Before you want to know about computers. you should know about "How computers have been evolved over the generation?"

1. MCA 101 1

2. Introduction
 Computer, a part and parcel of our lives, has
revolutionized the society.
 Almost everything can be computerized.
MCA 101 2

3. Information Concepts
 Data: Collection of raw facts and figures.
 Information: Data which has been
converted and processed so that it gets a
definite form and shape, becomes useful
and acts as a basis for decision making
process.
 Knowledge: The information which
contains wisdom is knowledge. Knowledge
can be classified as Facts based and
Heuristic Knowledge.
MCA 101 3

4. WHAT IS INFORMATION PROCESSING?
 Modification of information to achieve
desired results is called information
processing.
 For example:
◦ Conversion of speech to text
◦ Formatting of text to produce Banners
◦ Preparation of results from Answer Books
MCA 101 4

5. MCA 101 5
INTRODUCTION TO IT
Information Technology (IT) is everyday
technology used to acquire, store, manipulate
or transmit information; such as telephones
and telecommunications products, video
equipment, websites, message systems,
computer hardware, and more.

6. MCA 101 6
DEFINITION
“Information Technology is the use of hardware,
software, services, and supporting infrastructure to
manage and deliver information”
INFORMATION TECHNOLOGY INDUSTRY
COUNCIL DEFINES IT as “It serves as the voice of the
high tech community, advocating policies that
advance industry leadership in technology and
innovation; open access to new and emerging
markets; promote e-commerce expansion; protect
consumer choice; and enhance the global
competitiveness of its member companies”

7. MCA 101 7
IT INCLUDES
 all computers with a human interface.
 all computer peripherals which will not operate unless
connected to a computer or network.
 all voice, video and data networks and the equipment,
staff and purchased services necessary to operate them.
 all salary and benefits for staff whose job descriptions
specifically includes technology functions, i.e. network
services, applications development, systems
administration.
 all technology services provided by vendors or contractors.
 operating costs associated with providing information
technology.
 all costs associated with developing, purchasing, licensing
or maintaining software.

8. MCA 101 8
SOME EXAMPLES OF IT
 Telephone and radio equipment and switches used for voice
communications.
 Traditional computer applications that include data storage and
programs to input, process, and output the data.
 Software and support for office automation systems such as word
processing and spreadsheets, as well as the computer to run them.
 Users' PCs and software.
 Server hardware and software used to support applications such as
electronic mail/groupware, file and print services, database,
application/ web servers, storage systems, and other hosting
services.
 Data, voice, and video networks and all associated
communications equipment and software.
 Peripherals directly connected to computer information systems
used to collect or transmit audio, video or graphic information,
such as scanners and digitizers.
 Voice response systems that interact with a computer database or
application.
 The state radio communications network.
 Computers and network systems used by teachers, trainers, and
students for educational purposes

9. MCA 101 9
IT EXCLUDES
 "Closed/stand-alone" computer systems that monitor or
automate mechanical or chemical processes, such as the
fire alarm system in the capitol building.
 Audio-visual equipment which can be operated as a
standalone piece of equipment, such as televisions, tape
recorders, VCRs, video cameras, and overhead projectors.
Stand-alone video editing equipment is excluded.
 Copy machines and fax machines.
 Licenses or subscriptions to electronic information
provided to users in lieu of books or magazines.
 Salaries of staff who use technology but are not directly
involved in developing, implementing or supporting
technology as documented on their PIQ. Data entry staff,
staff who digitize drawings, staff who do desktop
publishing are excluded. "Power users" who use advanced
features of spreadsheets or word processing software are
excluded.
 Data entry services

10. MCA 101 10
HISTORY OF IT
 The first commercial business computer was developed in
the United Kingdom in 1951, by the Joe Lyons catering
organization. This was known as the Lyons Electronic Office'
- or LEO for short.
 It was developed further and used widely during the 1960s
and early 1970s.
 Early commercial systems were installed exclusively by large
organizations
 At first, individual organizations developed their own
software, including data management utilities, themselves.
Different products might also have 'one-off' custom
software. This fragmented approach led to duplicated effort
and the production of management information needed
manual effort.
 High hardware costs and relatively slow processing speeds
forced developers to use resources 'efficiently'.

