CAB UNIT 1 with computer details details

Computer Application in Business
– Unit(1) Introduction
Prepared by:
Sarita Gautam & Vikki Sharma
Assistant Professor
Shri Ram College of Commerce

BASIC COMPUTER SKILLS
INTRODUCTION
WHAT IS A COMPUTER?
The word “Computer” is derived from the word
„compute". It means „to calculate". We all are familiar with
calculations in our day-to-day life. We apply mathematical
operations like addition, subtraction, multiplication, division,
etc. and many other formulae for calculations. Simple
calculations take less time. But complex calculations take
much longer time. Another factor is accuracy in calculations.
So man explored with the idea to develop a machine,
which can perform this type of arithmetic calculation faster,
and with full accuracy. This gave birth to a device or
machine called „computer".
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DEFINITION OF A COMPUTER
“A computer is an electronic device,
which can be programmed to perform
highspeed mathematical or logical
operations. Computer accepts, stores,
correlates, manipulates and processes
information in binary format and display the
results in a human understandable language.”
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To put it simply, a computer is an electronic
device that is designed to work with information.
The Computer...
• 1. Takes in the INPUT information, then.
• 2. PROCESS the information, and then.
• 3. Displays the OUTPUT results.

CHARACTERISTICS OF A COMPUTER
Let us identify the major characteristics of a computer.
1. Speed
As you know computer can work very fast. It takes
only few seconds for calculations that we take hours to
complete. You will be surprised to know that computer can
perform several million (1,000,000) of instructions and even
more per second. Therefore, we determine the speed of
computer in terms of microsecond (10-6 part of a second) or
nano-second (109 part of a second). From this you can
imagine how fast your computer can perform.

2. Accuracy
Suppose someone calculates faster but commits a lot
of errors in computing, then such a result is useless. There is
another aspect, suppose you want to divide 15 by 7. You
may work out up to 2 decimal places and say the quotient is
2.14. I may calculate up to 4 decimal places and say that the
result is 2.1428. Someone else may go up to 9 decimal
places and say the result is 2.142857143.
But a computer can give up to 100 decimal places
within a fraction of second and that too accurately. Hence, in
addition to speed, the computer provides very high level of
accuracy or correctness in computing.

3. Diligence
A computer is free from tiredness, lack of
concentration, fatigue, etc. It can work for hours or
days together very attentively without creating any
error.
If millions of calculations are to be
performed, a computer will perform every
calculation with the same accuracy. Due to this
capability it is better than human being in routine
and repetitive types of work.

4. Versatility
It means the capacity to perform completely
different type of work. You may use your computer
to prepare payroll slips. Next moment you may use
it for inventory management or to prepare
electricity bills or prepare accounts, etc. Therefore
computer is highly versatile.

5. Multi-tasking
A human being cannot do more than one task
at the same time without losing his concentration
or with his full efficiency. But for a computer, it is
a normal thing to do many tasks simultaneously
without compromising in its efficiency. For
example, at the same time you may use the
computer to type a letter and to listen to your
favourite music and also you can open internet
web pages to get some information. This is known
as Multi-tasking.

6. Power of Memory or Storage
Computer has the power of storing huge amount of
information or data. Information can be stored and recalled
as long as you require it, for any number of years. It depends
entirely upon you, how much data you want to store in a
computer and when to use or retrieve these data. It will not
fade away like human memory as years pass.
The computer has an in-built memory where it can
store a large amount of data. You can also store data in
secondary storage devices such as floppies and CDs, which
can be kept outside your computer and can be carried to
other computers.

7. No IQ
Believe me! Computer is a dumb machine
and it cannot do any work without instructions
from the user. It is considered as a faithful idiot
that can only perform the instructions given to it at
a tremendous speed and with high accuracy
without understanding of the work being done by
it.
Computer has to be guided as to what you
want to do and in what sequence. So a computer
cannot take its own decision as you can. So we
humans are great!!!

7. No Feelings
Computers do not have feelings or
emotion, taste, knowledge and experience. Thus a
computer does not get tired even after doing long
hours of work. It does not distinguish between
users and different kinds of work being done by it.

HISTORY OF COMPUTERS
• History of computer could be traced back to the effort of man to count
large numbers. This process of counting of large numbers generated
various systems of numeration like Babylonian system of numeration,
Greek system of numeration, Roman system of numeration and Indian
system of numeration. Out of these the Indian system of numeration has
been accepted universally. It is the basis of modern decimal system of
numeration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). '
• Later you will know how the computer solves all calculations based on
decimal system. However, you will be surprised to know that the
computer does not understand the decimal system but it uses binary
system of numeration (0 and 1) for processing.

