KOROGWE
WE TEACHERS’ COLLEGE
CO
Essentialss of
o Information Tech
echnology
Computer,
r, Data,
Da Information and Knowledge
Know
Diplo
iploma in Education, Science, Mathematics
and
Information
Info
Communication Technologies
Mussa Msengi Gunda
www.jiandae.co.tz | info@jiandae.co.tz
VOLUME ONE | 2019
Essentials of Information Technology
Introduction
Information Technology (IT) is a technology which uses computers to gather, process, store,
protect, and transfer information. Today, it is common to use the term Information and
Communications Technology (ICT) because it is unimaginable to work on a computer which is
not connected to the network. This is the use of technology in managing and processing
information.
ICT is the digital processing and utilization of information by the use of electronic computers. It
comprises the storage, retrieval, conversion and transmission of information. (Ifueko Omoigui
Okauru, 2011).
Information and Communication Technologies (ICTs) are defined, as a varied set of
technological equipments and resources used to communicate and to generate, disseminate,
store and handle information.
ICT Tools
There are various ICT tools available which can be utilized for the knowledge creation and
dissemination in the recent world. Tools include Radio, TV, Internet, Mobile phone, Computer,
Films, Projectors, Microscopes, Potentiometers, Liquid crystal displays, Microphones and many
other hardware and software applications.
Data, information and knowledge
In normal conversation, the meanings of data, information and knowledge can often be used
interchangeably.
What is Data?
The word "data" is the plural of datum (although the singular form is rarely used) which means fact,
observation, assumption or occurrence. Data are any facts, numbers, or text that can be processed by a
computer.
•
•
•
•
•
Data is a stream of raw facts representing things or events that have
happened.
Data is a collection of unprocessed items, which can include text, numbers,
images, audio, and video.
Data is the facts, figures, or symbols that haven't been processed.
A collection of text, numbers and symbols with no meaning.
Data are numbers, words or images that have yet to be organized or
analyzed to answer a specific question.
2
Today, organizations are accumulating vast and growing amounts of data in different formats and
different databases. This includes:
• operational or transactional data such as, sales, cost, inventory, payroll, and accounting
• non-operational data, such as industry sales, forecast data, and macro economic data
• meta data - data about the data itself, such as logical database design or data dictionary definitions
Data therefore has to be processed, or provided with a context, before it can have meaning. In
ICT, we usually say that data is made up from four basic types:
•
•
•
•
Numbers
Text
Images
Sound
In IT, symbols, characters, images, or numbers are data. These are the inputs an IT system
needs to process in order to produce a meaningful interpretation. In other words, data in a
meaningful form becomes information.
Example
• 3, 6, 9, 12
• cat, dog, gerbil, rabbit, cockatoo
• 161.2, 175.3, 166.4, 164.7, 169.3
These are meaningless sets of data.
When does data become information?
Data on its own has no meaning. It only takes on meaning and becomes information when it is
interpreted. Data consists of raw facts and figures. When that data is processed into sets
according to context, it provides information.
Here’s an example of some data:
21072019
But what does it mean? It's just numbers - it's raw data!
If I were to add some formatting so that the numbers read 21/07/2019 you can see that it
becomes a date. The formatting has added meaning; it became interpretable and gains
significance.
3
Where is the data from?
Internal or External?
•
•
Internal communication is communication with people inside the same organisation or
company
External communication is with people outside the company, such as suppliers or
customers.
Direct or Indirect?
•
•
Direct data is collected for the purpose of the processing being undertaken – e.g. time
cards for pay
Indirect data was originally collected for another purpose, but is now being processed to
provide extra information - e.g. spending patterns from credit cards
Storing Data
Inside the computer, however, all data is stored as numbers:
•
•
•
•
Numbers – are stored as numbers, obviously!
Text characters are stored as a code that represents each – e.g. ASCII
Images are stored as numbers representing the amounts of red, green and blue for each
pixel
Sounds are stored as numbers representing the loudness at given intervals
Characteristics of Data
The definitions that follow are examples of those that refer only to the objective characteristics of data:
“Data represent unstructured facts.” (Avison and Fitzgerald [1995: 12] quoted by Checkland and Holwell
[1998])
“Data: Facts collected from observations or recordings about events, objects or people.” (Clare and
Loucopoulos [1987: 2] quoted by Checkland and Holwell [1998])
“Data: The raw material of organizational life; it consists of disconnected numbers, words, symbols and
syllables relating to the events and processes of the business.” (Martin and Powell [1992: 10] quoted by
Checkland and Holwell [1998])
The following are six key characteristics of good quality data.
Accuracy
Data should be sufficiently accurate for the intended use and should be captured only once,
although it may have multiple uses. Data should be captured at the point of activity.
4
Validity
Data should be recorded and used in compliance with relevant requirements, including the
correct application of any rules or definitions. This will ensure consistency between periods and
with similar organizations, measuring what is intended to be measured.
Reliability
Data should reflect stable and consistent data collection processes across collection points and
over time. Progress toward performance targets should reflect real changes rather than
variations in data collection approaches or methods. Source data is clearly identified and readily
available from manual, automated or other systems and records.
Timeliness
Data should be captured as quickly as possible after the event or activity and must be available
for the intended use within a reasonable time period. Data must be available quickly and
frequently enough to support information needs and to influence service or management
decisions.
Relevance
Data captured should be relevant to the purposes for which it is to be used. This will require a
periodic review of requirements to reflect changing needs.
Completeness
Data requirements should be clearly specified based on the information needs of the
organization and data collection processes matched to these requirements.
DATA PROCESSING
Data processing is the computer process that converts data into information. The processing is usually
assumed to be automated and running on a mainframe, minicomputer, microcomputer, or personal
computer.
Data-processing systems typically manipulate raw data into information, and likewise information
systems typically take raw data as input to produce information as output.
In the context of data processing, data are defined as numbers or characters that represent
measurements from the real world.
Five types of data are stored and processed by computers. They are:
Text which consists of strings of characters.
Numbers
Audio, namely speech and music.
Pictures – monochrome and color.
5. Video which are sequences of pictures such as movies or animation. Usually video data has
accompanying sound track which is synchronized with the pictures.
1.
2.
3.
4.
5
Data Processing Activities
Data processing consists of those activities which are necessary to transform data into information. Man
has in course of time devised certain tools to help him in processing data. These include;
i.
manual tools such as;
o pencil and paper
ii. mechanical tools such as;
o filing cabinets
iii. electromechanical tools such as
o adding machines and typewriters and
iv. electronic tools such as
o Calculators and computers
Many people immediately associate data processing with computers. As stated above, a computer is not
the only tool used for data processing; it can be done without computers also. However, computers have
outperformed people for certain tasks.
The Data Processing Cycle
Data processing is the re-structuring or re-ordering of data to increase their usefulness & add values for
particular purpose.
The data processing activities described above are common to all data processing systems from manual
to electronic systems.
6
These activities can be grouped in four functional categories, viz., data input, data processing, data
output and storage, constituting what is known as a data processing cycle.
What is information?
•
Information can be defined as “data that has been transformed into a meaningful and useful
form for specific purposes”.
•
•
Information is data that has been processed to make it meaningful and useful
•
Information is the meaning that a human assigns to data by means of the known conventions
used in its representation. (Holmes, 2001).
Information is produced through processing, manipulating and organizing data to answer
questions, adding to the knowledge of the receiver.
