EGAC 1010

1
Essential introduction to computers Part 2
2
Outline

• Measuring the storage space
• Components of a computer
• Storage devices
• Floppy disks
• Hard disks
• Compact discs
• Computer software
• System software
• Application software
• Networks and the internet
• Types of networks
• The internet
• The world wide web
• Electronic commerce

3
Measuring the storage space

• Capacity is measured in multiples of bytes
• Byte
• Kilobyte
• Megabyte
• Gigabyte

4
Components of a computer Storage devices

• Floppy disk
• Size
• Capacity
• Floppy disk drive
• Formatting Tracks and sectors
• Access time
• Hard disk
• Has many metal platters.
• A hard disk system has a higher speed than that
  of a floppy disk system.
• A hard disk stores more than a floppy disk.

5
Components of a computer Storage devices

• Floppy disk

3.5
Wrap - around disk label
Write - protect notch
High - density indicator hole
Drive hub
Disk surface protected by a shutter
6
Components of a computer Storage devices

• Floppy disk

Each track 18 sectors
Formatted for 80 tracks per side
Each sector 512 bytes of data
Not used for storage
7
Components of a computer Storage devices

• Floppy disk drive

Access cover
Read/write head
Motor that spins the floppy disk
Verifies that write-protect is not on
8
Components of a computer Storage devices

• Hard disk

Sector on two platters
Cylinder
Vertical stack of tracks
9
Components of a computer Storage devices

• Compact disc read-only memory (CD-ROM)
• Size
• Capacity
• CD-ROM drive
• Used for multimedia material.
• Compact disc-recordable (CD-R)
• Compact disc-rewritable (CD-RW)
• Digital video disc-read only memory (DVD-ROM)
• It is an advanced version of the CD-ROM.
• Stores more than the CD-ROM.
• Offers better quality than the CD-ROM.

10
Components of a computer Storage devices
Compact disc (CD)
Optical pickup
Cover
CD
Volume control
Laser beam
Drive activity light
11
Computer software

• System software
• Operating system
• User interface Graphical user interface (GUI)
• Booting
• Application software
• Word processing
• Spreadsheet
• Database
• Presentation graphics

12
Networks and the internet
13
Networks and the internet ...

• A network is a collection of computers connected
  together via communications media
• A network allows sharing of resources
• Types of computer networks
• Local area networks (LANs)
• Metropolitan area networks (MANs)
• Wide area networks (WANs)

14
Networks and the internet ...

• The internet is the worlds largest computer
  network
• What can we use it for?
• Email, news, maps, financial data, shopping, etc.
• How to get connected to the internet?
• Need a computer and communications software
• Subscribe to an internet service provider (ISP)
  or an online service provider (OSP)
• The world wide web is a segment of the internet
  that contains hyperlinked documents called web
  pages

15
Networks and the internet ...

• Web terminology
• Web site
• Web page
• Hyperlink
• Web browser
• Uniform resource locator (URL)
• Web address
• Web server
• Electronic commerce (e-commerce)
• Business to consumer (B2C)
• Business to business (B2B)