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Jul 16, 2015
Introduction to Computers
Md Fazlul Kader, Assistant Professor
Dept. of APECE, Faculty of Engineering
University of Chittagong
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 parts:
3A 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?
Block Diagram of Computer
Input Whatever is put into a computer system.
Data Refers to the symbols that represent facts, objects, or ideas.
Information The results of the computer storing data as bits and bytes; the words,
numbers, sounds, and graphics.
Output Consists of the processing results produced by a computer.
Processing Manipulation of the data in many ways.
Memory Area of the computer that temporarily holds data waiting to be
processed, stored, or output.
Storage Area of the computer that holds data on a permanent basis when it is
not immediately needed for processing.
An Overview of the Computer System
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
Raw, unprocessed facts
Processing creates information
Stored electronically in files
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
Types of Computers
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:
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
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.
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 (digital) data.
These are special purpose computers. These are very fast and accurate.
These are used in scientific fields. In hospitals, these are used to watch patients health condition in ICU (Intensive Care Unit). These are also used in telemetry, spaceships, missiles etc.
Differentiate between Analog and Digital Computers
Types of Computers on the basis of size and
or Personal Computers
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
"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
Occupies specially wired, air-conditioned rooms
Capable of great processing speeds and data
Not as powerful as supercomputers
Large expensive computer capable of simultaneously processing data for hundreds or thousands of users.
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 microcomputers.
Minicomputers usually have multiple terminals.
Minicomputers may be used as network servers and Internet servers.
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
Four Types of Microcomputers
Notebook or laptop
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 case.
Has separate components (keyboard, mouse, etc.) that are each plugged into the computer.
A portable, compact computer that can run on an electrical wall outlet or a battery unit.
All components (keyboard, mouse, etc.) are in one compact unit.
Usually more expensive than a comparable desktop.
Sometimes called a Notebook.
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 tasks.
Can tackle tasks that require a lot of processing speed.
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 servers.
Wearable computers are computers that are worn on the body.
This type of wearable technology has been used in behavioral modeling, health monitoring