Information can be about facts, things, concepts, or anything relevant to the topic concerned. It
may provide answers to questions like who, which, when, why, what, and how.
If we put Information into an equation it would look like this:
Data + Meaning = Information
7
There is no hard and fast rule for determining when data becomes information. A set of letters and
numbers may be meaningful to one person, but may have no meaning to another. Information is
identified and defined by its users.
Example
Looking at the examples given for data:
•
•
3, 6, 9, 12
cat, dog, gerbil, rabbit, cockatoo
Only when we assign a context or meaning does the data become information. It all
becomes meaningful when we are told:
•
•
3, 6, 9 and 12 are the first four answers in the 3 x table
cat, dog, gerbil, rabbit, cockatoo is a list of household pets
Information Channels
Formal or Informal?
•
•
Formal channels are the official (or reliable!) ones, such as memos, letters, the company
noticeboard, etc.
Informal channels are the unofficial ones, such as office gossip, informal meetings and
rumours – these can often be unreliable.
The Value of Information
•
•
It is often said that we are in the information age, and that information is a valuable
commodity.
Why is information valuable? Because:
• It allows us to plan how to run our business more effectively – e.g. shops can
stock what customers want, when they want it, and manufacturers can
anticipate demand
• Marketing materials can be targeted at people and customers that you know
could be interested in your products and services
• This can lead to increased customer satisfaction and therefore profit
Good Quality Information
• The characteristics of good quality information – it should be:
• Accurate
• Up-to-date
• Relevant
• Complete
• On-time
• Appropriately presented
• Intelligible
8
Communication
Communication is the process by which a message or information is exchanged from a sender to a
receiver. For example a production manager (sender) may send a message to a sales manager (receiver)
asking for sales forecasts for the next 6 months so they can plan production levels. The sales manager
would then reply (feedback) to the production manager with the appropriate figures.
•
•
•
Communication is the sharing of information
Communication is the giving and receiving of messages
Communication is the transfer of information from one or more people to one or more other
people
The first of these three definitions is the simplest, and also the broadest. Because of those qualities, it is
also a little nonspecific. The second definition reminds us that information, here called a message, must
be received, as well as sent, to complete the process.
The goal of communication is to convey information—and the understanding of that information—from
one person or group to another person or group.
This communication process is divided into three basic components:
-
A sender transmits a message through a channel to the receiver.
receiver
The sender first develops an idea, which is composed into a message and then transmitted to the other
party, who interprets the message and receives meaning.
Measures to improve communication effectiveness
Measures to improve communication effectiveness are as follows;
i. Communication of Clarification of the idea.
ii. Communication should be according to the needs of the receiver.
iii. Consulting others before communication.
iv. Awareness about the language, tone and body postures and gestures.
v. Convey information useful to the receiver.
vi. Ensure proper feedback.
vii. Follow up communications.
viii. Be a good listener.
What is knowledge?
Knowledge is information that has been appropriate by the user. When information is adequately
assimilated, it produces knowledge, modifies the individual’s mental store of information and benefits
his development and that of the society in which he lives. Thus, as the mediating agent in the production
of knowledge, the information, qualifies itself, in form and substance, as significant structures able to
generate knowledge for the individual and his group.” (Aldo Barreto)
9
Knowledge deals with what is known by a person or persons. Involves interpreting
information received, adding relevance and context to clarify the insights the information
contains.
Theory
Knowledge can therefore be:
•
•
acquiring and remembering a set of facts, or
the use of information to solve problems.
The first type is often called explicit knowledge. This is knowledge that can be easily passed on
to others. Most forms of explicit knowledge can be stored in certain media. The information
contained in encyclopedias and textbooks are good examples of explicit knowledge.
The second type is called tacit knowledge. It is the kind of knowledge that is difficult to pass on
to another person just by writing it down. For example, saying that Dodoma is the capital city of
Tanzania is explicit knowledge that can be written down, passed on, and understood by
someone else.
However, the ability to speak a foreign language, bake bread, program a computer or use
complicated machinery requires additional pieces of knowledge (such as that gained through
experience) that are not always known explicitly and are difficult to pass on to other users.
How are data, information and knowledge linked?
If we put Knowledge into an equation it would look like this:
Information + application or use = Knowledge
Example I
Looking at the examples given for data:
•
•
•
3, 6, 9, 12
cat, dog, gerbil, rabbit, cockatoo
161.2, 175.3, 166.4, 164.7, 169.3
Only when we assign a context or meaning does the data become information. It all becomes
meaningful when we are told:
•
•
•
3, 6, 9 and 12 are the first four answers in the 3 x table
cat, dog, gerbil, rabbit, cockatoo is a list of household pets
161.2, 175.3, 166.4, 164.7, 169.3 are the heights of the five tallest 15-year-old students
in a class.
10
If we now apply this information to gain further knowledge we could say that:
•
•
•
4, 8, 12 and 16 are the first four answers in the 4 x table (because the 3 x table starts at
three and goes up in threes, the 4 x table must start at four and go up in fours)
The tallest student is 175.3cm.
A lion is not a household pet as it is not in the list and it lives in the wild.
Example II
Data: The number 40 000 is a piece of data, as is the name Jane John. Without anything else to
help us, these two items of data are meaningless.
Information: If we now say that ‘Jane John is a teacher’ and ‘$40 000 is a teacher’s salary’, the
data is given meaning or context, and makes more sense to us.
Knowledge: builds on the information. Knowledge is ‘Jane John is a teacher and he earns $40
000 per year’.
Quiz
i.
ii.
iii.
Explain the difference between data and information. [2 marks]
Describe how data becomes knowledge. [3 marks]
5, 10, 15, 20 are items of data. Explain how these could become information and
what knowledge could be gained from them. [4 marks]
Question
Distinguish between data, information, and knowledge.
Answer.
To distinguish between data, information, and knowledge we also used their descriptions
from. Here information is regarded as data interpreted by knowledge.
11
From the data definitions we came to know that data is raw facts or un-interpreted symbols
like words, numbers, characters, and signals, which do not provide any meaning.
Once the data is analyzed and arranged properly, and it is possible to understand data and
provide the meaning, then data will become information.
To convert the raw fact or un-interpreted data to interpreted data we need the process. This
process is called data interpretation. While interpreting the data humans have to make a
decision based upon their past experience, observation, culture, and educational
background to provide contextual meaning to data. Humans interpret data using their
knowledge that performs the process of data interpretation.
When it comes to computers, they need different algorithms to interpret the data. Once the
data is interpreted, it is transformed into information. This information has to be made
understandable. Thus, knowledge should be able to interpret data, elaborate information,
and learn from interpreted data and elaborated information.
Figure 1: Model for the relationship between data, information and knowledge.
12
Computer Fundamentals
Today’s world is an information
ation-rich world and it has become a necessity
ty fo
for everyone to know
about computers.
What is Computer?
•
•
•
A computer is an electro
ectronic data processing device, which accepts
ts and
a stores data input,
processes the data input,
inpu and generates the output in a required
d for
format.
A computer is an electr
ectronic device, operating under the control
ol o
of instructions stored
in its own memory that
tha can accept data (input), process the data
ata according to
specified rules, produc
duce information (output), and store the infor
formation for future
use.
A computer is a progra
grammable machine designed to perform arithmetic
arit
and logical
operations automatica
tically and sequentially on the input given byy th
the user and gives
the desired output after
afte processing.
Computer components are
e div
divided into two major categories namely har
hardware and
software.