11. MCA 101 11
BENEFITS OF IT
 Minimize costs
 Streamline workflow
 Increase productivity
 Manage change efficiently
 Optimize the benefits of change

12. Components of IT
 Hardware
 Software
 Data
 Users
 Storage
 Communications
MCA 101 12

13. What is a Computer?
 The word “Computer” comes from the
word “compute” .
 A computer is considered to be a
calculating device that can perform
arithmetic operation at enormous speed.
 More accurately a computer is an
electronic device used to process data.
 A computer can convert data into
information that is useful to people.
 It is also called Data Processor.
MCA 101 13

14. WHAT IS A COMPUTER?
 Computer is an electronic device which
can:-
◦ Accept information
◦ Process it and
◦ Give out results
MCA 101 14
Input Processing Output

15. Functions of Computer
 Accepting instructions from the user.
 Accepting data from the user.
 Performing various arithmetic and logical
operations as per instructions given.
 Presenting the information or output to the
user.
MCA 101 15

16. Characteristics of Computer
 Fastness
 Accuracy
 Reliable
 Large storage capacity
 Versatile
 Works automatically
 Diligent
 Intangible benefits
 Cost reduction
 No emotional, ego and psychological
problems
MCA 101 16

17. Limitations of Computer
◦ Computer does not work on itself, it requires set of
instructions to be provided for, else computer
(hardware) is a waste.
◦ Computers are not intelligent, they have to be
instructed about each and every step which they
have to perform, i.e. each and every task to be
performed by them should be given in detail.
◦ Computer cannot take decisions on its own, one has
to program the computer to take an action if some
conditions prevail.
◦ Computers, unlike humans cannot learn by
experience.
MCA 101 17

18. MCA 101 18

19. Pre-Mechanical
Computing:
From Counting on fingers
to pebbles
to hash marks on walls
to hash marks on bone
to hash marks in sand
MCA 101 19
Interesting thought:
Do any species, other than homo sapiens,
count?

20. Mechanical computers
MCA 101 20
From
The Abacus
c. 4000 BCE
to
Charles Babbage
and his Difference Engine (1812)

21. Mechanical computers:
The Abacus (c. 3000 BCE)
MCA 101 21

22. Napier’s Bones and
Logarithms (1617)
MCA 101 22
Picture courtesy IBM

23. Oughtred’s (1621) and
Schickard‘s (1623)
slide rule
MCA 101 23

24. Blaise Pascal’s
Pascaline (1645)
MCA 101 24

25. Gottfried Wilhelm von Leibnitz’s
Stepped Reckoner (1674)
MCA 101 25

26. Joseph-Marie Jacquard and his punched
card controlled looms (1804)
MCA 101 26

27. pattern for the cloth to be
woven
MCA 101 27

28. Charles Babbage (1791-1871)
The Father of Computers
MCA 101 28

29. Charles Babbage’s Difference Engine
MCA 101 29

30. Charles Babbage’s Analytical Engine
MCA 101 30

31. Lady Augusta Ada
Countess of Lovelace
MCA 101 31

32. Electro-mechanical computers
MCA 101 32
From
Herman Hollerith’s
1890
Census Counting Machine
to
Howard Aiken
and the Harvard Mark I (1944)

33. Herman Hollerith and his
Census Tabulating Machine (1884)
MCA 101 33

34. A closer look at the Census
Tabulating Machine
MCA 101 34

35. The Harvard Mark I (1944)
aka IBM’s Automatic Sequence
Controlled Calculator (ASCC)
MCA 101 35

36. MCA 101 36
Mechanical Calculators

37. The first computer bug
MCA 101 37
Rear Admiral Dr. Grace
Murray Hopper

38. Electronic digital computers
MCA 101 38
From
John Vincent Atanasoff’s
1939
Atanasoff-Berry Computer (ABC)
to
the present day

39. Alan Turing 1912-1954
MCA 101 39
The Turing Machine
Aka
The Universal Machine
1936

40. John Vincent Atanoff (1903-1995)
MCA 101 40
Physics Prof
At
Iowa State
University,
Ames, IA

41. Clifford Berry (1918-1963)
MCA 101 41
PhD student
of
Dr. Atanasoff’s

42. The Atanasoff-Berry Computer (ABC)
1939
MCA 101 42
The ABC was the first electronic digital computer,
invented by John Vincent Atanasoff

43. Bletchley Park’s Colossus
1943
MCA 101 43
The Enigma
Machine

44. The ENIAC
1946
MCA 101 44
John Presper Eckert
(1919-1995)
and
John Mauchly
(1907-1980)
of the
University of
Pennsylvania Moore
School of Engineering

45. The ENIAC:
Electronic Numerical Integrator and
Computer
MCA 101 45

46. ENIAC’s Wiring!
MCA 101 46

47. Programming the ENIAC
MCA 101 47

48. 1951
Univac
MCA 101 48
Typical 1968 prices—EX-cluding maintenance & support!

