Transcript computer viruses

COMPUTER SKILLS
CIS 100
http://www.just.edu.jo/~mqais/CIS%20100.html
1st semester 2013-2014
CH.01
INTRODUCTION TO
COMPUTERS
WHAT ARE COMPUTERS?
 Computers
are electronic devices that can follow
instructions to accept input, process the input and
then produce information. It is a machine that
manipulates data according to a set of instructions.
 Computers
are machines that perform tasks or
calculations according to a set of instructions, or
programs.

A computer is a programmable machine designed to
sequentially and automatically carry out a sequence of
arithmetic or logical operations. The particular sequence of
operations can be changed readily, allowing the computer to
solve more than one kind of problem. (Wikipedia free
encyclopedia)
‫‪HARDWARE‬‬
‫غير مطلوبة فقط للفهم‬
COMPUTERS ARE MADE OF
HARDWARE
SOFTWARE
COMPUTERS ARE MADE OF
•
Computers work through an interaction of
hardware and software.
•
Hardware refers to the parts of a computer
that you can see and touch, including the
case and everything inside it.
•
The most important piece of hardware
the central processing unit (CPU), or
microprocessor.
COMPUTERS ARE MADE OF
•
Software refers to the instructions, or
programs, that tell the hardware what to
do.
•
Ex. operating system (OS), A wordprocessing program.
HARDWARE

A computer is a system of many parts working
together. The physical parts, which you can see
and touch, are collectively called hardware .

System unit: It is the core of a computer
system. Usually it's a rectangular box.
Inside this box are many electronic
components that process information.
HARDWARE
 The
most important of these components is the
central processing unit (CPU ,or
microprocessor) which acts as the "brain" of
computer. The CPU has two main
components, namely:
 Control
Unit (CU): controls the fetching of
instructions from the main memory and the
subsequent execution of these instructions.
Among other tasks carried out are the control
of input and output devices and the passing
of data to the Arithmetic/Logical Unit for
computation.
 Arithmetic/Logical
Unit (ALU): carries out
arithmetic operations on integer (whole
number) and real (with a decimal point)
operands. It can also perform simple logical
tests for equality and greater than and less
than between operands.

‫)‪Mother-Board (or Main Board‬‬
‫غير مطلوبة فقط للفهم‬
‫غير مطلوبة فقط للفهم‬
‫‪CPU‬‬
‫‪RAM‬‬
‫‪ROM‬‬
PRIMARY MEMORY

Memory (fast, expensive, short-term memory): Enables a
computer to store, at least temporarily, data, programs,
and intermediate results.

Two general parts:
RAM
2. ROM
1.
RAM (MAIN MEMORY)
 its
a primary storage or random access memory
(RAM).
 it temporarily holds data and programs for use
during processing (volatile: information stored in
RAM is lost when the computer is turned off). The
more information being processed the more RAM
the computer needs.
 RAM consists of locations or cells. Each cell has a
unique address which distinguishes it from other
cells.
Address
Memory locations
1
Memory Cell
2
3
n
MAIN MEMORY
MAIN MEMORY
ROM: READ ONLY MEMORY
ROM is part of memory

Programmed at manufacturing time

Its contents cannot be changed by users

It is a permanent store
OTHER KIND OF MEMORY

PROM: Programmable Read Only Memory.

EPROM: Erasable Programmable Read Only
Memory

Cache Memory

Registers: not part of the main memory.
Input Devices
• Translate data from form that humans
understand to one that the computer can
work with
• Most common are keyboard and mouse
Selector Buttons
EXAMPLES OF INPUT DEVICES

Keyboard (QWERTY keyboard, ATMs keyboard)
ATM: automatic teller machine

Mouse

Scanner

Optical mark recognition (Light Pin , Bar code
scanners)

Microphone

Joystick .
EXAMPLES OF INPUT DEVICES(2)
Point
and Draw devices
Trackball
Touchpad

