The document provides an overview of operating systems, detailing their definition, goals, and the structure of computer systems. It classifies different types of operating systems such as batch systems, time-sharing systems, and distributed systems, discussing their unique features. Additionally, it explains the layered approach of operating system architecture and the various services they provide, such as program execution and resource allocation.

1. Mr Satyendra Mohan Srivastava JIT Barabanki

2. Mr Satyendra Mohan Srivastava, JIT Barabanki
Chapter 1: Introduction
 What is Operating System
 Computer System Structure
 Diagrammatic representation of a Computer System
 Operating System: Viewpoints
 Few important points
 Classification of OS
 Computer startup
 OS Layered approach
 System component
 OS services
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3. Mr Satyendra Mohan Srivastava, JIT Barabanki
Operating
System
 An Operating System is a program that acts as an
intermediate b/w the computer hardware and the user of a
computer
 An Operating System is a program that manages the
computer hardware
 Operating system goals
Convenience for the user
Efficiency
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4. Mr Satyendra Mohan Srivastava, JIT Barabanki
Computer System Structure
Computer system is mainly divided into four
components:
• Hardware
Memory, CPU and I/O devices
• Operating system
Coordinates and controls the use of hardware
• Application programs
Word processors, web browsers, compilers, database
systems and video games
• Users
Machines, people and other computers
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5. Mr Satyendra Mohan Srivastava, JIT Barabanki
Operating System:
Viewpoints
Operating System can be understood by following point
of views:
 User View
 System View
• USER VIEW
User emphasizes on ease of use, convenience, little on performance
and none to resource utilization
• SYSTEM VIEW
Resource allocator - Hardware and Software
Control Program – Manages the execution of user programs(errors
and improper use)
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6. computer hardware
Mr Satyendra Mohan Srivastava, JIT Barabanki
Diagrammatic representation of a
Computer System
User
3
… User
n
User
1
User
2
operating system
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compiler assembler text editor … database
system
system and application programs

7. Mr Satyendra Mohan Srivastava, JIT Barabanki
Diagrammatic representation of a
Computer System
User
3
… User
n
User
1
User
2
01/19/17 7
compiler assembler text editor … database
system
system and application programs
operating system
computer hardware

8. Mr Satyendra Mohan Srivastava, JIT Barabanki
Few Important Points
• Kernel is only program running all the time on the computer
system
• Other program will be an application program or system
program
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9. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
System
 Batch Systems
 Interactive Systems
 Multiprogrammed Systems
 Time Sharing Systems
 Desktop Systems
 Multiprocessor Systems
 Distributed Systems
 Client Server Systems
 Peer to Peer Systems
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10. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
Systems Conti…
 Real Time Systems
 Clustered Systems
 Interactive System
 Multiuser System
 Multithreaded System
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11. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
Systems Conti…
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 Batch System
 Job(Program, Data & Information) in job pool
 All job are kept in job pool
 Submit to the Job operator
 Operators together jobs(batch) as a group
 The output send back to appropriate program
 Disk technology allowed OS to keep all jobs on a disk
 OS perform job scheduling
 Multiprogrammed System
 Goal: To maximize the CPU load
 Atleast one job needs to execute, CPU never sit idle
 Job Scheduling

12. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
Systems Conti…
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 Time-Sharing or Multitasking System
 It is one of the extension of Multiprogramming
 The executable multiple jobs with short frequency time while running
 Minimum response time
 Resources are shared in many users
 CPU scheduling and Multiprogramming are mechanism for its
implementation
 Multiprocessor or Parallel or Tightly coupled Systems
 More than one processor with shared bus, clock, peripheral devices
 Sometimes even memory
 Advanages: Increased throughput, Economy of sale, Increased
reliability

13. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
Systems Conti…
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 Distributed System
Client-Server System
 Centralized systems act as server systems
 Server system satisfies the request generated by client
N/W
ClientClient Client Client
Server
Basic Client Server Architecture

14. Mr Satyendra Mohan Srivastava, JIT Barabanki01/19/17 14
Classification of Operating
Systems Conti…
 Peer-to-Peer Systems
 Clustered System
 Grouping of requirement
 Real-Time System
 Rigid time requirement
 Type: Hard and Soft real-time system
 Interactive System
 Provide interaction between Human and Computer system

15. Mr Satyendra Mohan Srivastava, JIT Barabanki
Classification of Operating
Systems Conti…
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 Multiuser System
 Concurrent access by multiple users
 Multithreaded System
 A thread is a lightweight process
 A thread is a flow of execution
 Goal: Parallelism

16. Mr Satyendra Mohan Srivastava, JIT Barabanki
Computer Startup
 Booting
The procedure or mechanism of starting a computer by loading Kernel
 Bootstrap program
 loaded at reboot or power-up
 stored in ROM or EPROM
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17. Mr Satyendra Mohan Srivastava, JIT Barabanki
Operating System Structure
Layered Approach
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 Operating System is divided or broken down into levels (layers)
 Built on top of lower layer
 The bottom layer (lower layer 0) is hardware and the highest layer is the
user interferences
 The Data Structures and a set of routines at the top layer can invoke
operations on lower layer
 Each layer hides some operations, certain data structures and hardware
from higher level layers

18. Mr Satyendra Mohan Srivastava, JIT Barabanki
Operating System
Structure Layered
Approach
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Hardware
Kernel
Program
Layered Architecture
 Modularity
 Simplifies debugging(errors)
 System verification
Advantage
:

19. Mr Satyendra Mohan Srivastava, JIT Barabanki
System Component
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 Process Management
 Main Memory Management
 File Management
 I/O System Management
 Secondary Memory Management
 Networking
 Protection System
 Command Interpreter System

20. Mr Satyendra Mohan Srivastava, JIT Barabanki
Operating System Services
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There are five type of services provided by operating system:
 Program Execution
 I/O Operations
 File System manipulation
 Communications
 Error detection
 Resource allocation
 Accounting
 Protection

21. Mr Satyendra Mohan Srivastava, JIT Barabanki
Any Question….
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