The document provides a comprehensive overview of computers, including their definition, history, types, characteristics, and applications in various fields. It discusses the evolution of computers through different generations, highlights key characteristics such as speed, accuracy, and storage capabilities, and categorizes computers based on operation, purpose, and size. Additionally, it explains the main components of a computer and the input devices like keyboards and mice.

1. Computer Application in Management
v
Arebu M.
ODA BULTUM UNIVERSITY
Prepared by 1

2. In this chapter you will specifically:
 Define clearly what is term computer.
 Explain History and generation of computer.
 Identify the characteristics of computer.
 Explain the application areas of computer.
 Identify the different type of computer.
 Main parts of computer
2

3. 3

4. • A computer is an electronic device that accepts data,
processes the accepted data, and then displays the
result.
• More accurately, A computer is a machine which
receive an input(data), processes it according to a
predefined program/instruction and then stores it,
and gives an output, i.e. provides the result in printed
or visual form.
• The word ‘computer’ comes from the Latin word
‘compute’ means to calculate.
Introduction to computers
What is COMPUTER?
4

5. 1) Inputting: It is the process of entering raw data, instructions and
information into the computer.
 It is performed with the help of input devices.
2) Storing: The computer has primary memory and secondary
storage to store data and instructions.
 It stores the data before sending it to CPU for processing and also
stores the processed data before displaying it as output.
3) Processing: It is the process of converting the raw data into
useful information.
 This process is performed by the CPU of the computer. It takes
the raw data from storage, processes it and then sends back the
processed data to storage.
The operations of computer components are given below
5

6.  4) Outputting: It is the process of presenting the
processed data through output devices like monitor,
printer and speakers.
 5) Controlling: This operation is performed by the
control unit that is part of CPU.
 The control unit ensures that all basic operations are
executed in a right manner and sequence.
Cont…
6

7. History of computers
 Computers was first invented to calculate huge
mathematical tasks.
 A. The Abacus
 It is the earliest mechanical computational device.
 It was in use in the middle east as early as 2500B.C.
 Simple addition and subtraction can be carried out
rapidly and efficiently by positioning the beads
appropriately.
7

8. B. Pascal’s calculator
 It is the first true mechanical calculator.
 It was invented by a French mathematician called Blasé
Pascal in 1642 and its known as Pascaline (Pascal's
calculator)
C. The difference engine
 Charles Babbage, a nineteenth century professor at
Cambridge University, is considered to be the father of
modern digital computers.
 The important contribution of Babbage’s engine was its
ability to perform computations and print results
automatically.
History of computers
8

9.  In 1842, Babbage comes out with his new idea of
Analytical Engine that was intended to be
completely automatic.
History of computers
9

10.  D. Herman Hollerith's tabulating machine
 Herman Hollerith is a statistician in 1880 and he develop
his machine to speed up the process of census data.
 He develops his machine that uses the punched card.
 E. Mark I
 Developed by Howard A. at Harvard university (1944)
 which were the first electromechanical computer.
History of computers
10

11.  F. The ENIAC (Electronic Numerical Integrator and Calculator)
 It was the first general purpose digital computer.
 It is very huge occupying 15,000 square feet room and use 18000 vacuum tubes.
 The major drawback was it has to be programmed manually by setting switches
and plugging & Unplugging cables.
 It doesn’t use internally stored memory.
History of computers
11

12.  G. The Von Neumann Machine
 Van Neumann forward the stored program. concept of the ENIAC
project.
i.e. It designing the computer to get its instruction by reading them
from memory.
 H. Commercial Computers
 The 1950s century was the birth of computers industry with two
companies, Spery and IBM, by demonstrating the market place.
i.e. The development of successful commercial computer called
UNIVACI(Universal Automatic Computer
History of computers
12

13. New Pen Computers
History of computers
13

14. Continue…
History of computers
14

15. Continue…
History of computers
15

16. Generation of computers
 Generation in computer language is a steps in technology.
 We have five generation of computer
 The major characteristics that distinguish these generations of
computer are the following.
 Types of electronic circuit element used
 Major secondary storage media used
 Computer language used.
Types of operating system used
Memory access time (time to store or retrieve a word of data from
memory).
16

17. Generation of computers
A. First Generation computers (1944-1955)
 used vacuum tubes as the principal electronic components.
 punched cards were the main sources of input and
 magnetic grams were used for internal storage.
 Memory access time was expressed in milliseconds.
 Very large in size, slow in performance and expensive in price.
 They uses machine & assembly language.
 Most application were scientific calculation.
 ENIAC & UNIVACI are examples of 1st generation computers.
17

18. Generation of computers
B. Second Generation Computers (1955-1964)
 Transistor were the main ckt element.
-Transistors are solid state device made from silicon.
 Magnetic tapes were used for main storage media.
 Memory access times were expressed in microseconds
 Emergence of high-level programming languages, like FORTRAN,
COBOL, & ALGOL. (Easy to write)
 Batch operating systems is used that permit rapid processing of
magnetic tape files.
 They are much faster than 1st generation computers.
18