49. MCA 101 49
UNIVAC 1

50. MCA 101 50
History & Evolution
Abacus
Difference Engine
Analytical Engine
1944 MARK I
Howard Aiken at
Harvard University
1951 - UNIVAC1
first commercial computer
1954 - Hewlett and Packard
Met and setup shop in
Garage at Silicon valley
Mechanical Calculator
Overview

51. MCA 101 51
1975 – Microsoft Founded
Bill Gates with Paul Allen
1976
Apple I and Apple II
1981-IBM PC
PC was
introduced.
1989 – WWW
Invented by
Tim Berners-Lee
1969 – Internet was
founded

52. MCA 101 52
1994 – Netscape
Founded by
Jim Clark and Marc Andreesen
Many more….

53. MCA 101 53
Computer Generation
1. 1st Generation
2. 2nd Generation
3. 3rd Generation
4. 4th Generation
5. 5th Generation

54. MCA 101 54
1st Generation (1944 - 1958) : Vacuum Tubes
IBM Punched Card (input)
Magnetic Tapes
(output)
Vacuum Tubes
(memory)
Memory was made up
of hundreds of vacuum
tubes or sometimes
magnetic drum.
Gave off so much
heat that even if they
were cooled by gigantic
air conditioners.
Input and output
media were punched
cards and magnetic
tapes.

55. Limitations
 Enormous in size
 Expensive
 Generated a lot of heat
 Used machine language to perform operations
 Could solve only one problem at one time
 Output displayed on printouts
MCA 101 55

56. Examples
MCA 101 56
UNIVAC ENIAC

57. MCA 101 57
•an electronic switch that alternately allow or disallow
electronic signal to pass, replaces vacuum tubes.
•These transistors were made of solid material, some of
which is silicon, therefore they were very cheap to
produce.
•Much smaller than vacuum tubes, draw less power,
and generate less heat, conduct electricity faster.
2nd Generation (1959 - 1964) : Transistor

58. Advantages over 1st Generation
 Transistors replaced vacuum tubes.
 The transistor was far superior to the vacuum
tube, allowing computers to become:-
◦ Smaller
◦ Faster
◦ Cheaper
◦ More energy-efficient and
◦ More reliable
 Relied on punched cards for input and
printouts for output.
 Moved from cryptic binary machine language
to symbolic, or assembly, languages, which
allowed programmers to specify instructions
in words.
MCA 101 58

59. MCA 101 59
Minicomputer

60. MCA 101 60
 An electronic circuit that packages transistors and other
electronic components into one small silicon chip called
semiconductor.
 The number of transistors that is placed on a single chip
has increased, shrinking both the size and cost of
computers.
 Keyboards and monitors were used.
 Magnetic disks were used widely as secondary storage.
3rd Generation (1964 - 1970):
Integrated Circuit

61. Advantages over 2nd Generation
 Reduced size and cost.
 Use of Keyboards and monitors instead of
punched cards and print outs.
 Operating system allowed the device to run many
different applications at one time with a central
program that monitored the memory.
 Computers for the first time became accessible to
a mass audience because they were smaller and
cheaper than their predecessors.
MCA 101 61

62. MCA 101 62
Minicomputer

63. MCA 101 63
•A silicon chip on which transistors are
integrated onto it.
•Microprocessor can do all the processing of
a full-scale computer – smaller in size , faster
in speed.
4th Generation (1971-Present):Microprocessor
•These circuit integrations are known as Large-
scale integrated (LSI) and Very Large-scale
integrated (VLSI) circuits
•Microprocessors led to the invention of
personal computers.

64. Microprocessor
MCA 101 64
•The Intel 4004 chip, developed in 1971, located all the
components of the computer - from the central
processing unit and memory to input/output controls -
on a single chip.
•As these small computers became more powerful,
they could be linked together to form networks, which
eventually led to the development of the Internet.
•Development of GUIs, the mouse and handheld
devices

65. MCA 101 65
5th Generation (Present & Beyond)
: Artificial Intelligence
Artificial Intelligence (AI)
concerns with making computers
behave and think like humans.
The branch of computer
science that deal with writing
computer programs that can
solve problems creatively
AI studies include robotics,
expert systems, games, etc..