Let us briefly know some of the path-breaking
inventions in the field of computing devices.
(a) Calculating Machines
It took generations for early man to build mechanical
devices for counting large numbers. The first calculating
device called ABACUS, was developed by the Egyptian and
Chinese people.
The word ABACUS means calculating board. It
consists of sticks in horizontal positions on which are
inserted sets of pebbles. A modern form of ABACUS is as
shown in the fig. It has a number of horizontal bars each
having ten beads. Horizontal bars represent units, tens,
hundreds, etc.

Abacus

(b) Napier’s bones
English mathematician John Napier built a
mechanical device for the purpose of multiplication in 1617
AD. The device was known as Napier"s bones.
7 x 1
=
7 x 2
=
7 x 3
=
7 x 4
=
7 x 5
=

(c) Slide Rule
English mathematician Edmund Gunter developed
the slide rule. This machine could perform operations like
addition, subtraction, multiplication, and division. It was
widely used in Europe in 16th century.

(d) Pascal’s Adding and Subtraction Machine
You might have heard the name of Blaise Pascal. He
developed a machine at the age of 19 that could add and
subtract. The machine consisted of wheels, gears and
cylinders.
(e) Leibniz’s Multiplication and Dividing Machine
The German philosopher and mathematician
Gottfried Leibniz built around 1673 a mechanical device
that could both multiply and divide.

(f) Babbage’s Analytical Engine
It was in the year 1823 that a famous English
man Charles Babbage built a mechanical
machine to do complex mathematical
calculations. It was called difference engine.
Later he developed a general purpose calculating
machine called analytical engine. You should
know that Charles Babbage is called the Father of
computers.
(g) Mechanical and Electrical Calculator
In the beginning of 19th century the mechanical
calculator was developed to perform all sorts of
mathematical calculations and it was widely used till 1960.
Later the routine part of mechanical calculator was
replaced by electric motor. It was called the electrical
calculator.

Babbage’s Analytical Engine

(h) Modern Electronic Calculator
The electronic calculator used in 1960s was run with
electron tubes, which was quite bulky. Later it was replaced
with transistors and as a result the size of calculators
became too small. The modern electronic calculators can
compute all kinds of mathematical computations and
mathematical functions. It can also be used to store some
data permanently.

You know that the evolution of computer started from
16th century and resulted in the form that we see today.
The present day computer, however, has also undergone
rapid changes during the last fifty years. This period,
during which the evolution of computer took place, can be
divided into five distinct phases known as Generations of
Computers.
Generation of computer means the technological
evolution over the period of time. Computers are classified
as belonging to specific “generations”. The term
generations was initially introduced to distinguish between
different hardware technologies. Gradually it shifted to
both hardware and software as the total system consists of
both of them.
COMPUTER GENERATIONS

(a) First Generation Computers (1946-59)
First generation computers used Thermion valves or
Vacuum tubes. These computers were large in size and
writing programs on them was difficult. Some of the
important computers of this generation were:
ENIAC: It was the first electronic computer built in 1946
at University of Pennsylvania, USA by John Eckert and
John Mauchly. It was named Electronic Numerical
Integrator and Calculator (ENIAC). The ENIAC was 30 x
50 feet long, weighed 30 tons, contained 18,000 vacuum
tubes, 70,000 resistors, 10,000 capacitors and required 150
kilowatts of electricity. Today your favourite computer is
many times as powerful as ENIAC; still the size is very
small.

• EDVAC: It stands for Electronic Discrete Variable
Automatic Computer and was developed in 1950. The
concept of storing data and instructions inside the computer
was introduced here. This allowed much faster operation
since the computer had rapid access to both data and
instructions. The other advantage of storing instruction was
that computer could take logical decisions internally.
• EDSAC: It was developed by M.V. Wilkes at Cambridge
University in 1949.
• UNIVAC-1: Eckert and Mauchly produced it in 1951 by
Universal Accounting Computer setup.

Followings were the major drawbacks of
first generation computers.
1. They were quite bulky.
2. The operating speed was quite slow.
3. Power consumption was very high.
4. It required large space for installation.
5. They had no operating system.
6. The programming capability was quite
low.

