Presentation on computer system

PRESENTATION
ON
COMPUTER SYSTEM
By: John Annavi P

Presentation Highlights
1. Computer System
2. Introduction
3. Description of a Computer System
4. Historical Background of Computer
5. Classification of Computers
6. Definition of a Computer
7. Operations of a Computer
8. Components of a Computer System
9. Diagrammatic Representation of a Computer System
10. The Input Unit
11. The Processing Unit
12. The Output Unit
13. The Storage Unit
14. Relationship Between Component Units
15. Computer Hardware
16. Computer Software
17. Characteristics of Computers
18. Limitations of Computers
02/08/2019 Presentation on Computer System by John Annavi 2

COMPUTER SYSTEM

INTRODUCTION
Today, almost all of us in the world make use of computers in one way
or the other. It finds applications in various fields of education,
entertainment, agriculture, engineering, medicine, commercial,
research and others.
Not only in these sophisticated areas, but also in our daily lives,
computers have become indispensable.
They are present everywhere, in all the devices that we use daily like
cars, games, washing machines, microwaves etc. and in day to day
computations like banking, reservations, electronic mails, internet and
many more.

DESCRIPTION OF A COMPUTER SYSTEM
Any system is defined as a group of integrated parts which are
designed to achieve a common objective. Thus, a system is made up
of more than one element or part, where each element performs a
specific function and where all the elements (parts) are logically
related and are controlled in such a way that the goal (purpose) of
the system is achieved.
A computer system is made up of a number of integrated elements
that performs a specific task.
However, none of these elements can function independently on
their own. They are logically related and controlled to achieve a
specific goal. When they are thus integrated they form a fully
fledged computer system.

HISTORICAL BACKGROUND OF COMPUTER
(EVOLUTION OF COMPUTERS)
First generation computers (1951-1958)
The computers of the first generation were very bulky and emitted large amount of heat which required
air conditioning. They were large in size and cumbersome to handle.
• The Abacus, which emerged about 5000 years ago in Asia Minor and is still in use today, allows users
to make computations using a system of sliding beads arranged on a rack. Early merchants used
Abacus to keep trading transactions.
• Blaise Pascal, a French mathematician invented the first mechanical machine, a rectangular brass
box, called Pascaline which could perform addition and subtraction on whole numbers.
• Charles Babbage a British mathematician invented the first analytical engine or difference engine.
This machine could be programmed by instructions coded on punch cards and had mechanical
memory to store the results. For his contributions in this field Charles Babbage is known as ‘the
father of modern digital computer.
• Some of the early computers included: ENIAC, UNIVAC, EDVAC etc

Second generation computers (1959-1963)
In the second generation computers:
• Vacuum tube technology was replaced by transistorized technology,
• Size of the computers started reducing,
• Assembly language started being used in place of machine language,
• Concept of stored program emerged,
• High level languages were invented.
This was the generation of Transistorized Computers. Vacuum tubes were replaced by
transistors. As a result, the size of the machines started shrinking. The entire software
industry began with the second generation computers.

Third generation computers (1963-1970)
The third generation computers were characterized by:
• Use of Integrated circuits,
• Phenomenal increase in computation speed,
• Substantial reduction in size and power consumption of the machines,
• Use of magnetic tapes and drums for external storage,
• Design-of Operating systems and new higher level languages,
• Commercial production of computers.
This generation was characterized by the invention of Integrated Circuits (ICs).This
reduced the size even further. The weight and power consumption of computers
decreased and the speed increased tremendously. Heavy emphasis was given to the
development of software.

Fourth generation computers (1971-1987)
The general features of the fourth generation computers were:
• Use of Very Large Scale Integration,
• Invention of microcomputers,
• Introduction of Personal Computers,
• Networking,
• Fourth Generation Languages.
Computer production became inexpensive and the era of Personal Computers
(PCs) commenced. As the computers started becoming more and more powerful,
they could be linked together or networked to share not only data but also
memory space and software.

Fifth generation computers (1971-1987)
Defining the fifth generation computers is somewhat difficult because the
field is still in its infancy. The computers of tomorrow would be characterized
by Artificial Intelligence (AI).
An example of Al is Expert Systems.
Computers could be developed which could think and reason in much the
same way as humans. Computers would be able to accept spoken words as
input (voice recognition).

CLASSIFICATION OF COMPUTERS
Computers are broadly classified into two categories depending upon the logic used in their design as:
• Analog computers:
In analog computers, data is recognized as a continuous measurement of a physical property like
voltage, speed, pressure etc.
• Digital Computers:
These are high speed electronic devices. These devices are programmable. They process data by way of
mathematical calculations, comparison, sorting etc.
• Hybrid Computers: Hybrid Computers are a combination of Analog and Digital computers. They
combine the speed of analog computers and accuracy of digital computers. They are mostly used in
specialized applications where the input data is in an analog form i.e. measurement. This is converted
into digital form for further processing.

DEFINITON OF A COMPUTER
A computer is an electronic machine which accepts data in pre-
described format; processes that data into information that is ready for
further processing.
Keywords:
1. Data: These are raw facts, unprocessed information or unorganized which can
be made up of words, numbers, images, or sounds
2. Information: These are processed data ready to be used or stored in a storage
device until when needed.

OPERATIONS OF A COMPUTER
• It accepts data or instructions as input,
• It stores data and instructions
• It processes data as per the instructions it gets,
• It controls all operations inside a computer, and
• It gives results in the form of output.