•
•
chine itself and its connected devices such as monitor, keyboard,
Hardware is the machi
mouse etc.
Software is the set of programs
p
that make use of hardware forr performing
pe
various
functions.
Functionalities of a Computer
ter
If we look at it in a very broad
oad sense, any digital computer carries out the following five
functions:
•
•
•
•
•
in
Step 1 - Takes data as input.
Step 2 - Stores the data/instructions
data
in its memory and uses them
em as required.
Step 3 - Processes the
he d
data and converts it into useful information
tion.
Step 4 - Generates the output.
Step 5 - Controls alll the above four steps.
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Advantages of Computers
Following are certain advantages of computers.
High Speed
•
•
•
•
Computer is a very fast device.
It is capable of performing calculation of very large amount of data.
The computer has units of speed in microsecond, nanosecond, and even the picosecond.
It can perform millions of calculations in a few seconds as compared to man who will
spend many months to perform the same task.
Accuracy
•
•
•
In addition to being very fast, computers are very accurate.
The calculations are 100% error free.
Computers perform all jobs with 100% accuracy provided that the input is correct.
Storage Capability
•
•
•
•
Memory is a very important characteristic of computers.
A computer has much more storage capacity than human beings.
It can store large amount of data.
It can store any type of data such as images, videos, text, audio, etc.
Diligence
•
•
•
Unlike human beings, a computer is free from monotony, tiredness, and lack of
concentration.
It can work continuously without any error and boredom.
It can perform repeated tasks with the same speed and accuracy.
Versatility
•
•
•
•
A computer is a very versatile machine.
A computer is very flexible in performing the jobs to be done.
This machine can be used to solve the problems related to various fields.
At one instance, it may be solving a complex scientific problem and the very next
moment it may be playing a card game.
Reliability
•
•
•
A computer is a reliable machine.
Modern electronic components have long lives.
Computers are designed to make maintenance easy.
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Automation
Computer is an automatic machine.
Automation is the ability to perform a given task automatically. Once the computer receives a
program i.e., the program is stored in the computer memory, then the program and instruction
can control the program execution without human interaction.
Reduction in Paper Work and Cost
The use of computers for data processing in an organization leads to reduction in paper work
and results in speeding up the process.
As data in electronic files can be retrieved as and when required, the problem of maintenance
of large number of paper files gets reduced.
Though the initial investment for installing a computer is high, it substantially reduces the cost
of each of its transaction.
Disadvantages of Computers
Following are certain disadvantages of computers.
No I.Q.
•
•
•
A computer is a machine that has no intelligence to perform any task.
Each instruction has to be given to the computer.
A computer cannot take any decision on its own.
Dependency
•
It functions as per the user’s instruction, thus it is fully dependent on humans.
Environment
•
The operating environment of the computer should be dust free and suitable.
No Feeling
•
Computers have no feelings or emotions.
It cannot make judgment based on feeling, taste, experience, and knowledge unlike
humans.
Applications of Computer
In this chapter, we will discuss the application of computers in various fields.
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Business
A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which has
made it an integrated part in all business organizations.
Computer is used in business organizations for:
•
•
•
•
•
•
Payroll calculations
Budgeting
Sales analysis
Financial forecasting
Managing employee database
Maintenance of stocks, etc.
Banking
Today, banking is almost totally dependent on computers.
Banks provide the following facilities:
•
•
Online accounting facility, which includes checking current balance, making deposits and
overdrafts, checking interest charges, shares, and trustee records.
ATM machines which are completely automated are making it even easier for customers
to deal with banks.
Insurance
Insurance companies are keeping all records up to-date with the help of computers. Insurance
companies, finance houses, and stock broking firms are widely using computers for their
concerns.
Insurance companies are maintaining a database of all clients with information showing:
•
•
•
•
•
•
•
Procedure to continue with policies
Starting date of the policies
Next due installment of a policy
Maturity date
Interests due
Survival benefits
Bonus
Education
The computer helps in providing a lot of facilities in the education system.
The computer provides a tool in the education system known as CBE (Computer Based
Education).
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CBE involves control, delivery, and evaluation of learning.
Computer education is rapidly increasing the graph of number of computer students.
There are a number of methods in which educational institutions can use a computer to
educate the students.
It is used to prepare a database about performance of a student and analysis is carried out on
this basis.
Marketing
In marketing, uses of the computer are following:
•
•
Advertising - With computers, advertising professionals create art and graphics, write
and revise copy, and print and disseminate ads with the goal of selling more products.
Home Shopping - Home shopping has been made possible through the use of
computerized catalogues that provide access to product information and permit direct
entry of orders to be filled by the customers.
Healthcare
Computers have become an important part in hospitals, labs, and dispensaries. They are being
used in hospitals to keep the record of patients and medicines. It is also used in scanning and
diagnosing different diseases. ECG, EEG, ultrasounds and CT scans, etc. are also done by
computerized machines.
Following are some major fields of health care in which computers are used.
•
•
•
•
•
Diagnostic System - Computers are used to collect data and identify the cause of illness.
Lab-diagnostic System - All tests can be done and the reports are prepared by
computer.
Patient Monitoring System - These are used to check the patient's signs for abnormality
such as in Cardiac Arrest, ECG, etc.
Pharma Information System - Computer is used to check drug labels, expiry dates,
harmful side effects, etc.
Surgery - Nowadays, computers are also used in performing surgery.
Engineering Design
Computers are widely used for engineering purpose.
One of the major areas is CAD (Computer Aided Design) that provides creation and
modification of images. Some of the fields are:
•
Structural Engineering - Requires stress and strain analysis for design of ships, buildings,
budgets, airplanes, etc.
17
•
•
Industrial Engineering – Computers deal with design, implementation, and
improvement of integrated systems of people, materials, and equipment.
Architectural Engineering – Computers help in planning towns, designing buildings,
determining a range of buildings on a site using both 2D and 3D drawings.
Military
Computers are largely used in defense. Modern tanks, missiles, weapons, etc. Military also
employs computerized control systems. Some military areas where a computer has been used
are:
•
•
•
•
Missile Control
Military Communication
Military Operation and Planning
Smart Weapons
Communication
Communication is a way to convey a message, an idea, a picture, or speech that is received and
understood clearly and correctly by the person for whom it is meant. Some main areas in this
category are:
•
•
•
•
•
•
E-mail
Chatting
Usenet
FTP
Telnet
Video-conferencing
Government
Computers play an important role in government services. Some major fields in this category
are:
•
•
•
•
•
•
•
Budgets
Sales tax department
Income tax department
Computation of male/female ratio
Computerization of voters lists
Computerization of PAN card
Weather forecasting
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Generation of Computers
Generation in computer terminology is a change in technology a computer is/was being used.
Initially, the generation term was used to distinguish between varying hardware technologies
used to fabricate the processors, memories and I/O units.
Nowadays, generation includes both hardware and software, which together make up an
entire computer system.
There are five computer generations known till date. Each generation has been discussed in
detail along with their time period and characteristics. Approximate dates against each
generation have been mentioned, which are normally accepted.
Following are the main five generations of computers.
First Generation Computers
The first electronic computer was designed and built at
the University of Pennsylvania based on vacuum tube
technology.
Vacuum tubes were used to perform logic operations
and to store data.
The period of this first generation was from 1946-1959.
The computers of first generation used vacuum tubes
as the basic components for memory and circuitry for
CPU (Central Processing Unit).
