Introduction to Operating System

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Re: Introduction to Operating System

Unread postby hamzakhalid » Tue May 12, 2015 8:36 pm

Introduction to Operating System
M.Hamza Bin Khalid (CMS 13947)
Abstract:
The operating system is the most important program that runs on a computer. An operating system is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
Introduction:
A program that acts as an intermediary between a user of a computer and the computer hardware. An Operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware. An Operating system is concerned with the allocation of resources and services, such as memory, processors, devices and information. The Operating System correspondingly includes programs to manage these resources, such as a traffic controller, a scheduler, memory management module, I/O programs, and a file system.
Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux.
The OS manages these resources and allocates them to specific programs and users. With the management of the OS, a programmer is rid of difficult hardware considerations. An OS provides services for
• Processor Management
• Memory Management
• File Management
• Device Management
• Concurrency Control
It all started with computer hardware in about 1945s. Computers were using vacuum tube technology. Programs were loaded into memory manually using switches, punched cards, or paper tapes. As time went on, card readers, printers, and magnetic tape units were developed as additional hardware elements. Assemblers, loaders and simple utility libraries were developed as software tools. Later, off-line spooling and channel program methods were developed sequentially. Then idea of multiprogramming came. Multiprogramming means sharing of resources between more than one processes. Now the CPU time was not wasted, while one process moves on some I/O work, the OS picks another process to execute till the current one passes to I/O operation.
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Re: Introduction to Operating System

Unread postby shahzeb tanveer » Fri May 15, 2015 3:00 pm

Operating System
In order to use computers, to solve some problems, a user has to write instructions (programs). But other than writing instructions for solving the problem every programmer will also have to write instructions for the following task.
• Read data from input devices.
• Show results on the output devices.
• Perform memory management.
• Organize data on the storage devices.
These tasks are very complex and only expert programmers can write this instructions.to make the computer easy; these programs are provided in the form of software, known as Operating System (OS).
An operating system is a set of programs running in the background of a computer system and providing an environment in which other programs can be executed and the computer system can be used efficiently.
The operating system provides the most common functions needed by any user. In this way the operating system wraps around the hardware and saves its users from the complex details of hardware.
Types of Operating System.
Depending upon the working, the operating systems are divided into following main types.
• Batch Processing Operating System.
• Real Time Operating System.
• Multi User Time Sharing Operating System.
• Network Operating System.
Functions of an Operating Systems.
Following are the main function performed by most operating system.
• Manage Hardware Resources.
• Load and Execute Programs.
• Memory Management.
• Secondary Memory Store Management.
• Providing interface to the user.
There are two commonly used user interfaces:
Command Line interface: In such interfaces the user communicates with the Operating System by typing command using the keyboard. Each command given to the OS activates one of the many programs in the OS. Example of such interface is the command prompt provided by MS-DOS to its users.
Graphical User Interface (GUI): The GUI interface consists of Windows, Menus, Icons and pointers. The user of the system communicates with the Operating System by selecting commands from the menus or by selecting different icons by using a pointing device like mouse.MS-Windows is a well-known example of an Operating System with a GUI interface. In MS-Windows the user selects commands by using a mouse and a keyboard e.g. Windows, XP, Linux etc.
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Re: Introduction to Operating System

Unread postby shahzeb tanveer » Fri May 15, 2015 9:07 pm

Shahzeb Tanveer
cms 13618
section A.




Operating System


In order to use computers, to solve some problems, a user has to write instructions (programs). But other than writing instructions for solving the problem every programmer will also have to write instructions for the following task.
• Read data from input devices.
• Show results on the output devices.
• Perform memory management.
• Organize data on the storage devices.
These tasks are very complex and only expert programmers can write this instructions.to make the computer easy; these programs are provided in the form of software, known as Operating System (OS).
An operating system is a set of programs running in the background of a computer system and providing an environment in which other programs can be executed and the computer system can be used efficiently.
The operating system provides the most common functions needed by any user. In this way the operating system wraps around the hardware and saves its users from the complex details of hardware.
Types of Operating System.
Depending upon the working, the operating systems are divided into following main types.
• Batch Processing Operating System.
• Real Time Operating System.
• Multi User Time Sharing Operating System.
• Network Operating System.
Functions of an Operating Systems.
Following are the main function performed by most operating system.
• Manage Hardware Resources.
• Load and Execute Programs.
• Memory Management.
• Secondary Memory Store Management.
• Providing interface to the user.
There are two commonly used user interfaces:
Command Line interface: In such interfaces the user communicates with the Operating System by typing command using the keyboard. Each command given to the OS activates one of the many programs in the OS. Example of such interface is the command prompt provided by MS-DOS to its users.
Graphical User Interface (GUI): The GUI interface consists of Windows, Menus, Icons and pointers. The user of the system communicates with the Operating System by selecting commands from the menus or by selecting different icons by using a pointing device like mouse.MS-Windows is a well-known example of an Operating System with a GUI interface. In MS-Windows the user selects commands by using a mouse and a keyboard e.g. Windows, XP, Linux etc.
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Re: Introduction to Operating System

