Transcript Introduction to computers

Introduction to Computers
© 2004 http://eduspace.org - Mahmud Shihab
What is a Computer?
Monitor
System Unit
Keyboard
Floppy Disk
Drive
CD-ROM /
DVD-ROM Drive
Mouse
A computer is an electronic machine that accepts information
(Data), processes it according to specific instructions, and provides
the results as new information.
Hardware vs Software
Hardware
• The physical Parts of
the computer. usually made
of plastic, metal or glass…
• Ex:
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–
–
–
–
Monitor
Mouse
System Unit
CPU
Keyboard
Printer...
Software
• Programs, instructions
and all information
related to them.
• Ex:
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MS Windows
MS Word
Lotus 123
Games…
Digital Nature of Computer
Information
• The Nature of Computer Information is based
on binary digits 0 & 1.
0 : representing an OPEN circuit. OFF
1 : representing a CLOSED circuit ON
The computer mother tongue uses binary notation ( 0 & 1)
which make the computer’s Machine Language.
0 = bit
1 = bit
All information to be used into computers have to be translated
into binary code. All Information, be it of any kind ( text, image,
sound, video), have its own binary representation inside the
computer.
Binary Notation
Every single character used in the computer was given a
standard decimal number (ASCII) whose binary equivalent can
be used during information processing. (Binary Digits)
ASCII = American Standard Code for Information Interchange
Letter
ASCII Code
Binary Notation
I
J
M
73
74
77
01001001
01001010
01001101
1 Character = 8 bits = 1 byte = 1 Octet
Units of Measuring Information
1 Character = 8 bits = 1 byte
1000 bits = 1 Kilobit (Kb)
~1000 bytes
~1000 Kilobytes
~1000 Megabytes
~1000 Gigabytes
=
=
=
=
1 Kilobyte (KB)
1 Megabyte (MB)
1 Gigabyte (GB)
1 Terabyte (TB)
Storage Devices
Magnetic Storage
• Floppy Disk (FD)
• Hard Disk
• Zip Disk
Optical Storage
• All types of CDs and
DVDs
All storage media need appropriate drives for reading/writing
information. These Drives may be either Internal or External.
Data Flow in the Computer
RAM
Input
Devices
010010
(Random Access
Memory)
+
CPU
010010
Output
Devices
(Central Processing Unit)
+
System Devices
Storage
Devices
Communication
Devices
Motherboard
It’s the main electronic board in a computer on which all
the electronic components are mounted.
Expansion Slots
RAM (SIMMs)
ROM
CPU - Intel 486
RAM & ROM
RAM: Random Access Memory
This is the active memory of your computer. When you run a
program it is first loaded in RAM where it becomes accessible
to the CPU which in turn will process all commands and
instructions. The more RAM you have the faster the
processing will be. RAM is volatile in nature, this means that
all information in it will disappear when you switch off your
machine. You should always save your files on permanent
storage devices (disks, etc.) if you want to keep them for
future use..
ROM: Read Only Memory
ROM is very important and will not be erased after you switch
off your computer. It keeps the essential information about
your computer hardware for the computer to be able to
startup.
CPU - Central Processing Unit
It is the computer’s control center and the place where
instructions and calculations are performed.
Ex:
286
386
486
Pentium
Pentium Pro = Pentium + Internal Cache
Pentium + MMX technology
Pentium II = Pentium Pro + MMX
Pentium III = Pentium II + MMX2
Cache = A special kind of fast
memory (RAM) reserved for
the temporary storage of
most recently accessed
information.
MMX = a set of 57
instructions that enhance
multimedia capabilities of the
CPU.
Pentium Pro
Pentium II
Monitor
Normal desktop computers use Cathode-Ray-Tube monitors
which are similar to the TV screen. This CRT contains three beams of
electrons that are responsible for displaying the computer images by
mixing the three basic colors: Red, Green, and Blue (RGB). Portable
computers use LCD monitors which use the Liquid Crystal Display
technology. LCD monitors are very similar to the tiny screens of digital
watches. TFT forms of LCD monitors give the best image quality and
are built in most portable TVs and Digital cameras.
