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Introduction to Computers

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  • pg 1
									Introduction to 
  Computers

                   1
      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.

• 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. (Wikipediafree encyclopedia)
                                              2
Computers are
  made of       HARDWAR
                E

                SOFTWARE
•   HARDWARE
•   SOFTWARE




                           3
 Computers are made of
1. HARDWARE 
2. SOFTWARE 




                         4
‫‪Hardware‬‬




  ‫‬ﻓﻘﻂ‪‬‭‬ﻟﻠﻔﻬﻢ‪‭‬‬‫‬ﻏﻴﺮ‪‬‭‬ﻣﻄﻠﻮﺑﺔ‪‭‬‬   ‫5‬
                Hardware

The parts of computer itself (tangible objects ) 
   including : 
  l Input devices i.e the keyboard and mouse
  l CPU (or Processor) and Primary memory (or 
     Main Memory) 
  l Output devices
  l Storage devices
                                            6
    Mother-Board (or Main Board)
‭‫‬ﻟﻠﻔﻬﻢ‬‭‫‬ﻓﻘﻂ‬‭‫‬ﻣﻄﻠﻮﺑﺔ‬‭‫‬ﻏﻴﺮ‬

                                  ‭‫‬ﻟﻠﻔﻬﻢ‬‭‫‬ﻓﻘﻂ‬‭‫‬ﻣﻄﻠﻮﺑﺔ‬‭‫ﻏﻴﺮ‬



                            CPU


             RAM


  ROM



                                                 7
             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




                                               8
    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 .
                              See Page 4 in text book
                                                        9
Examples of Input Devices(2) 

• Point and Draw devices 
• Trackball
• Touchpad
•  Touch screen 
• Magnetic stripes and smart cars. 
•  Digital Cameras 

                                      10
11
   Central Processing Unit (CPU)

• Is the portion of a computer 
  system that carries out the 
  instructions of a computer 
  program, and is the primary 
  element carrying out the functions 
  of the computer or other 
  processing device. 
• The speed (clock speed) of CPU 
  measured  by Hertz (GHz) 
                                        12
The CPU consists of :

q Control Unit (CU)
q Arithmetic and Logical Unit (ALU)
q Some Registers




                                      13
The Control Unit (CU) :
  coordinates all activities of the 
  computer by:

• Determining which operations to perform 
  and in what order to carry them out. 
• The CU transmits coordinating control 
  signals to other computer components.


                                       14
The ALU :
consists of electronic circuitry to 
  perform:

• Arithmetic operations (addition, 
  subtraction, multiplication and division)
• Logical operations (and, or, not, …) and 
  to make some comparisons (less-than, 
  equal, … etc.)

                                         15
Primary Memory

• Memory (fast, expensive, short-term 
  memory): Enables a computer to store, 
  at least temporarily, data, programs, 
  and intermediate results.

• Two general parts:
  1.RAM 
  2.ROM

                                      16
 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).
• RAM is the memory that the computer uses to 
  temporarily store the information as it is being 
  processed. 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.
                                                 17
          Main Memory
Address   Memory locations                            
   1                         Memory Cell
   2
   3




   n

                                           18
Main Memory




              19
  ROM: Read Only Memory

ROM is part of memory
n  Programmed at manufacturing time
n  Its contents cannot be changed by users
n  It is a permanent store

Q: Mention some examples of ROM?
A: (PROM & EPROM )

                                             20
       Other Kind of Memory

n PROM: Programmable Read Only Memory.
n EPROM: Erasable Programmable Read 
  Only Memory 
n Cache Memory
n Registers: not part of the main memory. 

Q : Registers are part of “ …… ” ? 