66. MCA 101 66
• Some applications, such as voice recognition, are
being used today.
• The use of parallel processing and
superconductors is helping to make artificial
intelligence a reality.
• Quantum computation and molecular and
nanotechnology will radically change the face of
computers in years to come.
5th Generation (Present & Beyond)
: Artificial Intelligence

67. MCA 101 67
REVIEW - GENERATIONS OF COMPUTERS
The Five Generations of Computers:
• First Generation - 1940-1956 : Vacuum Tubes
• Second Generation - 1956-1963 : Transistors
• Third Generation - 1964-1971 : Integrated Circuits
• Fourth Generation - 1971-Present : Microprocessors
• Fifth Generation - Present and : Artificial
Beyond Intelligence

68. CLASSIFICATION OF COMPUTERS
Computers, in general, can be classified into
two major categories based upon the
following criteria:-
 According to logic used by the computer
 According to the size of computer
MCA 101 68

69. 1. Analog Computers
2. Digital Computers
3. Hybrid Computers [Blend of 1 and 2]
MCA 101 69
CLASSIFICATIONS
AS PER LOGIC USED

70. CLASSIFICATION OF
COMPUTERS
 Analog Computers.
◦ These computers process analog information.
◦ Output is immediately available on applying
input.
◦ Required for real time applications.
 Digital Computers.
◦ All information is converted in binary form.
◦ Every information is represented in binary form.
◦ All processing is done on numbers in binary
form.
 Hybrid Computers.
◦ They have the advantages of both the types.
MCA 101 70

71. Analog Computers
 Operate on principle of creating a physical
analog of mathematical problems.
 Continuously measure physical variables.
 Use signals as inputs which can come from
devices like:-
◦ Thermometers
◦ Speedometers
◦ Barometers
 These signals are continuous flow of physical
quantities e.g.
◦ temperature,
◦ speed,
◦ pressure etc. which vary continuously
MCA 101 71

72. Analog Computers
 The result given by these computers is not
very precise, accurate and consistent.
 Because of the nature of operation, their
use is limited.
 Speedometer of a vehicle can be a good
example of analog computers where speed
varies continuously.
 Fuel indicator is another example.
MCA 101 72

73. DIGITAL COMPUTERS
 Accept digits and alphabets as inputs.
 This information is used for
◦ solving,
◦ controlling any problems which can be expressed
mathematically.
 Take data in the form of discrete signals
representing ON (high) or OFF (low) voltage
state of electricity.
 The data input can be represented as sets of
0’s and 1’s representing low and high
respectively.
MCA 101 73

74. DIGITAL COMPUTERS
 These computers convert data into discrete
form before operating on it.
 Digital watches can a good example of
digital computer as the time which is
displayed does not vary continuously but
changes from one discrete value to another.
 The term “Computer” used in our day to day
life is a reference to the digital computer
only.
MCA 101 74

75. DIGITAL COMPUTERS
 Digital computers can be further classified
based upon:-
◦ Purpose of use
◦ Size and capabilities
 Classification as per purpose:-
◦ General purpose digital computers
◦ Special purpose digital computers
MCA 101 75

76. GENERAL PURPOSE DIGITAL COMPUTERS
 These are those computers which can
theoretically 'used for any type of applications.
 These computers can be used in solving a
business problem as well mathematical
equation with same accuracy and consistency.
 Most of the computers now are general purpose
digital computers.
 All the PCs, which have become almost every
household affair are all general purpose digital
computers.
MCA 101 76

77. SPECIAL PURPOSE DIGITAL COMPUTERS
 These are those digital computers which are
designed, made and used for a specific job.
 These are usually used for those purposes which
are critical and need great accuracy and response
like:-
◦ satellite launching,
◦ weather forecasting,
◦ ignition instruments etc.
MCA 101 77

78. ACCORDING TO THE
SIZE AND CAPABILITIES
 Super computers
 Mainframe computers
 Medium sized computers
 Mini computers
 Micro computers
MCA 101 78

79. SUPER COMPUTERS
 These are the computers which are
characterized as:-
◦ being the fastest,
◦ with very high processing speeds,
◦ very large size,
◦ most powerful and
◦ most costliest of all their cousins.
 Used widely in:-
◦ complex scientific applications like
processing geological data,
◦ weather data,
◦ genetic engineering etc.
MCA 101 79

80. SUPER COMPUTERS
 Recognize words up to length of 64
bits and more.
 Speed of calculations is up to 1.2
billion instructions per second and
 They can take input from more than
1000 individual work stations.
 PARAM is an example of super
computer developed in India.
MCA 101 80

81. SUPER COMPUTERS
 Supercomputers are used for highly
calculation-intensive tasks such as:-
◦ weather forecasting
◦ climate research
◦ molecular modeling
◦ physical simulations
◦ Cryptanalysis etc
 Military and scientific agencies are heavy
users.
MCA 101 81

82. PARAM, the Supercomputer
MCA 101 82

83. MAINFRAME COMPUTERS
 Mainframe computer is a computer which
has capability:-
◦ to support many peripheral devices and
terminals,
◦ to process several million instructions per
second (MIPS),
◦ to support more than 1000 remote systems.
 Mainframes are mostly used for systems
like railway reservations etc.
MCA 101 83