These tubes, like electric bulbs, produced a lot of heat
and the installations used to fuse frequently. Therefore,
they were very expensive and only large organizations
were able to afford it.
In this generation, mainly batch processing operating system was used. Punch cards, paper
tape, and magnetic tape was used as input and output devices. The computers in this
generation used machine code as the programming language.
The main features of the first generation are:
•
•
•
•
Vacuum tubes were used – basic arithmetic operations took few milliseconds
Unreliable
Very costly
Consume more power with limited performance
19
•
•
•
•
•
•
•
•
Uses assembly language – to prepare programs. These were translated into machine
level language for execution.
Mercury delay line memories and Electrostatic memories were used
Fixed point arithmetic was used
100 to 1000 fold increase in speed relative to the earlier mechanical and relay based
electromechanical technology
Punched cards and paper tape were invented to feed programs and data and to get
results.
Magnetic tape / magnetic drum were used as secondary memory
Mainly used for scientific computations.
Generated a lot of heat
Some computers of this generation were:
•
•
•
•
•
•
ENIAC - Electronic Numerical Integrator And Calculator
EDVAC – Electronic Discrete Variable Automatic Computer
UNIVAC – Universal Automatic Computer
EDSAC – Electronic Delay Storage Automatic Calculator
IBM-701
IBM-650
Second Generation Computers
The period of second generation was from 1959-1965.
The Manufacturers are
In this generation, transistors were used that were cheaper, consumed less power, more
compact in size, more reliable and faster than the first generation machines made of vacuum
tubes.
In this generation, magnetic cores were used as the primary memory and magnetic tape and
magnetic disks as secondary storage devices.
In this generation, assembly language and high-level programming languages like FORTRAN,
COBOL were used. The computers used batch processing and multiprogramming operating
system.
The main features of second generation are:
•
•
•
•
•
•
•
Transistors were used in place of vacuum tubes. (invented at AT&T Bell lab in 1947)
Lesser power consumption and better performance
Reliable in comparison to first generation computers
Smaller size as compared to first generation computers
Generated less heat as compared to first generation computers
Consumed less electricity as compared to first generation computers
Faster than first generation computers
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•
•
•
•
•
•
•
•
•
•
•
Still very costly
AC required
Magnetic ferrite core memories were used as main memory which is a random-access
nonvolatile memory
Magnetic tapes and magnetic disks were used as secondary memory
Hardware for floating point arithmetic operations was developed.
Index registers were introduced which increased flexibility of programming.
High level languages such as FORTRAN, COBOL etc were used - Compilers were
developed to translate the high-level program into corresponding assembly language
program which was then translated into machine language.
Separate input-output processors were developed that could operate in parallel with
CPU.
Punched cards continued during this period also.
1000 fold increase in speed.
Increasingly used in business, industry and commercial organizations for preparation of
payroll, inventory control, marketing, production planning, research, scientific &
engineering analysis and design etc.
Some computers of this generation were:
•
•
•
•
•
•
•
•
IBM 7030,
Digital Data Corporation’s PDP 1/5/8
Honeywell 400
IBM 1620
IBM 7094
CDC 1604
CDC 3600
UNIVAC 1108
Third Generation Computers
The period of third generation was from 1965-1971.
The computers of third generation used Integrated
Circuits (ICs) in place of transistors. A single IC has
many transistors, resistors, and capacitors along with the associated circuitry.
The IC was invented by Jack Kilby. This development made computers smaller in size, reliable,
and efficient.
In this generation remote processing, time-sharing, multi-programming operating system were
used. High-level languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68 etc.)
were used during this generation.
21
The main features of third generation are:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
IC used
More reliable in comparison to previous two generations
ICs were used
Small Scale Integration and Medium Scale Integration technology were implemented in
CPU, I/O processors etc.
Smaller & better performance
Comparatively lesser cost
Faster processors
In the beginning magnetic core memories were used. Later they were replaced by
semiconductor memories (RAM & ROM)
Introduced microprogramming
Microprogramming, parallel processing (pipelining, multiprocessor system etc),
multiprogramming, multi-user system (time shared system) etc were introduced.
Operating system software were introduced (efficient sharing of a computer system by
several user programs)
Cache and virtual memories were introduced (Cache memory makes the main memory
appear faster than it really is. Virtual memory makes it appear larger)
Supported high-level language, High level languages were standardized by ANSI eg. ANSI
FORTRAN, ANSI COBOL etc
Database management, multi-user application, online systems like closed loop process
control, airline reservation, interactive query systems, automatic industrial control etc
emerged during this period.
Lesser maintenance
Costly
Consumed lesser electricity
22
Some computers of this generation were:
•
•
•
•
•
IBM-360 series
Honeywell-6000 series
PDP -8 (Personal Data Processor) Mini Computer from Digital
Equipment Corporation
IBM-370/168
TDC-316
Fourth Generation Computers
The period of fourth generation was from 1971-1980.
Computers of fourth generation used Very Large Scale Integrated (VLSI) circuits. VLSI circuits
having about 5000 transistors and other circuit elements with their associated circuits on a
single chip made it possible to have microcomputers of fourth generation.
Fourth generation computers became more powerful, compact, reliable, and affordable. As a
result, it gave rise to Personal Computer (PC) revolution.
In this generation, time sharing, real time networks, distributed operating system were used. All
the high-level languages like C, C++, DBASE etc., were used in this generation.
The main features of fourth generation are:
•
•
•
•
VLSI technology used
Very cheap
Microprocessors were introduced as CPU– Complete processors and large section of
main memory could be implemented in a single chip
Tens of thousands of transistors can be placed in a single chip (VLSI design
implemented)
23
•
•
•
•
•
•
•
•
•
•
CRT screen, laser & ink jet printers, scanners etc were developed.
Semiconductor memory chips were used as the main memory.
Secondary memory was composed of hard disks – Floppy disks & magnetic tapes were
used for backup memory
Parallelism, pipelining cache memory and virtual memory were applied in a better way
LAN and WANS were developed (where desktop work stations interconnected)
Introduced C language and Unix OS
Introduced Graphical User Interface
Less power consumption
High performance, lower cost and very compact
Much increase in the speed of operation
Some computers of this generation were:
•
•
•
•
•
•
•
•
DEC 10
STAR 1000
PDP 11
CRAY-1(Super Computer)
CRAY-X-MP(Super Computer)
Intel’s 8088,80286,80386,80486 ..,
Motorola’s 68000, 68030, 68040,
Apple II
Fifth Generation Computers
The period of fifth generation is 1980-till date.
In the fifth generation, VLSI technology became ULSI (Ultra Large Scale Integration) technology,
resulting in the production of microprocessor chips having ten million electronic components.
This generation is based on parallel processing hardware and AI (Artificial Intelligence)
software.
AI is an emerging branch in computer science, which interprets the means and
method of making computers think like human beings.
All the high-level languages like C and C++, Java, .Net etc., are used in this generation.
AI includes:
•
•
•
•
•
Robotics
Neural Networks
Game Playing
Development of expert systems to make decisions in real-life situations
Natural language understanding and generation
24
The main features of fifth generation are:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Generation number beyond IV, have been used occasionally to describe some current
computer system that have a dominant organizational or application driven feature.
Computers based on artificial intelligence are available
Computers use extensive parallel processing, multiple pipelines, multiple processors etc
Massive parallel machines and extensively distributed system connected by
communication networks fall in this category.
