Post on 03-Jan-2016
3 of 22
Operating systemSits between the user (you) and the
physical hardwareMakes tasks simple - you don’t need to be
a programmer to use a computerCommand line environment vs graphical
user interface (GUI)Customization
4 of 22
Operating systemSits between the user (you) and the
physical hardwareMakes tasks simple - you don’t need to be
a programmer to use a computerCommand 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!
7 of 22
Application softwareIs not part of the OS, although it may be
sold in the same packageAllows the user to perform a certain taskExamples:
Word processing software Games Web clients (browser, email) Database software
8 of 22
Security
Security flaws (install updates)Firewall (make sure it is turned on)Virus Protection (scan regularly!)SPAM FiltersNever open an email attachment from
a stranger! Archiving/backup
9 of 22
Virus SoftwarePopular Brands of Virus Software:
Symantec (USQ staff use this) Norton's PC-Cillin AVG (free version:
http://www.grisoft.com/)
Update the virus database regularlyScan 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
GW
PC PC
PC
Firewallneeded here.
Internetnot 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 structureFiles 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
15 of 22
Files (3)Text files:
Contain only text (ASCII)No fancy fonts, symbols, images etcJust characters you can type from the keyboard
Can be viewed in simple text editor like notepad
Examples: Files with .txt extensionHtml filesSource 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 Word Open with Notepad
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 numbersAll computer data is stored in the binary
number systemOnly uses 0 and 1
(binary=2 digits, decimal=10 digits)
One bit is either 0 or 1One byte is 8 bits
(28=2x2x2x2x2x2x2x2=256 possible values)
20 of 22
File Size Units1024 (=210) major scaling factor 1 KB (kilobyte) =1024 bytes (B)1 MB (megabyte) = 1024 KB1 GB (gigabyte) = 1024 MB1 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 !!!