Computer Peripherals and Internet

105th FoCARS

Foundation Course For Agricultural Research Service

Digital Repository of
Course Materials

Administrative Agriculture Scenario &
Procedures Research Systems

ICT Management Research Project
Management

Technology Diffusion © ICT Management
and Adoption
Technology
Management & IP

Human Resources
Management

• Basics of Computers
• Computer Peripherals and Internet
• An Overview of Database management
• General Features of MS EXCEL
• Statistical Analysis using MS-EXCEL
• Multimedia
• Application of Bioinformatics in Agriculture
• GIS and its Use in Agriculture

Course Coordinators
K. Kareemulla and S. Ravichandran

Support Team
P. Krishnan, K.V. Kumar and P. Namdev

Computer Peripherals and Internet

M.Balakrishnan1 and G.R.K.Murthy2

Introduction

A computer peripheral is a device that is connected to a computer but is not part of the core
computer architecture. The core elements of a computer are the central processing unit, power
supply, motherboard and the computer case that contains those three components. Technically
speaking, everything else is considered a peripheral device. However, this is a somewhat narrow
view, since various other elements are required for a computer to actually function, such as a hard
drive and random-access memory (or RAM).

Most people use the term peripheral more loosely to refer to a device external to the
computer case. You connect the device to the computer to expand the functionality of the system.
For example, consider a printer. Once the printer is connected to a computer, you can print out
documents. Another way to look at peripheral devices is that they are dependent on the computer
system. For example, most printers can't do much on their own, and they only become functional
when connected to a computer system.

Types of Peripheral Devices

There are many different peripheral devices, but they fall into three general categories:
 Input devices, such as a mouse and a keyboard
 Output devices, such as a monitor and a printer
 Storage devices, such as a hard drive or flash drive

Some devices fall into more than one category. Consider a CD-ROM drive; you can use it to
read data or music (input), and you can use it to write data to a CD (output). Peripheral devices can
be external or internal. For example, a printer is an external device that you connect using a cable,
while an optical disc drive is typically located inside the computer case. Internal peripheral devices
are also referred to as integrated peripherals. When most people refer to peripherals, they typically
mean external ones.

The concept of what exactly is 'peripheral' is therefore somewhat fluid. For a desktop
computer, a keyboard and a monitor are considered peripherals - you can easily connect and
disconnect them and replace them if needed. For a laptop computer, these components are built
into the computer system and can't be easily removed. The term 'peripheral' also does not mean it is
not essential for the function of the computer. Some devices, such as a printer, can be disconnected
and the computer will keep on working just fine. However, remove the monitor of a desktop
computer and it becomes pretty much useless.

1 Principal Scientist, ICM Division , NAARM
2 Principal Scientist, ESM Division, NAARM

105th FOCARS

Central Processing Unit - Though the term relates to a specific chip or the processor a CPU's
performance is determined by the rest of the computer's circuitry and chips.
Currently the Pentium chip or processor, made by Intel, is the most common CPU though there
are many other companies that produce processors for personal computers. Examples are the
CPU made by Motorola and AMD.

With faster processors the clock speed becomes more important. Compared to some of the first
computers which operated at below 30 megahertz (MHz) the Pentium chips began at 75 MHz in
the late 1990's. Speeds now exceed 3000+ MHz or 3 gigahertz (GHz) and different chip
manufacturers use different measuring standards (check your local computer store for the latest
speed). It depends on the circuit board that the chip is housed in, or the motherboard, as to
whether you are able to upgrade to a faster chip. The motherboard contains the circuitry and
connections that allow the various component to communicate with each other.

Though there were many computers using many different processors previous to this I
call the 80286 processor the advent of home computers as these were the processors that made
computers available for the average person. Using a processor before the 286 involved learning a
proprietary system and software. Most new software are being developed for the newest and
fastest processors so it can be difficult to use an older computer system.

Motherboard and Processor

An experience with PC depends on a combination of the processor, the memory, the
motherboard, the graphics and sound components and the hard disk that the PC has. The first two
things to consider when buying a PC are the motherboard and the processor, which are
interdependent. A particular processor only goes on a particular kind of motherboard. For each
kind of motherboard, there might be different brands available, with different features. It is better
to choose processor and then decide brand of motherboard, based on its features.