(b) Second Generation Computers (1959-64)
Around 1959 an electronic device called Transistor
replaced the bulky vacuum tubes in the first generation
computer. A single transistor contained circuit produced by
several hundred vacuum tubes. Thus the size of the
computer got reduced considerably. Transistors therefore
provided higher operating speed than vacuum tubes. They
had no filament and require no heating. Manufacturing
cost was also very low.
It is in the second generation that the concept of
Central Processing Unit (CPU), memory, programming
language and input and output units were developed. The
programming languages such as COBOL, FORTRAN
were developed during this period.

Some of the computers of the Second
Generation were
• IBM 1920 : Its size was small as compared to
First Generation computers and mostly used for
scientific purpose.
• IBM 1401 : Its size was small to medium and
used for business applications.
• CDC 3600 : Its size was large and used for
scientific purpose.

• The salient features of this generation were:
1. Relatively faster than the first generation
computers.
2. Smaller than the first generation computers.
3. Generated lower level of heat.
4. More reliable.
5. Higher capacity of internal storage.

(c) Third Generation Computers (1964-71)
The third generation computers were introduced in
1964. They used Integrated Circuits (ICs). These ICs are
popularly known as Chips. A single IC has many
transistors, resistors and capacitors built on a single thin
slice of silicon. So it is quite obvious that the size of the
computer got further reduced. Some of the computers
developed during this period were IBM-360, ICL-1900,
IBM-370, and VAX-750.
Higher-level language such as BASIC (Beginners All
purpose Symbolic Instruction Code) was developed during
this period.

The features of computers belonging to this
generation were:
> Used tiny ICs
> Relatively very small in size
> Made use of operating system
> High processing speed
> More reliable
> Power efficient and high speed
> Use of high level languages
> Large memory
> Low cost

(d) Fourth Generation Computers (1971 onwards)
The present day computers that you see today are the
fourth generation computers that started around 1975. It
uses Large Scale Integrated Circuits (LSIC) built on a
single silicon chip called microprocessors. Due to the
development of microprocessor it is possible to place
computer's central processing unit (CPU) on a single chip.
These computers are called microcomputers. Later Very
Large Scale Integrated Circuits (VLSIC) replaced
LSICs. These integrated circuits are so advanced that they
incorporate hundreds of thousands of active components
in volumes of a fraction of an inch.
Thus the computer, which was occupying a very large
room in earlier days, can now be placed on a table. The
personal computer (PC) that you see in your school is a
Fourth Generation Computer.

The salient features of this generation
are:-
■ Very fast
■ Very low heat generation
■ Smaller in size
■ Very reliable
■ Negligible hardware failure
■ Highly sophisticated

Some of the computers of the Second
Generation were
• IBM 1920 : Its size was small as compared to
First Generation computers and mostly used for
scientific purpose.
• IBM 1401 : Its size was small to medium and
used for business applications.
• CDC 3600 : Its size was large and used for
scientific purpose.

(e) Fifth Generation Computers
The computers, which can think and take decisions
like human beings have been characterized as Fifth
generation computers and are also referred as thinking
machines. The speed is extremely high in fifth generation
computer. Apart from this they can perform parallel
processing. The concept of Artificial Intelligence has
been introduced to allow the computer to take its own
decision. It is still in a developmental stage.
A lot of research and development work is going on
in this area in United States and Japan but it will take
some time before such machines are produced for use by
the industry.

CLASSIFICATION OF COMPUTERS
Differences in certain computer
characteristics have led to the development of
major computer classifications based on the type
of electronic signal and memory size.
Types of computers based on electronic
signal they transmit are:-
(i) Analog Computers
(ii) Digital Computers
(iii) Hybrid Computers

Types of computers based on memory size
are:-
l.Micro Computers:- Microcomputer is at the lowest end of
the computer range in terms of speed and storage capacity.
Its CPU is a microprocessor. The first microcomputers
were built of 8-bit
microprocessor chips. The most common microcomputer
is a personal computer (PC). The PC supports a number
of input and output devices. An improvement of 8-bit chip
is 16-bit and 32-bit chips. Examples of microcomputer are
IBM PC, PC-AT.

2. Mini Computers:- This is designed to support more than
one user at a time. (various users can work at the same
time) It possesses large storage capacity and operates at a
high speed than a microcomputer. This type of computer is
generally used for processing large volume of data in an
organization. They are also used as servers in Local Area
Networks (LAN).
3. Mainframe Computers:- These types of computers are
generally 32-bit computers. They operate at very high
speed, have very large storage capacity and can handle the
workload of many users. They are generally used in
centralized databases. They are also used as controlling
nodes in Wide Area Network (WAN). Example of
mainframes are DEC, ICL and IBM 3000 series.

