Introduction to Computer Science

1
Introduction toComputer Science

• Communications and Networks

2
Communications

• One computer transfers data, instructions, or
  information to another computer.

• Sending Device
• Signal converter
• Communications channel
• Signal converter
• Receiving device

3
Analog and Digital

• Analog signals are a continuous wave of varying
  strength.
• Music on a vinyl record is analog.
• Digital signals are on (1) and off (0), much like
  the signal of Morse code.
• Music on compact disc is digital.

4
Modem

• A modem that uses a phone line must convert a
  digital computer signal into an analog signal to
  travel over the phone line.
• A modem on the receiving end converts the analog
  signal back into a digital signal that the
  receiving computer can understand.

5
Sending/Receiving Devices

• A computer modem is a traditional send/receive
  device
• Some computers have built-in send/receive
  devices, that would NOT be called a modem.
• Cell phones, PDAs, and set-top boxes (Web TV)
  have built-in sending/receiving capabilities.
• Desktop computers still use a separate modem that
  may be external, but more than likely it is
  internal.

6
Uses of Communications

• Internet and Web
• FTP
• Voice Mail
• FAX
• E-mail
• Instant Messaging
• Chat
• Newsgroups
• Video Conferencing

7
Internet Telephony

• Using your computer like a telephone.
• A sound card converts your analog speech into
  digital signals that the computer can understand,
  and transmit to a different computer. The
  receiving computer converts your digital speech
  to analog speech.
• You use the Internet to carry your voice instead
  of the phone lines.

8
Web Services

• Web services are collections of software that aid
  communications between two or more computers.
• This allows different companies with different
  systems to use each others data.

9
Collaboration

• Collaboration is when two or more people in
  different locations can work together on the same
  project.
• Teleconferencing
• Videoconferencing

10
Groupware

• Software that allows a group (employees) to more
  easily work together and exchange information.
• E-mail
• Calendars
• address books

11
Public Internet Access Points

• Locations common around universities and public
  buildings where users with wireless devices can
  gain Internet access.
• UCF provides hot spots around campus where
  students and faculty can sign on with notebook
  PCs and handhelds.

12
Cybercafés

• Similar to a public Internet access point.
• Cybercafés are business that offer food/drinks
  and computers and wireless hotspots so customer
  can get Internet access.

13
Global Positioning Systems

• A navigation system that consists of one or more
  earth-based receivers that accept and analyze
  signals sent by satellites inorder to determine
  the receivers geographic location.

14
Messaging Services

• Technologies that go beyond traditionale-mail
  and allow people to send messages to each other
  using various devices.
• phone
• PDA
• PC

15
Computer Networks

• A network is two or more computers connected so
  that data and information can be exchanged
  electronically.
• The Internet is a networks of computer networks.
• You can set up a small network in your home to
  share a printer.

16
LANs, MANs, and WANs

• Different categories of networks
• Local Area Network (LAN) is a network within a
  structure. It could be two computers in your
  apartment or hundreds of computers within a
  building.
• Metropolitan Area Network (MAN) is a network
  confined to a town, city, or state.
• Wide Area Network (WAN) is a network that has no
  geographic boundries.

17
Peer-to-Peer Networks

• A good choice for setting up your first network.
• Peer-to-Peer networks dont have a central
  computer.
• Each computer in the network is equally
  important.
• Even if one computer has a common resource like a
  printer.

18
Client-Server Networks

• The network of choice in a large organization.
• Client-Server networks rely on a central computer
  (server) to serve common resources to individual
  compuers (clients).

The server in this type of network needs special
server software.
19
Network Topologies

• Topologies are the different types of network
  layouts.
• Bus
• Ring
• Star

20
Ethernet

• Ethernet is the most common network technology.
• Based on the bus topology
• If two computers send data at the same time, a
  collision may occur and the data must be sent
  again.

21
Token Ring

• An alternative to ethernet, token ring is based
  on a ring topology.
• To avoid data colisions, only one computer can
  send data at a time.
• One token is available on the network and moves
  from computer to computer.
• The computer with the token is the only one that
  can send data.

22
TCP/IP

• A network technology that splits up a string of
  data into small packets.
• Transmission Control Protocol (TCP) is used on
  the Internet.
• Each packet of data travels using the fastest
  path available to it at a given time.
• The packets meet up at the destiniation and
  arrange themselves in the proper order.

23
IP

• Internet Protocol (IP) works with TCP.
• IP addresses are numbers that identifity
  computers and networks and are the addresses a
  TCP packet uses to find its destination.

