The computer systems can be classified on the following basis: * Usage * Processing * Storage

1. CLASSIFICATION
OF COMPUTER

2. Objectives
• At the end of the class, the students
should be able to classify computers
by ;
i. Generation
ii. Types
iii. Size
iv. Degree of versatility

3. •CLASSIFICATION OF
COMPUTER BY
GENERATION

4. Definition of Terms
Classification refers to the grouping of
people or things according to size, type,
age, or any acceptable parameter given.
Computer refers to electronic machine
that can store and arrange information,
which can be used to do many different
things.

5. 1. Classification of Computer
According to Generation
The stages computer passed through
before becoming what we have now as
computer are known as Computer
generations. There are five stages of
development or generation of the
computers. Below are the generations of
computer, their characteristics,
technology used, date and examples.

6. First Generation
Computers
-Were very large
-Required a lot of power
-Unreliable & overheated
-Very expensive
--Used vacuum tubes & magnetic
drums
-1944/46
-e.g. Electronic Numerical
Integrator And Calculator
(ENIAC), UNIVAC etc.

8. Second
Generation
Computers
-Got smaller
-Required less power
-More reliable
-Still generated a lot of heat &
large in size
-Used transistors
-1956

11. Third
Generation
Computers
-Got smaller & used less power
-Used keyboards & monitors
-Contained memory management
- Support multi-programming,
multi-user & multi-processing
-Used Integrated Circuit (IC)
technology
-1964
-ICL 1900, IBM 360 Series etc.

13. Fourth
Generation
Computers
-Were cheaper, smaller, faster,
& more efficient
-Classified by first using
microprocessors
-The first viable personal
computers are produced
-Used large, very large, & ultra
large scale integration
- 1970

15. Fifth Generations
Computers
-Solves complex problems
-Robotic in nature
-Posses artificial brain
-Ultra Large Integrated Circuit
and Artificial Intelligence
-1995/ 96
-Expert System i.e. Teller
machine, washing machine
etc.

18. Classification of Computer According
to Types
Computers are grouped into types based
on their mode of processing data. Hence,
computers are grouped into 3 major
types namely;
i. Analog computer
ii. Digital computer
iii. Hybrid computer

19. Analog Computer
Analog computer operates on measure
of continuous physical quantities like;
voltage, pressure, temperature, humidity,
pulse etc.
Examples of Analog computers include;
Thermometer, Speedometer of a car etc.

20. Digital Computer
Digital computer operates on
discrete(fixed) quantities. Information is
represented in digital form i.e. By a
coded set of electrical pulse. Examples of
digital computer include; Calculator, PC,
Digital Wristwatch etc.

21. Hybrid Computer
Hybrid means combining two things that are not
the same to benefit from their different
advantages. Hence, hybrid computers combine
the feature of both analog and digital system
together. They process data by counting and
measuring. However, they are used mostly in
specialized applications such as the weapons
system, Scientific research project, etc.
Examples of Hybrid computers are pumping
machine, fuel dispenser, manufacturing robot
etc.

22. ASSIGNMENT
1. List two developmental characteristics of the
followings:
a. 1st generation computers
b. 2nd generation computers
c. 5th generation computers

23. Classification of
Computer According
to Size

24. Classification of Computer According
to Size
Computers can be grouped base on processing
speed (horse-power), size of internal memory,
auxiliary storage capacity, physical size, price
range, operational features and so on. These
factors determine in general the grouping of
computers into the following classes;
i. Mainframe Computer
ii. Supercomputer
iii. Minicomputer
iv. Microcomputer

25. MAINFRAMES
• Mainframes have even more access to
storage space and to input/output devices. To
work with these extra devices mainframes
also have more powerful 'processors'. This
power is useful and required by large
corporations who have large amounts of data
to process.

26. • The Mainframe is a multi-user computer
designed to meet the computing needs of a
large organisation. Hence, is the biggest range
of computer in terms of physical size. The
most popular maker of mainframes is I.B.M.
International Business Machines, a large
Multi-national Corporation headquartered in
the U.S.A. Other renowned vendors such as
NCR, Honeywell, Burroughs, Sperry Rand and
others built the most common Mainframes.

27. HOME WORK
1. Distinguish between the first
and second generation of
computers.
2. State three types of computer
with examples.

28. MAINFRAMES

29. SUPERCOMPUTER
• The major cause for the development of
super-class computers has been the
continuing need in the scientific community
for faster and faster calculations. Scientists
working on atomic physics, computer
intensive calculations such as natural speech
recognition continue to require more and
more computational speed to test their
theorems.

30. SUPERCOMPUTER

31. MINICOMPUTERS
• The Minicomputer is next to Mainframe in
term of Size and faster than the microcomputer
with access to more storage space and more
input and output devices, the minicomputer is
used when large groups need access to data
simultaneously. The minicomputer can do this
because the hardware is designed for plugging
in more devices, and the C.P.U. and support
chips are designed more for this kind of work
than the microcomputer's.

32. • Popular makers of minicomputers include -
Digital Equipment Corporation (DEC) who built
the popular VAX minicomputer used in
universities, banks and engineering firms. IBM
also creates a very popular mini computer
range with a branding of the AS400. Hewlett
Packard has a popular minicomputer range
branded the HP9000.

33. MINICOMPUTERS

34. MICRO-COMPUTER
The category is termed “micro” because the
fundamental component that allowed the
categories development was the CPU created on
a single chip (so this technology was affordable
in comparison to the mini/mainframe) created
with the introduction of ‘microprocessors.’
Most of the present-day computer in homes,
Offices, Cyber Cafe, Banks, Industries, Schools
etc fall under this group and were introduced
into the computing world in the 1980s.
However, the name Microcomputer is derived
from Microprocessor. Examples are the
“desktops” (flatbeds, Slimlines), tower systems,
mobile systems and hand held PCs.

36. Classification of Computer According
to Degree of Versatility
Computers can be classified base on usage.
They are group into two types namely:
i. General Purpose
ii. Dedicated or Special Purpose

37. General Purpose Computerse.g.
Personal Computers
- Perform a wide variety of processing tasks
- Programmed for general purpose
- These are the most common computers.

38. Dedicated or Special Purpose
Computers e.g. Air traffic control, Word
processing machine, calculator etc.
- Fundamentally the same as general purpose
computer
- Programmed for a specific purpose
- Used in a variety of consumer products,
microwaves, telephones, washing machine
etc.

39. QUESTION?