COMPONENTS OF COMPUTERS
HARDWARE OF COMPUTERS
Hardware is
any part of your computer that has a Physical
Structure such as the computer
monitor or keyboard.
Hardware is the
collection of physical elements that constitute computer system. Computer
hardware refers to the physical parts or components of a computer such as
monitor, mouse and keyboard, computer data storage, hard drive disk (HDD),
system unit (graphic cards, memory, motherboard and chips) etc.
Firmware:
Firmware is loaded from
the Read Only Memory (ROM) run from the Basic Input-Output System (BIOS). It is
a computer program that embedded in a hardware device, for example a
microcontroller. As it name suggests, firmware is somewhere between hardware
and software. Like software, it is a computer program which is executed by a
microprocessor or a microcontroller. But it is also tightly linked to a piece
of hardware and has little meaning outside of it. Most devices attached to
modern systems are special-purpose computers in their own right, running their
own software. Some of these devices store that software ‘firmware’ in a ROM
within the devices itself.
INPUT DEVICES
·
Keyboard
·
Image Scanner
·
Microphone
Pointing Device:
·
Graphics Tablet
·
Joystick
·
Light Pen
·
Mouse
·
Pointing Stick
·
Touchpad
·
Touch Screen
·
Trackball
Web Cam
·
Soft cam
1. Keyboard:
A keyboard typically has
characters engraved or printed on the keys and each press of a key typically
corresponds to a single written symbol. However, to produce some symbols
requires pressing and holding several keys simultaneously or in sequence. While
most keyboard keys produce letters, numbers or signs (characters), other keys
or simultaneous key presses can produce actions or execute computer commands.
2. Mouse:
A computer with the most
common standard features: two buttons and a scroll wheel, which can also act as
a third button.
·
Point:
To
point an item means to move the mouse pointers so that it’s touching the item.
·
Click:
Point to the item, then tap (press and release) the left mouse button.
·
Double-Click:
Point
to the item and the left mouse button twice in rapid succession –click-click as
fast as you can.
·
Right-Click:
Point
to the item, then tap the mouse button on the right.
·
Drag:
Point
to an item, then hold down the left mouse button as you move the mouse. To drop
the item, release the left mouse button.
·
Right-Drag:
Point
to an item, then hold down the right mouse button as you move the mouse. To
drop the item, release the right mouse button.
3. Image Scanner:
Scanner is a device that
optically scans images, printed text, handwriting or an object and converts it
to a digital image.
4. Microphone:
Microphone is an
acoustic-to-electric transducer or sensor that converts sound into an
electrical signal. Microphones are used in many applications such as
telephones, tape recorders, karaoke systems, hearing aids, motion picture
production, live and recorded audio engineering.
5. Graphic Tablet:
A graphics tablet
digitizer is a computer input device that enables a user to hand-draw images,
animations and graphics, similar to the way a person draws images with a pencil
ad paper. These tablets may also be used to capture data or handwritten
signatures. It can also be used to trace a image from a piece of paper which is
taped or otherwise secured to the surface. Capturing data in this way, either
by tracing or entering the corners of linear poly-lines or shapes is called
digitizing.
The device consists of a
flat surface upon which the user may draw or trace an image using an attached
stylus, a pen-like drawing apparatus. The image generally does not appear o the
tablet itself but, rather is displayed on the computer monitor.
6. Joystick:
A joystick is an input device consisting of a
stick that pivots on a base and reports its angle or direction to the device it
is controlling. A joystick, also known as the control column, is the principal
control device in the cockpit of many civilian and military aircraft, either as
a center stick or side stick. It often has supplementary switches to control
various aspects of the aircraft’s flight.
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. A popular variation of the joystick used on
modern video game consoles is the analogue stick.
7. Light Pen:
A light pen is a computer
input device in the form of a light-sensitive wand used in conjunction with a
computer’s CRT display.
It allows the user to
point to displayed objects or draw on the screen in a similar way to a touch
screen but with greater positional accuracy.
8. Pointing Stick:
A pointing stick is an
isometric used as a pointing device, as with a touchpad or trackball and
typically, mounted in a computer keyboard on a laptop or desktop computer.
Movements of the pointing stick are echoed on the screen by movements of the
pointer (or cursor) and other visual changes.
9. Touchpad:
A pointing device
featuring a tactile sensor, a specialized surface that can translate the motion
and position of a user’s fingers to a relative position on the operating system
that is outputted to the screen. Touchpad is a common feature of laptop
computers and are also used as a substitute for a mouse where desk space is
scarce. Because they vary in size, they can also be found on personal digital
assistants (PDAs) and some portable media players.