84. MEDIUM SIZED COMPUTERS
 These computers are mini versions of
mainframe computers.
 Smaller than mainframe and have smaller
power than mainframes.
 Their processing speeds are relatively high
with support for about 200 remote systems.
MCA 101 84

85. MINI COMPUTERS
 These computers are relatively smaller and less
expensive than mainframe.
 Medium sized, but they can if needed be portable in
comparison with mainframes.
 Faster and can support about 10-20 user terminals
connected to it.
 Easy to use.
 They can handle:-
◦ database,
◦ statistical problems,
◦ accounting etc. using special software designed for
above uses.
MCA 101 85

86. MCA 101 86

87. MICRO COMPUTERS
 These are the most widely used category of
computers which we commonly term as personal
computers (PCs).
 The word micro suggests only the size, but not the
capacity.
 These computers can fit themselves on to a desk
top.
 They are capable to do all input-output
operations.
 They can also be connected to few peripheral
devices.
MCA 101 87

88. MCA 101 88

89. HYBRID COMPUTERS
 The Hybrid computers are those computers
which adopt the best qualities of both analog
and digital computers.
 Thus becoming capable to work on analog or
digital data.
 These computers are mostly used for
automation of various complicated physical
processes and machines.
MCA 101 89

90. MCA 101 90

91. MCA 101 91
Personal computers
• This is the computer mostly preferred by the home
users.
• These computers are lesser in cost than the
computers given above and also, small in size.
• They are also called PCs in short for Personal
computers.
• A personal computer or PC is generally a
microcomputer intended to be used by one person
at a time.
• Suitable for general purpose tasks such as word
processing, programming, or game play.
• Usually used to run purchased or other software not
written by the user.

92. MCA 101 92
Classification of Personal
Computers
Personal computers can be categorized
by size and portability :
• Desktop computer
• Portable computer
• Notebook or laptop
• Tablet computer
• PDA
• Wearable computer

93. MCA 101 93
Desktop Computer
•A desktop computer is an
independent personal
computer that is made
especially for use on a
desk in an office or home.
•Desktops are currently
the more affordable and
most common computers,
and are frequently used
by businesses, schools,
households and other
organizations.
Desktop computer with several common
peripherals (Monitor, keyboard, mouse,
speakers, microphone and a printer)

94. MCA 101 94
Portable computer
•A Portable computer is a
computer that is designed to
be moved from one place to
another (in other words, it is
a computer that is portable).
•Portable computers, by
their nature, are
microcomputers.
The Compaq Portable; the first portable
IBM PC compatible

95. MCA 101 95
Notebook computers or Laptop
•A laptop computer (also known
as notebook computer) is a
small mobile personal
computer, usually weighing
from 1 to 3 kilograms (2 to 7
pounds).
•Computers larger than PDAs
but smaller than notebooks are
also sometimes called
"palmtops".
Laptop with touchpad.

96. MCA 101 96
Notebook computers or Laptop
•Laptops are capable of doing many of the same
tasks that desktop computers perform, although
they are typically less powerful for the same price.
•Having a small size and low weight the notebook
is easy to carry anywhere.
•This is easy to carry around and preferred by
students and business people to meet their
assignments and other necessary tasks.

97. MCA 101 97
Tablet PC
•A tablet PC is a portable
computer shaped in the form
of a notebook or a slate with
the capabilities of being
written on through the use of
digitizing tablet technology or
a touch screen.
•A user can use a stylus and
operate the computer without
having to have a keyboard or
mouse.
Toshiba Portege 3500 tablet PC, in tablet
configuration

98. MCA 101 98
Personal Digital Assistant
•Personal digital assistants (PDAs or
palmtops) are handheld devices that
were originally designed as personal
organizers, but became much more
versatile over the years.
•A basic PDA usually includes a clock,
date book, address book, task list,
memo pad, and a simple calculator.
•One major advantage of using PDAs
is their ability to synchronize data with
desktop, laptop, and desknote
computers.
Palm IIIxe PDA

99. MCA 101 99
Wearable computer
•A wearable computer is a small
portable computer that is designed
to be worn on the body during use.
•Wearable computers are usually
either integrated into the user's
clothing or can be attached to the
body through some other means,
like a wristband.
•They may also be integrated into
everyday objects that are
constantly worn on the body, like a
wrist watch or a hands-free cell
phone.
Wristwatch videoconferencing system running
GNU Linux, later featured in Linux Journal and
presented at ISSCC2000
Palm IIIxe PDA

100. MCA 101 100
Wearable computer
•Wearable computers are especially useful for
applications that require computational support
while the user's hands, voice, eyes or attention
are activly engaged with the physical
environment.
•Such applications include presentation of
information to mechanics, military or paramilitary
personnel, pathfinding for the blind, realtime
translation from one spoken language to
another, and continuous medical monitoring.