COMPONENTS OF A COMPUTER SYSTEM
There are basically FOUR major components that make up a computer
system. They are:
1. The Input Unit
2. The Processing Unit
3. The Output Unit
4. The Storage Unit
This unit work hand in hand in relation to one another right from the input
unit to the storage unit. A computer system without one or more units may
not give out a desirable quality information as expected.

DIAGRAMMATIC REPRESENTATION
INPUT UNIT
PROCESSING
UNIT
OUTPUT UNIT
FURTHER
PROCESSING

1. INPUT UNIT
• Input Unit consists of devices that
allows the user to feed the computer
raw data.
• In other words, an input device is a
piece of computer hardware
equipment used to provide data and
control signals to an information
processing system such as a
computer or information appliance.
• Examples of input devices are:
Mouse, Keyboard, Microphone,
Webcam, joysticks, etc.

2. PROCESSING UNIT
The central processing unit (CPU), also
called the main processor or brain of the
computer, carries out the instructions of
a computer program by performing the
basic arithmetic, logic, controlling, and
input/output (I/O) operations specified
by the instructions.
It takes data and instructions from the
storage unit and makes all sorts of
calculations based on the instructions
given and the type of data provided
which is then sent back to the storage
unit.

PROCEESSING UNIT (Contd)
• Arithmetic Logic Unit: All calculations and comparisons, based on the
instructions provided, are carried out within the ALU. It performs
arithmetic functions like addition, subtraction, multiplication, division
and also logical operations like greater than, less than and equal to
etc.
• Control Unit: Controlling of all operations like input, processing and
output are performed by control unit. It takes care of step by step
processing of all operations inside the computer.

3. OUTPUT UNIT
• Output Unit consist of devices that
allows the computer to relay or display
processed data (information) to the
user.
• In other words, output device is any
piece of computer hardware equipment
which converts information into
human-readable form.
• Examples of output devices are:
Monitors, projectors, speakers,
headphones, printers etc.

4. STORAGE UNIT
• The Storage/Memory Unit is used
for storing data and instructions
before and after processing.
• Computer’s memory can be
classified into two types;
1. Primary memory
2. Secondary memory

PRIMARY MEMORY
RAM (Random Access Memory)
Random access memory (RAM) is a type of data
storage used in computers that is generally
located on the motherboard. This type of
memory is volatile and all information that was
stored in RAM is lost when the computer is
turned off.
This is where the operating system, application
programs and the data in current use are kept
temporarily so that they can be accessed by the
computer’s processor.
ROM (Read Only Memory)
Read Only Memory (ROM) is non-volatile and
holds data permanently when the power is
turned off.
ROM also stores an initial program called the
‘bootstrap loader’ whose function is to start the
operation of computer system once the power
is turned on.

SECONDARY MEMORY
Since RAM is a volatile memory having a limited storage capacity which
cannot be accessed once the computer is shut down, then there is a
need for a secondary memory that is peripheral (external) and is
connected and controlled by the computer to enable permanent
storage of programs and data.
Examples of these secondary memory/storage devices are: Hard Disk,
Flash Drives, CDs, DVDs, Pen drive, Zip drive etc. An Hard Disk for
instance; can store data and information up to 1TB.

RELATIONSHIP BETWEEN EACH UNITS

COMPUTER HARDWARE
The hardware is the machinery itself.
It is made up of the physical parts or devices of the computer system like the
electronic Integrated Circuits (ICs), magnetic storage media and other
mechanical devices like input devices, output devices etc.
All these various hardware (parts) are linked together to form an effective
functional unit.
The various types of hardware used in the computers, has evolved from
vacuum tubes of the first generation to Ultra Large Scale Integrated Circuits
of the present generation.

COMPUTER SOFTWARE
• System software This are pre installed
software from the manufacturing company.
• It consists of a group of programs that control
the operations of a computer equipment
including functions like managing memory,
managing peripherals, loading, storing, and is
an interface between the application programs
and the computer.
• MS DOS (Microsoft’s Disk Operating System),
UNIX are examples of system software.
• Application software: This are software
installed into the computer by the owner or
user.
• It performs a specific task for the user, such as
word processing, accounting, budgeting or
payroll, fall under the category of application
software.
• Word processors, spreadsheets, database
management systems are all examples of
general purpose application software.
Computer software is the set of programs that makes the hardware perform a set
of tasks in particular order. Computer software is classified into two broad
categories;

CHARACTERISTICS OF COMPUTERS
1. Computers work at an incredible speed. A powerful computer is capable of
performing about 3-4 million simple instructions per second.
2. In addition to being fast, computers are also accurate. Errors that may occur
can almost always be attributed to human error or faulty instructions
3. Unlike human beings, computers are highly consistent. They do not suffer from
human traits of boredom and tiredness resulting in lack of concentration.
4. Computers are versatile machines and are capable of performing any task as
long as it can be broken down into a series of logical steps.
5. Today’s computers can store large volumes of data. A piece of information once
recorded (or stored) in the computer, can never be forgotten and can be
retrieved almost instantaneously.

LIMITATIONS OF COMPUTERS
Although the computers of today are highly intelligent and sophisticated, they have
their own limitations.
• The computer cannot think on its own, since it does not have its own brain. It can
only do what is has been programmed to do.
• It can execute only those jobs that can be expressed as a finite set of instructions
to achieve a specific goal.
• Each of the steps has to be clearly defined.
• The computers do not learn from previous experience nor can they arrive at a
conclusion without going through all the intermediate steps.
However the impact of computers on today’s society in phenomenal
and they are today an important part of the society.

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