Introduced ULSI (Ultra Large Scale Integration) technology – Intel’s Pentium 4
microprocessor contains 55 million transistors millions of components on a single IC
chip.
Superscalar processors, Vector processors, SIMD processors, 32 bit micro controllers
and
embedded processors, Digital Signal Processors (DSP) etc have been developed.
Memory chips up to 1 GB, hard disk drives up to 180 GB and optical disks up to 27 GB
are available (still the capacity is increasing)
Object oriented language like JAVA suitable for internet programming has been
developed.
Portable note book computers introduced
Storage technology advanced – large main memory and disk storage available
Introduced World Wide Web. (and other existing applications like e-mail, e Commerce,
Virtual libraries/Classrooms, multimedia applications etc.)
New operating systems developed – Windows 95/98/XP/…, LINUX, etc.
Got hot pluggable features – which enable a failed component to be replaced with a
new one without the need to shutdown the system, allowing the uptime of the system
to be very high.
The recent development in the application of internet is the Grid technology which is
still in its upcoming stage.
Quantum mechanism and nanotechnology will radically change the phase of computers
More user-friendly interfaces with multimedia features
Availability of very powerful and compact computers at cheaper rates
Some computer types of this generation are:
•
•
•
•
•
•
•
•
•
•
•
Desktop
Laptop
IBM NoteBook
UltraBook
ChromeBook
Pentium PCs-Pentium 1/2/3/4/
Dual core/Quad core
SUN work stations
Origin 2000
PARAM 10000
IBM SP/2
25
Computer Components
A computer is an electronic device for performing logical and mathematical operations
based on its programs.
As we have seen, Computer components are divided into two major categories namely
HARDWARE and SOFTWARE.
1. Computer Hardware:
Computer hardware refers to the physical parts or components of a computer such as the
monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit
(graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical
objects that can be seen and touched.
Types of Hardware
Hardware refers to all the physical devices that make up a computer system, both those
inside the computer “case” and those outside the case, like monitor, keyboard, and
mouse.
On a desktop computer, the case houses all the internal hardware, such as
CPU, RAM, motherboard and Hard disks. Peripherals sit outside the case (external
hardware) such as mouse, keyboard, and monitor.
Input Devices
This unit contains devices with the help of which we enter data into the computer. This unit
creates a link between the user and the computer. The input devices translate the data into
a form understandable by the computer. Most common are keyboard and mouse.
Example of Input Devices:•
•
•
•
•
•
•
•
•
•
•
•
•
Keyboard
Mouse (pointing device)
Microphone
Touch screen
Scanner
Webcam
Touchpad
MIDI keyboard
Graphics Tablets
Cameras
Pen Input
Video Capture Hardware
Microphone
26
CPU - Central Processing Unit
•
•
•
•
•
•
Trackballs
Barcode reader
Digital camera
Joystick
Gamepad
Electronic Whiteboard
Central Processing Unit (CPU)
The main component to make a computer operate is the computer chip or microprocessor.
This is referred to as the Central Processing Unit (CPU) and is housed in the computer case.
Together, they are also called the CPU. It performs arithmetic and logic operations. The CPU
(Central Processing Unit) is the device that interprets and executes instructions.
The CPU is comprised of three main parts:
i.
Arithmetic Logic Unit (ALU): Executes all arithmetic and logical operations.
Arithmetic calculations like as addition, subtraction, multiplication and division.
Logical operation like compare numbers, letters, or special characters
ii.
1.
2.
3.
4.
5.
iii.
Control Unit (CU): controls and co-ordinates computer components.
Read the code for the next instruction to be executed.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory.
Provide the necessary data to an ALU or register.
If the instruction requires an ALU or specialized hardware to complete, instruct the
hardware to perform the requested operation.
Memory
It facilitates the remembrance power to computer system. It refers to the physical devices
used to store programs (sequences of instructions) or data (e.g. program state information)
on a temporary or permanent basis for use in a computer or other digital electronic device.
The term primary memory is used for the information in physical systems which are fast (i.e.
RAM), as a distinction from secondary memory, which are physical devices for program and
data storage which are slow to access but offer higher memory capacity.
Primary memory stored on secondary memory is called virtual memory. Primary Memory
can be categorized as Volatile Memory & Non-Volatile Memory.
27
Primary Memory
i.
RAM
Random Access Memory (RAM
RAM) is a memory
scheme within the computer
ter ssystem
responsible for storing dataa on
o a temporary
basis, so that it can be prompt
mptly accessed by
the processor as and when needed.
ne
It is
volatile in nature, which mean
eans that data will
be erased once supply to the
he storage
s
device is
turned off. RAM stores data
ta randomly
ra
and the
processor accesses these data randomly from
the RAM storage. RAM is cons
onsidered "random
access" because you can acce
ccess any memory
cell directly if you know the
e ro
row and column
that intersect at that cell.
Volatile Memory (RAM)
Volatile memory is computer
ter memory
m
that requires power to maintain
n the
th stored
information. Most modern semiconductor
sem
volatile memory is either Stati
tatic RAM (SRAM) or
Dynamic RAM (DRAM).
Static RAM retains its content
tents as long as the power is connected and
d is easy to interface to
but uses six transistors perr bit.
bit
Dynamic RAM is more complic
plicated to interface to and control and needs
eds regular refresh
cycles to prevent its contents
nts being lost. However, DRAM uses only one
ne transistor and a
capacitor per bit, allowing it to reach much higher densities and, with more
mo bits on a
memory chip, be much cheape
eaper per bit. SRAM is not worthwhile for desk
esktop system
memory, where DRAM domin
minates, but is used for their cache memories
ies.
RAM comes in different formss: DDR, DDR2, DDR3 and DDR4.
DDR and DDR2 are old now and
an being phased out in favor of
DDR3 and DDR4. Most of the
he latest PCs will use DDR3 &
DDR4 RAM.
Notice the positions of the cut
cu out notches along the
bottom of the DIMM indicated
ated in red on the photograph
above. This is to make sure on
only the correct RAM fits in the
slot on the motherboard.
RAM speed is also measured
ed in
i Megahertz (MHz) and you’ll
likely see this when looking
g at buying RAM.
28
Laptops have their own type
pe o
of memory. It’s more or
less the same except for the
he physical
p
size. These
memory modules are called
d SO-DIMMs.
When buying memory, you need
ne to find out what
memory modules your compu
puter’s motherboard takes.
You should be able to find this
thi in the documentation
that came with your compute
uter.
ii.
ROM
ac
regardless of
Read Only Memory (ROM) is a permanent form of storage. ROM stayss active
whether power supply to it is turned on or off.
ROM devices do not allow dat
data stored on them to
be modified.
Non Volatile Memory (ROM))
Non-volatile memory is compu
mputer memory that
can retain the stored informat
mation even when not
powered.
emory are flash
Examples of non-volatile mem
memory and ROM/PROM/EPR
EPROM/EEPROM
memory (used for firmware such
su as boot
programs).
Cache Memory:
Cache memory is random access
acce memory (RAM) that a computer microp
roprocessor can access
more quickly than it can acces
cess regular RAM. As the microprocessor proc
rocesses data, it looks
first in the cache memory and if it finds the data there (from a previous
us reading
r
of data), it
does not have to do the more
ore time-consuming reading of data from large
arger memory. It is of
two types- L1 cache is on the
he same
s
chip as the microprocessor. L2 is usua
sually a separate static
RAM (SRAM) chip.
