1. Introduction To Computers
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
Reliability
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. CHARACTERISTICS OF COMPUTER (cont)
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.

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)
Reliability
It produces results without any error.
Only human made errors can occur
So they are trustworthy machines.

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. Generations of Computers

18. 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.

19. First Generation Computers(1940-1956):
Speed: Fastest computing device of its time
Technology: Vacuum Tubes :
Made up of glass contains filaments, when heated generates electrons which helps in amplification and de amplification of signals
I/p & O/p : Punched card and print out
Programming language: Machine level language
Example:
EDSAC: Electronic delay storage automatic calculator
EDVAC: Electronic discrete variable automatic computer

20. First Generation Computers(1940-1956):
Advantages:
Fastest computing device of their time
Execute complex mathematical problems in an efficient manner
Disadvantages:
Large & Bulky
Difficult to program
Cannot be transferred from one place to another
These are special purpose computers
Generates huge amount of heat and hence prone to hardware faults

21. 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.

22. Second Generation Computers (1956-1963):
Speed: Faster than first generation
Technology: Transistor :
Used to increase the power of incoming signals.
It has 3 connections:
Base : Through which incoming signals are sent
Collector : Collects amplified signal
Emitter : Emits amplified signal
I/p & O/p : Punched card and print out
Programming language: Assembly language
Example:
IBM 1401
IBM 1620

23. Second Generation Computers (1956-1963):
Advantages:
Fastest computing device of their time
Easy to program
Light weight
Low power consumption
Low maintenance
Transferred from one place to another easily
Disadvantages:
High cost
Limited to special purpose tasks
Generates considerable amount of heat

24. 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.

25. Third Generation Computers (1964-1975):
Speed: Fastest computing device of its time
Technology: Integrated Circuits : Also known as micro electronics technology
Programming language: High level language
Example:
IBM 360
Honeywell 6000

26. Third Generation Computers (1964-1975):
Advantages:
Computational time was measured in nano seconds
Requires low power to operate
Small size
Installation is very easy
Able to execute any type of applications
More reliable & requires less maintenance
Easily transportable
Disadvantages:
Storage capacity was very small
Performance will get degrade while executing large applications
Cost is very high
Required to be placed in air conditioned plates

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

28. Fourth Generation Computers (1975-1989):
Speed: Fastest computing device of its time
Technology: VLSI : Very large scale Integration
It leads to the development of GUI, Operating Systems, Various storage devices, I/O devices and LAN
It has 3 components:
Microprocessors
Memory
I/O Controls
Programming language: High level language
Example:
IBM PC series
Apple Series

29. Fourth Generation Computers (1975-1989):
Advantages:
Very powerful in terms of speed & time
Storage capacity is very high & it is very fast
Highly reliable and requires low maintenance
Provides user friendly environment using GUI(Graphical user interface)
Programs are highly portable
Highly versatile and requires less power
Disadvantages:
The soldering of VLSI chips on the wiring board was not an easy task
Working of these computers depends on instructions given by the programmer

30. Generations of Computers (Cont)
Fifth Generation Computer(1989-Till date)
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 .

31. Fifth Generation Computers (1989-Till date):
Speed: Faster of all times
Technology: ULSI : Ultra large scale Integration
It has more than10 million electronic components
It increases the power & speed of the microprocessor
Programming language:
High level language
Integrated development environment
Example:
Laptop
PDA

32. Fifth Generation Computers (1989-Till date)
Advantages:
Fastest & powerful computers till date
Able to execute a large no of application at very high speed.
ULSI Technology helps in decreasing the size of computers.
Multimedia features are available
Resource sharing is possible & is highly versatile
Disadvantages:
Lack of human like Intelligence

33. Classification of Computer

34. Classification of Computer
Based on
Operating Principles
Based on
Applications
Based on
Size & Capabilities
Analog Computers
Digital Computers
Hybrid Computers
Micro Computers
Mini Computers
Mainframe Computers
Super Computers
Special Purpose Computers
General Purpose Computers

35. 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.

36. Classification of Computer (Cont)
Mini Computer
This is designed to support more than one user at a time. (up to 200 users)
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).

37. 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(more than 200 users.
They are generally used in centralised databases.

38. 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

39. BASIC ORGANISATION OF COMPUTER

40. I/P UNIT MEMORY UNIT O/P UNIT CACHE MEMORY REGISTERS ALU CONTROL UNIT
Basic organisation of computer
I/P UNIT
MEMORY
UNIT
O/P UNIT
CACHE MEMORY
REGISTERS
ALU
CONTROL
UNIT
Block Diagram of a Computer System

41. Basic organisation of computer
INPUT
The input unit is used to feed information or instruction to the computer.
Input Devices:
Keyboard
Mouse
Scanner…

42. Basic organisation of computer (cont)
MEMORY UNIT
Used to store
Data
Instructions
Intermediate Results &
Final Processed Results
Types
Primary
Secondary
Internal Processor memory
Primary memory is used to store temporary data.
Ex:RAM, ROM etc,.
Secondary memory is used to store information permanently
Ex:Hard disk.
Internal Processor memory is used to store temporary processor data
Ex:CPU Registers

43. Basic organisation of computer (cont)
CENTRAL PROCESSING UNIT (CPU)
Responsible for processing the data & instruction and controlling all other components
Operation (4 Phases)
Fetching Instruction from the memory
Decoding the instruction
Executing the instructions
Storing the results in to the memory
It contains the following components
CONTROL UNIT
ALU
MEMORY

44. 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.