Motherboard

The motherboard is the base of a PC—all the components fit on it. It also has a master brain
called the chipset which decides what will work and how. The motherboards contains 3 essential
parts: Concept Map of Motherboards and main components

 Expansion Capabilities
 CPU (Processor)
 RAM (Memory)

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Nearly all modern motherboards will contain one or more expansion slots. The most common
type of slot is the PCI slot, which is used for peripherals such as TV Tuners, Network Cards, and
USB/Firewire Cards. The next most common expansion slot is the PCIe, or PCI Express, which is
nearly always used for video cards.

Of course nothing in the computer can work without the processing power of the CPU. Intel is the
largest manufacturer of these in the world. This is the part that is referred to when you hear the ads
"Intel Inside". The processor is measured by the speed at which it operates, or gigahertz. It is
essential when picking a processor that a pin-compatible motherboard is also selected.

The final essential addition to a motherboard is memory, or RAM. Memory is where
programs and data reside when you are working on them. It also holds the data for the processor
until it is ready to use it. The more memory there is in the computer, the more data it can hold and
work on at one time. This means that you can have more programs and files open at once without
the computer slowing down.The motherboard is chosen based on

Processor: The processor sits on a main board called the motherboard, in a particular slot or
socket. This slot determines which processor will go on the motherboard.

Graphics: Onboard graphics Motherboards can also be chosen based on whether they have
integrated graphics on them or not. The earlier graphics cards used to be PCI cards (fitting on the
PCI slot on the motherboard). Later something called the Accelerated Graphics Port, or AGP was
developed especially for graphics cards and made graphics faster. There are motherboards that
had graphics capabilities built into them. However, the graphics from these are only good enough
for browsing, Word, Excel, etc, not for heavy 3D games or graphics. The Intel 810 chipset come
with onboard graphics, and are a real money saver. For serious gaming and graphics, we need the
AGP slot to be there on the motherboard, and add a graphics card to it. The Intel 815 chipset
based motherboards come with onboard graphics, but also have an AGP slot on them, so we can
go with onboard graphics initially and get a good graphics card later. The new P4s go on the
Intel 850 chipset based motherboards, which have a slot for RDRAM memory modules, and an
AGP slot.Look for the number of slots for add-on cards. Apart from the AGP slot, look for the

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number of PCI slots on the board for- internal modem, TV tuner/video capture cards and other
accessories.

Look for the number of RAM slots and how much RAM it can take. Some new motherboards
have slots to take even 2 GB of RAM.

Buses

A bus is a subsystem that transfers data between computer components inside a computer
or between computers. Unlike a point-to-point connection, a bus can logically connect several
peripherals over the same set of wires. Each bus defines its set of connectors to physically plug
devices, cards or cables together. There are two types of buses: internal and external. Internal buses
are connections to various internal components. External buses are connections to various external
components. There are different kinds of slots that internal and external devices can connect to.

Processor

The processor, which is the brain of a PC, is often chosen with price as the main criteria,
but changing the processor often means changing the motherboard. The other extreme, when the
budget is unlimited, is to scramble for the latest, fastest processor. There will always be a faster
one just around the corner but it should not be exceedingly beyond our requirements, say if our
applications are simply writing documents in Word, browsing the Net and sending and receiving
e-mail. Choose the processor keeping in mind our activities on the PC, but don‟t be stingy either.
Both the processor as well as motherboard should be chosen keeping in mind the fact that they‟re
both very tough to upgrade—because they‟re expensive and when we change them, we have to
change a lot of things along with them, almost like overhauling the PC.

Types Of Processors

Pentium and AMD processor are some of the processor options. AMD processors have
been around for a long time. The processors that made an impact in recent times are the Duron
and the Athlon. Intel has the value option, Celeron and the high-performance processor, P4 ,
while AMD has Duron for value proposition and Athlon for high-end one. Nowadays, processors
are coming in as dual core which is a CPU with two separate cores on the same die, each with its
own cache. It's the equivalent of getting two microprocessors in one. A dual-core processor uses
slightly less power than two coupled single-core processors, principally because of the increased
power required to drive signals external to the chip and because the smaller silicon process
geometry allows the cores to operate at lower voltages; such reduction reduces latency.