19. Generation of computers
C. Third Generation Computers (1964-1975)
 Transistors are replaced by Integrated circuits(IC)
 Magnetic disc storage became popular and provided direct access to very large
data files.
 Access time in these computers was measured in nanoseconds (billionths of a
second).
 Structured programming languages were introduced :PASCAL and BASIC.
 Creation of an independent software industry.
19

20. Generation of computers
 D. Fourth Generation Computers (1975-1989)
 ICs are replaced by Large Scale Integration (LSI)
 Access time in these computers was measured in nanoseconds
(billionths of a second).
 Creation of MICROPROCESSOR. (for PCs).
 Spread of high-speed computer networking. (LAN & WAN)
 Several new operating systems were developed, like MS-DOS,
Ms- Windows, and UNIX.
 Totally general purpose machines.
20

21. Generation of computers
E. Fifth Generation computes (1989- Present)
 Totally general purpose machines.
 Very Large Scale Integration(VLSI) technology and also Ultra Large
Scale Integration (ULSI) emerged.
 Larger main memory > = 256 Mb, and hard disk >= 80 GB are
common
 Optical disks emerged named as CD-ROMs
 Distributed operating system for computer network.
 Portable notebook computers, powerful desktop PCs, and
workstations, powerful servers and supercomputers
21

22. Generation of computers
E. Fifth Generation computes (1989- Present)
 VLSI technology becomes Ultra Large Scale Integration (ULSI).
 Portable notebook computers, powerful desktop PCs, and workstations,
powerful servers and supercomputers
 Larger main memory > = 256 Mb, and hard disk >= 80 GB are common
 Optical disks emerged named as CD-ROMs
 Distributed operating system for computer network.
22

23. Generation 1st
2nd
3rd
4th
5th
Circuit
element
Vacuum tube Transistor IC LSI VLSI
SSD Punched
card
Magnetic
Tape
Magnetic
disk
Mass
Device
storage
Language Machine &
Assembly
Fortran,
COBOL
Etc
Structured
language
Application
oriented
Operating
system
Operator
control
Batch
system
Application
oriented
Time
sharing
Mem.
Access time
1ms 10µs 10ns 1ns
Approx. date 1946-57 1958-64 1965-71 From 1971
above
23 23

24. Characteristics of Computer
1. STORAGE
 Computes can handle large amount of data.
 Once recorded, The information can never be
forgotten and can be retrieved with a fraction of
a second.
Its storage capacity is measured as follows:
Bit = The smallest information stored in a computer(0 or
1).
 Byte = character = 8 bits.
 Kilobyte (KB) = 1024 bytes.
 Megabyte (MB) = 1024 Kilobytes.
 Gigabyte (GB) = 1024 Megabytes.
 Terabyte (TB) = 1024 Gigabytes 24

25. Characteristics of Computer
2. SPEED
 Computers are very fast devices.
 They work at an incredible speed and perform millions of
calculations and comparisons in a second.
Its speed is measured by:
 Millisecond = 1/1000 of a second.
 Microsecond = 1/1000,000 of a second.
 Nanosecond = 1/1000,000,000 of a second.
 Pico second = 1/1000,000,000,000 of a second.
25

26. Characteristics of Computer
3. ACCURACY
 Computers process vast amount of data in a very high speed
without committing errors
 Errors can occur mainly due to humans’ incorrect input data, and
program instructions with a problem.(often called GIGO).
4. DILIGENCE
 Computers are not bored or become tired of performing many
thousands of calculations repeatedly.
5. VERSATILITY
 A computer is capable of performing almost any task
provided that the task can be reduced to a series of logical
steps.
For example, the same computer used for process payroll can
also be used for Design computations or to track Inventory.
26

27. Characteristics of Computer
6. DURABILITY and RELIABILITY
 Computers are durable and extremely reliable devices.
 They can operate error-free over long periods of time.
7. LACK of DECISION-MAKING
 Computers do not have the capacity to think by their own.
 Their IQ is zero and they had to be told what to do and in what
sequence.
27

28. Types of Computers
 Their are different types of Computers. Their difference is
depending on different categories of characteristics.
Classification by the method of operation (processing)
1.Analog 2. Digital 3. Hybrid
1. Analog Computers
 Analog computers operate by measuring.
 They deal with continues variables;
 They are special purpose computers.
 They have limited accuracy.
Examples:
 Thermometer
 Voltmeter
 Speedometer
28

29. Types of Computers
2. Digital Computers
It deal with discrete variables.
They operate by counting rather than measuring.
Examples:
• Abacus
• Desk & pocket computers
• The general purpose computers.
Digital computers have higher accuracy and speed than the analog
ones.
29

30. Types of Computers
3. Hybrid computers
 The best features of analog and digital computers can
be combined into a single device to form a hybrid
computer.
Example:
 hospital insensitive (will convert the patient’s
heart function, temp, etc in to number and
supplied to digital comp,)
 Gasoline pomp (will convert the flow of pumped
fuel)
30

31. Types of Computers
Classification by purpose of application
 Classified into two(Special & General)
1. Special purpose computers
They are designed to solve a single type of problem,
Example:
 The public telephone box.
 Traffic control system .
 Ticket machines (used in hotel, super market etc.)
 Pocket calculators etc.
 Most Analog computers are special purpose computers.
31