101. Components of Computer
 Computer is basically composed of
essentially the following:
◦ Hardware
◦ Software
MCA 101 101

102. Hardware
 Computer hardware is the collection of various
physical components of the computer, like the:-
◦ computer itself,
◦ the input-output devices,
◦ printers and other peripheral devices.
 This computer hardware blindly perform some
basic operations like:-
◦ addition,
◦ subtraction,
◦ data transfer,
◦ control transfers and
◦ simple tests.
MCA 101 102

103.  These components are tangible, which
one can see and feel.
 To enhance the capabilities of the
hardware and to perform complex
operations, we need to take help of
software component.
MCA 101 103
Hardware

104. Software
 Software is set of instructions usually termed as
programs which are required for processing
activities of the computer.
 These set of programs can be used to solve real
world problems.
 The capability of computer depends largely on the
software component.
 Software refers not only to the programs which
make the computer work, but also those programs
which are used to solve real life problems.
 Thus, for a computer, both hardware and software
components are essential.
MCA 101 104

105. MCA 101 105
Block Structure of Computer/
Organization of Computer
INPUT UNIT
OUTPUT
UNIT
MEMORY
CONTROL
UNIT
ALU
CPU
CPU: Central Processing Unit
ALU: Arithmetic Logic Unit
INPUT
DATA
OUTPUT
DATA

106. Input Unit
 Instructions and data is given to the computer to work
with. These devices translate data from human
understandable form into electronic form
understandable by the computer.
 The most common input device is the keyboard. This
device is similar to the normal typewriter, using
which programmer types the instructions for any task
he wants to do. These instructions are called
programs.
 Other examples of input devices are mouse, trackball,
light pen, etc.
MCA 101 106

107. Central Processing Unit
 After accepting data, it is fed into Central Processing
Unit before the output is generated as data has to be
processed, which is done by CPU. This unit of the
computer is the brain of computer system, which does
all the processing, calculations, problem solving and
controls all other functions of all other elements of the
computer. The CPU consists of the following three
distinct units namely:
◦ The Memory Unit
◦ The Control Unit
◦ The Arithmetic and Logic Unit
MCA 101 107

108. PHYSICAL COMPONENTS of
CPU
MCA 101 108

109. MOTHER BOARD
MCA 101 109

110. CPU, HEAT SINK &
COOLING FAN
MCA 101 110

111. RAM
MCA 101 111

112. HARD DISK
MCA 101 112

113. CD WRITER
MCA 101 113

114. Memory Unit
 Data and results are stored.
 The major function is to remember the
instructions and data.
 The data stored can be accessed and used
whenever required by the CPU for necessary
processing.
 This unit consists of cells which are capable to
store unit of information. These cells can be
accessed as they are numbered sequentially,
which are called addresses. This memory unit is
usually referred as primary storage section. The
units in which memory unit is measured are
known as BYTES.
MCA 101 114

115. Memory Unit
 A BYTE is the space required to store one
character or alphabet or digit or any other
special character :
1 Byte (typically 1 keystroke) = 8 Bits
1 Kilobyte = 1024 Bytes
1 Megabyte = 1024
Kilobytes
Where Bits are spaces required to store one
Binary digits i.e. either o or 1.. ...
MCA 101 115

116. Control Unit
 This is that unit of CPU, which coordinates all the
activities of each and every element of computer.
 It decodes the instructions given by various users and
it sends commands and signals that determine the
sequence of various instructions.
 Though this unit does not process data but it acts as
the central system for data manipulation, as it
controls the flow of data to and from the main
storage. i.e. either 0 or 1.. ...
MCA 101 116

117. Arithmetic and Logic Unit
 This unit performs the arithmetic
operations such as addition,
subtraction, multiplication and
division.
 It also does logical operations such as
comparison of numbers etc. Thus this
unit helps by processing data and
taking logical decisions.
MCA 101 117

118. Output Unit
 After processing the data, the computer has to
provide the result of the processing to the
user. For this, computer uses output devices.
 The output device is that device which is used
to provide the user with the desired output.
Commonly used output devices are VDU
(Visual Display Unit) i.e. monitor, printers
(line printer, character printer etc.), plotter,
magnetic media like floppy, hard disks etc.
MCA 101 118

119. MCA 101 119
Memory
Main memory consists of a number of
storage locations, each of which is
identified by a unique address.
The ability of the CPU to identify
each location is known as its
addressability.
Each location stores a word i.e. the
number of bits that can be processed
by the CPU in a single operation.
Word length may be typically 16, 24,
32 or as many as 64 bits.
A large word length improves system
performance, though may be less efficien
on occasions when the full word length is
not used.

