The operating system is a computer software that manages the way in which different programs use the computer's hardware and regulates how the user controls the computer.
The operating system is the most important program on a computer. Any other application is executed through it. The operating system takes care of the basic functions of the computer such as accessing the keypad inputs, outputs to output devices, keeping track of changes to files and directories, and controlling peripheral devices such as drives and drives. There are different operating systems, but the first one that has been used was the DOS (Disk Operating System) introduced by the IBM firm in 1981. Since working with it has meant that the users should be advanced in knowledge Of the computer, the Microsoft firm introduced Windows 3.11 as a more dense operating system than DOS. Later on, Microsoft also introduced operating systems such as Windows 95, Windows NT, Windows 98, Windows Vista, and Windows Seven (7) in 2009, Windows (8) 2012. There are also other operating systems, such as UNIX, LINUX etc.
Computer programs can be divided into two main categories:
- system programs that run the processing system operations
• Implementing programs that solve the problems of their users;
COMPOSITION
The operating system consists of a separate system called the kernel and a number of system programs.
WHAT D.M.TH '' KERNEL ''?
In computing, the kernel is a software program that manages the input / output requirements from the software and translates them into the data processing instructions for the central processing unit and other electronic components of a computer. The kernel is a fundamental part of the computer operating system modern.
When a software program (in this case called a process) makes the kernel requirements, the request is called a system call. Different kernel designs vary in how they manage system calls (time allocation) and resources. For example, a monolithic kernel executes all operating system instructions in the same address space to improve system performance. A microcontroller runs most of the background process of the operating system in user space, to make the operating system more modular and, therefore, easier to maintain.
For computer programmers, the kernel interface is a low level abstraction layer.\
WHAT IS IT FOR OPERATING SYSTEM?
An operating system provides an environment for executing the programs by providing the necessary services from these programs. Software Applications Requirements fall into five categories .:
1. Process control
2. Media Systems
3. I / Operation O
4. Interprocess Communication
5. Maintenance Information
The operating system should try to meet these requirements in a multi-user, multi-process environment while managing:
• Assigning resources
• Finding Errors
• Protection
MEMORY
Modern general purpose computers, including personal computers and Mainframes, have an operating system to run other programs, such as application software. Examples of operating systems of personal computers are Microsoft Windows, Mac OS (and Darwin), UNIX, and Linux. The lowest level of each operating system is its kernel. This is the first layer of programs loaded into memory when a system boots or start up. The kernel provides different access and shared core services for the entire system and applications. These services include but are not limited to: disk access, memory management, task scheduling, and access to other device devices. As well as the kernel, an operating system is often deployed with tools for display programs and to manage a graphical user interface (although Windows and Macintosh have these tools built into the operating system), as well as service programs for task tasks Such as file management and operating system configurations. They are also often distributed to software applications because it can not connect directly to the basic operating system but in which the operating system is advantageous to distribute the operating system to the operating system. The specification path between the operating system and the application software does not Is correct, and is occasionally object of controversy. From commercial or legal points, the division may depend on the context of the interests involved. For example, one of the major queries in the United States in the Microsoft antitrust trial was whether the Microsoft web browser was part of its operating system, or whether it was a split part of the application software. Like the "system Operating "the very term, the question of what exactly should form the" Kernel "is subject to some controversy, with debates whether over things like file systems should be included in the kernel.Camps of various microkernels advocates, monolithic kernels, And so on. Operating systems are used in most, but not all, computer systems.The simple computers, including small embedded systems and many of the first computers are not operating systems Instead of relying on programs Of the application to manage the minimum hardware yourself, possibly with the help of libraries developed for this purpose.Commercially supplied Operating Systems are present in almost all modern equipment described as computers, personal computers for mainframes, and such mobile computers Like PDAs and cell phones.
Virtual memory
• Frequently computer memory is not enough to keep all the different codes of duty;
• It can simulate a larger memory that holds (RAM) only the part of the codes and data that serve at that time;
• Uses the concept of virtual memory.
• Inactive software data can be removed from the central memory and placed on the diskette in the swap area.
• The report of the dimensions of the swap and RAM area is 3: 1 (maximum);
• Modern processors have hardware tools to facilitate virtual memory
File System Manager
The file system controller is the operating system module that drives the information stored in the mass memory mechanisms. This manager should guarantee the correctness and coherence of the information. In multi-user systems, it has to put in place protection mechanisms in order to allow users to protect data from unauthorized users.
Typical functions to be performed are:
• Provide a mechanism for file identification;
• Make transparent the physical support structure of the memory;
• - Implementation of data protection mechanisms.
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