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Learning objective: Explain the purpose of an operating system
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The operating system does everything and does nothing. Unlike an application, like a word processor, the operating system is very unfocused with regards as what to do with it. Applications have boundaries and a sense of purpose. Operating system seem to have limitless boundaries and little sense of immediate purpose. Since the operating system does so much to make a computer function, it can be hard at times to find a place to start to understand what it is and what it does. For many users their main experience with their operating system is file management and a sense that the mouse is being controlled by the operating system.
An operating system is the software on a computer that manages the way different programs use its hardware, and regulates the ways that a user controls the computer. Operating systems are found on almost any device that contains a computer with multiple programs -- from cellular phones and video game consoles to supercomputers and web servers. Some popular modern operating systems for personal computers include Microsoft Windows, Mac OS X, and Linux. [Wikipedia]
An operating system has several capabilities that it must provide:
Hardware
The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware. [Wikipedia]
Kernel
In computing, the kernel is the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software components). Usually as a basic component of an operating system, a kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls. [Wikipedia] The two main kernels today are Microsoft NT and Linux/BSD.
Shell
A shell is a piece of software that provides an interface for users of an operating system which provides access to the services of a kernel. However, the term is also applied very loosely to applications and may include any software that is "built around" a particular component, such as web browsers and email clients that are "shells" for HTML rendering engines. The name shell originates from shells being an outer layer of interface between the user and the internals of the operating system (the kernel). Operating system shells generally fall into one of two categories: command-line and graphical. Command-line shells provide a command-line interface (CLI) to the operating system, while graphical shells provide a graphical user interface (GUI). In either category the primary purpose of the shell is to invoke or "launch" another program; however, shells frequently have additional capabilities such as viewing the contents of directories. [Wikipedia]
Application
Application software, also known as an application, is computer software designed to help the user to perform singular or multiple related specific tasks. Examples include enterprise software, accounting software, office suites, graphics software, and media players. Application software is contrasted with system software and middleware, which manage and integrate a computer's capabilities, but typically do not directly apply them in the performance of tasks that benefit the user. A simple, if imperfect analogy in the world of hardware would be the relationship of an electric light bulb (an application) to an electric power generation plant (a system). The power plant merely generates electricity, not itself of any real use until harnessed to an application like the electric light that performs a service that benefits the user. [Wikipedia]
Thinking: Why not have the application control the hardware directly?
Key terms: application, kernel, operating system, shell
Resources:
To maximize your learning, please visit these Web sites and review their content
to help reinforce the concepts presented in this section.
Quick links:
Operating system @ Wikipedia
Computer system @ Wikipedia
Kernel @ Wikipedia
Shell @ Wikipedia
Application software @ Wikipedia
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Operating system @ Wikipedia |
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Computer system @ Wikipedia |
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Kernel @ Wikipedia |
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Shell @ Wikipedia |
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Application software @ Wikipedia |
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