1. Ch2: Operating Systems Dr. Basel Mahafzah

2. 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

3. 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

4. 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.

5. 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.

6. 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.

7. 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:

8.  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.

9. 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.

10. Desktop Windows offers an improved user interface called Desktop. It consists of: Screen Area Taskbar

11. The Taskbar, provides the easiest method of switching between several open applications on your Desktop.

12. Taskbar Components It consists of three separate components, namely: –the Start Button, –the System Tray and –the Body of the taskbar.

13. 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.

14. 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).

15. 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:

17. Common Icons on Desktop My Computer Network Neighborhood Recycle Bin My Briefcase Netscape Communicator Internet Explorer

18. 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.

20. 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.

21. 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.

22. Recovering Deleted Files To recover a deleted file, double- click on the Recycle Bin icon, highlight the file by left-clicking on it and select Restore from the File Menu.

23. 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.