Module 1
DIFFERENT TYPES OF COMPUTERS
A Computer is an electronic device that processes data, converting it
into information that is useful to people.
Data:It consists of pieces of information that by themselves may not
make much sense to a person.Data is raw.It does not have meaning of
itself.A computer’s primary job is to process and convert data into useful
information.
Information: Information is data that has been given meaning by way of
relational connection. Information is the collection of meaningful data.
A.OPERATIONAL PRINCIPLE
Based on the operational principle of computers,they are categorized as
analog,digital and hybrid computers.
Analog Computer:These are almost extinct today.It can perform
several mathematical operations simultaneously.It uses continous
variables for mathematical operations and utilizes mechanical or
electrical energy.
Digital Computer:They use digital circuits.It has two states 0 and
1.They are analogous to states ON and OFF.Digital computers are
suitable for complex computation.It has higher processing speeds.They
are programmable.Digital computers are either general purpose
computers or special purpose computers.
Hybrid computer:Combination of both digital and analog computers.In
this ,digital segments perform process control by conversion of analog
signals to digital ones.
B.COMPUTERS FOR INDIVIDUAL USERS
1.Desktop Computers
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Most common type of personal computer
Designed to sit on table or desk
Used in schools,homes,offices etc
Used to communicate,produce music,edit photographs and
videos,play games etc..
 Used for learning,work and play
 Too big too carried around.Difficult to port.
 Two types:
:Horizontally oriented system unit,which usually lies flat on the
top of the user’s desk.Many users place their monitor on the top of
the system unit.
:Vertically oriented tower models,Place the system unit next to
or under the desk.
2.Workstations
 Single user computer
 More power and features than a standard PC.
 Popular among scientists, engineers and animators who need a
system with greater than average speed and the power to perform
sophisticated tasks.
 It has large and high resolution monitors and accelerated graphics
handling capabilities,making them suitable for engineering
design,modeling,animation and video editing.
3.Notebook Computers
 It can operate on alternating current or special batteries.
 Size approximately same as 8.5 * 11 inch notebook.
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Portable.
Easily fit inside a brief case.
Light weight
Also called laptop
It has liquid crystal color display,touchpad,full size keyboard.
Bluetooth facility available
More expensive than normal PC
Lesser hard disk storage than a PC
It comes under the category of mobile computers
It is possible to connect notebook computers to the network
During the use,the computer’s lid is raised to reveal a thin monitor
and a keyboard.When not in use,the device folds up for easy
storage.
 A docking station can make a notebook computer feel like a
desktop system,by adding a full size monitor,keyboard and other
features.
4.Tablet PCs
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Portable
Full featured computer
Lighter than PC
Accept input from a special pen called stylus or digital pen,that is
used to tap or write directly on the screen.
It has a built-in microphone
It has a special software that accepts input from user’s voice.
A few models even have fold out keyboard, so they can be
transformed into a standard notebook PC.
It can be connected to a network,keyboard and a full sized monitor.
5.Handheld PCs
 Small enough to fit in your hand
 A popular type of handheld computer is the PDA(personal digital
assistant).A PDA is no larger than a small appointment book and is
normally used for special applications, such as taking
notes,displaying telephone numbers and addresses and keeping
track of dates or agendas.PDA also connected to larger computers
to exchange data.Most PDAs come with a pen that lets the user
write on the screen.
 It has tiny built-in keyboard or microphone that allow voice input.
 PDA helps to access internet through wireless connection.
 Other features cellular phones,music players,cameras,GPS(global
positioning system)
6.Smart Phones
 Some cellular phones double as miniature of PCs.because these
phones offer advanced features not found in cellular phones,they
are called smart phones.
 Features includes web and e-mail access, special software such as
personal organizers, or special hardware such as digital cameras or
music players.
 The main difference between smart phone and PDA is that, smart
phone is voice centered whereas PDA is data centered.
C.COMPUTERS FOR ORGANIZATIONS
Some computers handle the needs of many users at the same time.These
powerful systems are most often used by organizations,such as business
or schools ,and are commonly found at the heart of organization’s
network.
1.Network Servers
 Individual user’s desktop computers connected to one or more
centralized computers,called network servers.
 Large organizations may have dozens or millions of servers
working together at the heart of their network,such group set up is
called clusters or server farms.
 They are designed to provide services to client machines in a
computer network.
 Running on them are programs that serve client requests and
allocate resources like memory and time to the client machines.
 They have large storage capacity, powerful processors and many
number of hard drives.
 They are designed to be fail-safe and resistant to crash.
2.Mainframe Computers
 Large and powerful systems
 Used for bulk data processing
 Used in large organizations such as banks and insurance companies
where many people need frequent access to the same data.
 In traditional mainframe environment,each user work at a
computer terminal.A terminal is a monitor and a keyboard wired to
the mainframe.
Two types of terminals:
a.Dumb Terminal: It does not process or store data,it is simply an
input/output device that functions as a window into a computer
located somewhere else.
b.Intelligent terminal:It can perform some processing
operations,but does not have any storage.
 It has capacity to host multiple Operating System.
3.Minicomputers
 Small in size
 Released in 1960
 The capabilities of a minicomputer are somewhere between those
of mainframes and personal computers. For this reason
,minicomputers are also called midrange computers.
 It can handle much more input and output than PC
 It can acts as a server computer
 Mainframe computer having smaller configuration is called
minicomputers.
 Eg:HP-3000
4.Supercomputers
 Most powerful computers
 Largest
 It can process huge amounts of data and the fastest super
computers can perform more than one trillion calculations per
second.
 Some supercomputers can house thousands of computers.
 Used to handle large and highly complex problems that require
extreme calculating power. eg: Mapping of human genome,
forecasting of weather and modeling complex processes such as
nuclear fission.