Transcript Ch2: Operating Systems

Ch2: Operating Systems
Dr. Basel Mahafzah
What is an Operating System?
An operating system (OS) is a collection
of programs which initializes the
hardware of the computer system;
provides basic routines for device
control; supports the management,
scheduling and interaction of tasks;
and maintains system integrity
Types of Operating Systems
• There are several types of operating system
depending upon types of function they
support.
– multi-user systems,
– single-user systems, and
– others are directed for the management of
particular devices like petrol pumps
Functions of Operating Systems
1. Transferring data between the
computer and various peripheral
devices (terminals, printers, floppy
diskettes, hard disks)
2. Managing computer files.
3. Loading programs into computer
memory and initiating program execution.
Loading the Operating System
(Booting)
• Some operating systems are already
present in the ROM (like operating
systems for petrol pumps or industrial
controllers). In such systems, the OS
will immediately gain control when the
power is turned on.
Continue Operating System
• Alternatively, the OS could be stored
on a secondary storage media like hard
disks or floppy disks and is loaded into
RAM when the power is turned on.
With this type of operating systems, it
is usually easier to add and implement
changes to the OS.
The Windows98 Operating System
Windows98 is an operating system for
personal computers developed by
Microsoft. It succeeded MSDOS and has
many advantages over it. Some of MS-DOS
disadvantages are listed below:
 It is limited to 640K of conventional
memory, which restricts the size of
programs which can be run.
 It was designed to run only one program at
once.
 It has non-graphical command driven
interface, which is hard to learn and
difficult to use.
 It has limited support for large capacity
drives and emerging technology.
Example: System Requirements
for Windows95
1. 386DX or higher,
2. 4MB memory or higher [8MB
recommended],
3. 35-40MB disk space,
4. 3.5" floppy drive or CDROM,
.VGA or higher resolution graphics card.
Desktop
Windows offers an improved user
interface called Desktop. It consists of:
• Screen Area
• Taskbar
Taskbar
•
The Taskbar, provides the easiest
method of switching between
several open applications on your
Desktop.
Taskbar Components
• It consists of three separate
components, namely:
–the Start Button,
–the System Tray and
–the Body of the taskbar.
Body of the Taskbar
The Body of the Taskbar is used to display
buttons of open programs.
• Pushed buttons on the Taskbar indicates that
the application program which corresponds
to this button is active.
• You can easily switch between open
programs by left clicking on their buttons
on the Taskbar.
Taskbar - System Tray
• The System tray contains the Clock,
and often icons for programs which
usually run in the background and need
only occasional user input. Examples
of such programs include printers
attached to your computer, anti-virus
programs (run in the background).
Taskbar - Start Button
• Finally the Start Button is an entry point
for carrying out many functions. A single
left click on this button will launch a pop-up
menu similar to the following menu:
Common Icons on Desktop
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•
•
•
My Computer
Network Neighborhood
Recycle Bin
My Briefcase
Netscape Communicator
Internet Explorer
My Computer
This window provides a graphic view of all hard
drives, floppy drives and CD-ROM drives
on your system. You can double-click on any of
these icons to manage the files or folders they
contain. For example, you can use the Control
Panel folder to manage many of your
computer’s settings and the Printers folder to
manage printing.
Recycle Bin
• All files deleted from your hard drives
end up in the Recycle Bin. You can
delete a file by left-clicking on the file,
dragging it over the Recycle Bin icon
with the mouse button held down, and
releasing the button.
Continue Recycle Bin
• The Recycle Bin gives you an extra
step to protect your files against
accidental deletions; a message will
pop up requiring you to confirm
whether you really want to delete a file.
Recovering Deleted Files
• To recover a deleted file, doubleclick on the Recycle Bin icon,
highlight the file by left-clicking
on it and select Restore from the
File Menu.
Continue….
• It is advised that you empty your Recycle
Bin periodically to delete unwanted files.
This can be achieved by double-clicking on
the Recycle Bin icon and choosing Empty
Recycle Bin from the File Menu; or by
right-clicking on the Recycle Bin icon and
choosing Empty Recycle Bin from the
pop-up menu.