Microsoft Office Tutorials and References
In Depth Information
Computer Software
System Software
System software manages the fundamental operations of your computer, such as loading
programs and data into memory, executing programs, saving data to disks, displaying
information on the monitor, and transmitting data through a port to a peripheral device.
There are four types of system software: operating systems, utilities, device drivers, and
programming languages.
An operating system controls basic input and output, allocates system resources, man-
ages storage space, maintains security, and detects equipment failure. You have already
learned the importance of data communications, both from a standalone computer and
from a workstation to other users on a network. The flow of data from the microprocessor
to memory to peripherals and back again is called basic I/O , or i nput/ o utput. The operat-
ing system controls this flow of data just as an air-traffic controller manages airport traffic.
A system resource is any part of the computer system, including memory, storage
devices, and the microprocessor, that can be used by a computer program. The operating
system allocates system resources so programs run properly. Most of today’s computers are
capable of multitasking —opening and running more than one program at a time—because
the operating system is allocating memory and processing time to make multitasking
possible. An example of multitasking is producing a document in your word processing
program while you check a resource on the Internet. Both the word processing program
and the Web browsing program are allowed to use parts of the computer’s resources, so
you can look at the resource periodically while you are writing about it in your paper. The
operating system is also responsible for managing the files on your storage devices. Not
only does it open and save files, but it also keeps track of every part of every file for you
and lets you know if any part is missing. This activity is like a filing clerk who puts files
away when they are not being used, and gets them for you when you need them again.
While you are working on the computer, the operating system is constantly guarding
against equipment failure. Each electronic circuit is checked periodically, and the moment
a problem is detected, the user is notified with a warning message on the screen.
The operating system’s responsibility to maintain security may include requiring a user-
name and password or checking the computer for virus infection. Unscrupulous program-
mers deliberately construct harmful programs, called viruses , which instruct your computer
to perform destructive activities, such as erasing a disk drive. Some viruses are more annoy-
ing than destructive, but some can be harmful, erasing data or causing your hard disk to
require reformatting. Computer users should protect themselves from viruses by using virus
protection software. Virus protection software searches executable files for the sequences
of characters that may cause harm and disinfects the files by erasing or disabling those
commands. The computer advertised in Figure 1 comes with virus protection software pre-
installed, and with the operating system Windows XP Professional.
Microsoft Windows, used on many personal computers, and the MAC OS, used exclu-
sively on Macintosh computers, are referred to as operating environments because they pro-
vide a graphical user interface ( GUI , pronounced “goo-ey”) that acts as a liaison between
the user and all of the computer’s hardware and software. In addition to the operating sys-
tem, Windows and the Mac OS also include utilities, device drivers, and some application
programs that perform common tasks.
User
Interfaces
 
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