Most of the processors are in 32-bit. This is the number of bits that can be processed in
parallel. Or the number of bits used to represent a single element in a data format. Future
software is going to be available in 64 bit format increasingly.

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Realities of bits in Processors

 A 32 bit CPU can process 32 bits of data at a time. If data has more than 32 bits,
processor takes up „32‟ bits of data first and processes it and then next group of „32‟
bits of data is taken up for processing

 Hence a 64-bit CPU performs better than a 32 bit processor
 64 bit is very useful for 3d animators, game developers, CAD/CAM engineers,

automobile manufacturers
 A 32 bit CPU can access only 4 GB (232 ) of main memory while a 64 bit CPU can

address up to 17 billion GB which is more than enough for any present and near
future application
 A 64 bit CPU needs 64 bit OS and 64 bit applications to deliver optimum results.
Some 64 bit CPUs allows to run 32 bit applications and OS but it is a point of under
utilization.
 A 64 bit processor doubles the bandwidth with the processor core while dual
coregives 2 processor cores inside a single processor. A 64 bit is like fitting a car with
a more powerful engine while a dual core is fitting the same with 2 engines which
may or may not be as powerful as the replaced one.
 The entry level is 915 chipset while others include 925,945 and 955 chipsets.
 945 and 955 based chipsets support dual core processors (called Pentium D).

Internal

Types of Slots

There are many different kinds of internal buses, but only a handful of popular ones.
Different computers come with different kinds and number of slots. It is important to know what
kind and number of slots you have on your computer before you go out and by a card that matches
up to a slot you don‟t have.

PCI

PCI (Peripheral Component Interconnect) is common in modern PCs. This kind of bus is
being succeeded by PCI Express. Typical PCI cards used in PCs include: network cards, sound
cards, modems, extra ports such as USB or serial, TV tuner cards and disk controllers. Video cards
have outgrown the capabilities of PCI because of their higher bandwidth requirements.

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PCI Slots

PCI Express

PCI Express was introduced by Intel in 2004. It was designed to replace the general-
purpose PCI expansion bus and the AGP graphics card interface. PCI express is not a bus but
instead a point-to-point connection of serial links called lanes. PCI Express cards have faster
bandwidth then PCI cards which make them more ideal for high-end video cards.

PCMCIA

PCMCIA (also referred to as PC Card) is the type of bus used for laptop computers. The
name PCMCIA comes from the group who developed the standard: Personal Computer Memory
Card International Association. PCMCIA was originally designed for computer memory
expansion, but the existence of a usable general standard for notebook peripherals led to many
kinds of devices being made available in this form. Typical devices include network cards,
modems, and hard disks.

AGP

AGP (Accelerated Graphics Port) is a high-speed point-to-point channel for attaching a
graphics card to a computer‟s motherboard, primarily to assist in the acceleration of 3D computer

graphics. AGP has been replaced over the past couple years by PCI Express. AGP cards and

motherboards are still available to buy, but they are becoming less common.

AGP Slot
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Hard Disk

When dealing with storage space required for the programs and files, space and speed
matter. 40 GB hard disks are common and adequate. As the capacity increases, the cost per unit
memory reduces. If we need to frequently transport lots of data to office and back, USB hard
disk is better. These are mobile hard disks and have a flash RAM that can be connected to the
USB port to store data in capacities of 16, 32, 64, 128 MB and 6 GB, 20 GB. The price range
starts from Rs 3,000. A 40 GB 5400 rpm disk costs Rs 4,500. Some brands available in the
market are Samsung, Seagate, Maxtor, and Western Digital.

Features of a hard disk

i. The interface speed: All recent model motherboards and hard disks support the IDE/ATA
interface. For those who need to work with huge files at blazing speeds, a SCSI hard disk is the
best option. But this will require a SCSI host adapter. The IDE/ATA interface available now is
rated at 100 Mbps. But a faster interface alone won‟t have a great bearing on the performance.
The controller too has to support it. That‟s where your motherboard specs come in.

ii. Spindle speed: The faster the speed, better the performance, ranging from 5400 rpm to
7200 rpm for ordinary purposes. For video rendering sort of work , go for higher speeds or
opt for SCSI drives that offer even 10000 to 15000 rpm speeds.

iii. Seek time: This is measured in milliseconds. How quickly can the disk store or retrieve
data influences the disk performance. The lesser the seek time, the faster the disk
performance.

