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3.3.2
• Different types of operating systems including:
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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:
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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:
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Single-user
Multi-user
Multi-tasking
Interactive
Real-time
Batch processing
Distributed processing systems
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Operating systems can be found in:
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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
communicate.
• 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
capabilities.
• Some operating systems allow you to
open more than one application at a
time.
• 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
interaction.
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
task.
• 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
accounts.
– People used to keep their money under their
mattress!
• Good for single purpose jobs.
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A brilliant example of this type of system can be
found in Sony’s PlayStation 3.
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The PS3 has a very powerful processor.
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Scientists are making use of this power by asking
people to accept a usage policy which turns their PS3
into a mini super computer.
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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
computer.
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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
inputs.
• 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!
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Write a definition for the following:
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Single-user
Multi-user
Multi-tasking
Interactive
Real-time
Batch processing
Distributed processing systems
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What is the difference between a single-user
and multi-user OS?
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How does a batch processing system differ
from an interactive OS?
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Describe the computer you have at home and
the computer you use at school. For each,
give a definition of it’s type.
– TIP: How was DOS defined?
Now I gotta do
work?! Dude...you
are so not as cool as I
thought you were!