32. Types of Computers
2. General purpose computers
 They are designed to solve variety of problems through the use of
“store program concept”.
 The same computer can be applied to solve another set of problem
using different program.
 They are more flexible and versatile.
Example:
 Micro computers
 Mini computers
 Super computers etc.
32

33. Types of Computers
Classification based on their size, cost and power of execution
• Supercomputers • Mainframe computers
• Minicomputers • Microcomputers
1.Supercomputers
Supercomputers are the largest, most powerful, fast, extremely high
storage and most expensive computers.
computing speeds several times faster than mainframe computers
primarily used for processing complex scientific applications.
speeds measured in nanoseconds and even in picoseconds
33

34. Types of Computers
Some application areas of super computers
 Weapons research (Military Industry)
 Large simulation in Aerospace & Automobile industry
 Oil exploration in the petroleum industry etc.
2. Main frame computers
 Mainframe computers are large computers frequently used in
large organizations like banks, insurance companies, hospitals,
airline reservation etc,
 Needs to process large number of transaction online and require
computer system having massive data storage and processing
power.
34

35. Types of Computers
 They are housed in a controlled and central location with several
user terminal connected to them.
 The main difference between a mainframe and a super computer is
that,
 a super computer channels all its power into executing a few
programs as fast as possible,
where as a mainframe uses its power to execute many
programs concurrently.
35

36. Types of Computers
3. Minicomputers
 They are mainframe having smaller configuration (small hosts,
less storage space and fewer user terminals)
 They are used in small companies.
 They can be accessed by more than one user at a time and are used
in many application areas.
 They are smaller & less powerful than mainframe.
 They are large and more powerful than micro computers
36

37. Types of Computers
4. Microcomputers
 Also known as personal computers (pc).
 Use Microprocessors inside it.
 Generally designed to be used by one person at a time. (Single
user).
 They have limited input and output capacities and little storage
capacity.
 A microcomputer with a powerful microprocessor & a high quality
monitor is called a workstation.
37

38. Types of Computers
 Two physical models of PCs are:
 Desktop model
 Tower model
 Other portable PCs are:-
Laptop, Notebook, palmtop etc.
38

39. Why we use Computers?
Store and process large amount of information with high
speed and accuracy.
Transmit information across continents through
communication medias.
Perform complex mathematical computations and make
comparisons.
Simulate events;
Monitor ongoing industrial operations;
Perform repetitive processes great ease, speed, and
reliability.
39

40. The main areas of computer applications
IN OFFICES: - Type writers are being replaced by
computers.
IN EDUCATION: - Computers are widely used in
educational fields; for instruction and administration
/Interactive education/
 CAL-Computer Aided Learning
 CAI-Computer Assisted Instruction
IN LBRARIES
40

41. IN COMMUNICATION:- Computers can be used in
different ways for communication purpose between users.
This can include:
- Fax- hard copy - Electronic mail -Internet
IN RESEARCH
IN BUSINESS
IN MANUFACTURING
Computers can be used in production process, from the
design stage to the manufacturing stage.
CAD- Computer Aided Design
CAM- Computer Aided Manufacturing
41

42. IN MEDICINE E.g. telemedicine
Application of Computers
42

43. Overview of a Keyboard
 Is an input device that goes into your computer which allows
you enter information such
 letters from the alphabets, numerical data, symbols, and
commands
 There are many keyboards, although not all have the same
layout style.
 most common kind is referred to as a QWERT keyboard,
which is named after the keys on the top rows of letters
 The keyboard is divided into several groups based on the
function.
Main Parts of a Computer
43

44. Cont…
44

45.  The functions keys, labeled from F1 to F12, are used to
perform specific tasks based on the operating system and
software used
 For an example, in many programs, the key F1 is commonly
used as the Help file
 In some cases, it can control the monitor brightness or the
sound volume.
 The functionality of these keys differentiates from program to
program and operating system to operating system
Function Keys
45

46. Special Keys
46
 The special keys are used alone or in combination with other
keys to perform certain actions
 These include the Control (ctrl), Alternate (Alt), Escape
(Esc), Windows, Tab,
 Caps Lock, and Shift keys. For an example, in many programs
pressing “Ctrl+S” will save a file automatically

47.  The Shift key is a combination key used with another letter to
type an uppercase letter
 The Caps Lock key allows all letters to be typed in uppercase
without having to press shift.
 This function can be turned on or off.
 An indicator light might be present to show that the function is
on
 Most keyboards include a special key called the Windows logo
key.
 This key is used to open the Start menu, or is used in
combination with a second key to perform common Windows
tasks
Cont…
47

48. Navigation Keys
 They are used for moving around in documents or webpages
and editing text.
 Navigation keys include Delete, Insert, Home and End, and
Page Up and Page Down keys
 The Home key is used to move the cursor to the beginning of
a line or to move to the top of the webpage
 The Left, Right, Up, and Down Arrow keys is used to move
the cursor or selection one space or line in the direction of the
arrow, or scroll a webpage in the
 direction of the arrow.
Cont…
48

49.  The PrtScn is used to capture an image of your entire screen
known as a screen shot which copies into your computer’s
clipboard.
Cont…
49

