This document provides an introduction to computers, including: - The definition of a computer as an electronic device that accepts data as input, processes it, and provides output. - The basic functions/operations of a computer: input, processing, output, storage, and control. - Characteristics of computers like speed, accuracy, diligence, versatility, and storage capacity. - The evolution of early calculating devices like the abacus to modern computers. - Generations of computers from the first vacuum tube-based generation to the current microprocessor-based generation. - Classifications of computers by size and capabilities. - The basic organization of a computer including its central processing unit

1. UNIT-I
Introduction To Computers

2. Introduction to Computer
• Early days people use fingers for
computing purpose.
• As years go, the computing needs also
grew. This leads to the invention of
calculators and computers.
• The term computer is derived from the
word compute, it means to calculate.

3. Definition
• Computer is an electronic device. It
accepts data, process the data and gives
the desired output.
COMPUTER
INPUT OUTPUT

4. Basic functions or operations
• Input
• Processing
• Output
• Storing
• Controlling

5. Basic operations (Cont)
• Input
It is the process of getting the data from
the user or from somewhere else into the
computer to process.
• Processing
It is the process of converting the input
to output.

6. Basic operations (Cont)
• Output
It is the outcome or result of the
process.
• Storing
It is the process of saving the data. so
that it can be retrieved whenever needed.

7. Basic operations (Cont)
• Controlling
It is the process of directing the
sequence in which the operations to be
performed.

8. Applications of computer:
• Business
• Industry
• Home
• Education
• Printing & publishing
• Entertainment etc.,

9. CHARACTERISTICS OF
COMPUTER

10. CHARACTERISTICS OF COMPUTER
• Speed
• Accuracy
• Diligence
• Versatility
• Resource sharing
• Storage

11. CHARACTERISTICS OF COMPUTER (cont)
• Speed
The computer process the data
extremely fast. (i.e.) in millions (1,000,000)
of instructions and even more per second.
A computer can perform a huge task in
few sec where a human being may take
hours or even days to complete the same
task.

12. • Accuracy
The degree of accuracy of computer is
very high and every calculation is
performed with the same accuracy. The
accuracy level is determined on the basis
of design of computer. The errors in
computer are due to human and
inaccurate data.
CHARACTERISTICS OF COMPUTER (cont)

13. CHARACTERISTICS OF COMPUTER (cont)
• Diligence
A computer is free from tiredness, lack
of concentration etc. It can work for hours
without creating any error. If millions of
calculations are to be performed, a
computer will perform every calculation
with the same accuracy. Due to this
capability it overpowers human being in
routine type of work.

14. CHARACTERISTICS OF COMPUTER (cont)
• Versatility
It means the capacity to perform
completely different type of work. For
example At a moment a computer can be
used to draft a letter. Next moment it can
be used print a document or play a music
file etc.,

15. CHARACTERISTICS OF COMPUTER (cont)
• Resource sharing
In organizations the computers are
connected to form a network. The
resources such as printers, scanner,
plotters are connected to the network and
it can be shared by the computers in the
network.

16. CHARACTERISTICS OF COMPUTER (cont)
• Storage
Computers are capable of storing huge
amount of data and it can be located and
retrieved very quickly. It uses storage
devices such as hard disk to store huge
amount of data.

17. Evolution of Computers

18. Evolution of Computers
• Abacus
The first calculating device called
ABACUS was developed by the Egyptian
and Chinese people. It consisted of sticks
in horizontal positions on which were
inserted sets of beads. It has a number of
horizontal bars each having ten beads.
Horizontal bars represent units, tens,
hundreds, etc.

19. Evolution of Computers (Cont)
• Napier’s bones
English mathematician John Napier
built a mechanical device for the purpose
of multiplication in 1617 A D. The device
was known as Napier’s bones.
• Slide Rule
This machine could perform operations
like addition, subtraction, multiplication,
and division. It was widely used in Europe
in 16th century.

20. Evolution of Computers (Cont)
• Pascal's Machine
Blaise Pascal developed a mechanical
calculating machine called Pascal’s calculating
machine. It could add and subtract. The machine
consisted of wheels, gears and cylinders.
• Leibniz’s Machine
The Pascal’s calculating machine can
perform addition and subtraction but it could not
perform multiply and division. Leibniz built a
mechanical device that could both multiply and
divide.

21. Evolution of Computers (Cont)
• Babbage’s Analytical Engine
In the year 1823 that a famous English
man Charles Babbage built a mechanical
machine to do complex mathematical
calculations. It was called difference
engine. Later he developed a general-
purpose calculating machine called
analytical engine. Charles Babbage is
called the father of computer.

