Operating System (OS)
The operating system is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs and applications. 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.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop — it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
The Classification of Operating systems
Multi-user: Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
Multiprocessing : Supports running a program on more than one CPU.
Multitasking : Allows more than one program to run concurrently.
Multithreading : Allows different parts of a single program to run concurrently.
Real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, are not real-time.
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.
Interacting With the Operating System
As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files, respectively. The commands are accepted and executed by a part of the operating system called the command processor or command line interpreter. Graphical user interfaces allow you to enter commands by pointing and clicking at objects that appear on the screen.
- Outline Processor Markup Language
Outline Processor Markup Language (OPML) is an XML-based format that allows exchange of outline-structured information between applications running on different operating systems and environments. The purpose of this format is to provide a way to exchange information between outliners (programs that allow you to read, edit and reorganize outlines) and Internet services that can be […]
- operating system virtualization
Operating system virtualization refers to the use of software to allow system hardware to run multiple instances of different operating systems concurrently, allowing you to run different applications requiring different operating systems on one computer system. The operating systems do not interfere with each other or the various applications. Not to be confused with operating […]
Short for operational data store, a type of database that serves as an interim area for a data warehouse in order to store time-sensitive operational data that can be accessed quickly and efficiently. In contrast to a data warehouse, which contains large amounts of static data, an ODS contains small amounts of information that is […]
(1) A symbol that represents a specific action. For example, a plus sign (+) is an operator that represents addition. The basic mathematic operators are + addition, – subtraction,* multiplication,/ division. In addition to these operators, many programs and programming languages recognize other operators that allow you to manipulate numbers and text in more sophisticated […]
- opt-in e-mail
A term that refers to promotional e-mails that have been requested by the individual receiving them. Unlike spam promotional e-mails that get sent out to large lists of recipients without regard to whether or not they want the information, opt-in e-mails are only sent to people who specifically request them. Opt-in e-mails are targeted and […]