• The User Interface

• Running Programs

• Managing Files

• Managing Hardware

• Utility Software

The User Interface

– Graphical User Interfaces (GUIs)

•Most modern operating systems, like Windows and
the Macintosh OS, provide a graphical user interface

•A GUI lets youcontrol the system by using a mouse
to click graphical objects on screen.

•A GUI is based on the desktop metaphor. Graphical
objects appear on a background (the desktop),
representing resources you can use.

-GUI Tools

• Icons are pictures that represent computer
resources, such as printers, documents, and

• You double-click an icon to choose (activate) it, for
instance, to launch a program.

• The Windows operating system ofers two unique
tools, caled the taskbar and Start buton. These
help you run and manage programs.

-Applications and the Interface

• Applications designed to run under one operating
system usesimilarinterface elements.

• Under an OS such as Windows, you see a familiar
interface no mater what programs you use.

• In a GUI, each program opens and runs in a separate
window—a frame that presents the program and its

• In a GUI, you can run multiple programs at once,
each in a separate window. The application in use is
said to be the active window.


•GUI-based programs let you isue commands by
choosing them from menus.

•A menu groups related commands. For example, the
File menu’s commands let you open, save, and print
document files.

•Menus let you avoid memorizing and typing
command names.

•In programs designed for the same GUI, menus and
commands are similar from one program to another.

-Dialog Boxes

•A dialog box is a special window that appears when
a programor the OS needs more information
before completing a task.

•Dialog boxes are so named because they conduct a
“dialog” with the user, asking the user to provide
more information ormake choices.

-Command-Line Interfaces

• Some older operating systems, such as DOS and
UNIX, use command-line interfaces.

• In a command-line interface,you type commands at a

• Under command-line interfaces, individual
applications do not need to look or function the same
way, so diferent programs can look very diferent

Running Programs

-Basic Services

•The operating system manages al the other
programs that run on the PC.

•The operating system provides services to programs
and the user, including file management, memory
management, and printing

•To provide services to programs, theOSmakes
system cals—requesting other hardware and
software resources to perform tasks.

– Sharing Information

• Some operating systems, such as Windows, enable
programs to share information.

• You can create data in one program and use it again
in other programs without re-creating it.

• Windows provides the Clipboard, a special area that
stores data cut or copied from one document, so you
can re-use it elsewhere.


•Multitasking is the capability of running multiple
proceses simultaneously.

•A multitasking OSlets you run multiple programs at
the same time.

•Through multitasking, you can do several chores at
one time, such as printing a document while
downloading a file from the Internet.

•There are two types of multitasking: cooperative and

Managing Files

• The operating system keeps track of al the files on
each disk.

• Users can make file management easier by creating
a hierarchical file system that includes folders and
subfolders arranged in a logical order.

Managing Hardware

•The OS uses interrupt requests (IRQs) to maintain
organized communication with the CPU and other
pieces of hardware.

•Each hardware device is controled by a piece of
software, called a driver, which allows the OS to
activate and use the device.

•The operating system provides the software necessary
to link computers and form a network.

Utility Software

A utility is a program that performs a task that is not
typically handled by the operating system.

Some utilities enhance the operating system’s

Some of the major categories of utilities include:
• File defragmentation
• Data compression
• Backup
• Antivirus
• Screen savers


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