10. Touch Screen:
A touch screen is an
electronic visual display that the user can control through simple or
multi-touch gestures by touching the screen with one or more fingers. Some
touch screens can also detect objects such as a stylus or ordinary or specially
coated gloves. The user can use the touch screen to react to what is displayed
and to control how it is displayed (for example by zooming the text size).
The touch screen enables
the user to interact directly with what is displayed, rather than using a
mouse, touchpad or any other intermediate device (other than a stylus, which is
optional for most modern touch screens).
Touch screens are common
in devices such as game consoles, all-in-one computers, tablet computers and
smart phones. They can also be attached to computers or as terminals, to
networks. They also play a prominent role in the design of digital appliances
such as personal digital assistants (PDAs), satellite navigation devices,
mobile phones and video games and some books.
11. Trackball:
A trackball is a pointing
device consisting of a ball held by a socket containing sensors to detect a
rotation of the ball about two axes-like an upside-down mouse with an exposed
protruding ball. The user rolls the ball with the thumb, fingers or the palm of
the hand to move a pointer.
Compared with a mouse, a
trackball has no limits on effective travel; at times, a mouse can reach an
edge of its working area while the operator still wishes to move the screen
pointer farther. With a trackball, the operator just continuous rolling,
whereas a mouse would have to be lifted and re-positioned.
12. Webcam:
A webcam is a video
camera that feeds its image in real time to a computer or computer network.
Unlike an IP camera (which uses a direct connection using Ethernet or Wi-Fi), a
webcams is generally connected by a USB cable, FireWire cable or similar cable.
13. Soft cam:
A soft cam is essentially
a software-based camera. Soft cams are computer software (that technically do
not replace webcams) that allows one to stream or broadcast image, video,
and/or audio files through a virtual Webcams device. This allows the video
stream to be used in place of a normal Webcams stream in video conferencing
applications like MSN Messenger, NetMeeting, Skype etc. or any other programs
that use Webcams devices.
OUT PUT DEVICES
·
Monitor
·
Printer
·
Speakers
·
Plotter
·
Projector
·
Head Phones
1. Monitor:
Monitor commonly called
as Visual Display Unit (VDU) is the main output device of a computer. It forms
images from tiny dots, called pixels, that are arranged in a rectangular form.
The sharpness of the image depends upon the number of the pixels.
There
are two kinds of viewing screen used for monitors:
·
Cathode –Ray Tube (CRT)
·
Flat-Panel Display
Cathode-Ray Tube (CRT)
Monitor:
In
the CRT, Display is made up of small picture elements called pixels for short.
The smaller the pixels, the better the image clarity or resolution. It takes
more than one illuminated pixel to form whole character, such as the letter ‘e’ in the word help.
A finite number of
characters can be displayed on a screen at once. The screen can be divided into
a series of character boxes-fixed location on the screen where a standard
character can be placed. Most screens are capable of displaying 80 characters
of data horizontally and 25 lines vertically. There are some disadvantages of
CRT:
·
Large in Size
·
High Power Consumption
Flat-Panel Display Monitor:
The flat-panel display
refers to a class of video devices that have reduced volume, weight and power
requirement compared to the CRT. You can hang them on walls or wear them on
your wrists. Current uses for flat-panel displays include calculators, video
games, monitors, laptop computer, graphics display.
The
flat-panel display are divided into two categories:
·
Emissive
Displays: The emissive displays are devices that convert
electrical energy into light. Example are plasma panel and LED (Light Emitting
Diodes).
·
Non-Emissive
Displays: The Non-emissive displays use optical effects
to convert sunlight or light from some other source into graphics patterns.
Example is LCD (Liquid-Crystal Device)
2. Printer:
Printer is the most
important output device, which is used to print information on paper.
There
are two types of printers:
·
Impact Printers
·
Non-Impact Printers
Impact Printers:
The printers that print
the characters by striking against the ribbon and onto the paper are called
impact printers.
Characteristics
of Impact Printers are the following:
·
Very low consumable cost
·
Impact printers are very noisy
·
Useful for bulk printing due to low
cost
·
There is physical contact with the
paper to produce an image
These printers are of two
types:
·
Character printers
·
Line printers
Character Printers:
Character Printers are
printers, which print one character at a time. These are of further two types:
·
Dot Matrix Printer (DMP)
·
Daisy Wheel
Dot Matrix Printer:
In the market, one of
the most popular printer is Dot Matrix Printer because of their ease of
printing features and economical price. Each character printed is in form of
pattern of Dot’s and head consists of a Matrix of Pins of size (5*7, 7*9, 9*7,
9*9) which comes out to form a character that is why it is called Dot Matrix
Printer.
