OPERATING SYSTEM CONCEPTS : OPERATING SYSTEM CONCEPTS BY:
Sugandha Singh
sugandha06@gmail.com
+91-9785774032
What is an Operating System? : What is an Operating System? An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer.
The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
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Slide 4 : Not all computers have operating systems. The computer that controls the microwave oven in your kitchen, for example, doesn't need an operating system.
Instead, the computer in a microwave oven simply runs a single hard-wired program all the time.
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. Computers without Operating System
PURPOSE OF O.S. : PURPOSE OF O.S. 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 you would be told, 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.
Services performed by operating system for applications : Services performed by operating system for applications In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.
It manages the sharing of internal memory among multiple applications.
It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
Contd… : Contd… It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.
It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.
Operating System Functions : Operating System Functions 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.
Slide 9 : ©2008 HowStuffWorks
Types of Operating Systems : 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:
Real-time operating system (RTOS) - 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.
Contd… : Contd… Single-user, single task - This OS 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.
Single-user, multi-tasking - This is OS 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.
Multi-user - A multi-user OS 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.
Slide 12 : It's important to differentiate between multi-user operating systems and single-user operating systems that support networking. Windows 2000 and Novell Netware can each support hundreds or thousands of networked users, but the operating systems themselves aren't true multi-user operating systems. The system administrator is the only "user" for Windows 2000 or Netware. The network support and all of the remote user logins the network enables are, in the overall plan of the operating system, a program being run by the administrative user.