4. Super Computers:-
This is the fastest and most expensive machines. It
has high processing speed compared to other computers.
They also have multiprocessing technique. One of the
ways in which supercomputers are built is by
interconnecting hundreds of microprocessors.
Supercomputer is mainly used for weather
forecasting, biomedical research, remote sensing, aircraft
design and other areas of science and technology.
Examples of supercomputers are CRAY YMP, CRAY2,
NEC SX-3, CRAY XMP and PARAM from India.

APPLICATIONS OF COMPUTERS IN VARIOUS FIELDS
Computers have their application or utility
everywhere. We find their applications in almost every
sphere of life-particularly in fields where computations are
required to be done at a very fast speed and where data is
so complicated that the human brain finds it difficult to
cope up with. As you must be aware, computer now-a-
days are being used almost in every department to do the
work at a greater speed and accuracy.
Some of the prominent areas of computer applications
are in Tourism, Banks, Industries, Transportation,
Education, Entertainment and so
on...

ENTIFY THE MODELS OF COMPUTERS
1) Tower; The system box is placed vertically adjacent
to monitor.
Tower Model Computer

2) Desktop; It is not designed for portability. The
expectations with desktop system are that we will set the
computer at permanent location. Most desktop offer more
power, storage versatility for less cost than their portable
brethren.
Desktop Computer

3) Laptop: There are also called note books. Laptops are
portable computers that integrate the display, keyboard,
pointing, device or track ball, processors, memory and
hard drive all in battery operated package slightly larger
than an average hard cover book.
Laptop Computer

4)Palmtop; There are also called as personal digital
assistants (PDA"s), palmtop are tightly integrated
computers. They often use flash memory instead of a
hard drive for storage. These computers do not have
keywords but relay on touch screen technology for user
input.
Palmtop Computer

CONCEPTS OF HARDWARE AND
SOFTWARE
Computer hardware is the collection of physical
elements that comprise computer system. Computer
hardware refers to the physical parts or components of
computer such as monitor, keyboard, hard disk,
mouse, etc.
“Hardware refers to objects that you can actually
see, touch, and feel” like disks, disk drives, display
screens, keyboards, printers, mother boards, and chips.

Computer software or just software, is a
collection of computer programs and related data that
provides the instructions for telling a computer what to do
and how to do it. In other words, software is a set of
programs, procedures, algorithms and its
documentation concerned with the operation of a data
processing system.
“Software refers to programs which we cannot touch,
cannot see and cannot feel by our senses”. Software exists
as ideas, concepts, and symbols, but it has no substance.
A combination of hardware and software forms a
usable computing system.

Entify and Understand Front Panel Switches
and Back Panel Connections of Computer
Front Panel details of Tower model computer
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1. Power on Switch.
2. Power on (LED)
indicator.
3. Reset Switch.
4. Hard Di sk Activity
indicator.
5. CD-Open / Close / Stop
button.
6. CD-Drive Activity
indicator.
7. Play / Skip button.
8. Previous Track button.
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9. Turbo button.
10. Head Phone Volume
controller.
11. Head Phone Jack.
12. Floppy Disk Eject
button.
13. Floppy Disk Insertion
slot.
14. Floppy Disk Activity
button.
15. CD-R/W Speed.
16. Emergency Eject hole.
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PC Back Panel details
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1. AC-Power in (From
Main or UPS)
2. AC-Power out (To
Monitor)
3. Exhaust Fan.
4. Keyboard Port(For AT2
Keyboard connector)
5. Keyboard port (For PS2
Keyboard connector)
6. Mouse Port(For PS2
Mouse connector)
7. USB Port (2 No"s for
Inkj et Printer)
8. Fire wall port
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9. Serial Port (COM1 and
COM2 for Mouse /
Modem Connector)
10. Parallel Port (LPT1 for
printer connection)
11. Video Port (For Monitor)
12. Multimedia Ports. (For
mic, speaker, line-in
connection)
13. Network Ports (RCA-
JACK / BNC for network
cable connection)
14. SCSI ports (For
connecting external SCSI
hard disk)
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PRACTICE CONNECTING THE CABLES
INTO THE BACK PANEL OF COMPUTER
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PHYSICAL COMPONENTS OF COMPUTER
Mother Board: It is also called as system board
/ panel board / main board. It is a large printed
circuit board (PCB) inside a system unit. It holds
the majority of crucial components of the system
providing connectors for other peripherals.

