1. Operating System
Introduction

2. Overview
Definition
Process
Types of OS
Kernal

3. Definition It is a system software.
It is an interface between user /application program and hardware.
It provides environment to application program so that they can run effectively and efficiently in the system.

4. Operating System Services
Process Management:
Create process
Delete process
Schedule process
Detect deadlock and avoid.
File system:
Allocate secondary memory to files.
Read / write from Secondary memory.
Memory Management:
Allocate memory
Deallocate memory
Memory protection

5. Process PCB Program under execution. PCB: Process Control Block CODE
DATA
Stack
To manage a process PCB is created.
It has information about the activities of a process.
It is a data structure.

6. Types of Operating Systems
Batch OS
Multi program OS
Multitasking OS
Multi tasking OS
Distributed OS

7. Batch Operating System
Job 1
Job 2
Job 3
Job 4 .
Job n
Operating System
Batch 3
Batch 1
Batch 2
CPU
OS runs jobs in a batch.
All the jobs are run without any manual intervention.
Jobs are run on FCFS basis.
Advantages
Increased performance
Less overhead on operator
Disadvantages
No intervention allowed
Debugging is difficult.

8. Multitasking OS When multiple jobs are executed by CPU simultaneously.
Switching occurs so fast that user can interact with all of the programs.
Need Scheduling Algorithms.
Time-shared operating systems
Operating System
Word
Browser
CPU

9. Multi Program OS Many jobs are loaded to main memory simultaneously.
Single shared processor.
High CPU utilization.
Memory management is required.

10. Distributed OS Multiple independent CPUs in an OS. S1
File sharing, Printer sharing can be done in distributed OS.
Communication is done through communication lines.
Each processor has its own memory.

11. Kernal It is a core of Computer’s OS.
It is one of the first programs loaded on start-up.
It is a set of critical services.
It performs it’s tasks in protected kernal space.
There are two types of kernals:
Monolothic Kernal
Micro Kernal

12. Monolithic Kernal
It is an OS architecture where the entire operating system including critical and non critical services reside in the kernal itself.
Everything like device drivers, file systems etc. work in the kernal space.
Disadvantage is : bug in one part may crash the whole system.

13. Micro Kernal
It is an architecture in which the core functionality is isolated from rest of the services.
It is comparatively hard to implement and debug.

14. Thank You