Operating system

It is integrated set of specialized program that to manage the resource and overall operations of the computer. It acts as the as the mediator between hardware and the computer application programs 

Operating system software makes a computer easier to use . it hides the details of hardware resources from users and provides them with a convenient interface for using a computer system . pt acts as an intermediary between hardware and its users providing a high level interface to use to those resources.

 Operating system softer manages all the resources of a computer system. This involves preforming such tasks as keeping track of who is using what resources granting resources request accounting for resource uses and mediating conflicting request from different programs and users. Efficient and fair sharing of system resources between users and hardware programs is  the main function of any operating system  software.

Features of operating systems are as follows: 

* To make a computer  system  convenient to use in an efficient 

* To hide the details of the hardware resources from the users 

* To provide users a convenient interface to use the computer system

* To act as an intermediary between the hardware and its users and making it easier for the users to access and use other resources 

* To manage the resources of  a computer system 

* TO keep track of who is using which resource using and mediating conflicting requests from different programs and users .

Function of OS

1. IO Management:

            Input/output(IO) is essential to operation of any computer. It allows computer to interact with peripheral devices such as keyboard, mouse,, terminals(like modem, TV card) etc.

2. Command Interpreter:

            The command interpreter reads the commands that a user types in at a computer hardware can understand. It varies widely from one OS to another. Every OS must provide command interpreter for its operation.

3. Data Management:

            Data management allows organizing their data into logical groupings called files. Earlier, only few OS provided data management, containing limited flexibility and usefulness.

4. Memory Management:

            Memory is a large array of words or bytes, each with its own address. When the user requests CPU for read/write operation, OS determines the amount of memory required for the program instructions and data into RAM.

5. Process Management:

            The process management allocates a processor to execute a chosen process. It finds the status of processors and processes (Traffic controller), chooses a job(Job scheduler), and chooses the process in the job when the processor is executed.

6. Device Management:

            The device management allocates a device to a process. It finds the status of the device, channels, and control units, finds answers to questions like which process, which device- how much and allocates the device to the process.

7. File Management:

            The file management keeps track of all information on files. It opens and closes files. It finds and records the following for all files: location, size, usage (attributes) status etc. It also finds as to which process wants which files, checks through the protection routine, opens the files if allowed, and allocates it to process.

8. Time Sharing:

            Time sharing management, a function of OS, involves the CPU to allocate time to a number of users on the same computer, property generally found in network operating system. As the number of users increase the response time for each terminal declines. Time sharing creates the illusion to the each user such that they are sole user of the system because the speed of the CPU compared to that of the monitor and terminal is so much faster thereby giving each time slice for each user to operate the program interactively.

9. Deadlock Prevention:

            During processing, a situation can arise in which a resource (hardware or software) shared by two of more processes cannot continue because the resource required by a process is held by another. This situation is known as deadlock.

10. Interrupt Handling:

             An interrupt is a signal generated from a device attached to a computer or from a program within the computer that causes the main program that operates the computer (the operating system) to stop and figure out what to do next. It is the event that makes the processor stop executing its program to perform some requested activity.