Secondary Memory:Stores data and programs per
permanently, it’s retained the data even after
ter the power is turned
off.
1. Hard drive (HD): A hard disk is part of a unit, often called a "disk
sk drive,"
d
"hard drive,"
or "hard disk drive,"" that
th store and provides relatively quick acces
cess to large amounts
of data on an electrom
romagnetically charged surface or set of surfac
rfaces.
29
2. Optical Disk
An optical disc drive (ODD) is a disk drive that uses laser light as part of the process of
reading or writing data to or from optical discs. Some drives can only read from discs,
but recent drives are commonly both readers and recorders, also called burners or
writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media
which can be read and recorded by such drives. Optical drive is the generic name;
drives are usually described as "CD" "DVD", or "Blu-ray", followed by "drive", "writer",
etc. There are three main types of optical media: CD, DVD, and Blu-ray disc. CDs can
store up to 700 megabytes (MB) of data and DVDs can store up to 8.4 GB of data.
Blu-ray discs, which are the newest type of optical media, can store up to 50 GB of
data. This storage capacity is a clear advantage over the floppy disk storage media (a
magnetic media), which only has a capacity of 1.44 MB.
Blu-Ray Disk: Blu-ray (not Blue-ray) also known as Blu-ray Disc (BD), is the name of a
new optical disc format. The format offers more than five times the storage capacity
of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a duallayer disc. While current optical disc technologies such as DVD, DVD±R, DVD±RW, and
DVD-RAM rely on a red laser to read and write data, the new format uses a blueviolet laser instead, hence the name Blu-ray.
Units of Memory:
The smallest unit is bit, which mean either 0 or 1.
1 bit
= 0 or 1
1 Byte
= 8 bit
1 Nibble
= 4 bit
1 Kilo Byte
= 1024 Byte= 210 Byte
1 Mega Byte = 1024 KB= 210 KB
1 Gega Byte
= 1024 MB= 210 MB
1 Tera Byte
= 1024 GB= 210 GB
1 Peta Byte
=1024 TB= 210 TB
1 Exa Byte
=1024 PB= 210 PB
1 Zetta Byte
= 1024 EB= 210 EB
1 Yotta Byte
= 1024 ZB= 210 ZB
3. Flash Disk
A storage module made of flash memory chips. A Flash disk have no mechanical
platters or access arms, but the term "disk" is used because the data are accessed as
if they were on a hard drive. The disk storage structure is emulated.
Output devices
An output device is any piece of computer hardware equipment used to communicate the
results of data processing carried out by an information processing system (such as a
computer) which converts the electronically generated information into human readable
form. Those are devices which help to display the processed information.
30
Example of Output Devices:
i.
ii.
iii.
iv.
v.
vi.
vii.
Monitor or screen
LCD Projection Panels
Printers (all types)
Computer Output Microfilm (COM)
Plotters
Speaker(s)
Projector
Note
Basic types of monitors are;
Cathode Ray Tube (CRT).
Liquid Crystal Displays (LCD).
Light-emitting diode (LED).
•
•
•
Printer types:
•
•
•
Laser Printer.
Ink Jet Printer.
Dot Matrix Printer
Types of Computer
Computers can be generally classified on the basis of working principal, size and power as
follows, though there is Considerable overlap:
A). On the basis of working principle
i.
Analog Computer
An analog computer is a form of computer that uses continuous physical phenomena
such as electrical, mechanical, or hydraulic quantities to model the problem being
solved.
Eg: Thermometer, Speedometer, Petrol pump indicator, Multimeter
31
ii.
Digital Computer
A computer that performs calculations and logical operations with quantities
represented as digits, usually in the binary number system.
iii.
Hybrid Computer (Analog + Digital)
A combination of computers those are capable of inputting and outputting in both digital
and analog signals. A hybrid computer system setup offers a cost effective method of
performing complex simulations. The instruments used in medical science lies in this
category.
B). On the basis of Size
i.
Super Computer
The fastest type of computer, Supercomputers are very
expensive and are employed for specialized applications that
require immense amounts of mathematical calculations.
For example, weather forecasting requires a supercomputer.
Other uses of supercomputers include animated graphics, fluid
dynamic calculations, nuclear energy research, and petroleum
exploration. PARAM, Pace & Flosolver are the supercomputer
made in india.
ii.
Mainframe Computer
A very large and expensive computer capable of supporting
hundreds, or even thousands, of users simultaneously. In the
hierarchy that starts with a simple microprocessor (in watches, for
example) at the bottom and moves to supercomputers at the top,
mainframes are just below supercomputers.
In some ways, mainframes are more powerful than
supercomputers because they support more simultaneous
programs. But supercomputers can execute a single program faster than a mainframe.
iii.
Mini Computer
A mid-sized computer, in size and power, minicomputers lie between workstations and
mainframes. In the past decade, the distinction between large minicomputers and small
mainframes has blurred, however, as has the distinction between small minicomputers and
workstations. But in general, a minicomputer is a multiprocessing system capable of
supporting from 4 to about 200 users simultaneously. Generally, servers are comes in this
category.
32
iv.
v.
Micro Computer:
a. Desktop Computer: a personal or micro-mini computer sufficient to fit on a
desk.
b. Laptop Computer: a portable computer complete with an integrated screen
and keyboard. It is generally smaller in size than a desktop computer and
larger than a notebook computer.
c. Palmtop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer.
Palmtops have no keyboard but the screen serves both as an input and output
device.
Workstations
A terminal or desktop computer in a network. In this
context, workstation is just a generic term for a user's
machine (client machine) in contrast to a "server" or
"mainframe."
Software
Software, simply are the computer programs. The instructions given to the computer in the
form of a program is called Software. Software is the set of programs, which are used for
different purposes. All the programs used in computer to perform specific task is called
Software.
Software Types
Software is often broken into two major categories: System Software that provides the
basic non task-specific functions of the computer, and Application Software which is used
by users to accomplish specific tasks.
A. System software is responsible for controlling, integrating, and managing the individual
hardware components of a computer system so that other software and the users of the
system see it as a functional unit without having to be concerned with the low-level
details such as transferring data from memory to disk, or rendering text onto a display.
Generally, system software consists of:
a) Operating System Software
Example: DOS, Windows XP, Windows Vista, Unix/Linux, MAC/OS X etc.
b) Utility Software
Examples: Windows Explorer (File/Folder Management), Compression Tool, Anti-Virus
Utilities, Disk Defragmentation, Disk Clean, Back-up, WinZip, WinRAR etc…
c) Language Processors
Examples: Compiler, Interpreter and Assembler.
33
Operating system
Operating system is a platform between hardware and user which is responsible for the
management and coordination of activities and the sharing of the resources of a computer.
It hosts the several applications that run on a computer and handles the operations of
computer hardware.
Functions of operating System:
•
•
•
•
Processor Management
Memory Management
File Management
Device Management
Types of Operating System:
•
Real-time Operating System: It is a multitasking operating system that aims at
executing real-time applications. Example of Use: e.g. control of nuclear power
plants, oil refining, chemical processing and traffic control systems, air.
•
Single User Systems: Provides a platform for only one user at a time. They are
popularly associated with Desk Top operating systems which run on standalone
systems where no user accounts are required. Example: DOS.