Unread postby Danyal Ijaz » Fri May 15, 2015 10:00 pm

INTRODUCTION TO OPERATING SYSTEM
Danyal Ijaz(14046)(Section A)
ABSTRACT:
An Operating system is software that manages computer hardware and software resources and provides common services for computer programs. The operating system is an essential component of the system software in a computer system. Application programs need an operating system to function. It is low-level software that supports computer basic functions, such as scheduling task and controlling peripherals (disk drives, printer etc.) Basically it is software that runs when you turn on your PC and it is the last software you see when you turn off your computer.
INTRODUCTION:
Operating system is a most important program that runs in a computer, every general-purpose computer must have operating system to run other programs. Operating system performs basic tasks such as recognizing input from the keyboard, sending signals to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices. On the first computers, with no operating system, every program the full hardware specification to run correctly and perform standard task, and its own drivers for peripheral devices like printers and punched paper card readers. The growing complexity of hardware and application programs made operating system a necessity for everyday use.
An operating system is the software component of a computer system that is responsible for the management and coordination of activities and the sharing of the resources of the computer. The operating system acts as a host for application programs that are run on the machine. As a host, one of the purposes of an operating system is to handle the details of the operation of the hardware. This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers use an operating system of some type. Some of the operating system used in computers is LINUX, Windows, and Macintosh etc.
In others words computer is nothing without an operating system, operating system is necessary in all type of computers without it you cannot apply anything in your computer. Operating system is only way of communication between user and computer.
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Re: Introduction to Operating System

Unread postby MUHAMMAD IBRAHIM » Sat May 16, 2015 11:53 am

Muhammad Ibrahim
CMS # 14040
Introduction to Operating System
Introduction:
An Operating system(OS) is software that creates a link between the user, software and hardware. All the computers need basic software known as an OS to work. The OS acts as an interface or interactive tool between the user, application programs, hardware and the system peripherals. The OS is the first software to be loaded when a computer gets active . The entire application programs are loaded after the OS. Whenever an application needs information it requests the OS which in turn queries the System clock on the motherboard. User interacts with the computer through the OS then OS interprets inputs given by a user through the keyboard, mouse or other input device and takes proper actions. Operating System (OS) primarily provides services for running applications on a computer system.
Types of operating system:
• Single user MS-Win 95-98, Win-ME, MS-Dos
• Multi user UNIX, Linux, XENIX
• Network Novel Netware, Win-NT, Win-2000-2003
1. Single user:
If the operating system of single user is there in computer’s memory then computer will control or handle one user only at a time.


2. Multi user:
If the multi-user operating system is loaded in computer’s memory, the computer would be able to handle more than one user at a time.
3. Network:
If the network OS is loaded in computer’s memory, the computer would be able to handle more than one computers at time.
Operating System Services
An operating system provides services to programs and to the users of those programs. It provided by one environment for the execution of programs. The services provided by one operating system is difficult than other operating system. Operating system makes the programming task easier.
The common service provided by the operating system is listed below.
1. Program execution
2. I/O operation
3. File system manipulation
4. Communications
5. Error detection
1. Program execution:
Operating system loads a program into memory and executes the program. The program must be able to end its execution, either normally or abnormally.


2. I/O Operation :
I/O means any file or any specific I/O device. Program may require any I/O(input/output) device while running. So operating system must provide the required I/O.

3. File system manipulation :
Program needs to read a file or write a file. The operating system gives the permission to the program for operation on file.
4. Communication :
Data transfer between two processes is required for some time. The both processes are on the one computer or on different computer but connected through computer network. Communication may be implemented by two methods: a. Shared memory b. Message passing.
5. Error detection :
Error may occur in CPU, in I/O devices or in the memory hardware. The operating system constantly needs to be aware of possible errors. It should take the appropriate action to ensure correct and consistent computing.

Principle of operation in computer

Let’s understand principle of operation of a computer system. Current systems are based on The Von-Neumann principle. The principle states that a program is initially stored in computer’s memory and executed by fetching an instruction at a time.
The basic cycle of operation is;
• Fetch an instruction (Fetch)
• Interpret the instruction (Decode)
• Execute the instruction (Execute)
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