Components of a Computer System

1
Components of a Computer System

• Lesson 18 Communications (ADCs)

2
Learning Objectives

• State the difference between analogue data and
  digital data.
• Describe the need for conversion between analogue
  and digital data.
• Name the general name for devices which do this
  conversion, giving two example and their
  purposes.

3
Structure Diagram
4
Communications

• Sending and receiving data to and from other
  computers.

5
Network Card

• Allows communication between computers in a LAN.

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Analogue Data

• Analogue devices such as
• Clocks
• Thermometers
• Phones
• Speakers
• Represent variables by an analogous quantity or
  variations (modulations)
• Time is represented by the angle of the hands
• Temperature is represented by the height of a
  column
• Sound waves on a normal phone line or from
  speakers.

7
Digital Data

• Computers work with data in a digital form.
• Streams of 0's and 1's

8
Need for conversion

• If computers are to receive or send analogue data
  (sensors, speakers, phone lines, etc).
• There must be conversion between analogue and the
  digital data computers use.
• Devices which do this are called
• ADCs (Analogue to Digital Converters)

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Modem

• Modem
• A hardware device that allows computers or other
  digital devices e.g. faxes to communicate using
  telephone lines.
• Converts analogue phone signals to digital data
  which the computer can understand.
• Converts digital data to analogue phone signals
  so they can be transmitted through the phone line

10
Data Loggers

• Data Loggers
• Convert analogue data from sensors to digital
  data which a computer can understand.

11
Sound Cards

• Sound cards
• Convert digital data to analogue data for
  speakers / headphones to use.
• Convert analogue data from microphones to digital
  data which a computer can understand.

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COMMUNICATIONS

• Students -- ICT -- IGCSE -- Computer System 13
  Communications
• Follow its instructions.

13
Plenary

• What is the difference between analogue data and
  digital data?
• Analogue data
• analogous quantity or variations (modulations)
• Time is represented by the angle of the hands
• Temperature is represented by the height of a
  mercury column
• Sound waves on a normal phone line and or from
  speakers.
• Digital data
• Streams of 0's and 1's

14
Plenary

• Why do we need to convert between analogue and
  digital data?
• Computers work with data in a digital form.
• What are devices that do this conversion called,
  can you name three examples and state when they
  are used?
• ADCs (Analogue to Digital Converters)
• Data Loggers - Convert analogue data from sensors
  to digital data.
• Modems - Converts analogue phone signals to
  digital data and vice versa.
• Sound Cards - Converts digital signals to
  analogue data and for speakers to use and vice
  versa from microphones.

15
Plenary

• In which types of network is a modem necessary
  and unnecessary?
• Modem needed
• WANs
• Modems not needed
• LANs