The document provides an overview of computer basics including system software, application software, file formats, and information security best practices. It defines key concepts like operating systems, word processors, spreadsheets, file location, passwords, viruses, and binary and decimal number systems. Common types of malware and how antivirus software works to detect and remove viruses are also summarized.

1. Learn how to use your computer for everyday work

2. By Jeewanthi Hettiarachchi

3.  System software
◦ Operating systems
◦ Device drivers
◦ Utilities
 Application software
◦ Word processor
◦ Spreadsheet
◦ Accounting application
◦ Web browser
◦ Email client
◦ Media player
◦ File viewer
◦ Aeronautical flight simulator
◦ Console game
◦ Photo editor.

4. ◦ Word Processor
◦ Spreadsheet
◦ Database
◦ Presentation
◦ And Many more

11. Save Button
Always Remember:
• File Name : Internet
• File type : pdf
• File Location : C:UsersDellDesktop

12. Name and Extension
Type of the file
Location
Size
Time

13. Copy Cut Paste
(Ctrl+C) (Ctrl+X) (Ctrl+Y)
New Open Undo Redo Print
(Ctrl+N) (Ctrl+O) (Ctrl+Z) (Ctrl+Y) (Ctrl+P)

15.  Information security is the practice of
defending information from unauthorized
access, use, disclosure, disruption,
modification, perusal, inspection, recording
or destruction.
Wikipedia

16.  Record keystrokes and steal passwords.
 Send spam and phishing emails.
 Harvest and sell email addresses and passwords.
 Access restricted or personal information on your
computer or other systems that you have access
to.
 Illegally distribute music, movies and software.
 Distribute child pornography.
 Infect other systems.
 Hide programs that launch attacks on other
computers.
 Generate large volumes of traffic, slowing down
the entire system.

17.  Use good, cryptic passwords that can‟t be easily
guessed. And keep your passwords secret.
 Make sure your computer‟s operating system and
applications are protected with all necessary
security “patches” and updates.
 Make sure your computer is protected with up-
to-date anti-virus and anti-spyware software.
 Don‟t click on unknown or unsolicited links or
attachments, and don‟t download unknown files
or programs onto your computer.

18.  Remember that information and passwords
sent via standard, unencrypted wireless are
especially easy for hackers to intercept.
 Look for “https” in the URL before you enter
any sensitive information or a password (The
“s” stands for “secure”).
 Also avoid standard, unencrypted email and
unencrypted Instant Messaging (IM) if you‟re
concerned about privacy.

19.  What is a computer virus?
a piece of code which is capable of copying
itself and typically has a detrimental effect,
such as corrupting the system or destroying
data.

20.  Common virus types
◦ Boot Sector Virus - This type of virus affects the
boot sector of a floppy or hard disk.
◦ Worms - Worms do not require user actions to
spread, they move from system to system over
networks on their own.
◦ Macro Viruses - Macro viruses infect to the files
that are created using certain applications or
programs that contain macros.

21.  Antivirus software, or anti-virus software,
also known as anti-malware, is a computer
program used to prevent, detect, and remove
malware. Antivirus software was originally
developed to detect and remove computer
viruses, hence the name.

23. 804 KB (823,301 bytes)
Bit (Binary Digit) = 1 or 0
8 Bits = 1 Byte (Charactor)
0 1 0 0 0 0 0 1

25. 804 KB (823,301 bytes)
1 byte = 8 bit
1Kilo byte = 1024 bytes
1Mega byte = 1024 Kilo bytes
1Giga byte = 1024 Mega bytes
1Tera byte = 1024 Giga bytes
1Peta byte = 1024 Tera bytes
(1024 is Approximately 1000)

26. 3 MB file
= 3x1024 KB = 3,072 KB
= 3x1024x1024 Bytes = 3,145,728 Bytes
= 3x1024x1024 x 8 Bits = 25,165,824 bits

28.  In mathematics and digital electronics, a
binary number is a number expressed in the
base-2 numeral system or binary numeral
system, which uses only two symbols:
typically "0" (zero) and "1" (one).
 Binary = 0,1 (Base is 2)
 Decimal = 0,1,2,3,4,5,6,7,8,9 (Base is 10)

29.  0 0 0 1 numerical value 20
 0 0 1 0 numerical value 21
 0 1 0 0 numerical value 22
 1 0 0 0 numerical value 23

30. 1 0 0 0 12
1x 24 + 0x 23 + 0x 22 + 0x 21 + 1x 20
1x 16 + 0x 8 + 0x 4 + 0x 2+ 1x 1
16+ 0+ 0+ 0+ 1
1710
1 0 0 0 12 = 1710

31.  Convert these Binary Numbers to Decimal
1. 1111112 = ? 10
2. 10101012 = ? 10
3. 111002 = ? 10

32. 1710 = 1 0 0 0 1 2

33.  Convert these Decimal Numbers to Binary
1. 6310 = ? 2
2. 8510 = ? 2
3. 2810 = ? 2