1. Operating Systems Overview

2. P2 grading criterion Report –
Why do PC’s need an Operating System (OS)
Features and Functions of a OS
How are operating system used to facilitate users?

3. Where to find the information?
Plenty of info out there!

4. What is an operating system?
A software program (or collection of programs) which manages a computer and allows other programs to run.
Manages computer’s resources
Provides an interface for
Programmers
Users
Provides a platform for application programs
Without O/S computer will not work!

5. Features / functions of O/S
File & Disk Management
Memory Management
Process Management
I/O Management
Configuration / administration
Networking
Security

6. Managing computer resources
File / Disk Management
Drive partitioning / formatting
Directory (folder) structures
File / folder management
Copy, Cut, Paste
Rename
Delete
File operations for programs
Open, Close, Save

7. Managing computer resources
Memory Management
Allocates memory to programs
Recovers memory after use
Prevents programs from accessing memory allocated to another program
Manages virtual memory

8. Managing computer resources
Process Management
CPU can only do one thing at a time
O/S allocates CPU time to programs
Allows >1 program to run at a time
Prevents one program hogging the CPU
Gives impression of multi-tasking

9. Managing computer resources
Input / output management
Wide range of peripherals
Screen, keyboard, mouse
Disk drives (HDD, FDD, CD, DVD)
Printers
Webcam, graphics tablets etc
Device drivers make O/S more flexible

10. Software types User Applications Operating System BIOS Device Drivers
Hardware

11. Platform for application software
Operating system sits between hardware and application software
Provides standardised way for applications to work on wide range of different computers
No need for software developers to know details of individual computers

12. What about programs like Calculator, Wordpad or Internet Explorer?
OS or Applications ?
Operating systems
DOS
Windows
3.1
95/98/ME
NT/2000/XP
Unix
Linux
Mac OS
Applications
Word
Excel
Photoshop
Visual Basic
Nero Burning ROM
Firefox
Outlook Express etc. etc. etc.
What about programs like Calculator, Wordpad or Internet Explorer?
Sometimes difficult to drawn a clear distinction e.g. is Internet Explorer an application program or part of the operating system? The courts took years to reach no real conclusion!

13. User Interface Command Line Interface (CLI)
Graphical User Interface (GUI)

14. User interface Allows User to manage the computer e.g.
Create files / folders
User management
Install / remove computers
Configure user interface
System configuration / maintenance

15. Programmer interface Standard system functions e.g.
Open a file
Save a file
List files in a folder
Use a printer
Display things on screen etc. etc.
Programmer does not need to know about the particular computer
Quicker, easier, safer etc.

16. Configuration / Maintenance
User Management
Device Management
Defragmenting
Updates / Patches
etc.

17. Networking Modern computers assumed to be networked
O/S provides means to
Add, remove network connections
Manage network connections
Share resources over network
Share network connections

18. Security Different aspects relating to other parts of O/S
User management
File / folder permissions
Network security
Program security etc.

19. Comparing Operating Systems
Parts you can see
User interface
File / Disk Management
Configuration / Administration
Security
Networking
Parts you can’t see (directly)
Process Management (Task Manager?)
Memory Management (VM settings?)
I/O Management (Device drivers?)

20. Comparing Operating Systems
Comparison
How it works in Windows
How it works in Linux
What do you think about this?