120. Computer Memory
 Main function – To store software
 Types of memory
 Primary memory
 Secondary memory
MCA 101 120

121. Primary Memory
 Primary storage or memory: Is where
the data and program that are currently
in operation or being accessed are
stored during use.
 Consists of electronic circuits:
Extremely fast and expensive.
MCA 101 121

122. Primary Memory
 Two types:
 RAM (non-permanent)
 Programs and data can be stored here for the computer’s
use.
 Volatile: All information will be lost once the computer
shuts down. RAM holds the programs and data that the
processor is actively working with.
 ROM contains software that is used in Input/Output
operations. It also contains software that loads the
Operating System in Primary Memory.
 The CPU can read and write to RAM but it can only read
from ROM.
 RAM is volatile while ROM is not.
 ROM (permanent)
 Contents do not change.
MCA 101 122

123. Secondary Memory
Used for long-term storage of programs and
data.
 Examples of secondary memory devices are:
hard disks, floppy disks and CD ROMs.
 Storage is permanent
MCA 101 123

124. Primary and Secondary Memory
Comparison
MCA 101 124
Primary memory Secondary memory
Fast
Expensive
Low capacity
Connects directly to the
processor
Slow
Cheap
Large capacity
Not connected directly to
the processor

125. MCA 101 125
Types of RAM
1. Dynamic Random Access Memory (DRAM)
• Contents are constantly refreshed 1000 times per second
• Access time 60 – 70 nanoseconds
Note: a nanosecond is one billionth of a second!
2. Synchronous Dynamic Random Access
Memory (SDRAM)
• Quicker than DRAM
• Access time less than 60 nanoseconds
3. Direct Rambus Dynamic Random Access Memory
(DRDRAM)
• New type of RAM architecture
• Access time 20 times faster than DRAM
• More expensive

126. MCA 101 126
4. Static Random Access Memory (SRAM)
• Doesn’t need refreshing
• Retains contents as long as power applied to the chip
• Access time around 10 nanoseconds
• Used for cache memory
• Also for date and time settings as powered by small
battery
5. Cache memory
• Small amount of memory typically 256 or 512 kilobytes
• Temporary store for often used instructions
• Level 1 cache is built within the CPU (internal)
• Level 2 cache may be on chip or nearby (external)
• Faster for CPU to access than main memory
Types of RAM

127. MCA 101 127
The operation of cache memory
1. Cache fetches data
from next to current
addresses in main
memory
2. CPU checks to see
whether the next
instruction it requires is in
cache
3. If it is, then the
instruction is fetched from
the cache – a very fast
position
4. If not, the CPU has to
fetch next instruction
from main memory - a
much slower process
Main
Memory
(DRAM)
CPU
Cache
Memory
(SRAM)
= Bus connections

128. MCA 101 128
Types of RAM
6. Video Random Access memory
• Holds data to be displayed on computer screen
• Has two data paths allowing READ and WRITE to occur at
the same time
• A system’s amount of VRAM relates to the number of
colours and resolution
• A graphics card may have its own VRAM chip on board

129. Types of RAM
7. Virtual memory
 Uses backing storage e.g. hard disk as a temporary location
for programs and data where insufficient RAM available
 Swaps programs and data between the hard-disk and RAM
as the CPU requires them for processing
 A cheap method of running large or many programs on a
computer system
 Cost is speed: the CPU can access RAM in nanoseconds but
hard-disk in milliseconds (Note: a millisecond is a
thousandth of a second)
 Virtual memory is much slower than RAM
MCA 101 129

130. MCA 101 130
Read only memory (ROM)
ROM holds programs and data permanently even when
computer is switched off
Data can be read by the CPU in any order so ROM is
also direct access
The contents of ROM are fixed at the time of
manufacture
Stores a program called the bootstrap loader that helps
start up the computer
Access time of between 10 and 50 nanoseconds

131. MCA 101 131
Types of ROM
1. Programmable Read Only Memory (PROM)
• Empty of data when manufactured
• May be permanently programmed by the user
2. Erasable Programmable Read Only Memory (EPROM)
• Can be programmed, erased and reprogrammed
• The EPROM chip has a small window on top allowing it to be
erased by shining ultra-violet light on it
• After reprogramming the window is covered to prevent new
contents being erased
• Access time is around 45 – 90 nanoseconds

132. MCA 101 132
Types of ROM
3. Electrically Erasable Programmable Read Only
Memory (EEPROM)
• Reprogrammed electrically without using ultraviolet light
• Must be removed from the computer and placed in a special
machine to do this
• Access times between 45 and 200 nanoseconds
4. Flash ROM
• Similar to EEPROM
• However, can be reprogrammed while still in the computer
• Easier to upgrade programs stored in Flash ROM
• Used to store programs in devices e.g. modems
• Access time is around 45 – 90 nanoseconds