50. What is Mouse?
 A mouse is a small hardware input device used by hand.
 It controls the movement of the cursor on the computer screen
and allows users to move and select folders, text, files, and icons
on a computer.
 It is an object, which needs to put on a hard-flat surface to use. Is
an input device that goes into your computer which allows you
can to move, select, and open items on your computer screen.
Overview of Mouse Device
50

51. A mouse is capable of performing various functions on a
computer, which are as follows:
 Move the mouse pointer:
 Select:
 Open or execute a program:
 Drag-and-drop:.
 Hovering:
 Scroll Up & Down:
 Playing Game:
What are the uses of a Mouse?
51

52.  There are different types of mouse used with a computer.
 In modern times, an optical mouse is one of the most common
types of the mouse for a desktop computer that connects to the
USB port, which is called a USB mouse.
 And the touchpad is the most popular type of mouse used for
laptop computers.
Types of Mouses
52

53. A list is given below with
several types of the mouse:
 Optical
 Joystick
 Mechanical
 Cordless (Wireless)
 Foot mouse
 Touchpad (Glide point)
 Trackball
 TrackPoint
 J-Mouse
 IntelliMouse (Wheel mouse)
 Laser Mouse
Cont…
53

54.  A monitor is a display device like a TV screen that
interprets and displays the graphical output signal from
your computer’s graphics card and displays it on the screen.
 There are 9 different types of monitors, which are given
below.
 LCD Monitor
 LED Monitor
 Curved Monitor
 CRT Monitor
 Flat Panel Monitors
 Touch Screen Monitors
 OLED Monitors
 DLP Monitors
 TFT Monitor
Overview of a Monitor (Screen)
54

55.  Monitor is an output device which display items on
the desktop/screen, this one is a CRT (Cathode Ray
Tube)
55

56.  All computers have a motherboard that is a circuit board to
connect all of the various parts of a computer together.
 Its main purpose is to hold the CPU and the connections between
the CPU and all the other subsystems.
 The RAM of the computer is found on the motherboard.
 Most motherboards have places were other types of devices such
as graphics accelerator cards and network cards, can be inserted to
extend or enhance the capabilities of the computer.
Overview of Computer case (system unit)
56

57.  The system unit houses an array of storage and file transfer
devices, located in the front panel for easy access
 A computer’s system unit typically contains circuit boards, a
power supply, and storage devices
 A few wires and cables connect storage devices to the power
supply and circuit boards
 Ports and sockets to connect to input and output
devices(Called peripheral devices)
 Fans to cool the components and indicator lights
Cont…
57

58. Internal of system unit
58

59.  A computer, works by changing information into binary
numbers (ones and zeros) and then using simple to make
decisions about how to rearrange those numbers into words or
actions.
 A digital system stores and operates on information in a very
specific way by storing information in a bit (or multiple
collections of bits).
 A bit is a variable that can have only one of two values: it can
either be a 1, or be a 0.
HOW COMPUTERS WORKS
59

60. Computer’s functions are based on the movement and
transformation of electrical pulses (representing ones and zeroes) in
electrical circuits.
 Inside the computer are electrical circuits that decode the zeros
and ones, by adding and subtracting them.
 These circuits are called the logic of the computer, because the
calculations they make are similar to simple logic decisions.
 For example, if you press the A key on the computer keyboard,
circuits inside the computer receive pulses of electricity
representing the A in binary form - 1000001.
 Those pulses are sent to logic circuits that make yes or no
decisions based on the input they receive.
 A very simple example would be a circuit that determines whether
the input send to it is a one or a zero.
 The output of the circuit is a new piece of information - a binary
one or zero that is the result of the simple yes or no decision.
Cont…
60

61. Data Representation Method in computer
 A word in the memory of computer can represent character data or
numeric data.
 When we say character data they are letters and digits (A-Z or a-z or
0-9), special symbols such as ?,*,+ … and control characters which
used to control devices.
 But since computers is an electronic device which understands
electrical signal there is no letter, symbol or number inside the
computer.
 The most elementary form to organize data in an electronic device is
in the form of a code which utilizes the “ON” & “OFF” states of
electric switches. (current & no current states)
61

62. Data Representation Method
 An electronic devices has similarity with the binary number system in
that both represent only two elementary states.
 Therefore binary number system is a convenient way to represent
data in a computer system.
 An “ON” corresponds to a 1 and “OFF” corresponds to a 0.
 In the computer “ON” is represented by the existence of a current and
“OFF” is represented by non existence of current.
 On a magnetic disk, the same information is stored by changing the
polarity on the disk’s surface. of magnetized particles
62

63. Data Representation Method
 Data are represent in the form of a code that can have a corresponding
electrical signal.
Coding Methods
 It is possible to represent any of the character in our language in a
way that a series of electronic switches in arranged manner.
 This switch arrangements can therefore be coded as a series of
equivalent arrangements of 0’s & 1’s (bits).
 There are different coding systems that convert one or more character
sets in to computer codes.
Some of them are: 1. EBCDIC,
2. BCD
3. ASCII-7 & ASCII-8.
63