•
Multi User Systems: Provides regulated access for a number of users by maintaining
a database of known users. Refers to computer systems that support two or more
simultaneous users. Another term for multi-user is time sharing. Example: All
mainframes are multi-user systems. Example: Unix
•
Multi-tasking and Single-tasking Operating Systems: When a single program is
allowed to run at a time, the system is grouped under the single-tasking system
category, while in case the operating system allows for execution of multiple tasks at
a time, it is classified as a multi-tasking operating system.
•
Distributed Operating System: An operating system that manages a group of
independent computers and makes them appear to be a single computer is known as
a distributed operating system. Distributed computations are carried out on more
than one machine. When computers in a group work in cooperation, they make a
distributed system.
Commonly used operating system
UNIX: Pronounced yoo-niks, a popular multi-user, multitasking operating system developed
at Bell Labs in the early 1970s. UNIX was one of the first operating systems to be written in a
high-level programming language, namely C. This meant that it could be installed on virtually
any computer for which a C compiler existed.
34
LINUX: Pronounced lee-nucks or lih-nucks. A freely-distributable open source operating
system that runs on a number of hardware platforms. The Linux kernel was developed
mainly by Linus Torvalds and it is based on Unix. Because it's free, and because it runs on
many platforms, including PCs and Macintoshes, Linux has become an extremely popular
alternative to proprietary operating systems.
Windows: Microsoft Windows is a series of graphical interface operating systems
developed, marketed, and sold by Microsoft. Microsoft introduced an operating
environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to
the growing interest in graphical user interfaces (GUIs). Microsoft Windows came to
dominate the world's personal computer market with over 90% market share, overtaking
Mac OS, which had been introduced in 1984.The most recent client version of Windows is
Windows 10; the most recent server version is Windows Server 2019 R2; the most recent
mobile version is Windows Phone 10 (Windows 10 Mobile was announced on January 21, 2015, as a mobile
operating system for smartphones and tablets with screens smaller than 8 inches, with the first build released on
February 12, 2015. It is the successor to Windows Phone 8.1 and replaced the Windows Phone brand, while
Microsoft has since ceased active development of Windows 10 Mobile. Windows Phone 8.1 devices are eligible for
upgrade to Windows 10, pursuant of manufacturer and carrier support. Some features may vary depending on
hardware compatibility).
SOLARIS: Solaris is a Unix operating system originally developed by Sun Microsystems. It
superseded their earlier SunOS in 1993. Oracle Solaris, as it is now known, has been owned
by Oracle Corporation since Oracle's acquisition of Sun in January 2010.
BOSS: BOSS (Bharat Operating System Solutions) GNU/Linux distribution developed by CDAC (Centre for Development of Advanced Computing) derived from Debian for enhancing
the use of Free/ Open Source Software throughout India. This release aims more at the
security part and comes with an easy to use application to harden your Desktop.
Mobile OS: A mobile operating system, also called a mobile OS, is an operating system that
is specifically designed to run on mobile devices such as mobile phones, smartphones, PDAs,
tablet computers and other handheld devices. The mobile operating system is the software
platform on top of which other programs, called application programs, can run on mobile
devices.
•
Android: Android is a Linux-based mobile phone operating system developed by
Google. Android is unique because Google is actively developing the platform but
giving it away for free to hardware manufacturers and phone carriers who want to
use Android on their devices.
•
Symbian: Symbian is a mobile operating system (OS) targeted at mobile phones that
offers a high-level of integration with communication and personal information
management (PIM) functionality. Symbian OS combines middleware with wireless
communications through an integrated mailbox and the integration of Java and PIM
functionality (agenda and contacts). The Symbian OS is open for third-party
35
development by independent software vendors, enterprise IT departments, network
operators and Symbian OS licensees.
Booting
The process of loading the system files of the operating system from the disk into the
computer memory to complete the circuitry requirement of the computer system is called
booting.
Types of Booting:
There are two types of booting:
• Cold Booting: If the computer is in off state and we boot the computer by pressing
the power switch ‘ON’ from the CPU box then it is called as cold booting.
• Warm Booting: If the computer is already ‘ON’ and we restart it by pressing the
‘RESET’ button from the CPU box or CTRL+ALT and DEL key simultaneously from
the keyboard then it is called warm booting.
LANGUAGE PROCESSORS: Since a computer hardware is capable of understanding only
machine level instructions, so it is necessary to convert the High Level Language into Machine
Level Language. There are three Language processors:
A. Compiler: It is translator which converts the HLL language into machine language in
one go. A Source program in High Level Language gets converted into Object
Program in Machine Level Language.
B. Interpreter: It is a translator which converts the High Level Language into machine
language line by line. It takes one statement of High Level Language and converts it
into machine code which is immediately executed. It eliminates the need of separate
compilation/run. However, it is slow in processing as compare to compiler.
C. Assembler: It translates the assembly language into machine code.
Microprocessor:
A microprocessor is a semiconductor chip, which is manufactured using the Large Scale
integration (LSI) or Very Large Scale Integration (VLSI), which comprises Arithmetic Logic
Unit, Control unit and Central Processing Unit (CPU) fabricated on a single chip.
Terminologies:
Registers: A register is a very small amount of very fast memory that is built into the CPU
(central processing unit) in order to speed up its operations by providing quick access to
commonly used values. All data must be represented in a register before it can be
processed. For example, if two numbers are to be multiplied, both numbers must be in
registers, and the result is also placed in a register.
36
Bus:
A collection of wires through which data is transmitted from one part of a computer to
another. You can think of a bus as a highway on which data travels within a computer. When
used in reference to personal computers, the term bus usually refers to internal bus. This is a
bus that connects all the internal computer components to the CPU and main memory. All
buses consist of two parts -- an address bus and a data bus.
The data bus transfers actual data whereas the address bus transfers information about
where the data should go. The control bus is used by the CPU to direct and monitor the
actions of the other functional areas of the computer. It is used to transmit a variety of
individual signals (read, write, interrupt, acknowledge, etc) necessary to control and
coordinate the operations of the computer.
The size of a bus, known as its width, is important because it determines how much data can
be transmitted at one time. For example, a 16-bit bus can transmit 16 bits of data, whereas a
32-bit bus can transmit 32 bits.
Clock speed: Also called clock rate, the speed at which a microprocessor executes
instructions. Every computer contains an internal clock that regulates the rate at which
instructions are executed and synchronizes all the various computer components.
The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction.
The faster the clock, the more instructions the CPU can execute per second.
Clock speeds are expressed in megahertz (MHz) or gigahertz ((GHz).
16 bit Microprocessor: It indicates the width of the registers. A 16-bit microprocessor can
process data and memory addresses that are represented by 16 bits. Eg. 8086 processor
32 bit Microprocessor: It indicates the width of the registers. A 32-bit microprocessor can
process data and memory addresses that are represented by 32 bits. Eg. Intel 80386
processor, Intel 80486
64 bit Microprocessor: It indicates the width of the registers; a special high-speed storage
area within the CPU. A 32-bit microprocessor can process data and memory addresses that
are represented by 32 bits. Eg. Pentium dual core, core 2 duo.
37
128 bit Microprocessor: It indicates the width of the registers. A 128-bit microprocessor can
process data and memory addresses that are represented by 128 bits. Eg. Intel core i7
Difference between RISC and CISC architecture
RISC (Reduced Instruction Set Computing):
1.
2.
3.
4.
RISC system has reduced number of instructions.
Performs only basic functions.
All HLL support is done in software.
All operations are register to register.
CISC (Complex Instruction Set Computing):
1.
