An operating system (OS) is software, consisting of programs and data that runs on computers and manages computer hardware resources and provides common services for efficient execution of various application software. (wordnetweb.princeton.edu) An Operating System serves a variety of purposes including interacting with users in more complicated ways to keep up with needs that change over time. Operating systems provide a software platform on top of which other programs, called application programs, can run. Your choice of operating system, therefore, determines to a great extent the applications you can run.
Basic Idea of the interaction of an OSDescription: http://www.webopedia.com/FIG/OPER-SYS.gif
Operating System Services
Operating System services are responsible for providing functions that are useful to the user and also functions that ensure efficient operation of the system itself via resource sharing. First the analysis of functions that are useful to the user.
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Almost all operating systems have a user interface (UI) it can vary between two sorts Command-Line (CLI), and Graphics User Interface (GUI). Another useful function is Program execution in which the system must be able to load a program into memory and to run that program, the execute it, usually here is where errors are detected. One of the more common functions is known as I/O operations which stand for input -output operations. In perspective a program may need the use of I/O, which normally involves a files or some type of I/O device. Yet another is known as File-system manipulation. It is imperative that a program has the ability to read and write files and directories, search them, create and delete them, list file Information, and to observe permission management.
The other functions to ensure the efficient operation in resource sharing involves; Resource allocation, Accounting, Protection and Security. Considering Resource allocation multiple users or multiple jobs functioning at the same time, resources must be allocated to each of. Protection makes sure that accessibility to system resources is in a controlled manner, while Security of the system from outsiders requires user authentication, extends to defending external I/O devices from invalid access attempts. If a system is to be protected and secure, precautions must be instituted throughout it. (Operating System Hardware Dex OS , (2000). )
User Graphic Interfaces
Most Operating systems use the commonly known CLI and GUI interfaces, which respectively stands for Command Line Interface and Graphic User Interface. A command-line interface (CLI) is a mechanism for interacting with a computer's operating system or software by typing commands to perform specific tasks. This text-only interface contrasts with the use of a mouse pointer with a graphical user interface (GUI) to click on options. (In the Beginning... Was the Command Line 1986)
CLI example. Command Prompt
In computing a graphical user interface (GUI) is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and office equipment.( Tracing the roots of the graphical user interface 2001)
(Jonathan Bennett & AutoIt Team1999-2010)
Operating Systems Design and Implementation
Many Operating Systems are structured differently internally. One could start by defining goals and specifications. This of course is affected by the choice of hardware, and not to mention the type of system. To further analyze this phenomena one can break it down further and consider the user goals and the system goals. For user goals the operating system should be adaptable, convenient, an ease to understand and interpret, dependable, innocuous, and progressive. When considering System Goals an operating system should be easy to implement, design, and maintain, as well as flexible, reliable, error-free, and most off all efficient.
Originally MS-DOS was designed to be an operating system that could run on almost any computer. Each computer would have its own distinct hardware and its own version of MS-DOS, similar to the situation that existed for CP/M, and with MS-DOS emulating the same solution as CP/M to adapt for different hardware platforms. To this end, MS-DOS was designed with a modular structure with internal device drivers, minimally for primary disk drives and the console, integrated with the kernel and loaded by the boot loader, and installable device drivers for other devices loaded and integrated at boot time.( Bergmann, P. G. (1993)) In other words it was designed to run the most efficiently with maximum functionality in the least of amount of space possible.
Always on Time
Marked to Standard
MS-DOS Layer Structure
The operating system is divided into a number of layers (levels), each built on top of lower layers. The bottom layer (layer 0), is the hardware; the highest (layer N) is the user interface.
There are many vast ways to structure an operating system the purpose and the resources available mainly determine the method and the approach to use. It is very important that a program has the ability to read and write files and directories, search them, create and delete them, list file Information, and to observe permission management. And also it is vital to ensure the efficient operation in resource sharing involves; Resource allocation, Accounting, Protection and Security. When designing and Implementing Operating System Structures, one could start by defining goals and specifications
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