                                      21
            Secondary Storage
q Stores data and programs 
 permanently:  its retained after the 
 power is turned off
q Examples
  • Hard Drive (Hard Disk)
    Located outside the CPU, but most often 
    contained in the system cabinet
  • Floppy Disk
  • Optical Laser Discs
     vCD-ROM, CD-RW, and DVD                   22
Kinds of Disk Drives




                       23
       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




                                                  24
    Common Secondary Media
• Hard drive



  – Data is represented magnetically as with 
    diskettes
  – Normally more than one rigid platter in a 
                                  platter
    sealed unit
  – These disks are not removable
            disks
  – Significantly more capacity and faster 
    operating than diskettes
                                                 25
Common Secondary Media

       Hard drive




                         26
           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 (CD-RW)
           • Significantly more capacity and faster operating 
             than diskettes




                                                            27
DVD: Digital Video Disk 
        Common Secondary Media

                                        Approximate printed
   Disk size        Amount of storage
                                          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                 8.5 GB         a feature length movie
                                                          28
      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
                                           29
    CPU
                    Output Devices

            Pieces of equipment that translate the 
            processed information from the CPU into a 
                                  from           into
            form that humans can understand.
       at ed
            n
     rm ess
         io
in roc
   P
  fo




                                                  30
         Output Devices

§ Monitors
§ Printers
  Ø Dot matrix printers
  Ø Ink jet printers
  Ø Laser printers
§ Sound Blasters (Sound Card By Creative Lab)
§ Controlling other devices
                                         31
              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.




                                         32
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.         33
       System Software
                 The most important

            System Software
                       is the

            Operating System

Examples of operating systems:
Windows XP (GUI: graphical user interface )
DOS (Command base),
Apple,
UNIX

                                              34
                   System Software


     • The software that controls everything 
       that happens in a computer.
     • Background software, manages the 
       computer’s internal resources




                                                 35
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).



                                                         36
   Examples of Microcomputer 
   Operating System Software

• DOS - original standard for IBM 
  compatibles
• Windows - a graphical operating 
  environment
   Ø Windows VISTA, XP, millennium, 
    2000, 98,  and 95

  Continue …                           37
     Examples of Microcomputer 
      Examples of
    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

Question: List some examples of operating systems ?
Question
                                               38
       Application Software


          Packaged      Custom


• Packaged - “off the shelf”, pre-written 
  programs ( General purpose)
• Custom - written for an organization’s 
  specific purpose (Special purpose)

                                             39
    Application Software – Basic Tools


     • Word processors– example: Microsoft
       word
     • Spreadsheets-- example: Microsoft
       Excel
     • Database managers-- example:
       Microsoft Access
     • Graphics-- example: Photoshop
Spreadsheets: Computer software that allows the user to enter    40
columns and rows of numbers in a accounting book like format.
        Units of Measurements

§ 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
§   TB (Tera-byte)   = 1024 GB

Remark: 1024=210

                                                 41
     Four Kinds of Computers
1. Microcomputers        2. Minicomputers




3. Mainframe computers   4. Supercomputers




                                        42
Comparison between the previous 
Comparison
  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                     43
Microcomputers

• Microcomputer =>Personal 
  Computer => PC
• Personal Computer (PC): A small, single-
  user computer based on a 
  microprocessor. 



                                        44
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



                             45
       Portable Computers

• Easily transported from one place to 
  another




                                          46
          Portable Computers

• Four categories
  •   Laptops
  •   Notebooks
  •   Sub-notebooks
  •   Personal Digital 
      Assistants (PDA)

  Q: list all portable 
    computer categories?       47
PDA




      48
49
                 Minicomputers
• A multi-user computer capable of supporting up 
  to hundreds of users simultaneously. 
     hundreds          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

                                                    50
‭‫“ ‬ﻣﻄﻠﻮﺑﺔ‬OMITTED“
       ‭‫‬ﻏﻴﺮ‬




                     51
Mainframe Computers
  • A powerful multi-user computer 
    capable of supporting many hundreds 
                                hundreds
    or thousands of users 
    or thousands
    simultaneously. 
    simultaneously
  • Larger machines with special wiring 
    and environmental controls
  • Faster processing and greater storage 
    than minicomputers
  • Typical machine in large organizations

