Operating Systems Foundation Computing Half the people you know are below average.

2 of 22 Overview  Operating systems  Application Software  Security  Files  A mystery

3 of 22 Operating system  Sits between the user (you) and the physical hardware  Makes tasks simple - you don’t need to be a programmer to use a computer  Command line environment vs graphical user interface (GUI)  Customization

4 of 22 Operating system  Sits between the user (you) and the physical hardware  Makes tasks simple - you don’t need to be a programmer to use a computer  Command line environment vs graphical user interface (GUI)  Customization

5 of 22 Operating system (2)  Is responsible for Running and scheduling of programs (processes) Hardware management Memory allocation Networking (communication with other computers) Security (administrator, restricted permissions for users) File management And more!

6 of 22 Examples of popular OS's  Unix  Mac OS  Windows  Linux (free, open source)

7 of 22 Application software  Is not part of the OS, although it may be sold in the same package  Allows the user to perform a certain task  Examples: Word processing software Games Web clients (browser, ) Database software

8 of 22 Security  Security flaws (install updates)  Firewall (make sure it is turned on)  Virus Protection (scan regularly!)  SPAM Filters  Never open an attachment from a stranger!  Archiving/backup

9 of 22 Virus Software  Popular Brands of Virus Software: Symantec (USQ staff use this) Norton's PC-Cillin AVG (free version:  Update the virus database regularly  Scan your system regularly

10 of 22 A house or business Firewall  You will sometimes need to turn it off Firewalls prevent communication.  Don't forget to turn it on again later!  Firewall is often contained in ADSL modem GWGW PC Firewall needed here. Internet not needed here.

11 of 22 Files – get organised  Files are used for Documents Graphics Music Data  Files are organised in: Directories (folders) CD's Archives

12 of 22 File Systems  Files are stored in file systems.  Your computer may need to check or repair your file system from time to time.  Turning off without shutting down may damage the file system.

13 of 22 Files (2)  Hierarchical structure  Files have a name and a suffix Windows does not necessarily display the suffix In Windows the suffix is used to identify the file type, eg letter.txt

14 of 22 Files (2)

15 of 22 Files (3)  Text files: Contain only text (ASCII)  No fancy fonts, symbols, images etc  Just characters you can type from the keyboard Can be viewed in simple text editor like notepad Examples:  Files with.txt extension  Html files  Source code from most programming languages

16 of 22 Files (4)  Binary files Executable programs (eg.exe) Application specific formats (.doc,.xls,.ppt) Graphics, multimedia (.jpg,.gif,.mp3) Usually not easily readable if opened in Notepad Open with WordOpen with Notepad

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18 of 22 Files (5)  Windows associates file extensions with an application, eg:.txt -> opened in Notepad.doc -> opened in Word.html -> opened in Internet Explorer  The icon indicates which application is associated with a file

19 of 22 Binary numbers  All computer data is stored in the binary number system  Only uses 0 and 1 (binary=2 digits, decimal=10 digits)  One bit is either 0 or 1  One byte is 8 bits (2 8 =2x2x2x2x2x2x2x2=256 possible values)

20 of 22 File Size Units  1024 (=2 10 ) major scaling factor  1 KB (kilobyte) =1024 bytes (B)  1 MB (megabyte) = 1024 KB  1 GB (gigabyte) = 1024 MB  1 TB (terabyte) = 1024 GB

21 of 22 A mystery  I bought a hard disk with a size of 40 GB  Why does my computer tell me it can only store 37.3 GB?

22 of 22 A mystery (solved)  I bought a hard disk with a size of 40 GB  Why does my computer tell me it can only store 37.3 GB?  Answer: Hard disk manufacturers use file size units in a different way: They gave me 40,000,000,000 B and divided by 1000 each step, not by 1024, to reach GB But we know 40,000,000,000 B = 39,062,500 KB = 38,147 MB = 37.3 GB !!!