CRT
The size of the monitor is
measured by the length of
the diagonal of its screen.
15” is recommended for
general purpose computers.
LCD
Pointing Devices
These devices are used to point to, select, and manipulate items
on the screen. Examples of pointing devices that we use on the
computer are:
Mouse
Joystick used mainly for games
Track Ball
used with portable
Joypad
Touch Pad
computers
Tablet used by professional
painters and graphic designers.
Mouse
Track Ball
Tablet
Printers
Printers are of three basic types:
1- Dot Matrix: that use needles to transfer
ink from ribbons to paper - Lowest quality.
2- Inkjet: That pumps ink on paper - Good quality.
Plotter: It is a specialized Inkjet printer that prints
maps and very big charts and posters.
3- Laser: That uses laser beams to transfer very
finite plastic grains to paper - Best Quality.
1 inch
Quality of printing is measured by how many
dots per inch ( dpi ) a printer can print.
1 inch
Plotter
MODEM
Modulator
De-Modulator
A MODEM can convert digital information from the computer
into sounds (Modulation) for transmission over telephone
lines, or vice-versa (De-Modulation). The speed of the MODEM
is measured by Kbps (Kilobits per second) ex: 56 Kbps.
Internal Modem
External Modem
It is mounted on the
motherboard inside the
system unit.
It is connected to the
computer through the Serial
or USB ports.
Scanner
The scanner converts images or text found on paper into data
that can be stored on a computer. Then with a graphics
application we can edit and modify these images. OCR (Optical
Character Recognition) programs allows us to extract the
text from scanned images. This text can be modified in any
word processor. Flat-bed scanners give better photo quality
and are used by all professional designers.
1 inch
1 inch
Hand-held
(very low quality)
The quality of scanning is measured by how many dots per
inch (dpi) a scanner can capture from the original photos.
Flat-bed
(high quality)
Multimedia Upgrade Kits
A typical multimedia upgrade kit includes a CD-ROM drive, sound
card, speakers, and some multimedia titles. New multimedia
kits offer a DVD-ROM drive, a Dolby pro logic AC-3 decoder, an
MPEG-2 decoder in addition to some promotional DVDs.
CD-ROM Drive
Sound Card
Magnetic Storage Devices (1)
Hard Disk:
It’s A fixed disk inside the PC. It’s used for permanent storage of
huge amounts data and programs. It stores more data than
a floppy disk. It is usually called “ C: ”. The capacity of data
that a hard disk holds varies according to the needs of the
user. (The most common capacity 2.1 - 6.4 Gigabytes).
Platters
Reading/Writing
Head
Magnetic Storage Devices (2)
Floppy Disk:
A portable magnetic disk in a plastic case; used for storing or
transferring data or programs. It is usually called “ A: ”. It can
hold up to 1.44 Megabytes of data : (Approximately 300
thousand words) ~ the size of a novel (Text Only).
Floppy Disk
Drive
Floppy
Disk
Any magnetic disk needs
to be formatted to be able
to handle data (0s and 1s).
This process creates
sectors and concentric
tracks on which the
magnetic charges will be
recorded.
Sector
Track
Optical Storage Devices (1)
• CD-ROM: Compact Disc Read Only Memory
This type of CD contains data that can be read by a computer but not
modified. Its drive is usually called “ D: ”. A single CD-ROM can hold up to
650 MB of data (Approximately 400 Floppy Disks) or 74 minutes of audio
tracks. The diameter of this disc is 5.25 inches.
