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Telecommunications and Networks

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					             Telecommunications
• Telecommunications:
  • Electronic transmission of signals for
    communications, usually including:
     •   Telephone
     •   Radio
     •   Television
     •   Computer data




                                             5
            Telecommunications
• Data Communications:
  • A specialized subset of telecommunications and
    consists of:
     • Computer data
        • Includes the collection, processing, and distribution of
          computer data.




                                                                     6
Some Common Elements of a
Telecommunications System
                      Analog Signal




Digital Signal
                                        (Modem)




                 (Modem)




                                      Digital Signal

                                                       7
       Telecommunication
        Electronic Terms




Baud                       8
      Analog and Digital Signals

Analog Signal
• A continuously varying signal over time.
• Modem signal, household voltage,
  telephone voice, radio & TV signals




                                             9
      Analog and Digital Signals
Digital Signal
• A discretely varying signal between two
  states:
  • High (binary 1), 5 volts in a computer
  • Low, (binary 0), 0 volts in a computer




                                             10
                 Amplitude

Amplitude
• The height of the wave, as measured from
  peek to peek.
• Measured in volts.
• Applies to both analog and digital waves.




                                              11
                Frequency

Frequency
• The number of waves generated per second.
• Measured in Hz (Hertz) or cycles second.
• Applies to both analog and digital waves.
                 1 second
                                 1 Hz

                                 2 Hz

                                 4 Hz
                                         12
              AM, FM, and PM
  AM -- Amplitude Modulation
  • Two different amplitudes are used:
    • High (binary 1)
    • Low, (binary 0)




Modem                               Modem
                                            13
              AM, FM, and PM
  FM -- Frequency Modulation
  • Two different frequencies are used:
    • High frequency, (binary 1)
    • Low frequency, (binary 0)




                                          Modem
Modem
                                             14
                AM, FM, and PM

 PM -- Phase Modulation
 • An 180 degree phase shift denotes:
   • Binary 0
 • NO change in wave phase denotes:
   • Binary 1




Modem                                   Modem
           180 degree phase shift
                                                15
                   bps vs. Baud

 bps -- bits per second
   • bps is a measure of the amount of information
     transmitted in one second.
   • In other words, the number of 1’s and 0’s that
     can be transmitted in one second.
   • Common Modem speeds: 14,400, 28,800,
     56,600 bps.



                                     Modem            16
Modem
                      bps vs. Baud

 BAUD
   • BAUD -- The number to times per second the
     wave changes some physical characteristic.
        • Amplitude, Frequency and/or Phase.
   • Baud is NOT the same as bps.
   • It is a term which engineers use, not users.




                                          Modem     17
Modem
                  bps vs. Baud

Baud vs bps
• A modem with a Baud of 4,800 would have
  a bps speed of 9,600 if 2 bits of information
  were transmitted on every wave phase shift.
                             Shift       Bits
                             Degrees     Transmitted
                             0           00
                             90          01
                             180         10
                             270         11
                                                  18
                 bps vs. Baud
Summary (bps vs. Baud)
• Baud -- the number of times per second the
  signal changes its physical characteristics.
• bps -- the number of information bits (0’s
  &1’s) transmitted each second.
• PEOPLE OFTEN CONFUSE THE TWO.




                                             19
                     Bandwidth

• Bandwith -- is the difference between the
  upper and lower frequencies.
  •   Telephone: 3000 Hz (3300 - 300 Hz)
  •   Hearing: 19,980 Hz (20,000 - 20 Hz)
  •   Fiber optic cable: 200 trillion Hz
  •   The greater the bandwidth, the greater the
      transmission capacity.
       • Fiber optics can handle up to 32,000 calls
         simultaneously on a single fiber.

                                                      20
      Broadband vs. Baseband

• Broadband -- a type of transmission which
  uses analog signals.
  • Has a WIDE bandwidth
  • Can carry MANY channels at once, such as,
    cable TV, satellites, microwave, etc.




                                                21
      Broadband vs. Baseband

• Baseband -- a type of transmission which
  uses digital signals
  • Has a NARROW bandwidth
  • Carries only ONE channel at once, such as,
    LANs.
  • The single channel uses the entire
    bandwidth.



