The document provides an overview of computer science, including a definition of computers and their history through five generations from 1946 to the present. It covers different classifications of computers based on size, type, and purpose, highlighting supercomputers, mainframe computers, mini computers, and microcomputers, as well as digital, analogue, and hybrid computers. Additionally, it explains the usage of general-purpose and special-purpose computers in various fields, along with applications for each type.

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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