2.
3.
4.
A large and varied instruction set.
Performs basic as well as complex functions.
All HLL support is done in Hardware.
Memory to memory addressing mode
EPIC (Explicitly Parallel Instruction Computing):
It is a 64-bit microprocessor instruction set, jointly defined and designed by Hewlett Packard
and Intel, that provides up to 128 general and floating point unit registers and uses
speculative loading, predication, and explicit parallelism to accomplish its computing tasks.
By comparison, current 32-bit CISC and RISC microprocessor architectures depend on 32-bit
registers, branch prediction, memory latency, and implicit parallelism, which are considered
a less efficient approach in micro-architecture design.
PORTS: A port is an interface between the motherboard and an external device. Different
types of port are available on motherboard as serial port, parallel port, PS/2 port, USB port,
SCSI port etc.
Serial port (COM Port): A serial port transmits data one bit at a time. Typically on older PCs,
a modem, mouse, or keyboard would be connected via serial ports. Serial cables are cheaper
to make than parallel cables and easier to shield from interference. Also called
communication port.
Parallel Port (LPT ports): It supports parallel communication i.e. it can send several bits
simultaneously. It provides much higher data transfer speed in comparison with serial port.
Also called Line Printer Port.
USB (Universal Serial Bus): It is a newer type of serial connection that is much faster than
the old serial ports. USB is also much smarter and more versatile since it allows the "daisy
chaining" of up to 127 USB peripherals connected to one port. It provides plug & play
communication.
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PS/2 Port: PS/2 ports are special ports for connecting the keyboard and mouse to some PC
systems. This type of port was invented by IBM.
FireWire Port : The IEEE 1394 interface, developed in late 1980s and early 1990s by Apple as
FireWire, is a serial bus interface standard for high-speed communications and isochronous
real-time data transfer. The 1394 interface is comparable with USB and often those two
technologies are considered together, though USB has more market share.
Infrared Port: An IR port is a port which sends and receives infrared signals from other
devices. It is a wireless type port with a limited range of 5-10ft.
Bluetooth: Bluetooth uses short-range radio frequencies to transmit information from fixed
and mobile devices. These devices must be within the range of 32 feet, or 10 meters for
Bluetooth to effectively work. A Bluetooth port enables connections for Bluetooth-enabled
devices for synchronizing. Typically there are two types of ports: incoming and outgoing.
The incoming port enables the device to receive connections from Bluetooth devices while
the outgoing port makes connections to Bluetooth devices.
Internal Storage encoding of Characters:
ASCII (American standard code for information interchange): ASCII code is most widely
used alphanumeric code used in computers. It is a 7- bit code, and so it has 27 =128 possible
code groups. It represents all of the standard keyboard characters as well as control
functions such as Return & Linefeed functions.
ISCII (American standard code for information interchange): To use the Indian language on
computers, ISCII codes are used. It is an 8-bit code capable of coding 256 characters. ISCII
code retains all ASCII characters and offers coding for Indian scripts also.
Unicode: It is a universal coding standard which provides a unique number for every
character, no matter what the platform, no matter what the program, no matter what the
language. Unicode version 3.1 represented 94,140 characters.
B. Application software:
Are software used to accomplish specific tasks other than just running the computer
system. Application software may consist of a single program, such as an image viewer; a
small collection of programs (often called a software package) that work closely
together to accomplish a task, such as a spreadsheet or text processing system; a larger
collection (often called a software suite) of related but independent programs and
packages that have a common user interface or shared data format, such as Microsoft
Office, which consists of closely integrated word processor, spreadsheet, database, etc.;
or a software system, such as a database management system, which is a collection of
fundamental programs that may provide some service to a variety of other independent
applications.
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Unit of Measurements
Storage measurements: The basic unit used in computer data storage is called a bit (Binary
digit). Computers use these little bits, which are composed of ones and zeros, to do things
and talk to other computers. All your files, for instance, are kept in the computer as binary
files and translated into words and pictures by the software (which is also ones and zeros).
This two number system is called a “binary number system” since it has only two numbers in
it. The decimal number system in contrast has ten unique digits, zero through nine.
Computer Storage units
Bit
Kilobyte
Megabyte
Gigabyte
Terabyte
BIT
KB
MB
GB
TB
0 or 1
1024 bytes
1024 kilobytes
1024 megabytes
1024 gigabytes
Size example
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1 bit - answer to an yes/no question
1 byte - a number from 0 to 255.
90 bytes: enough to store a typical line of text from a book.
4 KB: about one page of text.
120 KB: the text of a typical pocket book.
3 MB - a three minute song (128k bitrate)
650-900 MB - an CD-ROM
1 GB -114 minutes of uncompressed CD-quality audio at 1.4 Mbit/s
8-16 GB - size of a normal flash drive
Speed measurement: The speed of Central Processing Unit (CPU) is measured by Hertz (Hz),
which represent a CPU cycle. The speed of CPU is known as Computer Speed.
1 hertz or Hz
1 MHz
1 GHz
CPU SPEED MEASURES
1 cycle per second
1 million cycles per second or 1000 Hz
1 billion cycles per second or 1000 MHz
Computers classification
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Personal computer: A small, single-user computer based on a microprocessor.
In addition to the microprocessor, a personal computer has a keyboard for
entering data, a monitor for displaying information, and a storage device for
saving data.
Workstation: A powerful, single-user computer. A workstation is like a
personal computer, but it has a more powerful microprocessor and a higherquality monitor.
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Minicomputer: A multi-user computer capable of supporting from 10 to
hundreds of users simultaneously.
• Mainframe: A powerful multi-user computer capable of supporting many
hundreds or thousands of users simultaneously.
• Supercomputer: An extremely fast computer that can perform hundreds of
millions of instructions per second.
Computer viruses
• Viruses: A virus is a small piece of software that piggybacks on real programs. For
example, a virus might attach itself to a program such as a spreadsheet program.
Each time the spreadsheet program runs, the virus runs, too, and it has the chance to
reproduce (by attaching to other programs) or wreak havoc.
• E-mail viruses: An e-mail virus travels as an attachment to e-mail messages, and
usually replicates itself by automatically mailing itself to dozens of people in the
victim's e-mail address book. Some e-mail viruses don't even require a double-lick they launch when you view the infected message in the preview pane of your e-mail
software.
• Trojan horses: A Trojan horse is simply a computer program. The program claims to
do one thing (it may claim to be a game) but instead does damage when you run it (it
may erase your hard disk). Trojan horses have no way to replicate automatically.
• Worms: A worm is a small piece of software that uses computer networks and
security holes to replicate itself. A copy of the worm scans the network for another
machine that has a specific security hole. It copies itself to the new machine using the
security hole, and then starts replicating from there, as well.
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What are some tips to avoid viruses and reduce their impact?
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Install anti-virus software from a reputable vendor. Update it and use it regularly.
In addition to scanning for viruses on a regular basis, install an "on access" scanner
(included in most anti-virus software packages) and configure it to start each time
you start up your computer. This will protect your system by checking for viruses
each time you run an executable file.
Use a virus scan before you open any new programs or files that may contain
executable code. This includes packaged software that you buy from the store as
well as any program you might download from the Internet.
If you are a member of an online community or chat room, be very careful about
accepting files or clicking links that you find or that people send you within the
community.
Make sure you back up your data (documents, bookmark files, important email
messages, etc.) on disc so that in the event of a virus infection, you do not lose
valuable work.
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