                                            22
Types of Communications Media




                           23
            Twisted-pair wire

Twisted-pair wire
• Local area networks
  • Shielded, high grade,100 Mbps
• Telephone
  • Unshielded, low grade, 56Kbps




                                    24
              Coaxial cable

Coaxial cable
• Local area networks & cable TV
• Shielded to reduce interference
• 1 Mbps to 200 Mbps




                                    25
           Fiber-optic Cable

Fiber-optic cable
• Network backbones, homes, businesses
• 2.5 Gbps and above.
• Can’t be tapped without detection




                                         26
         Fiber-optic Cable




Light pulses traveling through a fiber optic cable.




                                                      27
    Microwave Transmission

Microwave
• Telephone & computer data
• 275 Mbps
• Point-to-point (30 to 75 miles)
• Not secure


                                    28
      Satellite Transmission

Satellite
• Telephone, TV & computer data
• 2 Mbps
• Point-to-point (22,300 miles)
  • Geosynchronous orbit
• Not secure
• 3 Satellites can cover earth
                                  29
          Cellular Transmission
Cellular Transmission
   •A geographical area is divided into cells.
   •Calls can be made and received within cells.
   •Cell phone signals are integrated into regular
   telephone service where calls can originate and
   be sent.




                                                     30
THERE IS NO PROOF THAT SMOKING CAUSES CANCER
         COMMON STATEMENT YEARS AGO
     EDWARD BERNAYS (Start at 10 min point.)




                                 ELECTROPOLUTION
                                                  31
                           ELECTOMAGNETIC RADIATION (EMR)
                            Cellular Transmission




RAT STUDIES
Radio signals from cell phones caused cells in three areas of rats’ brains to die.
The three affected areas were the cortex, which plays a role in high-level mental function; the
hippocampus, which is important in learning; and the basal ganglia, which plays a role in the
experience of sensation.

Researchers exposed three groups of rats to different intensity radio frequency electromagnetic
fields for a period of two hours. Rats that received more intense exposure had more dead and
damaged neurons.

Damage to neurons appear to be selective, however, as damaged cells were often surrounded by
normal cells. The reasons for the selectivity, along with the mechanism causing the neuron death, are
not known.
Researchers say that the study does not demonstrate cell phone use is harmful to people, but
recommend the use of a hands-free device to keep the cell phone as far from the brain as possible,
                                                                                             32
adding that the use of cell phones is a "huge biological experiment."
                                 Cellular Transmission




Nerve Cell Damage in Mammalian Brain after Exposure to Microwaves from GSM Mobile Phones
Leif G. Salford,1 Arne E. Brun,2 Jacob L. Eberhardt,3 Lars Malmgren,4 and Bertil R. R. Persson3
1Department of Neurosurgery, 2Department of Neuropathology, 3Department of Medical Radiation Physics, and 4Department

of Applied Electronics, Lund University, The Rausing Laboratory and Lund University Hospital, Lund, Sweden

Abstract
www.protectingourhealth.org/newscience/learning/2003/2003-0129salfordetal.htm

The possible risks of radio-frequency electromagnetic fields for the human body is a growing concern for our society.
We have previously shown that weak pulsed microwaves give rise to a significant leakage of albumin through the
blood-brain barrier. In this study we investigated whether a pathologic leakage across the blood-brain barrier might
be combined with damage to the neurons. Three groups each of eight rats were exposed for 2 hr to Global System for
Mobile Communications (GSM) mobile phone electromagnetic fields of different strengths. We found highly
significant (p < 0.002) evidence for neuronal damage in the cortex, hippocampus, and basal ganglia in the brains of
exposed rats. Key words: blood-brain barrier, central nervous system, microwaves, mobile phones, neuronal33 damage,
rats. Environ Health Perspect 111:881-883 (2003)
                          Cellular Transmission




Albumin is the protein of the highest concentration in plasma. Albumin transports many small
molecules in the blood (forexample, bilirubin, calcium, progesterone, and drugs). It is also of prime
importance in maintaining the oncotic pressure of the blood (that is, keeping the fluid from leaking
out into the tissues). This is because, unlike small molecules such as sodium and chloride, the
concentration of albumin in the blood is much greater than it is in the extra cellular fluid.
Because albumin is synthesized by the liver, decreased serum albumin may result from liver
disease. It can also result from kidney disease, which allows albumin to escape into the urine.
Decreased albumin may also be explained by malnutrition or a low protein

www.protectingourhealth.org/newscience/learning/2003/2003-0129salfordetal.htm

                                                                                             34
  Cellular Transmission




      ELECTROPOLUTION            35
ELECTOMAGNETIC RADIATION (EMR)
                 Cellular Transmission




Johnnie Cochran
•Died at 67
•Brain Cancer
•Cell phone
•Wife and his doctor say cell phone usage
 caused his cancer.
•Used cell phone on left side of head,
exactly where tumor was located.
•Law suite
                                            36
                                    Cellular Transmission
US high court won't hear wireless radiation appeal by cell companies.