Nowadays hard disks are coming with faster spindle speeds, larger caches, better
reliability, and increased data transmission speeds. IDE is the commonly used hard disk. New
standard known as Serial ATA (Serial Advanced Technology Attachment). is around now
and is destined to become “the standard”

Tips for better disk management

 Partition,
 defragment,
 remove temporary files (files with extension .tmp),

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 check for bad sectors ,
 remove unused programs regularly,
 regularly scan for viruses,
 protect the data and
 be organized.

Input

Input devices are absolutely crucial to computers. The most common input devices are
mice and keyboards which barely every computer has. A new popular pointing device that may
eventually replace the mouse is touch screen which you can get on some tablet notebooks. Other
popular input devices include microphones, webcams, and fingerprint readers which can also be
built in to modern laptops and desktops. A scanner is another popular input device that might be
built-in to your printer.

Keyboard - The keyboard is used to type information into the computer or input information.

There are many different keyboard layouts and sizes with the most common for Latin based

languages being the QWERTY layout (named for the first 6 keys). The standard keyboard has

101 keys. Notebooks have embedded keys accessible by special keys or by pressing key

combinations (CTRL or Command and P for example). Ergonomically designed keyboards are

designed to make typing easier. Hand held devices have various and different keyboard

configurations and touch screens.

Some of the keys have a special use. They are referred to as command keys. The 3 most
common are the Control or CTRL, Alternate or Alt and the Shift keys though there can be more
(the Windows key for example or the Command key). Each key on a standard keyboard has one
or two characters. Press the key to get the lower character and hold Shift to get the upper.

Removable Storage and/or Disk Drives

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The same kinds of CD and DVD drives that could come built-in on your computer can
also be attached externally. You might only have a CD-ROM drive built-in to your computer but
you need a CD writer to burn CDs. You can buy an external CD writer that connects to your
USB port and acts the same way as if it was built-in to your computer. The same is true for DVD
writers, Blu-ray drives, and floppy drives. Flash drives have become very popular forms of
removable storage especially as the price of flash drives decreases and the possible size for them
increases. Flash drives are usually USB ones either in the form USB sticks or very small,
portable devices. USB flash drives are small, fast, removable, rewritable, and long-lasting.
Storage capacities range from 64MB to 32GB or more. A flash drive does not have any
mechanically driven parts so as opposed to a hard drive which makes it more durable and smaller
usually.

Non-removable Storage

Non-removable storage can be a hard drive that is connected externally. External hard
drives have become very popular for backups, shared drives among many computers, and simply
expanding the amount of hard drive space you have from your internal hard drive. External hard
drives come in many shapes and sizes like flash drives do. An external hard drive is usually
connected by USB but you can also have a networked hardrive which will connect to your
network which allows all computers on that network to access that hard drive.

Digital flash drives work slightly differently as they use memory cards to store information so
there are no moving parts. Digital cameras also use Flash memory cards to store information, in
this case photographs. Hand held devices use digital drives and many also use removable or
built in memory cards.

USB Flash Drive
Mouse - Most modern computers today are run using a mouse controlled pointer. Generally if
the mouse has two buttons the left one is used to select objects and text and the right one is used
to access menus. If the mouse has one button (Mac for instance) it controls all the activity and a
mouse with a third button can be used by specific software programs.

One type of mouse has a round ball under the bottom of the
mouse that rolls and turns two wheels which control the
direction of the pointer on the screen. Another type of
mouse uses an optical system to track the movement of the

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mouse. Laptop computers use touch pads, buttons and other devices to control the pointer. Hand
helds use a combination of devices to control the pointer, including touch screens.
Note: It is important to clean the mouse periodically, particularly if it becomes sluggish. A ball
type mouse has a small circular panel that can be opened, allowing you to remove the ball. Lint
can be removed carefully with a tooth pick or tweezers and the ball can be washed with mild
detergent. A build up will accumulate on the small wheels in the mouse. Use a small instrument
or finger nail to scrape it off taking care not to scratch the wheels. Track balls can be cleaned
much like a mouse and touch-pad can be wiped with a clean, damp cloth. An optical mouse can
accumulate material from the surface that it is in contact with which can be removed with a
finger nail or small instrument.

