PPT on Kernel of an Operating System.

1. KERNEL OF OPERATING SYSTEM
By - Kanan,Kirti& Sumit

2. 1. OS Architecture
2. OS & Kernel as a Window
3. What is Kernel
4. Diagrams Explanation
5. Responsibilities of Kernel
6. Kernel Mode vs User Mode
7. Necessity of Dual Mode
GLOSSARY

3. After this presentation, we will be able to answer
the following questions -
1. Why OS & Kernel act as a Window to the User ?
2. How OS Architecture looks ?
3. What is Kernel ?
4. What are the responsibilities of Kernel ?
5. How to differentiate between Kernel Mode & User Mode ?
6. What is the necessity of Dual Mode in OS ?
OBJECTIVE

4. Window
OS
User
Kernel
Devices
Hardware
Software

5. OS Architecture
1
2
3

6. K E R N E L
Kernel is the core component of Operating System where actual
code
and functionality of OS lies.
It is responsible for scheduling
running of user and
other processes.
It is responsible for allocating
memory.

8. Responsibilities of KERNEL
Device Management :
A system has many devices connected to it like CPU, a memory device, sound cards, graphic cards, etc.
A kernel stores all the data related to all the devices in the device driver
( without this kernel won't be able to control the devices ).
Thus kernel knows what a device can do and how to manipulate it to bring out the best performance.
It also manages communication between all the devices.
The kernel has certain rules that have to be followed by all the devices.
Handling system calls :
Handling system calls means a programmer can write a query or ask the kernel to perform a task.

9. Responsibilities of KERNEL
Memory management :
Another function that kernel has to manage is the memory management.
The kernel keeps track of used and unused memory and makes sure that processes
shouldn't manipulate data of each other using virtual memory addresses.
Process management :
In the process management, kernel assigns enough time and gives priorities to
processes before handling CPU to other processes.
It also deals with security and ownership information.

10. In Kernel Mode
The system starts in kernel mode when it boots and after the operating
system is loaded, it executes applications in user mode.
There are some privileged instructions that can only be executed
in kernel mode.
These are interrupt instructions, input output management etc.
If the privileged instructions are executed in user mode,
it is illegal and a trap is generated.
The mode bit is set to 0 in the kernel mode.
It is changed from 0 to 1 when switching from kernel mode to user mode.
KERNEL MODE Vs USER mode

11. KERNEL MODE Vs USER mode
In User Mode
The system is in user mode when the operating system is running
a user application such as handling a text editor.
The transition from user mode to kernel mode occurs when
the application requests the help of operating system or an interrupt or a system call occurs.
The mode bit is set to 1 in the user mode. It is changed from 1 to 0
when switching from user mode to kernel mode.

12. KERNEL MODE Vs USER mode
Kernel mode is used to perform lower level functionalities
& in user mode, the code has no access to hardware
or lower level resources like memory.
The kernel (which is the core of the OS and
has complete control over everything that occurs
in the system) is trusted software.
User Mode, A non-privileged mode for user programs,
that is, for everything other than the kernel.

13. Necessity of Dual Mode in Operating System
The lack of a dual mode i.e. user mode and kernel mode in
an operating system can cause serious problems.
Some of these are −
• A running user program can accidentally wipe out the operating
system by overwriting it with user data.
• Multiple processes can write in the same system at the same time, with
disastrous results.
These problems could have occurred in the MS-DOS operating system which had
no mode bit and so no dual mode.

14. 1. Kernel is heart of operating system.
2. To be sure, the kernel has unique qualities.
It enforces its own rules and stakes.
3. There are various responsibilities of kernel like managing devices,
Handling system call , managing memory and different process
also.
4. Both the modes are very important for OS and are dependent
on each other.