64. Data Representation Method
 In each case the character set group in to zones & digits.
 Zones:- group characters together to make the data process easier.
 Digit Code:- used to identify the individual character with in each
zone.
BCD (Binary Coded Decimal)
 BCD is one of the early memory codes.
 There are two types of BCD coding techniques.
 BCD (4 bits)
 BCD (6 bits)
64

65. Data Representation Method
BCD (4 bits)
 It is based on the idea of converting each digit of a decimal number
into its binary equivalent rather than converting the entire decimal
value in to equivalent binary form.
Example:-
To represent 2l9 using 4 bit BCD
21910= 0010 0001 1001 in BCD
Decimal
Digits
BCD
Equivalent
0 0000
1 0001
2 0010
3 0011
4 0100
5 0101
6 0110
7 0111
8 1000
9 1001
65

66. Data Representation Method
 But 4 bits can only represent 24
(16 characters) and also the 4 bits
BCD uses only 10 of them. (from 0000-1001)
 Because 4 bits are insufficient to represent various characters, the 4
bits BCD are used to represent only decimal numbers.
BCD (6 bits)
 It uses 6-bits to code a Character (2 for zone bit and 4 for digit bit)
 It can represent 26
= 64 characters (10 digits, 26 capital characters and
some other special characters).
66

67. Data Representation Method
BCD Coding Sample E.g.
EBCDIC
 Pronounced as “Eb-See-Dick” and stands for Extended binary Coded
Decimal Interchange Code.
 Mostly used by IBM Mainframe model and in similar machines
produced by other manufacturers.
 It is an 8-bits coding scheme (4 bits for zone and 4 bits for digit).
character
BCD code
Zone Digi
t
A-I 3 1-9
J-R 2 1-9
S-Z 1 2-9
0-9 0 0-9
characte
r
BCD code
Zone Digit
F 11 0110
L 10 0011
T 01 0011
8 00 1000
67

68. Data Representation Method
 It accommodates to code 28
or 256 different characters (00000000 –
11111111).
 It is a standard coding scheme for the large computers.
EBCDIC Coding Sample E.g.
character
EBCDIC code
Zone Digit
A-I 12 1-9
J-R 13 1-9
S-Z 14 2-9
a-i 8 1-9
j-r 9 1-9
s-z 10 2-9
0-9 15 0-9
characte
r
EBCDIC code
Zone Digit
B 1100 0010
M 1101 0100
Z 1110 1001
b 1000 0010
j 1001 0001
y 1010 1000
4 1111 0100 68

69. Data Representation Method
ASCII-7
 ASCII stands for American Standard Code for Information
Interchange.
 Widely used before launching of ASCII-8.
 Uses 7 bits to represent a character(3 bits for zone bit and 4 bits for
digit).
 With the seven bits, 27
( or 128) different characters can be coded
(0000000-1111111).
ASCII-7 Coding Sample E.g.
character
ASCII code
Zone Digit
0-9 3 0-9
A-O 4 1-15
characte
r
ASCII code
Zone Digit
0 011 0000
L 100 1100 69

70. Data Representation Method
ASCII-8
 Also referred as Extended ASCII.
 Is the most widely used type of coding scheme for Micro Computer
system.
 Uses 8-bits to represent alphanumeric characters (4 bits for zone and
4 bits for digit).
 With the eight bits, 28
( or 256) different characters can be coded
(00000000-11111111).
ASCII-8 Coding Sample E.g.
characte
r
ASCII-8 code
Zone Digit
0-9 3 0-9
A-O 4 1-15
P-Z 5 1-10
a-o 6 1-15
characte
r
ASCII-8 code
Zone Digit
0 0011 0000
L 0100 1100
T 0101 0100
a 0110 000170

71. Units of Data Representation
 Their is a Unit for the data to store, process or communicate with in
the computer system.
 The units from the smallest to the largest are called bit, byte and
word.
 This units are based on the binary number system.
Bit
 Bit stands for binary digits.
 Bits are the smallest units and can convey only two possible states 0
or 1.
 A bit is a single element in the computer, on a disk that stands for
either “ON” indicating 1 or “OFF” indicating 0.
71

72. Unit of Data Representation
 In the computer “ON” is represented by the existence of current and
“OFF” is represented by the non-existence of current. On a magnetic
disk, the same information is stored by changing the polarity or
magnetized particles on the disk’s surface.
Byte
 It is a group of bits used to represent a symbol.
 It is the “basic unit of data representation” in the computer system.
 The term byte is commonly used to mean an 8 bit byte.
72

73. Unit of Data Representation
 Since each bit has two states and there are 8 bits in a byte, the total
amount of data that can be represented is 28
or 256 possible
combinations.
 Each byte can represent a character. (a character is either a letter, a
number or a special symbol such as +,-,?,*,blank space, $, etc.)
 A byte is then used as a unit of measurement in the computer
memory, processing unit, external storage and during communication.
73

74. Unit of Data Representation
 If the computer memory is 524288 byte, this is expressed in short by
saying 512KB, where KB stands for kilobyte.
1 Kilobyte (1KB) is 210
or 1024 bytes.
1 Megabyte (MB) is 220
bytes or 210
kilobytes.
1 Gigabyte (GB) is 230
bytes or 220
kilobytes.
Word
 A combination of bytes, then form a “word”.
 Word refers the number of bits that a computer process at a time or a
transmission media transmits at a time.
74

