Operating system

Operating system

If you have a computer then you have heard about OS .any desktop or laptop PC that you but normally comes pre-loaded with windows XP. Many corporate server use Linux or Unix OS, without OS a computer is useless we cannot  do perform any task.

More recently, operating systems have started to pop up in smaller computers as well. If you like to tinker with electronic devices, you are probably pleased that operating systems can now be found on many of the devices we use every day, from cell phones to wireless access points. 

The computers used in these little devices have gotten so powerful that they can now actually run an operating system and applications. 

The computer in a typical modern cell phone is now more powerful than a desktop computer from 20 years ago, so this progression makes sense and is a natural development. In any device that has an operating system, there's usually a way to make changes to how the device works. 

This is far from a happy accident; one of the reasons operating systems are made out of portable code rather than permanent physical circuits is so that they can be changed or modified without having to scrap the whole device.

The purpose of an operating system is to organize and control hardware and software so that the device it lives in behaves in a flexible but predictable way. In this article, we'll tell you what a piece of software must do to be called an operating system, show you how the operating system in your desktop computer works and give you some examples of how to take control of the other operating systems around you.

Essential Elements of OS

OS Bare Bones-:

Not all computers have operating systems. The computer that controls the microwave oven in your kitchen, for example, doesn't need an operating system. It has one set of tasks to perform, very straightforward input to expect (a numbered keypad and a few pre-set buttons) and simple, never-changing hardware to control. 

For a computer like this, an operating system would be unnecessary baggage, driving up the development and manufacturing costs significantly and adding complexity where none is required. Instead, the computer in a microwave oven simply runs a single hard-wired program all the time

For other devices, an operating system creates the ability to-:

• serve a variety of purposes
• interact with users in more complicated ways
• keep up with needs that change over time

All desktop computers have operating systems. The most common are the Windows family of operating systems developed by Microsoft, the Macintosh operating systems developed by Apple and the UNIX family of operating systems (which have been developed by a whole history of individuals, corporations and collaborators). 

There are hundreds of other operating systems available for special-purpose applications, including specializations for mainframes, robotics, manufacturing, real-time control systems and so on.

           Types of Operating System

The broad categories are:

1-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.

2-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.

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 Mac OS   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.

Task of OS-

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

1- 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, etc. (On a cell phone, they include the keypad, the screen, the address book, the phone dialer, the battery and the network connection.)

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

The operating system's tasks, in the most general sense, fall into six categories-

1- Processor management
2-Memory management
3- Device management
4- Storage management
5- Application interface
6- User interface

While there are some who argue that an operating system should do more than these six tasks, and some operating-system vendors do build many more utility programs and auxiliary functions into their operating systems, these six tasks define the core of nearly all operating systems. 

Let's look at the tools the operating system uses to perform each of these functions