Touch screen
Magnetic

stripes and smart cars.
Digital Cameras
Secondary Storage
 Stores data and programs
permanently: its retained after the
power is turned off
 Examples
• Hard Drive (Hard Disk)
Located outside the CPU, but most often
contained in the system cabinet
• Floppy Disk
• Optical Laser Discs
CD-ROM, CD-RW, and DVD
KINDS OF DISK DRIVES
Common Secondary Media
• Diskettes
– Data represented as magnetic spots on removable
flexible plastic disks
– Most common size is 3 1/2 inches, in a rigid plastic
case
– Disk drive holds the diskette, reads or retrieves
the data and writes or stores data
Common Secondary Media
• Hard drive
– Data is represented magnetically as with
diskettes
– Normally more than one rigid platter in a
sealed unit
– These disks are not removable
– Significantly more capacity and faster
operating than diskettes
Common Secondary Media
Hard drive
Common Secondary Media
 OPTICAL LASER DISCS

CD ROM & DVD’s

Data is represented as pits and lands

Some kinds are read only (CD-ROM) and some Kinds are rewritable (CDRW)

Significantly more capacity and faster operating than diskettes
DVD: Digital Video Disk
Common Secondary Media
Disk size
Amount of storage
Approximate printed
8.5 x 11 inch pages
5.25 low density
360 Kb
180 pages
3.5 low density
720 Kb
360 pages
5.25 high density
1.2 Mb
600 pages
3.5 high density
1.44 Mb
720 pages
CD
700 MB
a small library
DVD
4.7 GB /8.5 GB
a feature length movie
Common Secondary Media

tapes

Panasonic's LS120 3.5 inch diskettes

Iomega's Zip & Jazz disks

VCR tape (Video Cassette Recorder )

Flash USB disks

MMC (Multi Media Card )

SD
CPU
Output Devices
Pieces of equipment that translate the
processed information from the CPU into a
form that humans can understand.
OUTPUT DEVICES

Monitors

Printers

Dot matrix printers

Ink jet printers

Laser printers

Sound Blasters (Sound Card By Creative Lab)

Controlling other devices
Software
• A collection of computer programs and
related data that provide the
instructions for telling a computer what
to do and how to do it.
TYPES OF SOFTWARE
1- System software: helps run the computer
hardware and computer system.
2- Application software: allows end users to
accomplish one or more specific (not
directly computer development related)
tasks.
3- Programming software : usually provides
tools to assist a programmer in writing
computer programs, and software using
different programming languages in a
more convenient way.
System Software
• The software that controls everything
that happens in a computer.
• Background software, manages the
computer’s internal resources
Resources examples : CPU, RAM , I/O devices, …
All hardware and software are under the control of the operating
system.
Among other things,
the operating system:
1.
Determines how valuable RAM is allotted to programs.
2.
Performs tasks related to file management.
3.
Sets priorities for handling tasks.
4.
Manages the flow of instructions, data and information
to and from the processor (CPU).
Examples of Microcomputer
Operating System Software
• DOS - original standard for IBM
compatibles
• Windows - a graphical operating
environment
 Windows VISTA, XP, millennium,
2000, 98, and 95
Continue …
Examples of Microcomputer
Operating System Software Cont.
• Windows NT - for powerful workstations &
networks
• OS/2 - competitor to Windows 2000
• Macintosh Operating System
• Unix - originally for minicomputers, now used
on microcomputers and Internet servers
Application Software
Packaged
Custom
• Packaged - “off the shelf”, pre-written
programs ( General purpose)
• Custom - written for an organization’s
specific purpose (Special purpose)
Application Software – Basic Tools
• Word processors– example: Microsoft
word
• Spreadsheets-- example: Microsoft
Excel
• Database managers-- example:
Microsoft Access
• Graphics-- example: Photoshop
Bit (Binary Digit)(takes two values: 1 or 0)
 Byte = 8 bits

KB (Kilo-byte) = 1024 bytes
 MB (mega-byte) = 1024 KB
 GB (giga-byte) = 1024 MB
UNITS OF MEASUREMENTS
 TB (Tera-byte) = 1024 GB