75. Unit of Data Representation
 Although bytes can store or transmit information, the process can
even be faster if more than one byte is processed at a once;
 A word can contain one, two, three or four bytes based on the
capacity of the computer.
 Word length is usually given in bits.
 We say that a computer is an 8-bits, a 16 bit, a 32 bit or a 64 bit
computer to indicate that the amount of data it can process at a time.
 When the word length is larger a computer will became more
powerful and faster.
75

76. CHAPTER
TWO
76

77. Components of a Computer System
A computer system composed of Computer hardware and Computer
software.
Computer Hardware
 The physical components which we can touch and see.
We can further classify the hardware as follows:
Input devices
Central Processing Unit (CPU)
Memory Unit (Primary memory/Main memory)
Secondary storage devices
Output devices.
Storage unit
77

78. Components of a Computer System
1. Input Devices
 Input is the process of giving or inserting data and
instructions to the computer system.
 Functions of input devices are:
 It accepts (read) instructions and data from the outside
world
 It converts these instructions and data into computer
acceptable form.
Examples of input devices:-
• Keyboard • Mouse
• Scanner • Light pen
• Microphone • Bar code reader
• Voice synthesizer • Touch Screen etc.
78

79. Components of a Computer System
Basic organization of a computer system
79

80. Components of a Computer System
2.The Central Processing Unit (CPU)
 It is the main component of a computer.
 Consists of the Control Unit, Arithmetic Logic Unit
 Very costly.
Purpose of CPU
 Fetch instruction from memory.
 Interpret instruction.
 Fetch data from memory or input units.
 Process data.
 Write data to the user or output devices.
80

81. Components of a Computer System
The Control Unit
 Performs all the control functions of the computer.
 Fetches the instruction from memory.
 Determines the next instruction to be executed by the computer.
 Serves as the computer traffic cope.
The Arithmetic Logical Unit (ALU)
 Referred as the computers "number crunchier".
 Performs the arithmetic operations (addition, subtraction,
multiplication and division)
Registers: are temporary storage locations for managing instructions
and data as they are being processed in control & ALU.
81

82. Components of a Computer System
Memory Unit (Primary Memory)
 Directly accessible by the control unit and ALU.
 The main memory has two parts.
 RAM (Random Access Memory)
 ROM (Read only Memory)
RAM is:-Small in storage capacity
- Fast in processing speed
- Volatile
- Expensive in price.
ROM is:-non-volatile
-permanent data storage
82

83. Components of a Computer System
Secondary storages:
 Are non-volatile, they store data and information permanently,
 Are cheap or low in cost,
 Operating speed far slower than the primary storage.
 Store large amount of information.
Example : Types of magnetic disks
Floppy disk
Hard disk
Types of optical disks
CD-R
CD-RW
DVD R/RW
83

84. Components of a Computer System
Output Devices
 Output is computer produced text, graphics, or sound in hard-copy
or soft-copy format that can be used by people.
 Output device- is an electromechanical device that accepts data
from a computer and translates them into a form suitable for use by
the user.
Examples of output device are:
-Printers -Monitors (screens)
-Speakers -Plotters ,etc
84

85. Components of a Computer System
 BUS:- is an electrical pathway through which bits are
transmitted between the various computer components.
There are three buses inside the computer
 Address Bus: is a unidirectional bus over which digital
information is transferred to identify either a particular memory
location or particular I/O address.
 Data Bus: a bus system which interconnects the CPU, memory
and all the peripheral Input/output devices of a computer system for
the purpose of exchanging data.
 Control Bus: a bus used to select and enable an area of main
storage and transmit signals required to regulate the computer
operation.
85

86. Computer Software Components
 Software is a set of instruction or programs that order the hardware
what to do or to do something
 Program is a finite set of instructions (steps) that the computer follow
to perform a given job.
 Software: - Is a collection of programs.
 Software also includes documentations, rules and operational
procedures.
 It is an essential component of the computer system. Without the
software, the computer hardware cannot solve our problems.
 Software acts as intermediate b/n
the user and the electronic components
of the computer.
USER
Software
Hardware 86

87. Computer Software Components
Computer software is classified into two major class
1. System software 2. Application software
1. System software
Are programs which facilitate the work of the computer hardware.
It organizes and manages the machine’s resources, handles the
input/output devices.
It controls the hardware by performing functions that users shouldn’t
have to or are unable to handle
System programs make complex hardware more user friendly.
It enables the computer to understand programming languages i.e. it
serves as means of communication between user and a computer.
87

88. Computer Software Components
 The important categories of system software are:
A) Operating system B) Language software
A) Operating system
 Operating system coordinates the activity between the user and the
computer.
 It also provides an interface between a user and an application
program and the hardware.
 Directing all processing activities within computer,
 calling in other systems software when needed, scheduling jobs,
allocating storage facilities, activating input and output devices, etc.
are some of the importance of operating systems software.
88

