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2. Different Types of Computers
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INTRODUCTION TO COMPUTER SYSTEMS
INTRODUCTION
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There are many different
types of computer available
today.
They are categorised into
different types depending
upon their size and
processing power:
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What are the categories?
1. DESKTOP PC
In the early days (1980's)
these types of machine were
called a micro-computer
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The desktop PC has a central
processing unit housed in a
metal case (often a 'tower').
Along with a keyboard,
mouse and monitor.
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Engineering work - designing kitchens at a
showroom
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Video work - for handling your camcorder
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Music - creating, playing and storing
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Entertainment and information - internet.
ADVANTAGES
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Office applications such as wordprocessing, spreadsheets and databases.
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DESKTOPS ARE USED FOR:
They can be easily upgraded to include new software
or hardware
 They are relatively robust and can be used almost
continually for very long periods of time.
 It is possible to 'mix and match' specifications and
components, in effect creating a custom made machine.
 It is easy to replace an individual part if damaged or
worn out.
 They can run a vast range of software, often
simultaneously.
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DISADVANTAGES
Desktop PCs are not easily portable. They are large
and heavy.
 They require a large amount of permanent office space.
 They need a fan to prevent overheating. Thus they
can be fairly noisy.
 They can only be run on mains electricity and need to
be situated near to a power point.
 New advances in technology means that PCs get out of
date very quickly.
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ADVANTAGES
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They are portable and very easy to carry around. They
can be used almost anywhere e.g. airports
They are light to carry. Older laptops were fairly
heavy, but advances in technology and much improved
batteries have allowed them to become very lightweight.
They are compact and can be easily stored in a
standard briefcase.
They are quiet to run as unlike a Desktop PC, there is
often only a small (or no) cooling fan creating a noise.
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Laptop computers generally cost
more than a Desktop PC with
exactly the same specification
because they are more difficult to
design and manufacture.
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The key difference between a
Desktop PC and a laptop is that
the laptop is built as a relatively
small one-piece unit.
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2. LAPTOPS
DISADVANTAGES
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They are easily damaged if dropped
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They are more expensive to purchase than a similar
Desktop PC
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They cannot be expanded in the same way as a
Desktop PC e.g. new graphics cards, more memory.
Can run on battery power for only a relatively short
time, usually between 1-6 hours.
They are attractive to thieves and can be easily stolen.
The screen may be small if needed for detailed work e.g.
CAD/CAM design
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ADVANTAGES
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Palmtops are very similar
to PDAs in their use. The
main difference is that
Palmtops have a built in
keyboard.
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Originally developed as an
electronic organiser.
 Rapid development has resulted in
palm tops and PDAs becoming
almost cut down computers
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3. PDA
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Small, can easily be fitted into a pocket or handbag.
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Lightweight to carry - typically 200g
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Long battery life compared with laptop (up to 30 hours)
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Power up immediately when they are turned on, no need to go
through boot up sequence.
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Many have cut down versions of common office software
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They can be connected to a desktop PC or Laptop and the files can
be transferred over.
Many (but not all) Palmtops and PDAs are much lower in cost than
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PCs or Laptops
DISADVANTAGES
The screen is small
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Keyboards tend to be small and cramped
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They cannot be easily upgraded
They cannot be used for such a wide range of tasks as
the laptop or Desktop
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They are easy to steal
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They can be damaged if dropped
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They have a relatively small amount of memory and
cannot store large amounts of data
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Large, powerful computers that
can carry out different tasks
for many people at the same
time
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They execute billions of
process large volumes of data
MAINFRAMES
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They are usually
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simultaneously.
• They are operated by specialist,
trained personnel and
kept in air-conditioned rooms away from the office or
factory floor.
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instructions per second and can
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4. MAINFRAMES
connected to a large
number of peripherals
e.g. printers, disc drives,
terminals and so on
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Very expensive an
average mainframe would
cost around 4 million
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pounds to build.
MAINFRAMES ARE USED FOR:
Mainframe computers are often used to control an entire
factory assembly line - recording the movement of
materials, paying of bills, sending invoices and so on
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Gas and Electricity suppliers - for Billing
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Banks - for managing your accounts
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Insurance companies - looking after your policies
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Airlines - handling your tickets
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Police - crime detection
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Car companies - managing factories
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and most expensive
computers in the world
They are used for performing
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trillions of complex
calculations in a very short
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time.
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Supercomputers are the fastest
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5. SUPERCOMPUTERS
SUPERCOMPUTERS ARE USED FOR:
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Weather forecasting
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Space exploration
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Military establishment weapons research.
Pharmaceutical \ Drug
testing
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Advanced scientific
research
BLUE GENE/L
 reported to
operated at 280.6
teraflops per second
processors
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 130,000
 32
trillion bytes of memory
 400
TBytes of Hard Disk
Storage
 2.500
square feet of floor space
 built
to simulate the physics of
a nuclear explosion
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SUPERCOMPUTERS CONT…
Whilst they are working,
supercomputers generate
so much heat that an air
conditioning system is
required.
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• The atmosphere must be kept free of dust
particles. Special filters have to be
installed to ensure that the air is kept clean.
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The supercomputer
usually requires its own
electricity generator
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There can be many miles
of cables which connect
the computer to the
various peripherals.
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6. EMBEDDED COMPUTERS
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The embedded computer
is a single chip that
contains all the elements
that are essential for any
computer i.e.
RAM / ROM
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CPU

Input / Output
Another term often used for an
embedded computer is a
'microcontroller'.
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Clock
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EMBEDDED COMPUTERS CONT…
Computer chips are now cheap enough to
install in everyday items. They offer
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many functions that would otherwise be
far too expensive to produce.
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Telephones
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Televisions
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Microwaves
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Washing Machines
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Cars
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