22. Evolution of Computers (Cont)
• Electronic Calculator
The electronic calculator used in
1960’s was run with electron tubes, Later it
was replaced with transistors and as a
result the size of calculators became too
small. It can compute all kinds of
mathematical computations. Some
calculators have in-built programs to
perform some complicated calculations.

23. Generations of Computers

24. Generations of Computers (Cont)
First Generation Computers:
• These computers were vacuum tube
based machines.
• They used magnetic drums for memory.
• Input were fed into the computer using
Punched cards
• The size of these computers were very
large and it produce more heat.
• They lacked in versatility and speed.
• They were more expensive.

25. Generations of Computers (Cont)
Second Generation Computers
• Here the Transistor replaced the bulky
vacuum tubes.
• Transistors are smaller than vacuum tubes
and have higher operating speed.
• Thus the size of the computer got reduced
considerably.
• Manufacturing cost was also very low.

26. Generations of Computers (Cont)
Third Generation Computers
• These computers were based on
Integrated Circuits (ICs) Technology.
• A single IC has many transistors, registers
and capacitors built on a single thin slice of
silicon.
• So that the size of the computer got further
reduced.
• These Computers were small in size, low
cost, large memory and processing speed
is very high.

27. Generations of Computers (Cont)
Fourth Generation Computers
• It uses large scale Integrated Circuits (LSIC)
built on a single silicon chip called
microprocessors .
• Later very large scale Integrated Circuits
(VLSIC) replaced LSICs
• These computers are called microcomputers.
• Thus the size of the computer got reduced.
• The personal computer (PC) are comes
under the Fourth Generation.

28. Generations of Computers (Cont)
Fifth Generation Computer
• The speed is extremely high in fifth
generation computer.
• The concept of Artificial intelligence has been
introduced to allow the computer to take its
own decision.
• It is still in a developmental stage .

29. Classification of Computer

30. Classification of Computer
• Microcomputer
• Mini Computer
• Mainframes
• Supercomputer

31. Classification of Computer
Microcomputer Supercomputer
Mini Computer Mainframes
Computer
Desktop
N/W Servers
Laptops Smart phones

32. Classification of Computer (Cont)
Microcomputer
• Microcomputer is at the lowest end of the
computer range in terms of speed and
storage capacity.
Eg: Desktop, Laptop, Tablet PC, Smart
Phones.

33. Classification of Computer (Cont)
Mini Computer
• This is designed to support more than one
user at a time.
• It possesses large storage capacity and
operates at a higher speed.
• This type of computer is generally used for
processing large volume of data in an
organisation.
• Eg:Servers in Local Area Networks (LAN).

34. Classification of Computer (Cont)
Mainframes
• They operate at very high speed, having
very large storage capacity and can
handle the work load of many users.
• They are generally used in centralised
databases.

35. Classification of Computer (Cont)
Supercomputer
• They are the fastest and most expensive
machines.
• They have high processing speed
compared to other computers.
• They have also multiprocessing technique.
• Supercomputers are mainly being used
for whether forecasting, biomedical
research, and other areas of science and
technology

36. Classification of Computer (Cont)
• The computers can also classified based
on the hardware design as follows
–Analog computer.
–Digital computer.
–Hybrid computer.

37. BASIC ORGANISATION
OF
COMPUTER

38. CONTROL
MEMORY
ALU
OUTPUT
INPUT
Basic organisation of computer

39. Basic organisation of computer
• INPUT
– The input unit is used to information or
instruction to the computer.
– It accept the information or instruction from
user or from some where else.
– Convert it to a computer understandable form
and send it to the computer.
Eg:Keyboard,mouse,Joystick,MICR, etc,.

40. Basic organisation of computer (cont)
• CENTRAL PROCESSING UNIT (CPU)
– It is the heart of the computer.
– It performs all operations.
– It contains the followings
• CONTROL UNIT
• ALU
• MEMORY

41. Basic organisation of computer (cont)
• CONTROL UNIT
– It controls all other units in the computer.
– It directs the sequence in which operations to
be performed.
– It also controls the flow of data between
various units.

42. Basic organisation of computer (cont)
• ARITHMETIC & LOGICAL UNIT
– It performs all arithmetic & logical operations.
– i.e. arithmetic operations like addition,
subtraction, multiplication, division etc,. And
logical operations like AND,OR,NOT etc,.

43. Basic organisation of computer (cont)
• MEMORY UNIT
– Place for holding the information.
– Types
• Primary
• Secondary
– Primary memory is used to store temporary
data.Eg:RAM,ROM etc,.
– Secondary memory is used to store
information permanently. Eg:Hard disk.

44. Basic organisation of computer
• OUTPUT
– The output unit is used to display the result of
the process.
Eg:Monitor,printer,speakers, etc,.

