In this post we will share definition of operating system, type of OS ,Features and Examples.
What is an Operating System?
An operating system (OS) is a set of programs that control the execution of application programs and act as an intermediary between a user of a computer and the computer hardware. OS is software that manages the computer hardware as well as providing an environment for application programs to run.
Examples of OS are: Windows, Windows/NT, OS/2 and MacOS.
Functions of Operating System
The operating system manages computer resources, especially the allocation or assignment of the resources among other programs. Management tasks include
scheduling the resources to avoid conflicts and interference between programs.
Process Management
We know that a program is a set of logical instructions given to the computer. A program that is in an execution state is called a process. For example, a word processing program like MS-Word being run by a user on a personal computer is a process. A system task, such as sending output to a printer, can also be a process.
A process needs certain resources-such as CPU time, memory, files and I/O devices to accomplish its tasks. These resources are allocated to the process either when they are created or while they are executing. The operating system helps in the allocation of resources to each process. The most critical task for an operating system is allocation of the CPU time. The operating system is responsible for creation, deletion, and scheduling of various processes that are being executed at any point of time.
Memory Management
A computer program remains in main (RAM) memory during its execution. To improve CPU usage several processes are being executed simultaneously in the
memory. The OS keeps track of every memory location, that is either assigned to some process or is free. It also checks how much memory should be assigned to
each process.
Input/Output Management
Humans interact with machines by providing information through input output devices. Management of input/output (I/O) devices is one of the most important
functions of an operating system. A few examples of the variety of input/output devices on a modern computer are- mouse, keyboards, disk drives, USB devices,
I/O, printers, special devices for the physically challenged, etc. Operating system provides a generic, consistent, convenient and reliable way to access I/O
devices.
OS responds to the user keystrokes, mouse clicks and other input formats. It then interprets the I/O requests so that requested input/output functions can be
performed. For this the operating system requires device driver software to interact with a particular hardware device.
File and Disk Management
Computer systems have secondary storage devices like magnetic disk, magnetic tape, optical media, flash drives, etc. for permanent storage of programs and data.
The programs and the user data are stored in files. In general, a file is a sequence of bits, bytes, lines or records. The operating system is responsible for allocating
space for files on secondary storage media. A file, especially a large file, may or may not be stored in a contiguous location on a physical disk drive. If the file is of
large size, it is fragmented into smaller pieces. The OS then keeps track of the memory location allocated to each piece of the file on the storage disk.
The operating system is thus responsible for the organization of the file system. It guarantees that the read and write operations performed on the secondary storage
device are secure and reliable. The operating system must be able to read, write and search each file whenever it is required, keeping the access time to the
minimum. Operating systems like DOS, Windows, Macintosh and Unix follow the hierarchical structure to store files and folders, e.g. in case of windows, a file is
placed in the desired folder or a subfolder
User Interface
A User Interface (UI) is the part of an operating system, program or device that the user uses to input and receive data. A Text User Interface (TUI) or Command Line Interface (CLI) allows users to interact with an operating system by typing commands in a terminal or console window. The users type a command or series of commands for each task they want to perform on a visual prompt. Examples of command line based operating systems are DOS (Disk Operating System), and UNIX etc.
Graphical User Interface (GUI) is an easy to use interface. It uses graphics, along with a keyboard and a mouse, to provide an easy-to-use interface to a
program. A GUI makes interaction for the user easy with the operating system or applications because it provides you with features like pull-down menus, buttons,
scrollbars, iconic images, wizards and other icons. Examples of GUI operating systems are Windows, Linux, and Solaris.
Operating systems have been evolving through the years. Following table shows the history of OS.
