operating_systems

 In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.

 It manages the sharing of internal memory among multiple applications.

 It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.

 It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.

 It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.

 On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.

The Linux open source operating system, or Linux OS, is a freely distributable, cross-platform operating system based on Unix that can be installed on PCs, laptops, netbooks, mobile and tablet devices, video game consoles, servers, supercomputers and more.

The official name of the Macintosh operating system. Earlier versions were called System x.x, where x.x were the version numbers. With the release of Mac OS 8, however, Apple dropped the System moniker.

Windows is a personal computer operating system from Microsoft that, together with some commonly used business applications such as Microsoft Word and Excel, has become a de facto "standard" for individual users in most corporations as well as in most homes.

A command line interface is a means of interacting with a computer program where the user issues commands to the program in the form of successive lines of text.

Command-line interfaces to computer OS are less widely used by casual computer users, who favour graphical user interfaces. Command-line interfaces are often preferred by more advanced computer users, as the often provide more concise and powerful means to control and program or OS. Programs with command-line interfaces are generally easier to automate via scripting.

GUI is an abreviation for Graphical Interface User. components:

pointer : A symbol that appears on the display screen and that you move to select objects and commands. Usually, the pointer appears as a small angled arrow. Text -processing applications, however, use an I-beam pointer that is shaped like a capital I.

pointing device : A device, such as a mouse or trackball, that enables you to select objects on the display screen.

icons : Small pictures that represent commands, files, or windows. By moving the pointer to the icon and pressing a mouse button, you can execute a command or convert the icon into a window. You can also move the icons around the display screen as if they were real objects on your desk.

desktop : The area on the display screen where icons are grouped is often referred to as the desktop because the icons are intended to represent real objects on a real desktop.

windows: You can divide the screen into different areas. In each window, you can run a different program or display a different file. You can move windows around the display screen, and change their shape and size at will.

menus : Most graphical user interfaces let you execute commands by selecting a choice from a menu.