CMOS
Socket 7
CPU
AGP Slot
RAM Slots
PCI Slots
Floppy
EIDE Connector
Connectors
ISA
Slots
Battery
Motherboard
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Processor Chip: It is also called as Central Processing
Unit (CPU). It carries out the instructions of a computer
program by performing the basic arithmetical, logical, and
input/output operations of the system. All calculations and
processing of computer is executed using processor. The
CPU plays a role of somewhat analogous to the brain in
the computer.
Two typical components of a CPU are the Arithmetic
Logic Unit (ALU), which performs arithmetic and logical
operations, and the Control Unit (CU), which extracts
instructions from memory and decodes and executes them,
calling on the ALU when necessary.
Eg: Intel Pentium 4, AMD Athlon

C.P.U.
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MEMORY
Memory: It is a storage device used to store information in
computers. The semiconductor memory is organized into
memory cells or bistable flip-flops, each storing one
binary bit (0 or 1). The memory cells are grouped into
words of fix word length, for example 1, 2, 4, 8, 16, 32, 64
or 128 bit. Each word can be accessed by a binary address
of N bit, making it possible to store 2 raised by N words in
the memory

What are bits, bytes, and other units of measure
for digital information?
A bit is a binary digit, the smallest increment of data on a
computer. A bit can hold only one of two values: 0 or 1,
corresponding to the electrical values of off or on,
respectively.
Because bits are so small, you rarely work with information
one bit at a time. Bits are usually assembled into a group of
eight to form a byte. A byte contains enough information to
store a single ASCII character, like “k” (maybe 00101101).

So in computer jargon, the following
memory units are used:
Unit
1 bit 1 nibble 1
Byte
1 Kilobyte (KB)
1 Megabyte
(MB) 1 Gigabyte
(GB)
1 Terabyte (TB)
1 Petabyte (PB)
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Equivalent
0 or 1
a group of 4 bits a
group of 8 bits 103
(i.e.,1024 bytes) 106
bytes 109 bytes 1012
bytes 1015 bytes
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There are different types of memories
in computers:-
Registers: Small memory, internal to processor, where actual
processing is done.
Cache Memory: Catches some of content of main memory
which current in use of the processor.
Main Memory (RAM/ROM): Large memory which is fast
but not as internal Processor memory.
All the above memories are volatile memories
because the stored information is lost when the power is
removed from the system.
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RAM; Random Access Memory. It is volatile memory.
It allows both read/write operations.
ROM: Read Only Memory. It is non-volatile memory.
It allows only read operations.
Random Access Memory (RAM) is a form of
computer data storage. Today, it takes the form of integrated
circuits that allow stored data to be accessed in any order.
Other memory devices (magnetic tapes, floppy discs, CDs and
DVDs) can access the storage data only in a predetermined
order, because of mechanical design limitations. The two
main forms of modern RAM are Static RAM (SRAM) and
Dynamic RAM (DRAM).
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R.A.M.
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SECONDARY MEMORY
Secondary Memory; Very large memory. It is a nonvolatile
permanent memory.
• Eg; Magnetic disk (Hard / Floppy) memory, Magnetic Tape
memory etc.,
HDD (Hard Disk Drive): It is a mechanism which drives
Hard Disks to rotate and controls the flow of data between
hard disk and computer. Both hard disk and hard disk
drive comes in a single unit, it is permanently fixed in a
system unit.

A Hard Disk Drive (HDD) is device for storing and
retrieving digital information, primarily computer data. It
consists of one or more rigid (hence "hard") rapidly
rotating discs (platters usually rotating at 7,200 RPM)
coated with magnetic material, and with magnetic heads to
write data to the surfaces and read it from them.
Magnetic recording A hard disk drive records data
by magnetizing a thin film of ferromagnetic material on a
disk. Sequential changes in the direction of magnetization
represent binary data bits. The data is read from the disk
by detecting the transitions in magnetization.