By Jeremy Pelofsky

WASHINGTON (Reuters) - Class-action lawsuits against wireless telephone providers and manufacturers over
radiation emissions will be able to go forward, after the U.S. Supreme Court Monday declined to hear an appeal by
the companies.

The high court rejected hearing an appeal by companies like Nokia and Cingular
Wireless challenging a decision by a U.S. appeals court that reinstated the lawsuits that
argued manufacturers knew about and hid the risks of radiation emissions wireless
phones posed to users.

Wireless phones are radios that emit frequency radiation and in the United States the Federal Communications
Commission must approve any device that sends out such radiation.
Exposure to high levels of radiation can cause adverse health effects, but it is less clear the impact on a wireless
phone user who is exposed to low levels of radiation when a phone is held to an ear directly.

Health advocates have expressed concerns about radiation causing problems ranging from headaches to tumors.
                                                       scientific evidence so far has
But the wireless industry has pointed to U.S. government statements that
not shown any health problems associated with wireless phone use.

Five class-action lawsuits were filed in state courts seeking damages, including money for wireless users to buy a
headset or reimburse those who had already had purchased one.

A U.S. district court judge dismissed the five lawsuits on the grounds that state regulation of wireless phone
                                                                                                               and
emissions was preempted by the FCC, but the U.S. Court of Appeals for the 4th Circuit overturned that decision 37
reinstated the cases.
                               Cellular Transmission
US high court won't hear wireless radiation appeal by cell companies
By Jeremy Pelofsky

"The court was satisfied that the issues had been treated responsibly by the Fourth Circuit," said
Harley Thomas Howell, a lawyer at Howell & Gately who represents those who sued the
manufacturers.

Nokia spokeswoman Arja Suominen said the company was disappointed by the decision, but
declined further comment. Cingular, the largest U.S. wireless carrier, declined to comment.

The wireless industry is worried about being required to adhere to numerous different emissions
requirements imposed by states, something the service providers and manufacturers argue would
wreak havoc on the industry and consumers.

"This court's intervention is necessary to prevent the balkanization of network standards ... which
will, if uncorrected, undermine the ability of consumers to use an FCC-approved wireless telephone
in every state of the union," they said in their appeal to the court.

Other companies that joined in the appeal include Motorola Inc. and Qualcomm Inc. Cingular
Wireless is a joint venture of BellSouth Corp. and SBC Communications Inc.

As a result of the top court's action, one lawsuit will go forward in federal court while the four other
lawsuits will advance in state court.
                                                                                                     38
                RF Transmission
RF (Radio Frequency) Transmission
•Radio Frequency waves sed to connect computers and
peripheral devices.


          Look, a mouse
           with no tail.                   WHAT?




                                                  39
Telecommunications Devices




        Fax modem


       Special-purpose
          modems
                             40
      Telecommunications Devices

Modem (MO+DEM)
• Encodes a digital wave into an analog wave.
  • MOulation.
• Decodes an analog wave into a digital wave.
  • DEModulation.




                                            41
             Telecommunications Devices
WiFi - Short for Wireless Fidelity

802.11b
– A protocol (Standard) from IEEE (Institute of Electrical and Electronics Engineers)
_ Speed: 11 Mbps
_ Frequency: 2.4 GHz
_ Distance: About 100 to 200 feet

802.11g
– A protocol (Standard) from IEEE
_ Speed: 54 Mbps
_ Frequency: 2.4 GHz
_ Distance: About 100 to 200 feet