Output
There are lots of different kinds of output devices that you can get for your computer.

The absolute most common external output device is a monitor. Other very popular output
devices are printers and speakers. There are lots of different kinds of printers and different sizes
of speakers for your computer. Monitors are connected usually through the HD-15 connector on
your video card. Printers are usually connected through a USB port. Speakers have their own
audio out port built-in to the sound card.

Monitors - The monitor shows information on the screen when you type. This is
called outputting information. When the computer needs more information it will display a
message on the screen, usually through a dialog box. Monitors come in many types and sizes.
The resolution of the monitor determines the sharpness of the screen. The resolution can be
adjusted to control the screen's display.

Monitor
Most desktop computers use a monitor with a cathode tube or liquid crystal display. Most
notebooks use a liquid crystal display monitor.
To get the full benefit of today's software with full colour graphics and animation, computers
need a colour monitor with a display or graphics card.

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Printers - The printer takes the information on your screen and transfers it to paper or a hard
copy. There are many different types of printers with various levels of quality. The three basic
types of printer are; dot matrix, inkjet, and laser.

 Dot matrix printers work like a typewriter transferring ink from a ribbon to paper with a
series or 'matrix' of tiny pins.

 Ink jet printers work like dot matrix printers but fires a stream of ink from a cartridge
directly onto the paper.

 Laser printers use the same technology as a photocopier using heat to transfer toner onto
paper.



Modem - A modem is used to translate information transferred through telephone lines, cable,
satellite or line-of-sight wireless.
The term stands for modulate and demodulate which changes the signal from digital, which
computers use, to analog, which telephones use and then back again. Digital modems transfer
digital information directly without changing to analog.

Modems are measured by the speed that the information is transferred. The measuring
tool is called the baud rate. Originally modems worked at speeds below 2400 baud but today
analog speeds of 56,000 are standard. Cable, wireless or digital subscriber lines can transfer
information much faster with rates of 300,000 baud and up.

Modems also use Error Correction which corrects for transmission errors by constantly
checking whether the information was received properly or not and Compression which allows
for faster data transfer rates. Information is transferred in packets. Each packet is checked for
errors and is re-sent if there is an error.

Anyone who has used the Internet has noticed that at times the information travels at
different speeds. Depending on the amount of information that is being transferred, the
information will arrive at it's destination at different times. The amount of information that can
travel through a line is limited. This limit is called bandwidth.

There are many more variables involved in communication technology using computers,
much of which is covered in the section on the Internet.

Scanners- Scanners allow you to transfer pictures and photographs to your computer. A scanner
'scans' the image from the top to the bottom, one line at a time and transfers it to the computer as
a series of bits or a bitmap. You can then take that image and use it in a paint program, send it
out as a fax or print it. With optional Optical Character Recognition (OCR) software you can

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convert printed documents such as newspaper articles to text that can be used in your word
processor. Most scanners use TWAIN software that makes the scanner accessible by other
software applications.

DIGITAL CAMERA
Digital cameras allow you to take digital photographs. The images are stored on a memory chip
or disk that can be transferred to your computer. Some cameras can also capture sound and
video.

Digital camera comes with accessories like a

 battery pack, Digital cameras consume more power than

the film-based cameras do, plus they have the added power

consumption of the LCD preview screen. So it‟s very

important that they have enough power to last a good number of shots. It‟s very important

that the battery be rechargeable

 amemory card, The 8 MB, 16 MB memory cards that come with camera are just not

good enough. Buy an extra 32 or 64 MB card. Floppy-based cameras are also available.

 an AC power adapter and
 something to connect camera to the PC.

Case - The case houses the microchips and circuitry that run the computer. Desktop models
usually sit under the monitor and tower models beside. They come in many sizes, including
desktop, mini, midi, and full tower. There is usually room inside to expand or add components at
a later time. By removing the cover off the case you may find plate covered, empty slots that
allow you to add cards. There are various types of slots including IDE, ASI, USB, PCI and
Firewire slots.

Depending on the type notebook computers may have room to expand . Most Notebooks
also have connections or ports that allows expansion or connection to exterior, peripheral devices
such as monitor, portable hard-drives or other devices.