89. Computer Software Components
 An operating system has three major functions.
i. Controlling operations (control program)
ii. Input/output Management
iii. Command Processing (command Interpreter)
i. Controlling operations (control program)
 Coordinates, or supervises the activity of the computer system.
 Decides where programs and data should be stored in the computer
memory.
 Handles communications among the computer components,
applications software and the user.
 Controls the saving and retrieving of files to and from disks in the
disk drive.
 It performs all its controlling tasks with out the involvement or
awareness of the user.
89

90. Computer Software Components
ii. Input/output Management
 The I/O manager coordinates,
The computers communication with outside world,
The flow of data to the display screen and other output devices
(printers/ plotters) and
The flow of data from the key board or other input devices.
 Handles the flow of data to and from the disk drives (file
management).
 Handles the process of preparing a disk for use, the copying,
renaming, erasing task of a file.
90

91. Computer Software Components
iii. Command Processing (command Interpreter)
 It interprets the commands or what you enter using the keyboard or
other input devices.
 If you write an internal command it carries out the function of that
command if it is external command or other executable file it searches
for the corresponding file in the default (current disk) or the user
specified disk, loads the file into memory and transfers control to that
program. Once this program is terminated, control returns to
command and the program for that command or file is discarded from
memory.
91

92. Computer Software Components
Types of Operating Systems
 Operating systems can be classified by:
The number of programs they can handle at a time and
The number of users they serve at once at one or different stations
(i.e. terminals or micro-computers connected to a central
computer).
i. Single tasking operating systems.
ii. Multi user operating system.
iii. Real Time Operating System.
92

93. Computer Software Components
i. Single tasking operating systems
 With single tasking operating systems only one program can be run
on a computer at a time.
ii. Multi user operating system
 It supports a number of work stations connected to a central system.
 A number of users can use the resources of one high capacity
computer by the help of terminals.
iii. Real Time Operating System
 A real time is a system that is capable of processing data so quickly
that the results are available to influence the activity currently taking
place.
93

94. Computer Software Components
B) Language Software.
 Are systems software that serves to write set of instructions or
programs that are required to solve a problem.
 Are software which are used by programmers to develop application
software and translate programs to machine code.
 They provide a set of rules, symbols, and special words to construct a
program.
 They serve as editors and translators to develop programs in a number
of programming languages.
 Includes:- translators, general purpose routines & utilities and high
level languages
94

95. Computer Software Components
 Translator:- is a program that converts one or more languages to
another language.(3 types)
Assemblers:-is a program that translates assembly languages into
machine code.
Compiler:-is a program that translates a high level language into
machine code.(Pascal, Fortran, Cobol)
Interpreter:-is a program that translates each instruction of high level
language & executes the instruction before translating the next
instruction.
 The general-purpose routine and utilities include programs which are
used to handle file processing, editing and debugging.
 High level language software is a software which has its own
compilers to detect syntax errors of the user’s program code.(E.g.
COBOL, Fortran etc)
95

96. Computer Software Components
Application Software
 Is a software that is designed to perform tasks for the specific areas.
Type of application software
1.Word Processors/ Word processing
 It is a computerized typewriter which permits the
electronic creation, editing, formatting, filing and
printing text.
Example:-WordStar, WordPerfect, Microsoft word
2.Spreadsheet (is an electronic worksheet)
 Using the programs built-in function you can perform complicated
calculations complex mathematical problem.
E.g. Lotus 1-2-3,MicrosoftExcel,Quatropro
96

97. Computer Software Components
3. Database management system.
 Allow you to store information on a computer, retrieve it when you
need it and update it when necessary.
Example: Microsoft Access, Oracle, SQL Server Dbase IV, FoxPro, etc.
4. Computer Graphics
 Computer graphics is the technique of creating, editing, displaying
and printing graphs, diagrams, charts and images in a computer
system.
 Graphics can communicate information that would be difficult or
even impossible to put into words.
Popular e.g. Lotus Freelance, Harvard Graphics, Print master, etc
97

98. System Software Application Software
 The main purpose of this software is to manage the
resources available in the system. It serves as an effective
forum for the execution of application software
 Application software designed to
achieve a certain set of tasks.
 System software is documented in a low-level programming
language like machine code or assembly language.
 Application software is composed in a
high-level language like Java, C++,.Net,
or PHP.
 Usually, when the computer is switched on, system software
begins to run and stops when the computer is switched off.
 When a user requests, application
software runs according to the task it is
assigned.
 Without system software, a computer system cannot even
activate.
 User-specific application software is
definitely not required to run the
system.
 System software comprises language processors
(interpreters, compilers, and assemblers), operating systems,
and so on.
 Payroll software, accounting software,
MS Office, and so on are perfect
examples of an application software.
98
Difference Between System Software and
Application Software

