The operating system

The operating system

In computer science, operating system or in English: the operating system or OS is a software system that served to make the control and management of hardware and basic system operations, including the execution of software applications such as word processing programs and web browsers.
In general, the Operating System is the software on the first layer is placed on the computer's memory when the computer is turned on. While other software is run after the operating system is running, and the OS will perform core public services for that software. Common core services such as access to the disk, memory management, task scheduling, and user interfaces. So that each software no longer have a common core tasks, because it can be served and performed by the operating system. Sections of code that perform core tasks and general called the "kernel" an Operating System.
Table of contents
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• 1 Introduction
• 2 common core services
• 3 Operating System currently
• 4 Process
o 4.1 Status Process
• 5 See also
• 6 External links

[Edit] Introduction
Typically, the term is often addressed Operating System to all software included in the package with your computer system before the software applications installed. In computer science, operating system or in English: the operating system or OS is a software system that served to make the control and management of hardware and basic system operations, including the execution of software applications such as word processing programs and web browsers.
In general, the Operating System is the software on the first layer is placed on the computer's memory when the computer is turned on. While other software is run after the operating system is running, and the OS will perform core public services for that software. Common core services such as access to the disk, memory management, task scheduling, and user interfaces. So that each software no longer have a common core tasks, because it can be served and performed by the operating system. Sections of code that perform core tasks and the general is called the "kernel" of a Operating System
If the computer system is divided into layers, then the operating system is the link between the hardware layer and the software layer. Beyond that, the Operating System perform all important tasks in the computer, and ensure that different applications can run simultaneously smoothly. Operating System ensure other software applications can use the memory, input and output to other equipment, and have access to the file system. When multiple applications running simultaneously, then the Operating System set skedule right, so far as possible all running processes get enough time to use the processor (CPU) and do not interfere with each other.

In many cases, the operating system provides a library of standard functions, which other applications can call functions, so that in any new program, it is not necessary to make these functions from scratch.

Operating systems generally consist of several parts:
1. Boot mechanisms, namely putting the kernel into memory
2. Kernel, the core of an operating system
3. Command Interpreter or shell, which reads input from the user
4. Libraries, which provide a collection of basic functions and standards that can be called by other applications
5. Driver to interact with external hardware, as well as to control them.

Some operating system allows only one application running at a time (eg DOS), but most of the new operating system allows multiple applications to run simultaneously at the same time. Operating systems are referred to as Multi-tasking Operating System (eg UNIX family of operating systems). Some Operating Systems are very large and complex, and their input depending on the user input, while the other Operating Systems are very small and are made with the assumption that work without human intervention at all. The first type is often referred to as a Desktop OS, while the second type is a Real-Time OS

For example, it is the operating system include Windows, Linux, Free BSD, Solaris, palm, symbian, and so on.
[Edit] a common core services
Along with the development of operating systems, more and more services become the core public service. Now, the OS may need to provide network and Internet connectivity, which was not a common core services. Operating systems also need to keep the damage to a computer system from interference destructive programs from other computers, such as viruses. List of common core services will continue to grow.

Programs communicate with each other with Application Programming Interface, Application Programming Interface or API abbreviated. With the API is an application program to communicate with the Operating System. As human beings communicate with computers through a user interface, the program also communicate with other programs via the API.

However a computer is not powerful API entirely to programs that run on the operating platform. For example, if a program created for Windows 3.1 when run on Windows 95 and later generations will see a striking difference between the program window with other programs.
[Edit] Operating System currently
Operating system-the major operating systems commonly used computer systems (including PC, personal computer) are divided into 3 major groups:
1. Family Microsoft Windows - which is comprised of the Windows Desktop Environment (version 1.x to version 3.x), Windows 9x (Windows 95, 98, and Windows ME), and Windows NT (Windows NT 3.x, Windows NT 4.0 , Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows 7 (Seven), which was released in 2009, and Windows Orient to be released in 2014)).
2. Unix family of operating systems that use the POSIX interface, such as SCO UNIX, families BSD (Berkeley Software Distribution), GNU / Linux, MacOS / X (based on a modified BSD kernel, and is known by the name of Darwin) and GNU / Hurd.
3. Mac OS, an operating system for Apple's computers which is called Mac or Macintosh. The newest operating system is Mac OS X version 10.4 (Tiger). Beginning in 2007 planned launch of version 10.5 (Leopard).
While mainframe computers, and the Super Computer operating systems use a lot of different, usually a derivative of the UNIX operating system developed by vendors such as IBM AIX, HP / UX, etc..
[Edit] The process
The processor executes computer programs. The processor is a chip in the computer system running the computer program instructions. In every second the processor can execute millions of instructions.
The program is a series of instructions given to a computer. While the process is a part of the program that are in a particular status in the execution sequence. In the discussion of the operating system, we often discuss the process compared to the program. In modern operating system, at a time not all programs loaded in memory, but only one part of the program. While other parts of the program remains rest in the disk storage media. Only in times of need alone, part of the program is loaded in memory and executed by the processor. This is to save memory consumption.
Some systems run only a single process at a time, while others run multi-process at a time. Though most of the computer system has only one processor, and the processor can only execute one instruction at a time. So how does a single-processor system can run multi-process? Surely, in a very small granularity, the processor executes only one process at a time, then quickly he moved to run other processes, and so on. So for vision and feeling human user, as if the processor run multiple processes simultaneously.
Each process in an operating system to get a PCB (Process Control Block) that contains information about the process, namely: an identification process (Process ID) and a unique identification number, the status of the process, process execution priorities and process location information in memory . Priority of the process is a value or quantity that indicates how often the process should be executed by the processor. The process that has a higher priority, it will run more frequently or executed earlier than the lower-priority processes. An operating system can only determine all processes with the same priority, so that each process has an equal opportunity. An operating system can also change the priority value of a particular process, that process will be able to have a greater chance at the next execution (for example: the process that was already too long waiting for execution, the operating system raise the value of priority).
[Edit] Status Process
Types of status that may be embedded in a process on any operating system may vary. But there are at least three kinds of status are common, namely:
1. Ready, the state where the process is ready to be executed on the next turn
2. Running, the status of which is currently being executed by the processor
3. Blocked, the state where the process can not be executed when the processor is ready / free
[Edit] See also
• Haiku
• Linux
• Unix
• Windows
[Edit] External links
• Introduction to Computer Operating Systems Linux Kernel Plus Case Studies Digital Community Mutual Assistance (MDGR).
• Operaing System
• Collection of Open-Content Textbook: Wikibooks: Operating System Design
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l • b • s
The operating system

Kernel
Microkernel, monolithic kernel, Kernel hybrid, space kernel, kernel modules, nanokernel, device drivers, user space, Userland


Management process
Process (computer), Multiprogramming, Interrupt, Protected mode, Supervisor mode, Computer multitasking, process management, Scheduling (computer), context switches, Cooperative multitasking, Preemptive multitasking, CPU modes


Memory management Memory protection, Segmentation, Paging, Memory management unit, Segmentation fault, General protection fault


AmigaOS example, Microsoft Windows, Linux, GNU, UNIX, Mac OS, MS-DOS


Other concepts Boot loader, API, VFS, Computer network, GUI, History of operating systems, the HAL