Web Camera

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Webcams are used to take snapshots or record short video clips which you can then send
by e-mail to friends and relatives around the world. Another cool place where Webcams can be
put to use is video chat which lets us actually see the person we are chatting with.

Some of the Webcams available are
 Vcam Eye for PC
 IBM PC Camera
 Logitech QuickCam Home
 NetView PC Camera
 Kensington VideoCAM
 Creative WebCam Go Plus
 Kensington VideoCAM Super VGA
 Logitech QuickCam Pro

Cards - Cards are components added to computers to increase their capability. When adding a
peripheral device make sure that your computer has a slot of the type needed by the device.
Sound cards allow computers to produce sound like music and voice. The older sound cards
were 8 bit then 16 bit then 32 bit. Though the human ear can't distinguish the fine difference
between sounds produced by the more powerful sound card they allow for more complex music
and music production.

Sound Cards
Graphic cards allow computers to produce colour (with a
colour monitor of course). The first colour cards were 2 bit
which produced 4 colours [CGA]. It was amazing what could
be done with those 4 colours. Next came 4 bit allowing for 16
[EGA and VGA ]colours. Then came 16 bit allowing for 1064 colours and then 24 bit which
allows for almost 17 million colours and now 32 bit and higher allow monitors to display almost
a billion separate colours.

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Video cards allow computers to display video and animation. Some video cards allow
computers to display television as well as capture frames from video. A video card with a digital
video camera allows computers users to produce live video. A high speed connection is required
for effective video transmission.

Video cards
Network cards allow computers to connect together to
communicate with each other. Network cards have
connections for cable, thin wire or wireless networks. For
more information see the section on Networks.

Network Card
Cables connect internal components to the Motherboard,
which is a board with series of electronic path ways and
connections allowing the CPU to communicate with the
other components of the computer.

cables
Memory - Memory can be very confusing but is usually one of the
easiest pieces of hardware to add to your computer. It is common to
confuse chip memory with disk storage. An example of the
difference between memory and storage would be the difference
between a table where the actual work is done (memory) and a filing
cabinet where the finished product is stored (disk). To add a bit more
confusion, the computer's hard disk can be used as temporary memory when
the program needs more than the chips can provide.
Random Access Memory or RAM is the memory that the computer uses to temporarily store
the information as it is being processed. The more information being processed the more RAM
the computer needs.

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One of the first home computers used 64 kilobytes of RAM memory (Commodore 64). Today's
modern computers need a minimum of 64 Mb (recommended 128 Mb or more) to run Windows
or OS 10 with modern software.

RAM memory chips come in many different sizes and speeds and can usually
be expanded. Older computers came with 512 Kb of memory which could be expanded to a
maximum of 640 Kb. In most modern computers the memory can be expanded by adding or
replacing the memory chips depending on the processor you have and the type of memory your
computer uses. Memory chips range in size from 1 Mb to 4 Gb. As computer technology changes
the type of memory changes as well making old memory chips obsolete. Check your computer
manual to find out what kind of memory your computer uses before purchasing new memory
chips.

iPod

iPod is a brand of portable media players designed and marketed by Apple Computer.It
stores media on a built-in hard drive, while the smaller iPod use flash memory (ie., with
additional memory). It functions as a mass storage device for storage of user files and can
transfer files from and to computer using its memory. With an ipod, there is no need of carrying
bulky floppies/ CDs for carrying data and presentations outside. It works on Mac and Windows
(present models) platforms. We can keep track of meetings, schedules, deadlines to meet targets,
organize our activities using an ipod.

With time, ipods are evolved

considering the features of
• lighter weight
•Smaller size
•color displays
•Video playing
•Extendable memory

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•Platform compatibility
The present models available are ipod (to play audio), ipodnano (to play audio and viewimages)
and ipod video (to play audio, video and images).

iPad

The iPad is a 9.7 inch touch screen tablet PC made by Apple . The iPad is basically a netbook
without a keyboard. It has a multi-touch LED-backlit 9.7 x 7.5 inch front display and weighs 1.5
pounds, with a battery that lasts up to ten hours

 The iPad is the only one of the three that is a proper tablet.
 It is available with Wi-Fi only or with Wi-Fi and 4G.
 25cm screen (the largest of all three).
 Available with 16GB, 32GB or 64GB.
 Up to 10 hours of battery life (based on watching videos and listening to music).



iPhone

iPhone is a smartphone made by Apple that combines an iPod, a tablet PC, a digital camera
and a cellular phone. The device includes Internet browsing and networking capabilities.

