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Introduction To Operating System

OPERATING SYSTEM:

Introducation To Operating System
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It is a system that provides a platform to execute the application program and control the internal activities. A system is organized with different hardware component and software, the operating system helps us to interest these components to the user. There are different memories used in a system like RAM, ROM, Cache etc and it also controls by operating system the user access the application and hardware component or other resources for data processing it helps to manage and control the user instruction. It is the first program which is loaded into the computer when the system gets started. The DOS, Windows, UNIX, LINUX etc are the example of the operating system.

There are the following types of operating system:

1. Single User Operating System:

 

Input-Output Interface
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It is an operating system that allows only one user to work on a computer at a window operating system is the example of a single user.

2. Multi-User Operating System:

Multi-user os
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The operating system allows a number of users to work together or a single component it means this operating system can control more than one user and provide existing features to all. Unix, Linux is the multiuser operating system.

3. Multitasking Operating System

Multitasking os
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This is an operating system that allows the user to perform more than one task at a time. The window, Unix etc are the example o the multitasking operating system.

4. Single-tasking Operating System:

Single user os
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It is an operating system that processes the task into the system only one at a time. It means the user can execute the single job at same time. DOS operating system is an example of this operating system.

5. Real-time Operating System:

Realtime
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It is an operating system that works process and provide immediate processing and also responding to users command in short time. This operating system basically uses for the medical purpose, space vehicles control, aim plan control etc. The HP-RT is an example of this operating system.

6. Network Operating system:

Network of os
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Networking is a way to connect multiple systems for exchanging the information between connected computers. The operating system support networking concept to share the value of multiple systems. Window server etc are the example of this operating system.

7. Distributing Operating System:

DOS
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The file or data are shared between multiple systems, the o/s help us to distribute the file between multiple users for processing. This o/s provides single system image to multiple users to control the as different computer.

Processing Method Of Operating System:

1. Social Processing:

Social perception
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It is the processing of o/s that executes the task one by one in a particular order which supplied by the CPU to the system.

2. Batch Processing:

Batch Processing
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In this processing method, a  number of jobs are store together and execute in a grouped. It means the system collect different task with different users and placed into batch then process together and generate output.

3. Multi-Programming Processing:

Multiprogramming
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It is a process for managing more than one programs at a time by the CPU. The CPU runs the particular program at the same time on the base of task processing time. The CPU switches the control to another job if the existing job more time for processing. The o/s reep to CPU for managing multiprogramming process.

Services Of Operating System:

Services
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1. Processing Management:

states of process
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A process is the smallest unit of the system that executes the task and generates output. The o/s controls the processing. The CPU collects resources for an existing job like input-output devices memory to execute instructions. Unix o/s supports multiple processes at a time so it arranges the process in a particular sequence and executes one by one.

2. Memory Management:

Memory Management
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The computer uses the different type of memory like cache memory, RAM, hard disk etc that are controlled by the o/s and provide to CPU on the base of data size. It also reep to allocate and reallocate the memory and the time of job execution.

3. Input-Output Management:

I/O Management
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The system uses the different type of input-output devices like keyboard, mouse and other hardware devices etc. Operating system helps us to interact with existing components and manage like processing. It provides the resources to the user on the base of application.

4. File Management:

Management Of Files
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The data are stored in the system as the file format. The file management module of the o/s manages the files and its part and provide to the user for accessing. It maintains the file name, storage location, sharing security etc of the file.

5. Scheduling:

Scheduling
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This operating system manages multiple users and command so it uses a method to arrange the processes and execute on the base of priority that is known as scheduling.

6. Security Management:

Security
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This module of operating system software secure the data from the unauthorized user using the data security and integrity. Operating system use login process to check the authorized user and provide required data for processing.

System Call:

System Call
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The operating system is involved by application programming and provides a service to access the application with the help of system call. It allows control over system operations and direct access to hardware components and its features. System calls include RON and ABROT related scheduling. It also identified as API.

Process Management

Management of Process
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A process is the smallest limit that creates the memory at the time of creation and removes also after execution. A process is an individual identified as code, data, attribute, and state.

1. Code:

It is composed of machine instructions and operating system calls.

2. Data:

It identifies the input information for the particular task.

3. Attribute:

It includes the properties of a process like a priority, access and rights etc.

4. State:

It identifies the processing step of the o/s to execute or terminate the process.

A) Dormant state:

In this state of the process, the jobs are not known to the o/s and not tracked also. All programs not yet submitted to the o/s as well as processes in waiting and considered to be dormant.

B) Ready state:

In this processing state the o/s of an existing job. The o/s does not provide processer to CPU in this state. All ready processes are waiting to have the processor time allocated to them by the o/s.

C) Running state:

In this state, the operating system provides a processor for execution including all resources on a single processor system. Only one process can be in the running state at any point in time. The processes are arranged in a particular sequence and execute one by one in machine instructions. The operating system may return control to running processes after performing the input-output services scheduler select another process for execution.

D) Suspended state:

In this state, the operating system terminates the process due to lack of resources like input-output, processor, application etc. The input-output provide the process for getting input and return output operating system get any problem into the existing resources then terminate the running process select another which is waiting for execution.

Process Relationship:

The processes are related together to the base of its resources.