45. Components of Computers

46. Components of Computers
• Hardware
The physical components present in
the computer.
• Software
It is a collection of programs and it can
perform some operaions.

47. Components Present inside the
cabinet
• Motherboard
• Processor
• SMPS
• Disk drives
• RAM & ROM etc,.

48. Types of Memory
MEMORY
SECONDARY
PRIMARY
RANDOM ACCESS
SEQ.ACESS

49. • Primary Memory:
It is used to store data temporary.

50. RAM
• Random Access Memory
• It is possible to randomly select and use
any location of the memory.
• It is a volatile memories i.e. It loose their
content when the power is switched off

51. ROM
• Read Only Memory
• The data in the ROM is permanent .
• It is a non-volatile memories i.e. It does
not loose their content when the power is
switched off .

52. • Programmable Read Only Memory
• It is supplied in blank by the manufacturer.
• It is possible to store program in PROM
chip.
• Once the programmes are written it cannot
be changed and remain even if power is
switched off.
PROM

53. • Erasable Programmable Read Only
Memory.
• Information stored in EPROM can be
erased by exposing the chip in ultraviolet
light and it is reprogrammed using a
special programming facility.
EPROM

54. • Electrically Erasable Programmable Read
Only Memory.
• Information stored in EEPROM can be
erased by applying some voltage.
EEPROM

55. • Secondary Memory:
It is used to store data permanently
• TYPES: sequential access , random
access

56. Sequential Access
Magnetic Tape:
• Magnetic tapes are used by large
computers like mainframe computers
where large volume of data is stored for a
longer time.
• The cost of storing data in tapes is
inexpensive.
• Tapes consist of magnetic materials that
store data permanently.

57. Random Access
Hard Disk:
• It uses circular disk ,coated with magnetic
material called platters.
• It rotates with very high speed inside the
drive.
• Data is stored on both the surface of the
disk.
• Each disk consists of a number of invisible
concentric circles called tracks.
• The information stored in a disk can be read
many times without affecting the stored data.

58. Magnetic Hard Disk Mechanism

59. Random Access (cont)
Optical disk
• It uses a circular plastic disk coated with
aluminium or silver storing data.
• The data are stored in the circular tracks.
• Laser beam is used for storing and
retrieve data from the disk

60. INPUT OUTPUT DEVICES
• Input Devices
Input devices are necessary to convert
our information or data in to a form which
can be understood by the computer.
• Eg: Keyboard, Mouse, MICR,OMR,OCR.

61. Keyboard
• This is the standard input device.
• The layout of keyboard is just like the
traditional typewriter of the type QWERTY.
• It also contains some extra command
keys and function keys.
• The computer can recognise the electrical
signals corresponding to the correct key
combination and processing is done
accordingly

62. Mouse
• Mouse is an input device.
• When the mouse is moved across a flat
surface the screen pointer is also moved
in the direction of mouse movement.
• It is easier to move the cursor through a
mouse

63. Magnetic Ink Character
Recognition (MICR)
• This is widely used by banks to process
large volumes of cheques and drafts.
• Cheques are put inside the MICR.
• As they enter the reading unit ,the
magnetic field which causes the read head
to recognise the character of the cheques.

64. Optical Mark Reader (OMR):
• This technique is used in objective type
tests and the answer are marked by
darkening a square or circular space by
pencil or pen.
• These answer sheets are directly fed to a
computer for grading where OMR is used.

65. Optical Character Recognition
(OCR):
- It is used to recognize any printed
character.
- This characters are compared with
patterns stored inside the computer.
- Whichever pattern is matched is called a
character read.
- Patterns that cannot be identified are
rejected. OCRs are expensive though
better the MICR.

66. Output Devices

67. Visual Display Unit
• The most popular output device is the
Visual Display Unit (VDU).
• It is also called the monitor.
• Monitor is used to display the input data
and to receive massages from the
computer.
• It can be color or monochrome.

68. Printer
• It is an important output device which can
be used to get a printed copy of the
processed text or result on paper.
• printers are classified as impact and
non-impact printers.

69. NUMBER SYSTEM

70. Number System
•Number Base B => B symbols
–Base 16(Hexa):0, 1,……9, A ,…, E, F
–Base 10 (Decimal): 0, 1, 2,……, 7, 8, 9
–Base 8(Octal): 0, 1, 2, 3, 4, 5, 6, 7
–Base 2 (Binary): 0, 1

71. Number System (cont)
• Number representation:
• d31d30 ... d2d1d0 is a 32 digit number
• value = d31x B31 + d30 x B30 + ... + d2 x B2
+ d1 x B1 + d0 x B0

72. Decimal Numbers: Base 10
•Base or Radix is 10
•Digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
•Example:
41210 = 4x102 + 1x101 + 2x100
= 400 + 10 +2 = 412

