage
• Reduced idle time
📙CHAPTER 2: SYSTEM DEVELOPMENT LIFE CYCLE
2.1 System Development Life Cycle
De nition:
SDLC is a step-by-step process to develop a computer system or
so ware.
Example:
Making a school management so ware.
Applications:
• So ware development
• System planning
2.1.1 A System