802.11n
– A protocol (Standard) from IEEE
_ Speed: 200 + Mbps
_ Frequency: 2.4 or 5 GHz
_ Distance: About 100 to 200 (or more) feet
_ Not fully standardize yet.                                                   42
           Telecommunications Devices
Hot Spot
_ It is connection point for a WiFi network.
_ Has a 802.11 radio
    _ It is connected to the Internet by Cable or DSL
    _ Up to 100 users
    _ Transmits 100 to 200 feet.
_ Found in:
    _ Universities
    _ Restaurants (Now in McDonalds)
    _ Hotels
    _ Libraries
    _ Airports
    _ Homes
    _ Coffee Shops
                                                        43
      Telecommunications Devices
WiFi Adapters
                WiFi Chip Adpater
                                        WiFi Routers
                            PDA
                            Personal      WiFi Router
Built-in WiFi               Digital
                            Assistant



         WiFi Laptop Adapter                     Cable




         WiFi USB Adapter




                                                  USB WiFi Router
                WiFi PCI Adapter

                                                         USB Cable
                                                                     44
Telecommunications Devices
        Satellite




                             45
              Telecommunications Devices
WEP and WPA
_ Wired Equivalent Privacy (WEP)--OK                                WiFi Hotspots
- Wi-Fi Protected Access (WPA)--Better
_ A security code that is needed to get into the network
_ is part of the IEEE 802.11 standard (ratified in September
1999), and is a scheme used to secure wireless networks (WiFi).
Because a wireless network broadcasts messages using radio, it is
particularly susceptible to eavesdropping; WEP was designed to
provide comparable confidentiality to a traditional wired
network, hence the name: WEP

                Hot spot finder




                                                                            46
           Telecommunications Devices
DSL
– Digital Subscriber Line
_ Uses telephone lines
_ Must be close to telephone
   company’s central office.
   (Within 4 miles.)
_ Typical Speeds
   1.5 Mbps (Download)
   64 to 640 Mbps (Upload)
_ Best Possible Speeds
   8 Mbps (Download)
   640Kbps (Upload)


                                        47
      Telecommunications Devices


Modem
• Internal




• External
                                   48
         Telecommunications Devices


Copy machines
• Modem within machine
• Many have other features:
  •   Computer printer
  •   Copier
  •   FAX
  •   Scanner

                                      49
      Telecommunications Devices


Cellular modem
  • Inside notebook computers.
  • Can communicate with other computers and fax
    machines through telephone companies.




                                              50
          Telecommunications Devices

Multiplexing
• Multiplexing allows two or more devices,
  such as computers and terminals, using
  multiplexers, to share a single data channel.
           A


                     1 Channel         A
       B                               B
                       ABC
               MUX               MUX   C

      C
                                                  51
      Telecommunications Devices

Multiplexers:
• Time division multiplexer
• Frequency division multiplexer




               A (low frequency)

                                   52
          Telecommunications Devices
Sprint’s Fiber-optic Multiplexer
• Optical Wavelength Digital Multiplexing
Asynchronous Transfer Mode (ATM)
• Merge Data, Video, and Voice




                                            53
       Telecommunications
       Carriers and Services

                Common carriers
            Digital subscriber line
                      PBX


             Value-added carriers
                                      WATS
Caller ID           ISDN
                                             54
      Telecom. Carriers & Services

• Telecom Carriers provide:
• telephone lines,
• satellites, microwave,
• switching circuits,
• modems, MUXs,
• other equipment, and technology.
                                     55
           Telecom. Carriers & Services


Two types of carriers:
• Common carriers
  • Own lots of equipment.
• Value-added carriers
  • Use common carriers’
    equipment, but add a value
    such as packet switching, or
    frame relay, and better rates.
                                          56
Telecom. Carriers & Services




              Leased line
              Switched Line    57
Telecom. Carriers & Services
PBX - Private Branch Exchange




                                58
OLD TELEPHONE SWITCH BOARD




                        59
       Telecom. Carriers & Services
                    WATS Line
WATS - Wide-Area Telecommunications Services
  • 800 & 888 numbers
  •Cost varies by geographical location and usage.
                          900? But, I thought
                          the psychic network
                           was an 800 number.




                                                     60
       Telecom. Carriers & Services
                     Caller ID
                                            Caller ID stopped
                                            those weird calls
Caller ID                                   from normal people.
•ANI - Automatic Number Identification
•Identifies caller
•Can link caller to information stored in
  a computer.                                             Wall Set (1882)




                                                                            61
      Telecom. Carriers & Services
             Digital Subscriber Line
DSL
•Developed by Bellcore Labs
  •Owned by 7 Bell companies.
•Upload speed MAX ( 640Kbps)
•Download speed MAX (8 Mbps)
•Cost ($ 29 to $48 per month)
•Twisted pair cable



                                       62
Telecommunications Act 1996


      Promote competition

            V-chip

         TV Bandwidth

                              63
Computer Networks




                    64
 Computer Network Characteristics
• Networks consist of communications media, devices, and software.
• Networks connect two or more computers or devices.
• Network computers can share data, information, and the
  processing of jobs.




