15- OPERATING SYSTEM

An operating system is a program that acts as an intermediary between a user and the computer hardware. The purpose of an operating system is to provide an environment in which a user can execute programs in comfortable and efficient manner. The operating system enables the user to use the system resources and access  several other programs effectively.

BASICS OF OPERATING SYSTEM:

An operating system (OS) is a set of system software programs in a computer that regulate the ways applications software  programs use the computer hardware and the ways that user control the computer. For hardware functions such as input/output and memory space allocation, operating system programs act as an intermediary between application program are usually executed directly by the hardware.

The job of an operating system for a computer is mainly to menage the hardware and software resources of the system. The hardware sources include processor, hard disk, memory, mouse, printer, other peripherals are the controls and executes by the help of drivers of these hardware & operating system program.

All kinds of application and utilities are runs and repairs with the help of operating system program in the computer. It provides a platform for operate the applications.

Some examples of operating systems include Apple macOS, Microsoft Windows, Google’s Android OS, Linux Operating System, and Apple iOS. Apple macOS is found on Apple personal computers such as the Apple Macbook, Apple Macbook Pro and Apple Macbook Air. Microsoft Windows is found on a variety of personal computer platforms from brands such as HP, Dell, and Microsoft itself.

FUNCTIONS OF OS:

An operating system performs the following functions:

• Processor Management: The operating system assigns processors (if a computer has more than one processor) to the different tasks that must be performed by the computer system.
• Memory Management: It allocates the main memory and secondary memor to the system programs, user programs and data.
• Input and Output Management: It carries out the input and output management and co-ordinates and assigns different input and output devices.
• File Management: -It manages files on various storage devices and the transfer of these files from one storage to another. It also allows all files to be easily changed and modified through the use of text editors or some other file manipulation software applications.
• Scheduling: It establishes and enforces the job priority. That is, it determines and maintains the order in which jobs are to be executed in the computer system.
• Timesharing: It co-ordinates and assigns compilers, assemblers, utility programs and other software applications to various users working on the computer system.
• Security Management: It establishes data security and integrity. That is, it keeps different programs and data in such a manner that they do not interfere with each other. Moreover, it also protects data from being destroyed by wrong user.
• It produce dumps, traces, error messages and other debugging and error-detecting codes.
• It maintains internal time clock and log of system usage for all other users.
• If facilities easy communication between the computer system and the computer operation (Human).

TYPES OF OPERATING SYSTEM:

All Operating System can be classified into four categories:

1- Single User and Single task Operating System:

An operating system that allows a single user to perform only one task at a time is called a Single-User Single-Tasking Operating System. Functions like printing a document, downloading images, etc., can be performed only one at a time. Examples include MS-DOS, Palm OS, etc.

2- Single User and Multitask Operating System:

An operating system that allows a single user to perform more than one task at a time is called Single-User Multitasking Operating System. Examples include Microsoft Windows and Macintosh OS.

3- Multi User and Multitask Operating System:

Multi User and Multitasking operating system is a powerful operating system that supports more than one user at a time, performing more than one task at a time, UNIX, LINUX are the example of a multi User and multitasking operating system.

4- Real Time Operating System:

A real-time operating system, or RTOS, is a type of operating system that is specialized for use in electronic control systems. An operating system is the software at the heart of a computer system upon which all the other software depends. The operating system controls the allocation of all of a computer system's resources, such as processor cycles, memory, communications, and security. The operating system must satisfy the competing demands for resources required by the many different functions that the computer is supposed to perform. The operating system is the most critical software in any computer system. If the operating system does not work, nothing else will work.

Examples of the real-time operating systems: Airline traffic control systems, Command Control Systems, Airlines reservation system, Heart Peacemaker, Network Multimedia Systems, Robot etc. Hard Real-Time operating system: These operating systems guarantee that critical tasks be completed within a range of time.