73. Binary Numbers: Base 2
•Base or Radix is 2
•Digits: 0, 1
•Example:
1012 = 1x22 + 0x21 + 1x20
= 4 + 0 +1 = 5

74. Octal Numbers: Base 8
•Base or Radix is 8
•Digits: 0, 1, 2, 3, 4, 5, 6, 7
•Example:
1238 = 1x82 + 2x81 + 3x80
= 64 + 16 +3
= 83

75. Hexadecimal Numbers: Base 16
•Digits: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F:
–A  10
–B  11
–C  12
–D  13
–E  14
–F  15
•Example:
1216 = 1x161 + 2x160
= 16 +2
= 18

76. Conversions
Decimal to Base N Base N to Decimal
Successive Division by N
(Remainder Method)
Multiplication with
power of N

77. Decimal to Binary

78. Conversion of 2510 to Binary
2 25
2 12 -1
2 6 - 0
2 3 - 0
1 - 1
2510=110012

79. • Binary to decimal conversion
11001
1X20 = 1
0X21 = 0
0X22 = 0
1X23 = 8
1X24 = 16
2510

80. Decimal to Octal

81. Conversion of 12510 to Octal
8 125
8 15 - 5
1 - 7
12510=1758

82. • Octal to decimal conversion
175
5X80 = 5
7X81 = 56
1X82 = 64
125
1758 = 12510

83. Conversion of 8410 to Octal
8 84
8 10 - 4
1 - 2
8410=1248

84. • Octal to decimal conversion
124
4X80 = 4
2X81 = 16
1X82 = 64
84
1248 = 8410

85. Decimal to Hexa

86. Conversion of 45010 to Hexadecimal
16 450
16 28 - 2
1 - 12
45010=1C216

87. • Hexa to decimal conversion
1C2
2X160 = 2
12X161 = 192
1X162 = 256
450
1C216 = 45010

88. Conversion of 38510 to Hexadecimal
16 385
16 24 - 1
1 - 8
38510=18116

89. • Hexa to decimal conversion
181
1X160 = 1
8X161 = 128
1X162 = 256
385
18116 = 38510

90. Other Conversions
• BINARYOCTAL
• BINARYHEXA
• OCTALHEXA etc,.

91. • BINARYOCTAL
• OCTAL – BASE 8 = 23
• 3 DIGIT BINARY NUMBER
Example:110012  OCTAL
11 001
011 001
3 1
110012=318

92. Example:11100112  OCTAL
1 110 011
001 110 011
1 6 3
11100112=1638

93. • BINARYHEXA
• HEXA – BASE 16 = 24
• 4 DIGIT BINARY NUMBER
Example:110012  HEXA
1 1001
0001 1001
1 9
110012=1916

94. Example:11100112  OCTAL
1 110 011
001 110 011
1 6 3
11100112=1638

95. • OCTALHEXA
• OCTALBINARYHEXA
Example:318  HEXA
3 1
011 001
0001 1001
1 9
318=1916

96. • HEXA  OCTAL
• Example: 1BD  OCTAL
1 B D
0001 1011 1101
000 110 111 101
0 6 7 5
1BD = 6758

97. Conversion of 25.12510 to Binary
2 25
2 12 -1
2 6 - 0
2 3 - 0
1 - 1
2510=110012

98. 0.125 X 2 = 0.250
0.250 X 2 = 0.5
0.5 X 2 = 1.0
25.12510 = 11001.0012

99. • Binary to decimal conversion
11001.001
1X2-3 = 0.125
0X2-2 = 0
0X2-1 = 0
1X20 = 1
0X21 = 0
0X22 = 0
1X23 = 8
1X24 = 16
25.12510

100. Conversion of 84.25010 to Octal
8 84
8 10 - 4
1 - 2
8410=1248

101. 0.250 X 8 = 2.000
25.12310 = 124.28

102. • Octal to decimal conversion
124.2
2X8-1 = 0.25
4X80 = 1
2X81 = 0
1X82 = 0
25.25010

103. ASSIGNMENT

104. DECIMAL TO BINARY
• 43
• 79
• 107
• 241
• 476

105. DECIMAL TO OCTAL
• 39
• 152
• 284
• 758
• 2534

106. DECIMAL TO HEXA
• 75
• 826
• 3128
• 7359
• 4756

107. DECIMAL TO OTHER
• 63 BASE4
• 279 BASE6
• 161 BASE7

108. BINARY  OCTAL,HEXA
• 1010101
• 11010101011
• 111010110111
• 1011110111
• 101000101

109. OCTAL  HEXA
• 473
• 1235
• 724
• 5774
• 4625

110. • 75.12510 BASE2
• 356.52310 OCTAL
• 527.4210 HEXA