24
802.11

• Family of standards for wireless LANs
• 802.11b
• 802.11a
• 802.11g
• the current standard providing the fastest data
  transfer rates.

25
Wirless Network
26
Bluetooth

• Bluetooth is a wireless technology available in
  many handheld devices.
• Transimits using radio waves
• Only transmits for short distances.

The Toyota Prius comes with a Bluetooth
optionusers can use the Toyotas on-board
computer screen to interact with the Bluetooth
enable phone or PDA.
27
IrDA

• The infrared technology used for your TV remote
  control is very popular on phones and PDAs.
• Allows handheld devices to easily transmit data
  to a PC.
• Only short distances.
• Must have line-of-sight

28
Wireless Application Protocol

• The collection of software on a handheld computer
  that is used to gain access to the Internet and
  display Web content
• A WAP-enabled handheld or phone can get Internet
  access from wireless access points.

29
Intranets

• Intranets use Internet technology in-housewithin
  the company.
• Because of the successful nature of TCP/IP and
  peoples familiarity with Web browsing, many
  company are now using Intranets.
• The network is accessible using a web browser.
• Employees navigate the network like a web page.
• The Intranet is not accessible from outside of
  the network.

30
Communications Software

• programs that
• help users establish a connection to another
  computer or network
• manage the transmission of data, instructions,
  and information
• provide an interface for users to communicate
  with one another

31
Dial-up Lines

• A traditional way of connecting to another
  computer (or the Internet) using standard analog
  phone lines.
• A modem is used to translate computer signals
  into analog signals that travel over the lines.

32
Dedicated Lines

• Dedicated lines are set up to carry computer data
  and offer better quality.
• ISDN
• DSL
• T-carrier lines
• ATM
• CATV

33
ISDN and DSL

• Both use standard copper telephone lines
• Able to send data at very high speeds by sending
  streams of data at the same time
• Proximity of the computer to the phone company is
  important.
• Often the choice for business users, but some
  home users have DSL.

34
Cable

• The most common choice for broadband Internet in
  the home.
• Users already had the cable hardware set up, so
  it didnt take much for cable companies to send
  computer data along with audio and video.

35
T-carrier Lines

• Long distance digital telephone lines
• Medium and large-sized business use T1 lines to
  connect to the Internet.
• This allows for faster transfer of data than what
  home users experience.
• T3 lines are even faster than T1 and are used as
  the Internet backbone.
• T3 lines connect the large business and
  universities to each other.

36
Modems

• The devices used to translate data between the
  computer and the transmission medium (cable)
• Different types of connections require different
  types of modems.

37
Network Cards

• The device used to physically connect your
  computer (the motherboard) to the network.
• The cable connects to the network card and the
  network card is installed in the computer.

38
Hubs and Routers

• Hubs work like a powerstripthey distribute
  network connections to multiple devices.
• Routers are smarter in that they direct network
  traffic to the specific computer that requested
  it.
• Routers act as a firewall and prevent
  unauthorized data transfers.

39
Setting up a Home Network

• Office supply stores and computer stores sell
  everything necessary.
• Network cards, cables (if necessary), and a
  router.
• The Windows OS already has basic networking
  features installed, so you only need the hardware

40
Network Cabling

• Different types of networks require different
  types of cabling.
• Some networks use combinations of cabling.
• Category 5 network cable is the most common for
  connecting computers together.
• Coaxial cable is used to carry the data into the
  home and to the cable modem.

41
Twisted Pair Cable

• Pairs of cable are twisted around each other.
• The twisting helps cancel out electronic noise
  produced by the wire.
• Twisted cable doesn't tranmsit data as fast as
  coaxial or fiber optic, but is very affordable
  and the popular choice.

42
Wireless Communications Mediums
43
Microwaves

• Transmit wireless signals in one direction over
  long distances.
• Cant move over the curve of the earth, so
  multiple towers are necessary to carry the signal.

44
Satellites

• Receivers and transmitters on the ground can send
  signals into space to the satellite.
• The satellite can send a signal back to different
  receivers.
• The satellite has greater range, so the curve of
  the Earth is not as big of an issue.

45
Online Resources

• From howstuffworks.com
• http//computer.howstuffworks.com/cable-modem.htm
• http//www.howstuffworks.com/wireless-internet.htm
  
• http//www.howstuffworks.com/home-network.htm
• http//www.howstuffworks.com/wireless-network.htm
• http//www.howstuffworks.com/bluetooth.htm
• From Webopedia.com
• http//www.webopedia.com/TERM/U/UTP.html
• http//www.webopedia.com/TERM/E/Ethernet.html