99. Chapter 4
Introduction to computer security
99

100. 10
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101. Computer Information and Data Security
 It is important to avoid data and information loss in case of hard disk
crashes.
 The only solution is to regularly keep backups of all the data on other
media such as magnetic tapes, CD-ROM, etc.
 It is a good practice to store the media off-site and in case of a disk
crash, restore the information from the backup media onto the new
disk.
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102.  Computer Information and Data Security
 In case a backup media is not affordable, one should try and store the
files on at least two different media devices.
 These media devices should be systematically kept at a place which is
safe and secured, as the information contained may be confidential.
 People usually backup database files, spreadsheet files and large
documents.
 As the technical constraints are always there, it is better to take
regular backups, in order to avoid any loss of information.
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103.  Computer security is a technical developed to protect single
computers and Network- Lined computer system from accidental or
intentional harm including destruction of computer hue & sue.
 One of the causes of disaster on a computer system is computer
virus. There are different types of security methods. Some of which
are as follows:-
1)Disaster Recovery Plans: It is Periodical testing and upgrading of
the contents of the computer. It helps to safe guard documents from
sudden damage.
2)Application Safeguards: Protecting the computer itself and the
document within the system from internal and external damage.
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104. 3) Intrusion Selection Systems: it Security software called intrusion detection
systems may be used in computers to detect unusual and suspicious activity and, in
some cases, stop a variety of harmful actions by authorized or unauthorized
persons.
 Abuse and misuse of sensitive system and application programs and data such as
password, inventory, financial, engineering, and personnel files can be detected by
these systems
4)Firewalls: Software placed between the networked computers and protects the
networked computers. The firewall examines, filters, and reports on all information
passing through the network to ensure its appropriateness.
5)Passwords
6)Backup
7)Encryption 10
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105.  Computer system security threats
 A computer system can be exposed to risk of security threats. These
security threats can be of different types.
 The following are the major threats which can disrupt security in a
computer system.
 Trojan Horse
 Viruses
 Worms
 Trojan Ho
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106. Computer Virus
 It is a computer program that can copy itself and infect a computer
without permission or knowledge of the user.
 They are deliberately created by programmers, or by people who use
virus creation software.
 A virus can only spread from one computer to another when:-
A user sends it over the network,
A user carry it on a removable medium such as a floppy disk, CD,
or USB drive.
 viruses can spread to other computers by infecting files on a
network file system.
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107.  Boot Sector Virus – It is a type of virus that infects the boot sector of
floppy disks or the Master Boot Record (MBR) of hard disks.
 The Boot sector comprises all the files which are required to start the
Operating system of the computer. The virus either overwrites the existing
program or copies itself to another part of the disk.
 Direct Action Virus – When a virus attaches itself directly to a .exe or .com
file and enters the device while its execution is called a Direct Action
Virus.
 If it gets installed in the memory, it keeps itself hidden. It is also known as
Non-Resident Virus.
 Resident Virus – A virus which saves itself in the memory of the computer
and then infects other files and programs when its originating program is
no longer working. This virus can easily infect other files because it is
hidden in the memory and is hard to be removed from the system.
Types of Computer Virus
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108.  Multipartite Virus – A virus which can attack both, the boot sector and the
executable files of an already infected computer is called a multipartite
virus.
 If a multipartite virus attacks your system, you are at risk of cyber threat.
 Overwrite Virus – One of the most harmful viruses, the overwrite virus can
completely remove the existing program and replace it with the malicious
code by overwriting it. Gradually it can completely replace the host’s
programming code with the harmful code.
 Polymorphic Virus – Spread through spam and infected websites, the
polymorphic virus are file infectors which are complex and are tough to
detect. They create a modified or morphed version of the existing program
and infect the system and retain the original code.
 File Infector Virus – As the name suggests, it first infects a single file and
then later spreads itself to other executable files and programs. The main
source of this virus are games and word processors.
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109. Computer Security Practices
Virus prevention
 Purchase an anti virus program that runs as you boot or work your
computer and update it frequently.
 Execute only programs of which you are familiar as to their origin.
 Load only software from original disks or CD’s. Pirated or Copied
software is always a risk for a virus.
 Programs sent by email should always be suspicious.
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110. Virus removal
 One possibility on Windows XP is a tool known as System Restore,
which restores the registry and critical system files to a previous
checkpoint.
 There are so many anti-virus software in the computer market that we
can use to remove virus from an infected file. MacAfee, Dr. Solomon,
Norton etc
 Operating system re-installation.
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111. Backup
 In information technology, a backup or the process of backing up refers to
making copies of data so that these additional copies may be used to restore
the original after a data loss event.
 These additional copies are typically called "backups." The verb is back up
in two words, whereas the noun is backup (often used like an adjective in
compound nouns).
 Backups are useful primarily for two purposes. The first is to restore a state
following a disaster (called disaster recovery).
 The second is to restore small numbers of files after they have been
accidentally deleted or corrupted. Data loss is also very common. 66% of
internet users have suffered from serious data loss. 11
1

112. Backup
 In information technology, a backup or the process of backing up refers to
making copies of data so that these additional copies may be used to restore
the original after a data loss event.
 These additional copies are typically called "backups." The verb is back up
in two words, whereas the noun is backup (often used like an adjective in
compound nouns).
 Backups are useful primarily for two purposes. The first is to restore a state
following a disaster (called disaster recovery).
 The second is to restore small numbers of files after they have been
accidentally deleted or corrupted. Data loss is also very common. 66% of
internet users have suffered from serious data loss. 11
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113. Encryption
 a process of converting messages or data into a form that
cannot be read without decrypting or deciphering it.
 The root of the word encryption—crypt—comes from the
Greek word kryptos, meaning “hidden” or “secret.”
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114. Thank you !
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