A) Competition relationship:

The processes use individual resources for execution that is known as a competitive relationship. CPU provide input-output devices memory and execution space separately to each process.

B) Co-operation relationship:

The process uses resources for executing the instructions and it shares the particular resources to another process on the base of process attribute known as co-operation relationship. It is basically used to manage the resources with multiple processes and generate output.

C) PCB:

It is the process to manage the details of the task in a particular format as rows and column format. It created by the operating system to contain process id, process name, process CPU time and help to CPU for controlling the process details.

Scheduling:

Scheduling
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It refers to a set of policies and built-in methods into the operating system to execute the process in a particular order. A schedule is a part of operating system that selects the process from the given order and provides to CPU for execution.

A) Round-robin scheduling:
Gantt Chart of RRS
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It is a scheduling method assign a time slice on each process for executing the processes are run in sequential order on given time slice. The timer is set to interrupt the operating system whenever a time slice expires and thus force the scheduler to be select another process in case of termination.

B) Preemptive scheduling:
Preemptive Scheduling
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In this scheduling method, each process is allocated a priority level. The processes are executed on the base of its priority. The operating system may remove and low priority process in running state if it gets the higher priority then existing process.

C) Non-preemptive scheduling:
Non-Preemptive Scheduling
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This scheduling method similar to preemptive scheduling to process higher priority job but it doesn’t replace lower priority process with higher at running time. This process retains the CPU until it completes its job or waits for an Input-output operation.

d) co-operating scheduling:

In this scheduling, the responsibility for releasing control its placed to the application program and not managed by operating system. The application system controls the task and executes on own responsibility.

E) FCFS Scheduling:
FCFS Gantt chart
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In this scheduling method, the workload processes in the order of first come. It means it processes those type of process which is arranged on the base of FCFS.

F) SRTF scheduling:
Example of SRTF
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In this scheduling method, the operating system checks CPU time of each process and arrange on the base of the smallest job at first position and execute it. The schedule compares the remaining process execution time of all the running and ready to run process including new process. Then provide to CPU for execution that uses minimum processing time.

Process Context Switching:

Example of Context Switching
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If the process selected by the schedule is not the currently running process the current processes must be suspended and select another process to run. The PCB also maintain the newly selected process is read and all machine states are loaded this process identified as process content switching or process swapping.

Threads:

Linux Thread
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It is a basic unit of scheduling process that holds each process and relates together with the help of program counter register, state, address_(space), stack memory etc. The processes are connected together and provide memory space for running and threads is using the process to switch from one to another. It is basically used to manage the smallest unit of the process and it execute an individual.

Memory management:

Memory management
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The system used a different type of memory like RAM, ROM, Virtual memory etc. The operating system manages all type of memory and provides to the process for executing the data are stored into memory on the base of its size, the operating system derived particular memory for particular data.

1. Virtual Memory:

Virtual memory
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It is a memory that allows managing big application with the help of RAM. It means the operating system controls the memory using hard disks when the system executed a large amount of data. The user can define the virtual memory into the system that exits the main memory at the time of processing.

2. Swapping:

Swapping in os
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The operating system used transferring method from existing block to another memory on the base of requirement. The data are stored in main memory at the time of processing the CPU, Swap, old file from main memory to secondary memory which are non-used for the long time that is not are swapping. It is basically used to manage the large size of the program to be executed is the small-sized main memory of the computer.

3. Disk And File System:

Disk and File system
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The o/s used different related file and data so it used the related directory or file structure for better existing. A file system is a structure that organizes and stores data on the computer in simplest format and easy to access. There are following directory structure:

A) Flat directory structure:
FDS
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It is a directory structure that store file in a single directory. It means multiple files related to gather and store in the single directory structure and it helps to access the related file.

B) Two-level directories:
Two level directory
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It is a directory structure that stores multiple sub-directory and related files. It means a main directory content different sub-directory them store files.

C) Three-level directories:
Three level directories
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It is a structure that stores multiple directories multiple files in the form of parent and child as hierarchical.

Security:

The operating system provides security operation to protect the data and allow to access require in function to require in user on the base of permission. The operating system identity authorized the person with the help of user and password them provide data and files.

A) External security:

It is a type of security that protects the data from outside of the computer to the system use device or networking process to check the authorized person for security purpose. The operating system checks the authorized with the help of device and provide data.

B) Internal security:

It is also security method that protects the data with the help of internal user and password. The system use application program to manage the login process at the time of system setup or opening the file to authorized person security basically used to manage multiple users and provide the required file to the authorized user on the base of permission the operating system also own security as internal to lock the file.

GUI:

GUI
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It is a process of an operating system to manage user instructions on the base of graphical icons. It means the operating system provides a graphical interface to get the response and generate output. The user can interact with a system with the help of its command get instant output. Similarly, the user can also execute the instructions using built-in icons. The operating system provides menus, buttons, radio button etc for controlling the user instructions. There are the different operating system like Linux, windows, GMU etc provide GUI features to control the user processing with the graphical interface.

Device Drivers:

Device Drivers
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It is a type of system software that manages the hardware components for exchanging the information. The external device like the printer, an input device is attached to the system then we need to install specific program for communication with the existing device that is known as the device driver. Each device contains an application program to connect with a system and help to exchange the info user and machine.

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