Operating Systems by ee3kYaGM


• Different types of operating systems including:
   –   Single-user
   –   Multi-user
   –   Multi-tasking
   –   Interactive
   –   Real-time
   –   Batch processing
   –   Distributed processing systems

• The aim is to help you describe the features of each OS
  and understand their major characteristics.
•   A lot of computer users understand that a computer needs an operating system
    (OS) ...but they don’t really understand    they are needed.

•   The OS is responsible for:
     –   User interface
     –   Memory management
     –   CPU management
     –   File management
     –   Error detection
     –   Utility software

•   Any installed applications, like the one you are using to view this presentation, will
    be calling upon the OS to access system resources.
     – Applications can’t control memory allocations, processing time etc...they need to ask the
       OS to do it for them.
• There are different types of operating systems
  out there too...each with a different role to play!

• These include:
   –   Single-user
   –   Multi-user
   –   Multi-tasking
   –   Interactive
   –   Real-time
   –   Batch processing
   –   Distributed processing systems
•   Operating systems can be found in:
    –   Digital watches
    –   Calculators
    –   Washing machines
    –   Computer controlled microwave
    –   Missile guidance systems
    –   Mobile phones
    –   Computer controlled burglar alarms

•   Some are generic, and some are purpose-built.
• Allows a single user to access any particular computer at any one time.

• A few example single-user OS:
    – DOS
    – Windows
    – Linux

• Don’t be confused with multiple accounts on a computer...for someone
  else to use their account you have to log off yours first!

                                       Sorry, but you’ll
                                      just have to wait
                                       until I am done!         *grumble*
• Allow lots of users to share
  data and resources at
  (apparently) the same time.

• This is called a network.

• A server controls how the
  computers run and

• The server needs a Network
  Operating System (NOS).
• A network allows multiple users to multi-task.

• The set up usually consists of multiple single-user OS
  computers connected to a multi-user OS server.

• UNIX is an example of OS that allows this to happen.

• Dumb terminals are often used in businesses where
  data processing takes place.
• A computer that has:
  – Keyboard
  – Monitor

• However, they lack the power and facilities of
  desktop computers as they do not have any
  independent data processing or storage
• Some operating systems allow you to
  open more than one application at a
• e.g. You could be listening to music in
  iTunes             whilst working on an
  essay in MS Word.
• Many single-user operating systems
  allow users to run multiple applications.
• Early operating systems, such as DOS,
  didn’t allow this to happen.
   – They were not complex enough.

• Dos is a single-user single-task OS.
• Simply put...

• This type of OS requires direct user
                          Aw dude...you mean I
                           actually HAVE to do
                           something? Lame.
• Usually used in embedded application.

• This means it is a system that runs inside another system for a specific

• For example, most modern cars have ECU (Engine Control Units) built in.
  This control how the car performs under acceleration. These can be
  modified to change the behaviour of the car.

• Cars also have other systems in place which monitor tyre pressures, grip,
  weather and light conditions...
• Batch OS systems were used to process jobs
  one at a time.

• People used to write programs on punch hole
  cards and feed them into a special card reader.

• The OS would interpret these cards one at a
  time and select the correct compiler for them
• The demand to process large quantities of
  data has never been greater.

• More people use banks and have multiple
  – People used to keep their money under their

• Good for single purpose jobs.
•   A brilliant example of this type of system can be
    found in Sony’s PlayStation 3.

•   The PS3 has a very powerful processor.

•   Scientists are making use of this power by asking
    people to accept a usage policy which turns their PS3
    into a mini super computer.

•   They system performs calculations using the
    remaining processing power (which isn’t needed at
    the time). After the calculations have been
    completed the results are sent off to another

•   The result of this distributed system is that months
    can be saved in processing data compared to using a
    single super computer to do it.
• Some super computers have thousands of
  processors all working together...sharing the work
  load to produce very fast results from data

• Compare this to the distributed system of the PS3
  and you could probably see that if enough people
  allowed their PS3 system to be used results could
  be produced a lot faster than a super computer!

• So far, scientists have been able to map out
  climate change in a matter of days rather than
  years and analyse complete DNA structures!
•   Write a definition for the following:
     –   Single-user
     –   Multi-user
     –   Multi-tasking
     –   Interactive
     –   Real-time
     –   Batch processing
     –   Distributed processing systems

•   What is the difference between a single-user
    and multi-user OS?

•   How does a batch processing system differ         Now I gotta do
    from an interactive OS?                         work?! Dude...you
                                                   are so not as cool as I
•   Describe the computer you have at home and      thought you were!
    the computer you use at school. For each,
    give a definition of it’s type.
     – TIP: How was DOS defined?

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