Operating System
An operating system is a program that acts as an interface between the user of a computer and the computer hardware. The purpose of operating system is to provide an environment in which a user can execute programs in a convenient and efficient manner.
Operating system is a first program that gets loaded into the memory through a process called booting.
Its primary objective is to improve the performance and efficiency of a computer system and make it user friendly.
Its secondary objective is to manage the resources of computer.
Functions of operating system
- Process Management
- Main Memory Management
- Secondary storage Management
- File Management
- I\O Management
- Protection and Security
- Networking
- Command Interpretation
Operating System Services
- Program Execution
- I|O operations
- File system Manipulation
- Communication
- Error Direction
- Resources Allocation
- Accounting
- Protection
Classification of operating system
- Single user operating system
- Multi-user operating system
- Batch operating system
- Multiprogramming operating system
- Multitasking operating system
- Multiprocessing operating system
- Timesharing OS
- Real time OS
- Distribued system
Single user operating system
In Single user operating system , a user can access the computer at a particular time. The computer , that are based on this operating system, have only single processor and execute only a single program at all the time.
Single user operating system is of two types
- · Single user, single –tasking operating system
- · Single user, multi- tasking operating system
Single user, single –tasking operating system
This operating system allows a single user to execute one program at a particular time
Example MS- DOS and Palm OS
Single user, multi- tasking operating system
This operating system allows a single user to execute multiple programs at a same time.
Multi-user operating system
In this multiple number of users can access different resources of a computer at a same time. The access is provided using a network that consist of various personal computers attached to a mainframe computer system.
Example UNIX, Window 2000
Batch operating system
it is one of oldest method of running the programs. The users did not interact directly with computer system. The users prepare their job that consisted of the programs, data and some control information . This job was usually in form of punched cards. Users submit their job to a computer operator, when a batch of programs have been collected, the operator loads this batch of programs into the computer at one time where they are executed one after the after
The batch operating system was called a monitor that resides in the main memory is known as resident monitor
Multiprogramming operating system
It is used for multi – user systems i.e the systems that are used by many users at the same time.
It refers to the concurrent execution of multiple jobs that may be of same user or different users.
Requirements of multiprogramming os
- · Large Memory
- · Memory Protection
- · Job status Preservation
- · Proper job Mix
- · CPU Scheduling
Multitasking operating system
It is used for single user systems I,e the systems that are used by only one user at a time. It refers to the concurrent execution of multiple jobs of a same user.
Types of Multitasking operating system
- · Cooperative Multitasking
- · Pre-emptive Multitasking
Multiprocessing operating system
This concept is implemented in systems with multiple processors. Multiprocessing refers to the simultaneous execution of two or more processes by system with multiple processor.
In multiprocessing , several programs segments of one or more programs are executed simultaneously
Multiprocessing systems are cateforized into two different types
- · Symmetric multiprocessing
- · Asymmetric multiprocessing
· Timesharing OS
The time sharing system executes one job up to certain period of time and then switches to another job and so on. Concepts like job scheduling, memory swapping are used for handling timesharing systems.It seems to execute many jobs at the same time. It is impossible to predict response in advance in timesharing system
Real time OS
This OS has well defined fixed time constraints, process must be done within the defined constraints or system will fail. It execute one jon dedicatedly. Real time OS give users the ability to prioritize tasks so that the most critical task can always take control of the process when needed
Real time OS are categorized into two different types
- · Soft real-time OS
- · Hard real-time OS
· Distributed system
A distributed system is a collection of processors located in geographical dispered physical location. In this the workload is distributed or divided between two or more computers that are linked together by a communication network. That is the different processors communicate using communication links, such as telephone lines and buses.
thanks your for spread article on Functions of Operating system.
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