Begin your journey as computer scientist by this beautiful small introductory booklet. Check the YouTube videos on the same subject at. https://youtube.com/channel/UCqwjq2yqObDqNX08AKXSQLQ This booklet deals with Generations of computers and ends with classes of computers.

1. Introduction to Computer Science
What is a Computer?
• A computer is an electronic device responsible
accepting data, processing it, output and store it.
• A computer ACCEPTS, then PROCCESS, then
OUTPUT and lastly STORES the accepted data
when necessary.
• Examples of computers are: laptops, desktops,
cellphones, calculators etc.

2. Introduction to Computer Science
History of computers?
• There are five generations of computers for a
period from 1946 to date.
First generation computers (1946 - 1959)
• Examples are ENIAC, EDVAC and UNIVAC.
• Used vaccum tubes for processing.
• Used punched cards for storage.

3. Introduction to Computer Science
First generation computers (1946 - 1959)
• They were large.
• They were very expensive.
• They were very slow.
• They generated a lot of heat.
• They used a lot of electricity.
• They had no perating system.
• Used Low level language fo input.
• Not Portable and reliable.

4. Introduction to Computer Science
Second generation computers (1959 - 1964)
• Examples are IBM1401 and UNIVAC3.
• Used transistors as part of the processor.
• Had RAM and ROM, and used Assembly language
and some high level langauge.
• Could process about 200000 instructions per
second.
• Size reduced compared to 1st computers.

5. Introduction to Computer Science
Third generation computers (1964 - 1970)
• Examples are IBM360 and IBM370.
• Used intergrated circuits for the processor.
• Keyboard for input an monitor for output.
• Main memory comprised of the P-ROM and the D-
RAM.
• They were small and portable.
• They were reasonably fast and reliable.

6. Introduction to Computer Science
Third generation computers (1964 - 1970)
• Had an oparating system and used High level
language making it easy to learn.
• Nevertheless, intergrated circuits required air
conditioning.
• Very advanced technology was required to
produce these circuits.

7. Introduction to Computer Science
Fourth generation computers (1971 - 1981)
• Used microprocessor like LSIC and VLSIC for
processing.
• Output was done by a monitor.
• Had an oparating system like MS Dos or PC Dos.

8. Introduction to Computer Science
Fifth generation computers (1981 to date)
• These include the laptops, desktops and others
computers we see today.
• Used EEPROM, DIMM and SIMM as part of the
processor.
• Portable and used keyboard and pointing devices
for input

9. Classification Of Computers
Criteria used for classification of computers
• Computers can be classified according to:
①Size
②Type
③Purpose
Classification According to Size.
• Computers can be classified according to their
size, how big they are.
• That is how many users can use the computer at
the same time.

10. Classification Of Computers
• This gives us four classes namely:
①Super computers
②Mainframe computers
③Mini computers
④Micro computers

11. Classification Of Computers
Super computers
• These are the fastest in terms of
processing capacity.
• They are the most expensive computers
world wide.
• They can process billions of instructions per
second.
Applications of Super computers
• Weather forecasting
• Used for chemical analysis in labs
• Used in space exploration

12. Classification Of Computers
Applications of Super computers
n.b and many other applications where data
processing is required to be fast.
• The demand for these computers is increasing Day
by day as the need for fast data processing is also
increasing daily.

13. Classification Of Computers
Mainframe computers
• These computers are designed to
support hundreds or even v thousands of
users simultaneously.
• Not only users but supports multi
programs to be run at the same time.
• They are also capable of processing large amounts
of data, with no bugs or runtime errors.
• They got a long life of at least 50 years without any
problem.

14. Classification Of Computers
Applications of Mainframe computers
• Health centers where they will be used to keep
and manage patients' records.
• Education especially at Universities to manage all
the activities like results publication as well as
registration.
• Banking where it will be responsible for processing
large transactions and stuff.

15. Classification Of Computers
Mini computers
• These are midsize computers supporting up to 200
users at the same time.
• Mini computers lie between mainframe and micro
computers.
• They are less expensive than mainframe
computers and are generally fast, compared to
their sizes.

16. Classification Of Computers
Uses of Mini computers
• They can be used in control systems to control
processes in industries
• Also used for data management in organization, to
manage , store and keep organization's data.

17. Classification Of Computers
Micro computers
• Also known as personal computers.
• Less expensive and got limited softwares
available for use.
• They are the smallest and easy to
handle.
• Examples being your personal computer or your
tablet or your cellphone.

18. Classification Of Computers
Classification According to type
• Classification According to type only gives us three
different groups of computers which are
①Analogue computers
②Digital computers
③Hybrid computers.

19. Classification Of Computers
Analogue computers.
• These are computers designed to
process data in continuous varying form,
that is analogue data.
• Data that is changing continuously.
• They do not give discrete or exact values, but
rather different values depending on the changes
happening to the input.
• For example speedometers. As speed changes, so
is the output on the speedometer.

20. Classification Of Computers
Digital computers.
• Digital computers are the ones that
process data in discrete forms.
• They are used to compute calculations and logical
operations.
• All these tasks involve data in exact or discrete
forms.

21. Classification Of Computers
Hybrid computers.
• These got features of both analogue computers
and digital computers.
• They are fast like analogue computers and
accurate like digital computers.

22. Classification Of Computers
Classification According to Purpose
• Classification According to purpose gives us
①General purpose computers.
②Special purpose computers.

23. Classification Of Computers
General purpose computers
• These are computers used for general tasks like
playing games, playing music, creating documents
and other things you may think of.

24. Classification Of Computers
General purpose computers
• These are computers used for general tasks like
playing games, playing music, creating documents
and other things you may think of.
Special purpose computers.
• They are used for special purpose like control and
monitoring.
• Examples, are computers used in hospitals for
monitoring patients.
• Embedded computer is also a special example of a
special purpose computers.

25. Classification Of Computers
• Embedded computers are microprocessors
Attached to non computer equipment like stoves ,
where they will be used for control and
maintenance.

26. YouTube Video Links
• https://youtu.be/uS_VHDAmCxA
• https://youtu.be/BJLNXXTMWu4
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