A computer’s operating system is a collection of programs that manage and coordinate the activities taking place within the computer and it is the most critical piece of software installed on the computer. The operating system boots the computer, launches application software, and ensures that all actions requested by a user are valid and processed in an orderly fashion. For example, when you issue the command for your computer to store a document on your hard drive, the operating system must perform the following steps:
1) make sure that the specified hard drive exists,
1) make sure that the specified hard drive exists,
2) verify that there is adequate space on the hard drive to store the document and then store the document in that location, and
3) update the hard drive’s directory with the filename and disk location for that file so that the document can be retrieved again when needed. In addition to managing all of the resources associated with your local computer, the operating system also facilitates connections to the Internet and other networks.
3) update the hard drive’s directory with the filename and disk location for that file so that the document can be retrieved again when needed. In addition to managing all of the resources associated with your local computer, the operating system also facilitates connections to the Internet and other networks.
In general, the operating system serves as an intermediary between the user and the computer, as well as between application programs and the computer system’s hardware. Without an operating system, no other program can run, and the computer cannot function. Many tasks performed by the operating system, however, go unnoticed by the user because the operating system works in the background much of the time.
Functions of an Operating System:
Operating systems have a wide range of functions.Interfacing with Users
One of the principal roles of every operating system is to translate user instructions into a form the computer can understand. It also translates any feedback from hardware—such as a signal that the printer has run out of paper or that a new hardware device has been connected to the computer—into a form that the user can understand. The means by which an operating system or any other program interacts with the user is called the user interface; user interfaces can be text-based or graphics-based. Most, but not all, operating systems today use a graphical user interface (GUI).
Booting the Computer
The first task your operating system performs when you power up your computer is to boot the computer. During the boot process, the essential portion, or core, of the operating system (called the kernel) is loaded into memory. The kernel remains in memory the entire time the computer is on so that it is always available; other parts of the operating system are retrieved from the hard drive and loaded into memory when they are needed. Before the boot process ends, the operating system determines the hardware devices that are connected to the computer and configured properly, and it reads an opening batch of instructions. These startup instructions (which the user can customize to some extent when necessary) assign tasks for the operating system to carry out each time the computer boots, such as prompting the user to sign in to an instant messaging program or launching a security program to run continually in the background to detect possible threats.Typically, many programs are running in the background at any one time, even before the user launches any application software. These programs are launched automatically by the operating system, and they all consume memory and processing power.
In Windows, users can see some of the application programs that are running in the background by looking at the icons in the system tray. To close a program, right-click the icon and select the appropriate option. To view the programs that will run each time the computer boots or to remove a program from this startup list, Windows users can use the Startup tab on the Microsoft System Configuration Utility. To open this utility, type msconfig in the search box at the bottom of the Start menu and then click the msconfig program name when it is displayed.
To avoid creating a problem with your computer, however, be sure not to disable a program from the startup list without knowing absolutely what the program does and that it can be safely disabled. Other system configuration information is stored in the Windows registry files, which should be modified only by the Windows program itself or by advanced Windows users.
Configuring Devices
The operating system also configures all devices connected to a computer. Small programs called device drivers (or simply drivers) are used to communicate with peripheral devices, such as monitors, printers, and keyboards. Most operating systems today include the drivers needed for the most common peripheral devices. In addition, drivers often come on a CD packaged with the peripheral device, or they can be downloaded from the manufacturer’s Web site. Most operating systems today look for and recognize new devices each time the computer boots. If a new device is found, the operating system typically tries to install the appropriate driver automatically in order to get the new hardware ready to use—a feature called Plug and Play. Because USB and FireWire devices can be connected to a computer when the computer is running, those devices are recognized and configured, as needed, each time they are plugged in to the computer.Once a device and its driver have been installed properly, they usually work fine. If the device driver file is deleted, becomes corrupted, or has a conflict with another piece of software, then the device will no longer work. Usually, the operating system detects problems like this during the boot process and notifies the user, and then tries to reinstall the driver automatically. If the operating system is unable to correct the problem, the user can reinstall the driver manually. You may also need to update or reinstall some device drivers if you upgrade your operating system to a newer version. To keep your system up-to-date, many operating systems have an option to check for operating system updates automatically—including updated driver files—on a regular basis. Enabling these automatic updates is a good idea to keep your system running smoothly and protected from new threats.
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