A typical HDD design consists of a spindle that holds
flat circular disks, also called platters, which hold the
recorded data. The platters are made from a nonmagnetic
material, usually aluminium alloy and are coated with a
shallow layer of magnetic material typically 10-20 nm in
depth, with an outer layer of carbon for protection. Today,
most consumer hard drives operate at a speed of 7,200 rpm.
Information is written to and read from a platter as it
rotates past devices called read and write heads operate
very close (often tens of nanometers) over the magnetic
surface. The read-and-write head is used to detect and
modify the magnetization of the material immediately under
it.

In modern drives there is one head for each
magnetic platter surface on the spindle, mounted
on a common arm. An actuator arm (or access
arm) moves the heads on an arc (roughly
radially) across the platters as they spin, allowing
each head to access almost the entire surface of
the platter as it spins.
A write head magnetizes a region by
generating a strong local magnetic field, and a
read head detects the magnetization of the
regions.

Hard Disk Drive
66

Spindie Head
Power Connector
Actuator
Jumper Block
IDE Connector
Platter
Actuator Arm
Hard Disk Drive
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FDD (Floppy Disk Drive): Floppy disk drive is a
mechanism which drives FD to rotate for read / write
operations. It has a control circuit which transfers data
between FD and computer.
Floppy
Floppy Disk Drive
FLOPPY DISK DRIVE

A floppy disk, or diskette, is a disk storage medium
composed of a disk of thin and flexible magnetic storage,
sealed in a rectangular plastic carrier lined with fabric that
removes dust particles.
Housing
Paper
Hub
Write-protect tab
Magnetic
disk
Paper ring
Plastic flap
Spring
Shutter
Inside of a Floppy Disk Drive
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CDDfR/W! (Compact Disk Drive TRead / Write):
The CD-Drive is a mechanism used to read / write
digital information on a CD. CD-Drives are available in
different forms,
1. CD-Drive for reading purpose only (CD/R)
2. CD-Drive for both reading and writing (CD/RW)
CD drive is an optical disc drive that uses LASER light
or Electromagnetic waves of suitable wavelength as part of
the process of reading or writing data to or from CD. CD
drives are commonly both readers and recorders, also called
burners or writers. Compact Disc (CD), Digital Versatile Disc
(DVD) and Blue-ray Disc (BD) are common types of
Basipli^puter Skills - Grille
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COMPACT DISK DRIVE

Compact Disk Drive
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A recorder encodes (or burns) data onto a
recordable CD-R, DVD-R, DVD+R. or BD-R disc
(called a “blank”) by selectively heating parts of
an organic dye layer with a laser. This changes the
reflectivity of the dye. thereby creating marks that
can be read like the pits and lands on pressed
discs.
Initially. CD lasers with a wavelength of 780
nm were used. being within infrared range. For
DVDs. the wavelength was reduced to 650 nm
(red color). and the wavelength for Blu-ray Disc
was reduced to 405 nm (violet color).
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A CD is made from 1.2 millimetres (0.047 in)
thick,.polycarbonate plastic and weighs 15-20 grams. A thin
layer of aluminium or, more rarely, gold is applied to the
surface making it reflective. The metal is protected by a film
of lacquer normally spin coated directly on the reflective
layer. The label is printed on the lacquer layer, usually by
screen printing or offset printing.
For rewritable CD-RW, DVD-RW, DVD+RW, DVD-
RAM, or BD-RE media, the laser is used to melt a
crystalline metal alloy in the recording layer of the disc.
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CD data is stored as a series of tiny indentations
known as "pits", encoded in a spiral track moulded into the
top of the polycarbonate layer. The flat areas between pits
are known as "lands". Each pit is approximately 100 nm
deep by 500 nm wide, and varies from 850 nm to 3.5 pm
in length. The distance between the tracks, the pitch, is 1.6
pm.
The pits and lands themselves do not directly
represent the zeros and ones of binary data. Instead, non-
return-to-zero encoding is used: a change from pit to land
or land to pit indicates a one, while no change indicates a
series of zeros.

Compact Disk (CD)
Optical Disk Drive Mechanism
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SMPS: It refers to Switched Mode Power Supply. It is
a buffer circuit, make the computer system load,
compatible with its power source.
A switched-mode power supply is an electronic
power supply that incorporates a switching regulator to
convert electrical power efficiently. Like other power
supplies, an SMPS transfers power from a source, like
mains power, to a load, such as a PC, while converting
voltage (from 230 V to 12V or 5V) and current (from AC
to DC) characteristics. An SMPS is usually employed to
efficiently provide a regulated output voltage.
Switched Mode Power Supply

S.M.P.S.