• CD-R: Recordable (diameter=5.25” capacity=650 MB)
We need a special machine called CD recorder ( also called burner ) in order
to record on such discs. Once information is recorded it can never be
deleted (write once). We can write information on the CD-R at different
times until it is full this process is called Multi-session. CD-Rs are excellent
for backups and recording music CDs. (CD-Rs can be read by normal CDROM Drives)
• CD-RW: Rewritable (diameter=5.25” capacity=650 MB)
These CDs also need a special recorder. The advantage of using them is that
they are re-writable. We can write and delete information from them at any
time. (CD-RWs can be read by normal CD-ROM Drives)
Optical Storage Devices (2)
•DVD-ROM: Digital Versatile Disc - Read Only Memory
This type of disc contains data that can be read by a computer but not
modified. A very advanced optical disc made up of two double-sided
layers on which data is stored. It can store as much as 17GB (26 CDROMs) of information or four feature films with Dolby pro logic AC-3
sound and great MPEG-2 video. New versions of DVD-ROM drives read
all CD formats in addition to DVDs, but they cannot read DVD-RAM
discs. All DVD formats have the same diameter size of a regular CDROM (5.25”)
•
DVD-RAM: Random Accesss Memory (capacity=5.2 GB)
DVD-RAMs require a special recorder, a DVD-RAM drive.
The advantage of using them is that they are re-writable.
We can write and delete information from them
at any time.
Optical Storage Devices (3)
• Unlike Magnetic storage media which store charges on
concentric tracks, CDs and DVDs have burned pits and
reflective lands representing (0s &1s) recorded on a spiral
path from the center to the periphery.
Sound Cards
• Sound Cards are needed in computers in order
to play music files.
Graphics Cards
•Video cards are responsible for generating the picture you
see on your screen.
Types of Software (s)
1- Operating Systems
2- Applications
3- Games: …
4- Communication/Internet
5- Development (Programming)
6- System Tools / Utilities
Operating Systems
Regular Users / Clients
•Character based
Network Servers
• UNIX (AT&T & Novell)
– MS-DOS
(Microsoft Disk Operating System)
•GUI (Graphical User Interface)
– Apple Macintosh OS
• Mac OS
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MS Windows 3.1
MS Windows 95
MS Windows 98 & 98 SE & ME
MS Windows 2000 & XP
•Netware (Novell)
•MS Windows NT server
•MS Windows 2000 server
(Microsoft)
•LINUX
Applications
•Word Processing
–MS Word
–Word Perfect
–Word Pro
–Wordpad
–Notepad
•Spreadsheet
–MS Excel
– Lotus 123
•Database (DBMS)
–MS Access
–MS Fox Pro
–ORACLE
•Presentations
– MS Power Point
– Lotus Freelance
•Graphics
– Adobe Photoshop
– Paint Shop Pro
Development (Programming)
Regular Programming
Languages
•Basic
•Visual Basic
Internet Programming
Languages
•HTML
Hypertext Markup Language
•DHTML
•Pascal
•Delphi
•C
•Visual C++
Dynamic HTML
•JavaScript
•VB Script
•CGI / Perl
•Java
•ASP, JAVA, JSP, PHP, XML, etc…
Internet / Communication
•Web Browsers
–MS Internet Explorer
–Netscape Navigator
•E-Mail
–MS Internet Mail
–MS Outlook / Express
–Netscape Messenger
–Eudora
•Fax
–MS Fax
–Winfax
•Chatting/Collaboration
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MS NetMeeting
M-IRC
ICQ
FreeTel
•FTP
– WS-FTP
– Cute FTP
System Tools & Utilities
• Norton Utilities
– Disk Utilities
– Diagnostic Tools
• Anti-Virus Programs
– Norton Anti-Virus
– McAFee
– etc...
References
• Graphics are taken from Sierra Print Artist 4.0
available from: www.sierra.com
• How computers Work - QUE (Book + CD)
available from: www.que.com
• A Guide to Microsoft Office 97 Professional
available from: from Laurenceville Press: www.lvp.com