Operating Systems

The Operating System is a program with the following features −

An operating system is a program that acts as an interface between the software and the computer hardware.

It is an integrated set of specialized programs used to manage the overall resources and operations of the computer.

It is specialized software that controls and monitors the execution of all other programs that reside in the computer, including application programs and other system software.

Objectives of the Operating System

The objectives of the operating system are −

• To make the computer system convenient to use in an efficient manner.
• 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, 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, granting resource requests, and mediating conflicting requests from different programs and users.
• To provide an efficient and fair sharing of resources among users and programs.

Characteristics of Operating System

Here is a list of some of the most prominent characteristic features of Operating Systems −

• Memory Management − Keeps track of the primary memory, i.e. what part of it is in use by whom, what part is not in use, etc. and allocates the memory when a processor program requests it.
• Processor Management − Allocates the processor (CPU) to a process and deallocates the processor when it is no longer required.
• Device Management − Keeps track of all the devices. This is also called the I/O controller that decides which process gets the device, when, and for how much time.
• File Management − Allocates and de-allocates the resources and decides who gets the resources.
• Security − Prevents unauthorized access to programs and data by means of passwords and other similar techniques.
• Job Accounting − Keeps track of time and resources used by various jobs and/or users.
• Control Over System Performance − Records delays between the request for a service and from the system.
• Interaction with the Operators − Interaction may take place via the console of the computer in the form of instructions. The Operating System acknowledges the same, does the corresponding action and informs the operation by a display screen.
• Error-detecting Aids − Production of dumps, traces, error messages, and other debugging and error-detecting methods.
• Coordination Between Other Software and Users − Coordination and assignment of compilers, interpreters, assemblers, and other software to the various users of the computer systems. In this chapter, we will see what is the Internet and Intranet, as well as discuss the similarities and differences between the two.

AVAILABLE OPERATING SYSTEMS

The most popular and widely-known operating system is Windows, a family of operating systems introduced by the Microsoft Corporation in 1985. Windows employs a graphical user interface (GUI), which eliminates the need for the user to learn complex commands. With a GUI, the user instructs the operating system by using a mouse to point and click icons that are displayed on the screen. 

The first version of Windows, released in November 1985, was designed as a GUI add-on for MS-DOS (short for Microsoft Disk Operating System), Microsoft's original command-line operating system. In order to communicate with the computer, DOS users had to type commands or instructions at a command prompt, and then the command-line interpreter executed those commands. DOS has limited use with modern computer systems and applications because it does not support multiple users or multitasking. It is also not as “user-friendly” as a GUI operating system. By the late-1990s, most command-line operating systems had been replaced by user-friendly systems using a GUI.

By the time Windows 3.1 was released in 1991, Windows had gained significantly in market share, and from the mid-1990s on, Microsoft dominated the operating-system market. Microsoft released Windows 95 in August 1995. It was so well marketed and in such high demand that people bought the operating system even if they did not own a home computer. 

With each new release, from Windows 98 to Windows 2000 to Windows XP to Windows Vista, Microsoft gained popularity. By 2004, Microsoft commanded around 90 percent of the operating-system market. The latest Windows release, Windows Vista, was introduced worldwide in January 2007, five years after the introduction of its predecessor, Windows XP—the longest time between releases of Windows. Vista is only slowly gaining in popularity, while Windows XP remains the world's dominant operating system, commanding 79 percent market share in September 2007 (compared to only 7 percent for Vista).

If you were to break up the different types of computers into categories, the most popular operating system for each category is as follows.

• Windows 7 is the most popular operating system for desktop and laptop computers.

• Android is the most popular smartphone operating system.

• iOS is the most popular tablet operating system.

• Variants of Linux are most widely used in the Internet of things and smart devices.

• Other variants of Linux are the most popular operating system on other web servers and supercomputers.