Subject: – OS (Operating System)

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#Define Operating System: –

-An Operating System is a program that act as an interface the user and the computer hardware and control the execution of all kinds of program.

-Operating system manage overall function of computer system such as fill management, security management and input/output management etc.

-Example of OS: – MS Dos, Windows-7,8,10, Windows 95, Windows 98, Windows 2000 Server Linux, and Unix etc.

-An operating system is the system software that control and manage overall of computer system to perform of tasks.

#Function of Operating System: –

  • Memory Management
  • Process Management
  • Device Management
  • Files & Folder Management
  • Security Management
  • Input & Output Management
  • Control Over System Performance 

1. Memory Management: –

–Memory management refer to management of primary or main memory. Main memory is large array of word or bytes. Where each word or byte has its own address.

-Main memory provide a fast storage that can be accessed directly by CPU.

-Keeps tracks of primary memory

-In multiprogramming, the OS decides the which process will get memory when and how much allocate the memory when a process requested to do.

-De-allocate the memory when a process no longer need its or has been terminated.

2. Process Management: –

-The operating system tasks that must be performed by computer system.

3. Device Management: –

-Operating system performs the tasks of allocates and de-allocate of the device.
-Operating system co-ordinates with all devices like keyboard, printer, monitor, mouse etc.

4. File and Folders Management: –

-Operating system manage all file in computer.
-It keeps record of file name, type, size, location etc.

5. Security Management: –

-Operating system provide a security mechanism while using computer for example password is used in a system to prevent an authorized access.

6. Input & Output Management: –

–etc so the Operating System help to manage input, process, and output devices.

7. Control Over System Performance: –

–Recording delays between request for a service and response from the system.

8. Co-ordination between other S/W and User: –

-Co-ordination and assignment of compiler, interpreter, assemblers and other software to the various users of computer system.

Types of OS

#Based on Processing Method: –

  • Batch operating System
  • Time Sharing Operating System
  • Multi-Processor Operating System
  • Multi-Tasking Operating System
  • Real Time Operating System
  • Distributed Operating System

a) Batch Operating System: –

(i) The User Of Batch operating system do not interact with the computer directly
(ii) Each user prepares his job on off-line device like punch cards and submits it to the computer operator
Eg: – Payroll system, Bank statements, etc.

b) Time Sharing Operating System: –

(i) Time sharing is a technique which enables many people, located at various terminals, to user a particular computer at the same time
(ii) Provides the advantage of Quick response.

c) Multi-Processor Operating System: –

(i) multi-Processor operating system are also known as parallel OS
(ii) A operating system have more than one Processor.

d)  Multi-Tasking Operating System: –

(i) Multi-tasking term used in a modern computer system. It. is a logical extension of a multiprogramming system that enables the execution of multiple programs simultaneously
(ii) In an operating system, multitasking allows a user to perform more than one computer task simultaneously.

e) Real-Time Operating System: –

(i) These types of OSs serve real-time systems
(ii) The time interval required to process and respond to inputs is very small
(iii) This time interval is called response time
(iv) Real-time system are used when there are time requirements that are very strict like missile systems, air traffic control systems, robots etc.

f) Distributed operating system: –

(i)  Distributed system contains multiple nodes that are physically separate but linked together using the network.
(ii) All the nodes in this system communicate with each other and handle processes in tandem. 
(iii) each of these nodes contains a small part of the distributed operating system software.

#Types of operating system on the basis user interface: –

(i) Command user interface

(ii) Graphical user interface

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