45. 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,.

46. Basic organisation of computer (cont)
Registers
CPU contains a few special purpose, temporary storage units called registers
They are high speed memory locations
Used for handling instructions, data & intermediate results that are currently being processed
Program Counter(PC)
Instruction Register(IR)
Memory Address Register(MAR)
Accumulator

47. Basic organisation of computer
OUTPUT
The output unit is used to display the result of the process.
Data processed by CPU is made available to the end user by O/P devices
Commonly used O/P devices:
Monitor
Printer
Speaker

48. Components of Computers

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

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

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

52. Primary Memory:
It is used to store data temporary.

53. 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

54. 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 .

55. PROM 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.

56. EPROM 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.

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

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

59. 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.

60. 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.

61. Magnetic Hard Disk Mechanism

62. 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

63. 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.

64. 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

65. 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

66. 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.

67. 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.

68. Output Devices

69. 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.

70. 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.

71. NUMBER SYSTEM

72. 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

73. NUMBER SYSTEM Number System
A computer is a digital system that stores and process data in the form of 0’s and 1’s(Binary/Machine language)
Hence there is a need to change the data in the form of 0’s &1’s
Positional Number System
Numbers are represented using some symbols called digits and the values of these no’s can be determined by taking the position of digits
Catagories:
Decimal System
Binary System
Hexa Decimal System
Octal System

74. NUMBER SYSTEM …. Decimal System
Uses 10 as a base & is called base 10 no system
10 symbols are available for representing values (0-9)
Used to represent both integer & floating point values
Representation
(6x10^3)+(5x10^2)+(4x10^1)+(3x10^0)+(1x10^-1)+(2x10^-2)+(4x10^-3) =

75. NUMBER SYSTEM …. Binary System
Uses 2 as a base & is called base 2 no system
2 symbols are available for representing values (0 & 1)
Representation
(1x2^5)+(0x2^4)+(1x2^3)+(0x2^2)+(0x2^1)+(1x2^0)+(0x2^-1)+(1x2^-2)+(0x2^-3)+(1x2^-4) =

76. NUMBER SYSTEM …. Hexa Decimal System
Uses 16 as a base & is called base 16 no system
16 symbols are available for representing values (0-9 & letters A,B,C,D,E,F)
Representation
4A9.2B16
(4x16^2)+(10x16^1)+(9x16^0)+(2x16^-1)+(11x16^-2) =

77. NUMBER SYSTEM …. Octal System
Uses 8 as a base & is called base 8 no system
8 symbols are available for representing values (0-7)
Representation
(2x8^2)+(1x8^1)+(5x8^0)+(4x8^-1)+(3x8^-2) =

78. NUMBER SYSTEM ….
DECIMAL
BINARY
OCTAL
HEXA DECI.. 1 2 10 3 11 4
100 5
101 6
110 7
111 8
1000 9
1001
1010 12 A
1011 13 B
1100 14 C
1101 15 D
1110 16 E
1111 17 F
10000 20

79. Decimal to Binary

80. Conversion of 2510 to Binary
2 25
1 - 1
2510=110012

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

82. Decimal to Octal

83. Conversion of to Octal
8 125
12510=1758

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

85. Conversion of 8410 to Octal
8 84
8410=1248

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

87. Decimal to Hexa

88. Conversion of 45010 to Hexadecimal
16 450
45010=1C216

89. Hexa to decimal conversion
450
1C216 = 45010

90. Conversion of 38510 to Hexadecimal
16 385
38510=18116

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

92. Conversion of 25.12510 to Binary
2 25
1 - 1
2510=110012

93. 0.125 X 2 = 0.250
0.250 X 2 = 0.5
0.5 X 2 = 1.0 =

94. Binary to decimal conversion
1X2-3 =
0X2-2 = 0
0X2-1 = 0
1X20 = 1
0X21 = 0
0X22 = 0
1X23 = 8
1X24 = 16

95. Conversion of to Octal
8 84
8410=1248

96. 0.250 X 8 = 2.000 =

97. Octal to decimal conversion
124.2
2X8-1 =
4X80 = 1
2X81 = 0
1X82 = 0

98. ASSIGNMENT

99. DECIMAL TO BINARY 43 79
107
241
476

100. DECIMAL TO OCTAL 39
152
284
758
2534

101. DECIMAL TO HEXA 75
826
3128
7359
4756

102. DECIMAL TO OTHER
63 BASE4
279 BASE6
161 BASE7

103. BINARY  OCTAL,HEXA

104. OCTAL  HEXA
473
1235
724
5774
4625

105. BASE2
OCTAL
HEXA