133. Types of ROM
5. ROM cartridges
 Commonly used in games machines
 Prevents software from being easily copied
MCA 101 133

134. Communication Paths
 CPU consists of Memory Unit, Control
Unit and ALU.
 These sub units should have some
communication between them for making
them work properly.
 The communication links between these
sub units are called buses. These are:
 Control bus
 Address bus
 Data bus
MCA 101 134

135.  Control bus: The control bus is the path for
all controlling and timing functions sent by
the control unit to other units of the CPU.
 Address bus: This is the path used for
locating the address of the memory
location where the next instruction to be
executed or the next piece of data is found.
This is used for data retrieval storage and
manipulations where address of storage
locations are required.
 Data bus: This is the path on which actual
data transfer takes place.
MCA 101 135

136. MCA 101 136
CENTRAL
PROCESSING UNIT
INPUT/OUTPUT
UNIT
RAM/ROM
ADDRESS
BUS CONTROL
BUS
DATA
BUS

137. Working of CPU
 Computer undergoes through two basic
cycles:
 Instruction cycle
 Execution cycle
 Instruction cycle involves two steps:
 Fetch
 Decode
Fetch locates an instruction from memory and
sends it to the control unit, so that it can act
upon the instruction, then the decode step takes
up the task of decoding the instruction and sends
it to the ALU along with the required data.
MCA 101 137

138. FETCH DECODE EXECUTE CYCLE
 The CPU continuously transfers data to and from memory
 Data transfer is done in units called instructions or words
 When a computer is switched on, the CPU continuously
goes through a process called fetch-decode-execute cycle:
 The Control Unit fetches the current instruction from memory,
decodes it and instructs the ALU to execute the instruction.
 The execution of an instruction may generate further data
fetches from memory
 The result of executing an instruction is stored in either a
register or RAM
MCA 101 138

139. FETCH-DECODE-EXECUTE CYCLE
(CONT’D)
MCA 101 139
Main Memory
Control Unit
Arithmetic/Logic Unit
1
2
3
4
Instruction
Cycle
Execution
Cycle
Fetch Decode
Execute
Store
cpu
RAM

140. Computer Registers
 Special temporary storage locations which are
within the CPU.
 Registers are very fast. They accept, store,
transfer data and instructions which are in
immediate use.
 The instruction being executed is retrieved by
CPU from the main memory and stored in
registers.
MCA 101 140

141. SOFTWARE
Software is the programs and data that a computer
uses.
 Programs are lists of instructions for the processor
 Data can be any information that a program needs: character
data,
numerical data, image data, audio data, etc.
 Both programs and data are saved in computer memory in the
same way.
Computer software is divided into two main
categories:
1. Systems software
2. Applications software
System software manages computer resources and
makes computers easier to use
An applications software enables a computer user to
do a particular task
MCA 101 141

142. SOFTWARE
MCA 101 142
Application Programs System Programs
1. Word processors
2. Game programs
3. Spreadsheets
4. Data base systems
5. Graphics programs
6. Web browsers
1. Operating system.
2. Networking system.
3. Programming language software.
4. Web site server.
5. Data backup.

143. System Software
 It consists of :
 Operating systems
 Language Processors
 Device Drivers
 Utility Programs etc.
MCA 101 143

144. OPERATING SYSTEMS
 The most important systems program is the operating
system.
 It is a group of programs that coordinates the
operation of all the hardware and software
components of the computer system.
 It is responsible for starting application programs
running and finding the resources that they need
 Examples of operating systems are: Unix, Windows 98,
Windows NT, Windows XP, MS-DOS, Linux, Solaris,
VMS, OS/2 and System 7.
MCA 101 144

145. Operating System (OS)
 Major functions of OS
 Assigning tasks
 Memory management
 File management
 I/O management
 Establishing data security and integrity
 Provides data and time services.
MCA 101 145

146. Language Processors
 Translators
 Compilers
 Interpreters
 Assemblers
MCA 101 146

147. Service Utilities
 Device Drivers
 Directory and File management utilities
MCA 101 147

148. Application Software
 It consists of:
 Pre written application software
 User written application software
MCA 101 148

149. Pre written application S/W
 S/w packages which are developed by group
of people or an individual to be used by
others.
 Commonly available s/w are:
 Word processing s/w
 Electronic spreadsheets
 Database management
 Graph generator
 Report generator
 Communication s/w
MCA 101 149

150. Software
 Liveware
 Firmware
MCA 101 150