Types Of Operating Systems Computer Science Essay

An operating system, or OS, is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer would be useless.

In computing. operating system (OS) linked between hardware and user, which is responsible for the management and coordination of activities and the sharing of the resources of a computer, that acts as a host for computing applications run on the machine. One of the purposes of an operating system is to handle the resource allocation and access protection of the hardware. This relieves the application programmers from having to manage these details.

Explanation

At the simplest level, an operating system does two things:

It manages the hardware and software resources of the system. In a desktop computer, these resources include such things as the processor, memory, disk space and more (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the network connection).

It provides a stable, consistent way for applications to deal with the hardware without having to know all the details of the hardware.

Operating systems offers many services to application programs and usersApplications

access these services through application programming interfaces (APIs) or system calls. By invoking these interfaces, the application can request a service from the operating system, pass parameters, and receive the results of the operation. Users may also interact with the operating system with some kind of software user interface like typing commands by using command line interface (CLI) or using a graphical user interface. For hand-held and desktop computers, the user interface is generally considered part of the operating system. On large multi-user systems such as Unix-like systems, the user interface is generally implemented as an application program that runs outside the operating system.

Types of Operating Systems

As computers have progressed and developed so have the types of operating systems. Below is a basic list of the different types of operating systems.

Within the broad family of operating systems, there are generally four types, categorized based on the types of computers they control and the sort of applications they support. The categories are:

1.Real-time operating system (RTOS) – Real-time operating systems are used to control machinery, scientific instruments and industrial systems. An RTOS typically has very little user-interface capability, and no end-user utilities, since the system will be a “sealed box” when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time, every time it occurs. In a complex machine, having a part move more quickly just because system resources are available may be just as catastrophic as having it not move at all because the system is busy.

2. Single-user, single task – As the name implies, this operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system.

3. Single-user, multi-tasking – This is the type of operating system most people use on their desktop and laptop computers today. Microsoft’s Windows and Apple’s MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it’s entirely possible for a Windows user to be writing a note in a word processor while downloading a file from the Internet while printing the text of an e-mail message.

4. Multi-user – A multi-user operating system allows many different users to take advantage of the computer’s resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn’t affect the entire community of users. Unix, VMS and mainframe operating systems, such as MVS, are examples of multi-user operating systems.

Examples of most popular operating systems :

Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops, and media centers. It was released in 2001. The name “XP” is short for “eXPerience”.[3]

Windows XP is the successor to both Windows 2000 Professional and Windows Me, and is the first consumer-oriented operating system produced by Microsoft to be built on the Windows NT kernel and architecture. Windows XP was first released on October 25, 2001, and over 400 million copies were in use in January 2006, according to an estimate in that month by an IDC analyst.[4] It was succeeded by Windows Vista, which was released to volume license customers on November 8, 2006, and worldwide to the general public on January 30, 2007. Direct OEM and retail sales of Windows XP ceased on June 30, 2008. Microsoft continued to sell XP through their System Builders (smaller OEMs who sell assembled computers) program until January 31, 2009.[5][6] XP may continue to be available as these sources run through their inventory or by purchasing Windows Vista Ultimate or Business and then downgrading to Windows XP.

MS-DOS

MS-DOS is an operating system for x86 based personal computers, which was purchased by Microsoft. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for personal computers during the 1980s[citation needed] and 1990s. It was preceded by M-DOS (also called MIDAS), designed and copyrighted by Microsoft in 1979. MSDOS was written for the Intel 8086 family of microprocessors, particularly the IBM PC and compatibles. It was gradually replaced on consumer desktop computers by operating systems offering a graphical user interface (GUI), in particular by various generations of the Microsoft Windows operating system. MS-DOS developed out of QDOS (Quick and Dirty Operating System), also known as 86-DOS . Several versions were released under different names for different hardware.[3] MS-DOS had eight major versions released before Microsoft stopped development in 2000.

Unix

UNIX is an operating system which was first developed in the 1960s, and has been under constant development ever since. By operating system, we mean the suite of programs which make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren’t covered by a graphical program. The UNIX operating system is made up of three parts; the kernel, the shell and the programs. The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls. The shell acts as an interface between the user and the kernel.

http://en.wikipedia.org/wiki/Operating_system

http://www.howstuffworks.com/operating-system.htm/printable