                                                             65
Network Processing Stratagies
      Centralized Processing




                                66
Network Processing Stratagies
     Decentralized Processing




                                67
Network Processing Stratagies
      Distributed Processing




                                68
                  Benefits of Networks
Benefits:
•Help gain competitive advantage.
•Will allow for the sharing of hardware, software, and databases across
the organization.
•Distant workgroups could share documents and opinions.
•Could make the organization more creative.
•Better and faster information could make the organization more
effective and efficient.




                                                                          69
Network Topologies


     Bus



     Star

                     70
                       Ring Topology

Ring Topology              I have the token.

• One computer can talk at a time.
• Must have the token to talk.
• Only one token in a ring.
   • Token is an electronic signal.
• Token moves around the ring
  from computer to computer.

                                               71
                    Bus Topology

Bus Topology
• One computer talks at a time.
• Uses contention to talk.        We use
• Most popular topology.          contention
                                  to talk.




                                               72
                   StarTopology

Star Topology
• Hub computer controls all    I control
  communication.              everything.
• If hub computer goes
      down, the entire
  network goes down.


                                            73
                  Hybrid Topology

Hybrid Topology
• This a mixture of two or             Star and Ring

  more topologies.
                              I’m a
                             hybrid.




                                                       74
Types of Networks


     LAN



 Metropolitan

                    75
               Local Area Network (LAN)

LAN
• Connects computer systems and devices within the
  same geographical (or LOCAL) area, such as, an
  office
                                                      I’m a
  building.                                           LAN.
• Any network topology will work.




                                                     76
    Metropolitan Area Network (MAN)

MAN
• Connects computer systems
  and devices to a              Bay
                                area
  metropolitan area, such as,
  a city or county.
• May use microwave,
  telephone lines and cable.

                                       77
            Wide Area Network (WAN)



WAN
• Connects computer systems and devices to a
  WIDE geographical area, such as, across cities,
  states, or countries.
• May use satellites, microwave, telephone lines, and
  fiber-optic cable.



                                                        78
          Value-added Network (VAN)
VAN
• They lease communications America Online
  lines from a public company turns me on.
  and enhance services.
  • They add special equipment and
    services, such as, America
    Online.
  • Packet-switching service is
    another example.


                                             79
Distributed Processing




                         80
                  Client/Server Model
Client/Server
• Client and Server both hold components of the application
  and share running the application.
   • Server holds database and part of the application
   • Client holds the remaining part of the application.



     Server




                    Data & SQL             Client      81
     SPARC 330
                 Client/Server Model
                   Payroll Example
Database Server                      Client
•Update DB files from new data       •GUI.
entered by client.                   •Input data to server.
•Fetch requested data for client.    •Data queries to
•Process payroll.                    server.
                                     •Retrieved data for
                                     spread sheet
     Server
                                     analysis.



                    Data & SQL           Client      82
     SPARC 330
                 Client/Server Model
                 Advantages vs. Disadvantages
Possible advantages                 Possible
•Elimination of mainframes and      Disadvantages
proprietary software.               •Cost of conversion.
•Less traffic on network.           •Loss of control.
•Added security in stored           •Complex
procedures.                         multivendor
•Better use of processing power.    environment.

     Server




                     Data & SQL         Client     83
     SPARC 330
               Client/Server Model
                      Client/Server Defined
Client Server
•It is a model for computing that splits the processing
between clients and servers, assigning functions to the
machine on a network most able to perform that function.




                                                                 84
                 SPARC 330   SPARC 330   SPARC 330   SPARC 330
 Communications
Software & Protocols




                       85
                Network Operating System
NOS - Network Operating System
• Controls the operation of the network, and resides
  on server.
• Popular NOS’s
   • Windows XP and Vista
        • This OS has a NOS built in.
   • UNIX
        • This OS has a NOS built in.
   • LINUX
        • This OS has a NOS built in.




