OPERATING SYSTEM
(PCC-CS502)
OCTOBER 17, 2025
, OPERATING SYSTEM
( PCC-CS502 )
Created by - arka dutta
🧠 UNIT 1 — INTRODUCTION TO OPERATING SYSTEMS :
1. Concept of Operating Systems :
An Operating System (OS) is a system software that controls and
coordinates the hardware and software of a computer.
It acts as an interface between the user and the hardware.
Main Functions of OS:
• Controls CPU, memory, and I/O devices.
• Provides user interface (CLI/GUI).
• Executes and manages programs.
• Allocates system resources.
• Ensures system security and error handling.
Objectives:
• Convenience: Makes computer easier to use.
• Efficiency: Uses resources effectively.
• Ability to evolve: Supports new hardware/software
easily.
• Security: Protects user data and files.
• Resource Management: Manages CPU, memory, files,
and devices
,PYQs:
• 2022 – Define Operating System and list its functions.
• 2023 – Objectives of an OS.
2. Generations of Operating Systems :
1. First Generation (1940–1950):
o No OS, programs executed manually using switches
and punch cards.
2. Second Generation (1950–1960):
o Batch Processing Systems developed.
o Jobs were collected and processed in batches, no
user interaction.
3. Third Generation (1960–1970):
o Multiprogramming and Time-Sharing OS
introduced.
o Allowed multiple programs to reside in memory
simultaneously.
4. Fourth Generation (1970–1980):
o Personal Computers introduced.
o User-friendly interfaces (MS-DOS, early UNIX).
5. Fifth Generation (1980–present):
o Network, Distributed, and Mobile OS developed.
o Support for multi-user and cloud computing
environments.
PYQs: 2022 – Write about generations of OS.
, 3. Types of Operating Systems :
Type Description Example
Executes a batch of jobs with Early
Batch OS
no user interaction. mainframes
CPU time shared among
Time-Sharing OS UNIX, Linux
multiple users; interactive.
Multiprogramming Multiple programs in memory, Windows,
OS CPU switches between them. Linux
Real-Time OS Executes tasks within strict
QNX, VxWorks
(RTOS) time limits.
Manages a group of connected Amoeba,
Distributed OS
computers as one system. LOCUS
Allows multiple users to work UNIX, Windows
Multi-User OS
simultaneously. Server
Optimized for touch-based
Mobile OS Android, iOS
devices and battery use.
PYQs:
• 2022 – Types of OS with examples.
• 2023 – Explain Time-Sharing and Real-Time OS.
(PCC-CS502)
OCTOBER 17, 2025
, OPERATING SYSTEM
( PCC-CS502 )
Created by - arka dutta
🧠 UNIT 1 — INTRODUCTION TO OPERATING SYSTEMS :
1. Concept of Operating Systems :
An Operating System (OS) is a system software that controls and
coordinates the hardware and software of a computer.
It acts as an interface between the user and the hardware.
Main Functions of OS:
• Controls CPU, memory, and I/O devices.
• Provides user interface (CLI/GUI).
• Executes and manages programs.
• Allocates system resources.
• Ensures system security and error handling.
Objectives:
• Convenience: Makes computer easier to use.
• Efficiency: Uses resources effectively.
• Ability to evolve: Supports new hardware/software
easily.
• Security: Protects user data and files.
• Resource Management: Manages CPU, memory, files,
and devices
,PYQs:
• 2022 – Define Operating System and list its functions.
• 2023 – Objectives of an OS.
2. Generations of Operating Systems :
1. First Generation (1940–1950):
o No OS, programs executed manually using switches
and punch cards.
2. Second Generation (1950–1960):
o Batch Processing Systems developed.
o Jobs were collected and processed in batches, no
user interaction.
3. Third Generation (1960–1970):
o Multiprogramming and Time-Sharing OS
introduced.
o Allowed multiple programs to reside in memory
simultaneously.
4. Fourth Generation (1970–1980):
o Personal Computers introduced.
o User-friendly interfaces (MS-DOS, early UNIX).
5. Fifth Generation (1980–present):
o Network, Distributed, and Mobile OS developed.
o Support for multi-user and cloud computing
environments.
PYQs: 2022 – Write about generations of OS.
, 3. Types of Operating Systems :
Type Description Example
Executes a batch of jobs with Early
Batch OS
no user interaction. mainframes
CPU time shared among
Time-Sharing OS UNIX, Linux
multiple users; interactive.
Multiprogramming Multiple programs in memory, Windows,
OS CPU switches between them. Linux
Real-Time OS Executes tasks within strict
QNX, VxWorks
(RTOS) time limits.
Manages a group of connected Amoeba,
Distributed OS
computers as one system. LOCUS
Allows multiple users to work UNIX, Windows
Multi-User OS
simultaneously. Server
Optimized for touch-based
Mobile OS Android, iOS
devices and battery use.
PYQs:
• 2022 – Types of OS with examples.
• 2023 – Explain Time-Sharing and Real-Time OS.