Ports:- Ports are the sockets available on the system
box. They are used to connect external devices to the
computer.
Serial Port :- It is a Serial Communication physical
interface through which information transfers in or out one
bit at a time (in contrast to a parallel port). Serial Port is
used primarily to connect a Mouse or Keyboard to the PC.
It transfers data bit by bit.

Parallel Port It is a type of interface used to connect a printer
to the computer. It transfers 8 or more data bit
simultaneously.
ACK -* 10
EUSY -- 11
Paper Out —*■ 12
Select
14 ■+—► Line Feed
15 3— Error
16 RESET
17 —*■ Select Printer
13 - GMD
19 - GND
20 - GMD
21 - GND
22 - GND
23 - GND
24 - GND
25 - GMD
Parallel Port or Printer Port
79

USB (Universal Serial Bus):- It combines all the
advantages of multi-platform serials ports. We can connect
mouse, keyboard, digital camera, printer and storage
devices to USB.
Universal Serial Bus (USB) was designed in the
mid-1990s to standardize the connection of computer
peripherals both to communicate and to supply electric
power that defines the cables, connectors and
communication protocols used in a bus for connection,
communication and power supply between computers and
electronic devices.

U.S.B.
E-RESOURCE
81

VGA / SVGA / AGP
VGA (Video Graphic Array):- Video Graphics
Array is an IBM video standard capable of displaying
higher resolution of 800x600 pixels, with 256/6 bit colors
and 1024x780 pixels, with 256/16 bit colors.
AGP (Accelerated Graphic Port):- Accelerated
Graphics Port is a video card which interfaces the monitor
to the Mother board. An AGP card will allow game and 3D
application developers to store and retrieve larger, more
realistic textures in system memory rather than video
memory.

83

SOUND CARD It is an expansion card that
records and plays back sound by translating the
analog signal from a microphone into a digitized
form that the computer can store and process and
then translating back the modified data into
analog signals or sound.
A sound card (also known as an audio card)
is an internal computer expansion card that
facilitates the input and output of audio signals
to and from a computer under control of
computer

Sound Card
85

Network Card;- If we want to connect our computer
to another computer we will need a Network Interface
Card (NIC). NIC is an adapter card that physically
connects one computer to a network cable and to another
computer that has the same type of NIC.

MODEM (Modulator - Demodulator);- In order to go
online and surf the web or check E-mail, we need a
modem to connect to an internet service provider (ISP). A
modem is a device that we connect to a computer and to a
phone line. Basically, modems do for computers what a
telephone does for humans.
A modem is a device that modulates an analog carrier
signal to encode digital information, and also demodulates
such a carrier signal to decode the transmitted information.
The goal is to produce a signal that can be transmitted
easily and decoded to reproduce the original digital data.

There are two types of MODEM namely,
1) Internal MODEM: It is integrated with mother board
or attached to mother board.
2) External MODEM: It is an external device,
connected to mother board using serial port.
MODEM
88

INPUT DEVICES
Innut Devices: The input devices are used
for transferring / entering user command or data
or choice to the computer. Input unit captures or
reads data / information and converts these data
into form that computer understands and
transfers these data to memory unit for
execution.
• Eg: Keyboard, Mouse, Scanner, Joystick,
Floppy, CD, DVD etc.,

The keyboard is default input device, which bridges
the gap between the operator and their computer system.
The user communicates with the computer by typing
instruction or pressing keys on the key board. The keys on a
key board is almost similar to typewriter keys with some
additional keys such as programmed function keys,
programmable keys, cursor control keys and numeric keys.
Keyboard has an arrangement of buttons or keys, to act
as mechanical levers or electronic switches.
In normal usage, the keyboard is used to type text and
numbers into a word processor, text editor or other
programs.
KEY BOARD

Standard "full-travel" alphanumeric
keyboards have keys that are on three-quarter
inch centers (0.750 inches, 19.05 mm), and have
a key travel of at least 0.150 inches (3.81 mm).
Windows standard keyboards has 104-keys,
which includes alphabetic characters, punctuation
symbols, numbers and a variety of Function keys.
The internationally common 102/105 key
keyboards have a smaller 'left shift' key and an
additional key with some more symbols between
that and the letter to its right (usually Z or Y).
The Enter key is usually shaped differently.