                                                       86
            Communications Protocols
Protocols
• Common protocols allow computers of different
  types and from different manufactures to talk to
  each other.
            I’m an IBM
             running OS/2.             I’m an HP
                                     running UNIX.




                                                     87
       Communications Protocols
OSI - Open Systems Interconnection

               Application Layer (7)

               Presentation Layer (6)
               Session Layer (5)
               Transport Layer (4)

               Network Layer (3)
   SPARC 330
               Data Link Layer (2)
               Physical Link Layer (1)
                                         88
                    OSI Model (i)
• Application Layer (7)
   • Interfaces application programs to the network.
• Presentation Layer (6)
   • Handles the display, formatting and appearance of
      information on the screens.
• Session Layer (5)
   • Establishes logon/logoff process. Handles accounting and
      billing.
• Transport Layer (4)
   • Routes data through several networks. Handles data
      security.
• Network Layer (3)
   • Routes data within the network. Handles PADs.
• Data Link Layer (2)
   • Polling, error detection & correction.
• Physical Link Layer (1)                                       89
Bridges, Routers, Gateways (i)




                                 90
            Communications Protocols
Other popular protocols:
  • TCP/IP - Transmission Control Protocol/Internet
    Protocol
     • The major protocol used by the government and internet.
  • Ethernet
     • Used by LAN’s
  • X.400 and X.500
     • Used in e-mail systems.




                                                                 91
         Bridges, Routers, and Gateways
Bridge
• A bridge is a device used to connect networks using the
  same protocol, such as, Ethernet.
• The bridge interprets the data link portion of the message to
  see if the message needs to be sent to the connected LAN.

                   I use Ethernet.               I do too.


                             Bridge

                                                             92
Bridges, Routers, Gateways (i)




                                 93
       Bridges, Routers, and Gateways
Router
• Determines the best path between two networks
  having multiple paths between them.
• A router is a device used to connect networks using
  the same protocols, such as, Ethernet.




                        Router

                                                 94
Bridges, Routers, Gateways (i)




                                 95
        Bridges, Routers, and Gateways
Gateway
• A gateway is a device used to connect networks
  using very different protocols, such as, Ethernet and
  SNA.

                I use Ethernet.
                                         I use SNA.

                          Gateway


                                                      96
Bridges, Routers, Gateways (i)




                                 97
     Data Transfer Modes
    Packet Switching Network
PACKET SWITCHING NETWORK




                               98
Packet Switching (i)

128 Bytes in Length




                       99
                    Data Transfer Modes
ATM - Asynchronous Transfer Mode
• High speed network which transports:
   •   Voice, data, video, images, and text.
   •   Uses 53 byte cells.
   •   Switches data using only hardware, thus faster.
   •   Up to 2.4 Gbits/s
   •   Fiber Optic




                                                         100
Telecommunications Applications




                                  101
Voice Mail




             102
          E-Mail

No more E-mail!




                   103
Electronic Document Distribution




                                   104
Electronic Software Distribution




                                   105
Telecommuting
   Could this be happening
   to 7 million others?




                         106
                Videoconferencing
Mary, we must
release the
product by
March.




                                    107
      Electronic Data Interchange (EDI)



Chemical Factory
                             Could you spare
                             some change?




Chemical Distributor                   108
                       QUIZ
1. MODEM stands for modulation/demodulation.
   a. True
   b. False




                                        109
                        QUIZ
2. If a MODEM has a baud of 1,200 and uses phase
   shift modulation with 0, 90, 180, 270 degree
   shifts, what is it bps?
   a. 2,400 bps
   b. 4,800 bps
   c. 9,600 bps
   d. 19,200 bps


                                           110
                             QUIZ
3.   Cable TV uses:
a.   Frequency Division Multiplexing
b.   Phase Shift Modulation
c.   Time Division Multiplexing
d.   Statistical Time Division Multiplexing




                                              111
                          QUIZ
4. This computer model places one part of an
    application on the user’s computer and the
    other part on a server.
   a. Client-Server
   b. User-Server
   c. Application-Server
   d. Server Model
   e. Client Model
                                                 112
                       QUIZ
5. Protocols such as OSI and TCP/IP allow
   dissimilar computer systems to
   communicate with each other?
   a. True
   b. False




                                        113
       Electronic Data Interchange (EDI)



Chemical Factory

                               Could you spare
                               some change?




                                         114
Chemical Distributor

				
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