1. History of computers
By Anne Perera

2. Abacus The first man-made computing device is the “Abacus”
The abacus, also called a counting frame.
The Chinese abacus was developed about 5000 years ago.
Addition, subtraction, division and multiplication can be performed on a standard abacus.

3. Slide Rule
John Napier, a Scotland national, found the Logarithms to the world in 1617.
Using John Napiar’s logarithm concepts, the slide rule was designed in England in 1632.

4. Pascaline Around 1642, a French mathematician called
Blaise Pascal invented the adding machine that
helped mathematical calculations.
Additions and subtractions could be done easily
by using it.
Pascal’s machine was one of the first mechanical calculating machine.

5. Difference Engine
An Englishman called Charles Babbage designed the first model
required for a mechanical computer in 1822.

6. Analytical Engine
Charles Babbage designed the 'Analytical Engine' in 1833.
Components required for data input, storage, processing and output had been designed inside.
Computers designed later were greatly influenced by these concepts of Babbage and that is why Babbage is considered to be the ‘Father of computers’.

7. Ada Augusta Lovelace
A friend of Babbage called Ada Augusta Lovelace was keen on preparing programmes required for his engine.
Such programmes are considered to be the first
attempt of computer programming.
Ada Augusta Lovelace is considered to be the
first computer programmer in the world.
The computer language which was used later for
military purposes was named Ada to pay
respect for her.

8. Punch card Herman Hollerith adopted the punched card concept.
Early method of data storage used with early computers.
Punch cards also known as Hollerith cards and IBM cards.

9. Computer classification

10. Computer classification
A computer can be classified as follows:
Based on the generations
2) Size
3) Purpose
4)Design technology / Computational method / Type

11. Based on generation

12. Generations of computers
First Generation Computers ( ) – Vacuum tubes

13. First Generation Computers 1939-1958
Based on Vacuum Tubes
Used magnetic drums for main memory.

14. First Generation Computers 1939-1958
Can solve one problem at a time.
Input was based on punched cards and paper tape, and output was displayed on printouts.
First generation computers based on machine language, the lowest-level programming language understood by computers

15. First Generation Computers 1939-1958
Disadvantages
Very large in size.
Consumed a large amount of energy.
They heated very soon due to thousands of vacuum tubes.

16. First Generation Computers 1939-1958
Disadvantages
They were not very reliable.
Constant maintenance was required.
Very slow in speed.
Used magnetic drums which provide very less data storage.

17. First Generation Computers 1939-1958
ENIAC (Electronic Numerical Integrator and Computer)
- world’s first electronic digital computer in 1946

18. First Generation Computers 1939-1958
UNIVAC (Universal Automatic Computer)
- The first commercial computer

19. Generations of computers
2. Second Generation Computers ( ) – Transistors

20. Second Generation
The second generation of computers used transistors for
the internal operations.
They used magnetic core for the
memory
Still based on punched cards for input
and printouts for output.

21. Second Generation
The first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
Used symbolic, or Assembly language, which allowed programmers to specify instructions in words. 
High-level programming languages were also being developed at this time, such as early versions of COBOL  and FORTRAN.

22. Second Generation 1954-1959 Advantages:
Smaller in size as compared to the first generation computers.
Computers were more reliable
Used less energy and were not heated.

23. Second Generation 1954-1959 Advantages:
Better portability as compared to the first generation computers.
Used faster peripherals like tape drives, magnetic disks, printers etc.
Used Assembly language instead of Machine language.
Accuracy improved.

24. Second Generation 1954-1959 Disadvantages Cooling system was required
Constant maintenance was required
Commercial production was difficult

25. Second Generation 1954-1959 Disadvantages
Only used for specific purposes
Expensive
Punch cards were used for input.

26. Second Generation

27. Generations of computers
3. Third Generation Computers ( ) – Integrated
Circuits (IC)

28. Third Generation
These computers used integrated circuits on silicon chips.
A single IC chip may contain thousands of transistors.
Eg:- IBM 370, IBM System/360, UNIVAC 1108 and UNIVAC AC 9000

29. Third Generation 1959-1971 Advantages
Smaller in size as compared to previous generations.
More reliable.
Used less energy
Produced less heat as compared to the previous two generations.
Better speed and could calculate data in nanoseconds.
Used fan for heat discharge to prevent damage.

30. Third Generation 1959-1971 Advantages Totally general purpose
Could be used for high-level languages.
Good storage capacity.
Less expensive
Better accuracy
Commercial production increased.
Used mouse and keyboard for input.

31. Third Generation 1959-1971 Disadvantages
Air conditioning was required.
High technology required for the manufacturing of IC chips.

32. Third Generation

33. Generations of computers
4. Fourth Generation Computers (1971- Present) –
Microchips
Microprocessors

34. Fourth Generation 1971- Present
Use microprocessor chips.
The Microprocessor contains thousands of ICs.
The technology of integrated circuits improved rapidly.
The LSI (Large Scale Integration) circuit and VLSI (Very
Large Scale Integration) circuit was designed.
Reduced the size of computer.

35. Fourth Generation 1971- Present
The size of modern Microprocessors is usually one square inch.
It can contain millions of electronic circuits.
Examples :- Apple Macintosh & IBM PC.
Can be linked together to form networks, which led to the development of the Internet.
Introduced GUI’s and hand-held devices.

36. Fourth Generation 1971- Present
Advantages
More powerful and reliable than previous generations.
Small in size
Fast processing power with less power consumption
Fan for heat discharging and to keep cold.
Totally general purpose

37. Fourth Generation 1971- Present
Advantages
Commercial production
Less need of repair.
Cheapest among all generations
All types of High level languages can be used in this type of computers

38. Generations of computers
5. Fifth Generation computers (Present - Beyond) – Artificial Intelligence (AI)

39. Fifth Generation computers (Present - Beyond)
Based on the technique of Artificial Intelligence (AI). 
Computers can understand spoken words & imitate the human.
Can respond to its surroundings using different types of sensors.

40. Fifth Generation computers (Present - Beyond)
Scientists are constantly working to increase the processing
power of computers.
IBM Watson computer is one example for a 5th generation
computer. 
There are some applications, such as voice recognition, that are being used today. 

41. Based on size
Computers can be classified according to their sizes too.
Mainframe computers
Mini computers
Micro computers

42. Based on size
There are different types of Micro computers. Some of them are,
Personal Computers (PC)
Laptop Computers
Palmtop computers
Workstations
Server computers
Super computers

43. Based on the purpose
Computers can be categorized into two types based on their purpose.
General Purpose Computers
Computers used for usual and day - to - day activities.
2) Special Purpose Computers
Computers used for special purposes such as scientific experiments, air traffic control systems etc.

44. Based on their design technology
Digital computers
Computers designed by using the binary /digital number system are called digital computers.
A digital computer can count and accept numbers and letters through various input devices.

45. Based on their design technology
2) Analog computers
Computers which are designed considering the physical data such as temperature, sound, and pressure etc.
Analog computers process data input in a continuous form.

46. Based on their design technology
2) Analog computers
Data such as voltage, temperature are represented
in the computer as a continuous, unbroken flow of
information.
Analog computers are used in engineering and
scientific applications.

47. Based on their design technology
3) Hybrid computers
A combination of the above two types of computers.
Example: In Process Control Computer Systems,
the inputs comes from devices like pressure,
thermometers etc.

48. Based on their design technology
3) Hybrid computers
The inputs from analog devices are sent to a digital
computation unit that runs the mathematical model for
controlling the process.

49. END