2. An Overview of the Computer System
What is a Computer?
A computer is an electronic device used to process
A computer can convert data into information that is
useful to people.
A complete computer system includes four distinct
A computer is an electronic machine that can be programmed to accept
data (input), process it into useful information (output), and store it in a
storage media for future use
What is a Computer?
5. Basic Terminology
Whatever is put into a computer system.
Refers to the symbols that represent facts, objects, or ideas.
The results of the computer storing data as bits and bytes; the words,
numbers, sounds, and graphics.
Consists of the processing results produced by a computer.
Manipulation of the data in many ways.
Area of the computer that temporarily holds data waiting to be
processed, stored, or output.
Area of the computer that holds data on a permanent basis when it is
not immediately needed for processing.
Includes the electronic and mechanical devices
that process the data; refers to the computer as
well as peripheral devices.
A computer's hardware consists of electronic
devices; the parts we can see and touch.
The term "device" refers to any piece of
hardware used by the computer, such as a
keyboard, monitor, modem, mouse, etc.
A computer program that tells the computer
how to perform particular tasks.
Software – also called programs – consists of
organized sets of instructions for controlling the
Some programs exist for the computer's use, to help it
manage its own tasks and devices.
Other programs exist for the user, and enable the
computer to perform tasks for you, such as creating
People are the computer's operators, or
Some types of computers can operate without
much intervention from people, but personal
computers are designed specifically for use
14. Classification of computer depending on signal /
nature of I/O
Computers can also be divided into three
categories depending upon their instruction
and form of input data that they accept and
process. These are:
15. Analog Computers
The word “Analog” means continuously
varying in quantity.
The analog computers accept input data in
continuous form and output is obtained in the
form of graphs.
These computers accept input and give
output in the form of analog signals. The
output is measured on a scale.
These are used in industrial units to control
various processes and also used in different
fields of engineering
17. Digital Computers
The word “Digital” means discrete. It refers to binary
system, which consists of only two digits, i.e. 0 and 1.
Digital data consists of binary data represented by
OFF (low) and ON (high) electrical pulses. These
pulses are increased and decreased in discontinuous
form rather than in continuous form.
The main features of the computers are:
Give accurate result.
Having high speed of data processing.
Can store large amount of data.
Easy of program and are general purpose in use.
Consume low energy.
18. Hybrid Computers
The hybrid computers have best features of both
analog and digital computers.
These computers contain both the digital and analog
components. In hybrid computers, the users can
process both the continuous (analog) and discrete
These are special purpose computers. These are
very fast and accurate.
These are used in scientific fields. In hospitals, these
are used to watch patient’s health condition in ICU
(Intensive Care Unit). These are also used in
telemetry, spaceships, missiles etc.
21. Types of Computers on the basis of size and
or Personal Computers
22. Supercomputers are the most
powerful computers. They are
used for problems requiring
Because of their size and
expense, supercomputers are
Supercomputers are used by
agencies, and large businesses
23. "FLOPS" (FLoating Point Operations Per
Second), commonly used with an SI prefix
such as tera-, combined into the shorthand
"TFLOPS" (1012 FLOPS, pronounced
or peta-, combined into the shorthand
"PFLOPS" (1015 FLOPS, pronounced
24. Mainframe Computers
Occupies specially wired, air-conditioned rooms
Capable of great processing speeds and data
Not as powerful as supercomputers
computer capable of
processing data for
hundreds or thousands
Used to store, manage,
and process large
amounts of data that
need to be reliable,
secure, and centralized.
Usually housed in a
closet sized cabinet.
Known as midrange computers
Used by medium-size companies
Used by departments of large companies
Minicomputers are smaller than mainframes but larger than
Minicomputers usually have multiple terminals.
Minicomputers may be used as network servers and
A personal computer;
designed to meet the
computer needs of an
Provides access to a
wide variety of
such as word
editing, e-mail, and
29. Four Types of Microcomputers
Notebook or laptop
30. 1.Desktop Microcomputer
A microcomputer that
fits on a desk and runs
on power from an
electrical wall outlet.
The CPU can be
housed in either a
vertical or a horizontal
mouse, etc.) that are
each plugged into the
31. 2.Laptop Computer
A portable, compact
computer that can run
on an electrical wall
outlet or a battery unit.
(keyboard, mouse, etc.)
are in one compact unit.
Usually more expensive
than a comparable
Sometimes called a
32. 3.Tablet PC
Is a type of notebook computer that
accepts your handwriting. This input is
digitized and converted to standard text
that can be further processed by
programs such as a word processor.
Also called a PDA (Personal
A computer that fits into a
pocket, runs on batteries,
and is used while holding the
unit in your hand.
Typically used as an
appointment book, address
book, calculator, and
Can be synchronized with a
personal microcomputer as a
Are the smallest and are also known as
palm computers. These systems typically
combine pen input, writing recognition,
personal organizational tools, and
Powerful desktop computer designed for specialized
Can tackle tasks that require a lot of processing
Can also be an ordinary personal computer attached
to a LAN (local area network).
Workstations are powerful single-user computers.
Workstations are used for tasks that require a great
deal of number-crunching power, such as product
design and computer animation.
Workstations are often used as network and Internet
38. Wearable computer
Wearable computers are computers that are
worn on the body.
This type of wearable technology has been
used in behavioral modeling, health
monitoring systems, information technologies
and media development.
Wearable computers are especially useful for
applications that require computational
support while the user's hands, voice, eyes,
arms or attention are actively engaged with
the physical environment.
42. General Purpose Computers
General-purpose computers are designed to
solve a large variety of problems. That is they
can be given different programmes to solve
different types of problems.
General-purpose computers can process
business data as readily as they process
complex mathematical formulas. General-
purpose computers can store large amount of
data and the programmes necessary to
Because general-purpose computers are so
versatile, most businesses today use them.
Most digital computers are general computers
and it is mainly such computers that are used
in business and commercial data processing.
43. Special Purpose Computers
Special purpose computers are designed to solve a
specific problems; the computer programme for
solving the problem is built right into the computer.
Special purpose computers have many features of
general-purpose computers but are designed to
handle specific problems and are not applied to other
For example, special purpose computers may be
designed to process only numeric data or to
completely control automated manufacturing
processes. Moat analogue computers are special
Purpose is to “serve.”
A computer that has the
purpose of supplying its
users with data; usually
through the use of a
LAN (local area
45. •designed to support a computer network that allows you to share
files, application software, hardware, such as printers and other
•Mainframes, personal computers can be used as a server.
•Server computers usually have following characteristics:
•Designed to be connected to one or more networks
•The most powerful CPUs available
•Multiple CPUs to share the processing tasks
•Large memory and disk storage
•High-speed communications capabilities