Operating System is a core set of programs that control and supervise the hardware of a computer and provide services to other system software, application software, programmers, and users of the computer.
The basic functions of today’s modern operating system are:
1. Provide a consistent interface for running programs,
2. Saving the contents of files to a disk for permanent storage,
3. Reading the contents of a file from disk into memory using open dialog box,
4. Sending a document to the printer and activating the printer,
5. Providing resources that let you copy or move data from one document to another using the features of a clipboard,
6. Allocating RAM among various programs.
7. Recognizing keystrokes or mouse clicks an displaying characters or graphics on the screen,
8. Maintain a list of files hierarchically on a disk drive using different formats of partition tables and display it using windows explorer.
9. Keeps track of different disk drives and assigns names to them,
10. Manage different types of devices attached to the computer using the feature of plug and play, such as lcd display screen, pointing device, keyboard, printer, scanner, dvd-rom, etc.
The basic characteristics of an operating system are:
1. Single-User Processing
An operating system with single-user processing allows only one user at a time to access a computer. Most operating systems, such as DOS, are single-user operating systems.
2. Multi-User Processing
An operating system with multi-users processing allows more than one user i.e. two or more users at a time to access a computer. Most operating systems, such as Microsoft Windows, UNIX, Linux, etc., are multi-user operating systems.
An operating system with the capability of single-tasking allows only one program to execute at a time, and that program must finish executing completely before the next program can begin. Such as DOS, is a single-tasking operating system provides maximum ease of use but minimum professional support.
An operating system with the capability of multi-tasking allows more than one program i.e. two or more program to execute simultaneously, and that program executing concurrently with the next program. Such as Microsoft Windows, is a multi-tasking operating system provides not only maximum ease of use but also maximum professional support.
An operating system with the capability of multi-processing allows programs to execute on two or more processors used in a computer. Many computers, such as mainframes and supercomputers, have more than one CPU and us multi-processing operating systems.
An operating system with the capability of multi-threading allows several simultaneous functions to run with a single application.
7. Time Sharing
An operating system with the capability of time sharing allows using multiple users to access a single computer operates as a super-computer.
8. Virtual Memory
An operating system with the capability of virtual memory allows using the memory of disk drive as an extension of RAM.