Standard Keyboard (104 Keys)
92

Foldable Keyboard
Virtual Laser Keyboard
E-RESOURCE

A mouse is an input device. That can be
moved around a flat surface by the user. The
movement of the mouse is sensed by the
computer and translated into curser movements.
The mouse has switches on its back to send
command to the computer.
A mouse is a pointing device that functions
by detecting 2 dimensional motion (X and Y axis)
relative to its supporting surface (usually a Mouse
Pad). Physically, a mouse consists of an object
held under one of the user’s hands, with one or
more buttons.
MOUSE

The mouse sometimes features other elements, such
as "wheels", which allow the user to perform various
system-dependent operations, or extra buttons or features
that can add more control or dimensional input. The
mouse's motion typically translates into the motion of a
pointer on a display, which allows for fine control of a
graphical user interface.
Optical and laser mice
Optical mice make use of one or more Light Emitting
Diodes (LEDs) and an imaging array of photodiodes to
detect movement relative to the underlying surface, rather
than internal moving parts as does a mechanical mouse. A
laser mouse is an optical mouse that uses coherent (laser)
light.

Mechanical Mouse
Optical Mouse
96

Scanner is a device that optically scans images,
printed text, handwriting, or an object, and converts it to a
digital image. Common examples found in offices are
variations of the desktop (or flatbed) scanner where the
document is placed on a glass window for scanning.
In a scanner, the object is placed on a scanner and the
object scanned from left to right, at the end, image of an
object will appears on the screen. Scanner consists of two
components, the first one to illuminate the object so that
the optical image can be captured and the other to convert
the optical image into digital format for storage by
computer.
SCANNER

Flatbed Scanner
98

A joystick is an interactive input device consisting of
a stick that pivots on a base and reports its angle or
direction to the device it is controlling. Joysticks are often
used to control video games, and usually have one or more
push-buttons whose state can also be read by the computer
.
JOYSTICK

OUTPUT DEVICES
Output Devices: An output device is a computer
hardware equipment used to communicate the results of
data processing carried out by computer by converting the
electronically generated information into human-readable
form.
Output devices produces information in the form of
printouts, display on monitor etc., Output devices converts
processed data into form that the user understands
instantly.
• Eg: Monitor, Printer, Plotter, Speakers, Headphones,
Projectors etc.,

Monitor is a default output device. It shows the soft
copy of the output.
A monitor or display or visual display unit) is an
electronic visual display for computers. The monitor
comprises the display device, circuitry, and an enclosure.
The display device in modern monitors is typically a Thin
Film Transistor or Liquid Crystal Display (TFT-LCD) thin
panel, while older monitors use a Cathode Ray Tube (CRT)
about as deep as the screen size.
MONITOR

Cathode Ray Tube
The first computer monitors used Cathode Ray
Tubes (CRT). Until the early 1980s, they were known as
video display terminals and were physically attached to
the computer and keyboard.
cathode
focusing
anode
control
filament
accelerating
electron
electrode beam phospltor
screen

TFT-LCD
Thin film transistor liquid crystal display (TFT-
LCD) is a variant of LCD which uses thin-film transistor
(TFT) technology to improve image quality (e.g.,
addressability, contrast). TFT LCD is one type of Active
matrix LCD, though all LCD-screens are based on matrix
addressing.

LED and OLED
Organic light-emitting diode (OLED) monitors
provide higher contrast and better viewing angles than
LCDs, and are predicted to replace

PRINTER
A printer is a peripherals which produces the hard
copy output of a text or graphics of documents stored in
electronic form, usually on physical print media such as
paper or transparencies.
Many printers are primarily used as local peripherals,
and are attached by a printer cable or, in most new printers,
a USB cable to a computer which serves as a document
source.

There are two types of printers. Namely,
1) Impact Printer:- The paper actually comes in
contact with a type element in order to print.
Eg: Dot Matrix Printer
2) Non-Impact Printer: The print is created by
some other means.
Eg: Laser Printer, Inkjet Printer.

PLOTTER
Plotter is an output device similar to printer, which
produce hard copy output of graphs, maps, charts, etc., on
any sort of paper. The plotter is very convenient and
invaluable tool in business graphics applications for
printing on very large size papers like Film posters,
AutoCAD building drawings etc.,

An Operating System is a program that controls
the overall activity of your computer. It manages the
various files in your computer. It allows the computer
hardware to interact with your computer software.
Operating
System
Manages Oisks
A Files
Monitors
Activities
E-RESOURCE
Examples of Operating Systems are Windows, Mac.
Unix, Linux etc., Allocates
Resources
OPERATING SYSTEM

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