 The iPhone is the only one of the three that can be used as a phone.
 It is available with Wi-FI and 3G (and 4G depending on the model).
 Comes with a built in GPS receiver (needed for satelite navigation).
 iPhone comes with Siri - a voice activated intelligent assistant.
 9cm screen.
 Available with 16GB, 32GB or 64GB.
 With an iPhone 5S there's 10 hours of video playback, 40 hours of audio playback or 10

hours of talk time on 3G.

Networks and Internet

What is a network?

The generic term "network" refers to a group of entities (objects, people, etc.) which are
connected to one another. A network, therefore, allows material or immaterial elements to be
circulated among all of these entities, based on well-defined rules.

 network: A group of computers and peripheral devices connected to each other. Note
that the smallest possible network is two computers connected together.

 networking: Implementing tools and tasks for linking computers so that they can share
resources over the network.

Depending on what kind of entity is involved, the term used will differ:

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 transportation network: A combination of infrastructure and vehicles used for
transporting people and goods between different geographic areas.

 telephone network: Infrastructure for transporting voice signals from one telephone
station to another.

 neural network: A group of brain cells connected to each other
 criminal network: A group of con artists in cahoots (wherever there's one con artist,

there's usually another!)
 computer network: A group of computers linked to each other with physical lines,

exchanging information as digital data (binary values, i.e. values encoded as a signal
which may represent either 0 or 1)

Why networks are important

A computer is a machine used to manipulate data. Humans, being communicative
creatures, quickly understood why it would be useful to link computers to each other in order to
exchange information.

A computer network can serve several distinct purposes:

 Sharing resources (files, applications or hardware, an Internet connection, etc.)
 Communication between people (email, live discussions, etc.)
 Communication between processes (such as between industrial computers)
 Guaranteeing full access to information for a specified group of people (networked

databases)
 Multiplayer video games

Networks are also used for standardizing applications. The term groupware is generally used
to refer to tools that let multiple people work over a network. For example, email and group
scheduling can be used to communicate more quickly and efficiently. Here's a glimpse of the
advantages that such systems have:

 Lower costs, due to sharing data and peripherals,
 Standardizing applications,
 Providing timely access to data,
 More efficient communication and organization.

Today, with the Internet, networks have become more unified. It is clear, then, that there are
several reasons to install a network, whether for a business or an individual.

Similarities between types of networks

The different types of networks generally have the following points in common:
 Servers: computers which provided shared resources to users, by means of a network

server.

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 Clients: computers which access the shared resources provided by a network server.
 Connection medium: how the computers are linked together.
 Shared data: Files that can be accessed on the network servers
 Printers and other shared peripherals: files, printers, or other elements employed by

the network's users
 Miscellaneous resources: other resources provided by the server

Types of networks

There are usually said to be two types of networks:
 Peer-to-peer networks
 Networks organized around servers (Client/Server)

These two types of networks have different capabilities. Which type of network to install
depends on the following criteria:

 Size of the business
 Level of security required
 Type of activity
 Skills of the administrators available
 Volume of traffic over the network
 Needs of the network's users
 Budget set aside for operating the network (not just purchasing it, but also upkeep and

maintenance)

A server is a computer that provides services to clients and controls access to
hardware, software and other resources A client is a computer that request services from a server
computer

On a client/server network, one computer act as a server Client/Server that provides
services and the other computers (client) on the network request services from the server. A
server is a computer that controls access to the hardware, software and other resources on the
network and provides a centralized storage area for program. A client is a computer that request
services from a server computer. Peer-to-peer is a simple, inexpensive network that Peer-to-Peer
typically connects fewer than 10 computers. All computers in the network have equal capabilities
to use the resources (hardware, software, data and file) available on the network. With peer-to-
peer networks, there is no central server.