Remark: 1024=210
FOUR KINDS OF COMPUTERS
1.
Microcomputers
3. Mainframe computers
2. Minicomputers
4. Supercomputers
Comparison between the previous kinds of computers may
made based on :









Price
Processing Speed
Storage Capacity
Powerful
Single-user or Multi-user
Supporting hundreds (or thousands) of users simultaneously
Computer Size
Companies size
…etc.
Microcomputer
=>Personal
Computer => PC

Personal Computer (PC): A small, single-user computer based on a
microprocessor.
MICROCOMPUTERS
DESKTOP COMPUTER

Small enough for a desktop, but not easily
portable

Personal computers (PC’s) run general purpose
software and are employed by a wide spectrum of
users
PORTABLE COMPUTERS

Easily transported from one place to another
PORTABLE COMPUTERS
• Four categories
1. Laptops
2. Notebooks
3. Sub-notebooks
4. Personal Digital
Assistants (PDA)
PDA
MINICOMPUTERS
A
multi-user computer capable of supporting up
to hundreds of users simultaneously.
 Desk-sized
 More
processing speed and storage capacity
than microcomputers
 General data processing needs at small
companies
 Larger companies use them for specific
purposes
MAINFRAME COMPUTERS
A
powerful multi-user computer
capable of supporting many hundreds
or thousands of users
simultaneously.
 Larger machines with special wiring
and environmental controls
 Faster processing and greater storage
than minicomputers
 Typical machine in large organizations
SUPERCOMPUTERS

An extremely fast computer that can perform hundreds of millions of
instructions per second.

The most powerful of the four categories

Used by very large organizations, particularly for very math-intensive
types of tasks
Characteristics of Computers
1- Store a large amount of data and
information for a long period of time.
2- process data and information in high
accuracy level .
3- Speed in processing data information.
4- Sharing of information / network.
Understanding the difference between Data,
Information and Knowledge:
Data
Computer
Information
Knowledge
 Data: is the name given to basic facts such as
names and numbers.
 Information: is data that has been converted
into a more useful or intelligible form.
 Knowledge: arrangement of information and
classifying information of the same type or
the same topic.
e.
g.
-2 4 0 -3 10
(data)
||
sort
\ /
-3 -2 0 4 10 (information)
Data
• Document files
• Worksheet files
• Database files
Processing data produces
information, and processing
information produces
knowledge.
COMPUTER VIRUSES
COMPUTER VIRUSES
A
computer virus
are small software programs
that are designed to spread from one computer to
another and to interfere with computer operation.
A virus might corrupt or delete data on your
computer, use your e-mail program to spread itself
to other computers, or even erase everything on
your hard disk.
TYPES OF COMPUTER VIRUSES
 Macro
Viruses
 Network
Viruses
•Trojan Horses
 Logic
Bombs
Companion Viruses
 Boot
Sector Viruses
Multipartite Viruses
SOURCES OF COMPUTER
VIRUSES

Three primary sources

The Internet


Diskettes


Via downloads and exchanges
Exchanging disks
Computer networks

Can spread from one network to another
HOW DO YOU KNOW
IF YOU HAVE A VIRUS?

Lack of storage capability

Decrease in the speed of executing programs

Unexpected error messages

Halting the system
VIRUS PROTECTION
• The software package distributed with new
PCs always includes an antiviral program.
The best way to cope with viruses is to
recognize their existence and use an
antiviral, or antivirus program.
Some tips that will help minimize your
vulnerability to viruses:
Delete e-mails from unknown or suspicious,
untrustworthy (unreliable) sources, especially those
with files attached to an e-mail.
2. Never open a file attached to an e-mail unless you
know what it is, even if it appears to come from a
friend.
3. Download files from the Internet only from legitimate
and reputable sources.
1.
Update your antivirus software at least
every two weeks as over 200 viruses
are discovered each month.
2. Backup your files periodically
3. Traditionally virus protection has been
at the PC or client level. However, this
may change as companies look to
network and Internet service providers
for more services.
1.