                                    52
           “OMITTED“
‭‫‬ﻣﻄﻠﻮﺑﺔ‬‭‫‬ﻏﻴﺮ‬




                       53
            Supercomputers
• An extremely fast computer that can perform 
      extremely fast computer
  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




                                            54
Supercomputers




                 55
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.      56
Understanding the difference between Data,
Information and Knowledge:


Data                           Information
             Computer
                               Knowledge


                                        57
ü Data: is the name given to basic facts such as
  Data
    names and numbers.
ü Information: is data that has been converted
  Information
     into a more useful or intelligible form.
ü Knowledge: arrangement of information and
  Knowledge
    classifying information of the same type or
    the same topic.
                                               58
• e. g. 

      -2   4   0   -3   10      (data)
                                  data
                    | |     sort 
                   \  /
     -3   -2   0   4   10  (information)
                               information


                                         59
                    Data

• Document files

• Worksheet files

• Database files




                           60
                Information

Information: the result of processing data.
n   Information:
    Ø Must serve a useful purpose
    Ø Must be of an acceptable level of accuracy
    Ø Must be available at the right time
    Ø Must be relevant to the enterprise, person, … etc.



                                                  61
               Knowledge

• Putting a number of information with the same 
  type or same topic would be a knowledge.




                                           62
Processing data produces
information, and processing
information produces
knowledge.

                              63
Computer Viruses




                   64
          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.


                                           65
    Examples of Viruses

•  Win32/Conficker
• INF/Autorun
• Win32/PSW.OnLineGames
• n32/Agent




                          66
   Viruses and Virus Protection

• A virus program
  • Infects programs, documents, 
    databases and more …
  • It is man-made
  • It can hide and reproduce
  • It can lay dormant (inactive) 
    and then activate


       Anti-virus programs can help   67
   Types of Computer Viruses
• Macro Viruses
• Network Viruses
  •Trojan Horses
• Logic Bombs
  Companion Viruses
• Boot Sector Viruses
  Multipartite Viruses



                               68
    Types of Computer Viruses
• Macro Viruses
  A macro virus, often scripted into common application
  programs such as Word or Excel, is spread by
  infecting documents.

• Network Viruses
  rapidly spreads through a Local Network Area (LAN),
  and sometimes throughout the internet.

•Trojan Horses
   The Trojan virus once on your computer, doesn't
   reproduce, but instead makes your computer
   susceptible to malicious intruders by allowing them to
   access and read your files. Making this type of virus
   extremely dangerous to your computer's security and
   your personal privacy.

                                                      69
    Types of Computer Viruses

• Logic Bombs
  a piece of code that are inputted into a
  software system. When a certain and specific
  condition is met, such as clicking on an internet
  browser or opening a particular file, the logic
  bomb virus is set off.

• Companion Viruses
  takes advantage of MS-DOS. This virus creates
  a new file with typically the .COM extensions,
  but sometimes the .EXD extension as well.


                                                      70
    Types of Computer Viruses
• Boot Sector Viruses
  generally hide in the boot sector, either in the
  bootable disk or the hard drive. Unlike most
  viruses, this virus does not harm the files in the
  hard disk, but harm the hard disk itself.

• Multipartite Viruses
  spreaded through infected media and usually
  hides in the memory. Gradually, the virus moves
  to the boot sector of the hard drive and infects
  executable files on the hard drive and later
  across the computer system.


                                                       71
Sources of Computer Viruses

         • Three primary sources
           • The Internet
             • Via downloads and exchanges
           • Diskettes
             • Exchanging disks
           • Computer networks
             • Can spread from one network 
               to another

                                      72
       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


                                           73
           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.



                                        74
      Some tips that will help minimize your
              vulnerability to viruses:
1. 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.
4. Update your antivirus software at least every two 
   weeks as over 200 viruses are discovered each month.
5. Backup your files periodically
6. 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.                                          75

								
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