The Differences between Client/Server and Peer-to-Peer Client/Server Peer-to-Peer
 Server has to control ability
 All computers have equal while client‟s don‟t ability2) Higher cabling cost
 Cheaper cabling cost3) It is used in small and large
 Normally used in small networks with less than 104) Easy to manage computers5) Install
software only in the
 Hard to manage server while the clients share 5) Install software to every the software
computer6) One powerful computer

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ICAR-National Academy of Agricultural Research Management

 No server is needed acting as server

What is the Internet?

The Internet links are computer networks all over the world so that users can share
resources and communicate with each other. Some computers, have direct access to all the
facilities on the Internet such as the universities. And other computers, eg privately-owned ones,
have indirect links through a commercial service provider, who offers some or all of the Internet
facilities. In order to be connected to Internet, you must go through service suppliers. Many
options are offered with monthly rates. Depending on the option chosen, access time may
vary. The Internet is what we call a meta network, that is, a network of networks that spans the
globe. It's impossible to give an exact count of the number of networks or users that comprise the
Internet, but it is easily in the thousands and millions respectively. The Internet employs a set of
standardized protocols which allow for the sharing of resources among different kinds of
computers that communicate with each other on the network. These standards, sometimes
referred to as the Internet Protocol Suite, are the rules that developers adhere to when creating
new functions for the Internet. The Internet is also what we call a distributed system; there is no
central archives. Technically, no one runs the Internet. Rather, the Internet is made up of
thousands of smaller networks. The Internet thrives and develops as its many users find new
ways to create, display and retrieve the information that constitutes the Internet.

Introduction to the World Wide Web

The World Wide Web (also referred to as WWW or W3) is the fastest growing area of
the Internet. While gopher was an important step in allowing users to "browse" through the
Internet's vast resources, the World Wide Web has raised excitement about the Internet to new
heights.

What makes the World Wide Web appealing and innovative is its use of hypertext as a
way of linking documents to each other. A highlighted word or phrase in one document acts as a
pointer to another document that amplifies or relates to the first document. When looking at a
WWW document, the reader doesn't have to follow every pointer, or link (also called a hypertext
link), only those that look interesting or useful. In this way, the user tailors the experience to suit
his or her needs or interests. The other very appealing aspect of the World Wide Web is the use
of graphics and sound capabilities. Documents on the WWW include text, but they may also
include still images, video, and audio for a very exciting presentation. People who create WWW
documents often include a photograph of themselves along with detailed professional
information and personal interests. (This is often called a person's home page.)

What makes the WWW work?

WWW is another example of client/server computing. Each time a link is followed, the
client is requesting a document (or graphic or sound file) from a server (also called a Web
server) that's part of the World Wide Web that "serves" up the document. The server uses a
protocol called HTTP or HyperText Transport Protocol. The standard for creating hypertext

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105th FOCARS
documents for the WWW is HyperText Markup Language or HTML. HTML essentially codes
plain text documents so they can be viewed on the Web.

Uniform Resource Locators or URLs:
A Uniform Resource Locator, or URL is the address of a document you'll find on the

WWW. Your WWW browser interprets the information in the URL in order to connect to the
proper Internet server and to retrieve your desired document. Each time you click on a hyperlink
in a WWW document, you're actually instructing your browser to find the URL that's embedded
within the hyperlink.
The elements in a URL: Protocol://server's address/filename
Hypertext protocol: http://www.aucegypt.edu
Gopher protocol: gopher://gopher.umm.tc.edu
File Transfer Protocol: ftp://ftp.dartmouth.edu
Telnet Protocol: telnet://pac.carl.org
News Protocol: news:alt.rock-n-roll.stones
WWW Clients, or "Browsers":

The program you use to access the WWW is known as a browser because it "browses"
the WWW and requests these hypertext documents. Browsers can be graphical, like Netscape
and Mosaic, allowing you to see and hear the graphics and audio; text-only browsers (i.e., those
with no sound or graphics capability) are also available. All of these programs understand http
and other Internet protocols such as FTP, gopher, mail, and news, making the WWW a kind of
"one stop shopping" for Internet users.

******

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ICAR-National Academy of Agricultural Research Management

(ISO 9001:2008 Certified)
Rajendranagar, Hyderabad-500030, Telangana, India

https://www.naarm.org.in