Advantages:
·
Inexpensive
·
Widely Used
·
Other language characters can be
printed
Disadvantages:
·
Slow Speed
·
Poor Quality
Daisy Wheel:
Head is lying on a wheel
and Pins corresponding to character are like petals of Daisy that is why it is
called Daisy Wheel Printer. These printers are generally used for
word-processing in offices which require a few letters to be send here and
there with very nice quality representation.
Advantages:
·
More reliable than DMP’s
·
Better quality
·
The fonts of character can be
easily changed
Disadvantages:
·
Slower than DMP’S
·
Noisy
Line Printers:
·
Line printers are printers, which
print one line at a time.
Non-Impact Printers:
The printers that print
the characters without striking against the ribbon and onto the paper are
called Non-Impact Printers. These printers print a complete page at a time,
also called as Page Printer.
These Printers are of two
types:
·
Laser Printers
·
Inkjet Printers
Characteristics of Non-Impact
Printers:
·
Faster than impact printers
·
They are not noisy
·
High quality
·
Support many fonts and different
character size
Laser Printers:
These are non-impact page
printers. They use laser lights to produce the dots needed to form the
characters to be printed on a page.
Advantages:
·
Very high speed
·
Very high quality output
·
Gives good graphics quality
·
Supports many fonts and different
character sizes
Inkjet Printers:
Inkjet printers are
non-impact character printers based on a relatively new technology. They print
characters by spraying small drops of ink onto paper. Inkjet printers produce
high quality output with presentable features. They make less noise because no
hammering is done and these have many styles of printing modes available. Color
printing is also possible. Some models of Inkjet printers can produce multiple
copies of printing also.
Advantages:
·
High quality printing
·
More reliable
Disadvantages:
·
Expensive as cost per page is high
·
Slow as compared to laser printer
3. Speakers:
Speakers receive the
sound in the form of electric current from the sound card & convert it to
sound format. These are used for listening music, chatting, seminars for
representations etc.
4. Plotters:
A plotter is a
special-purpose output device that draws images with ink pens. That is the
plotter is a graphics printer for making sophisticated graphs, charts, maps and
three-dimensional graphics as well as high-quality colored documents. It can
also produce larger size of documents. Plotters require data in a vector
graphics format that can produce images with a series of lines. There are two
main types of plotters:
i.
Drum
Plotter: This is a plotter that has a drum. A paper
wraps the drum that rotates to produce plots. Pens in a drum plotter move
across the paper while the drum is turning. A drum plotter is usually used to
produce smaller drawings.
ii.
Flatbed
Plotter: This is a plotter that has a bed. This is also
called a table plotter. The plotter draws graphics on the paper placed on the
bed. There are several size of beds. This plotter is usually used for producing
large drawings.
5. Projector:
An output device that can
take the display of a computer screen and project a large version of it onto a
flat surface. Projectors are often used in meetings and presentations to help
make sure everyone in the room can view the presentation. In the picture to the
right, is a View Sonic projector and an example of what a projector may look
like. Projectors used with computers are small devices that are rarely much
larger than a toaster and typically weigh a few pounds
6. Head Phones:
Headphones give sound
output from the computer. They are similar to speakers, except they are worn on
the ears so only one person can hear the output at a time.
PROCESSING DEVICES
·
Soundcards
·
Graphic Cards
·
Net cards or NIC cards
·
Mother board
·
Microprocessor
1. Sound Cards:
A sound card captures
sounds and changes them into digital binary numbers that are stored as files in
your computer.
When outputting sounds
the sound card reverses the process and changes binary data held in the sound
files into analogue signals that are used control the speakers attached to the
computer. Speakers convert analogue audio signals into the equivalent air
vibrations in order to make audible sound. A pair of speakers plugs into the
computer’s sound card.
2. Graphic Cards:
Alternatively referred to
as a display adapter, graphics card, video adapter, video board or a video
controller, a video card is an internal circuit board that allows a display
device uch as a monitor to display images from the computer. Today’s video
cards are most commonly connected to the AGP, PCI or PCIe expansion slot on the
motherboard however, can also be found-on-board.
3. Net Cards or NIC Cards:
NETWORK Interface Card or
a NIC is also commonly referred to as an Ethernet card network adapter and is
an expansion card that enables a computer to connect to a network such as a
home network or the Internet using an Ethernet cable with a RJ-45 connector. In
the picture to the right, is an example of a SMC EZ Card 10/100 PCI network
card, a network card commonly found in most desktop computers today that do not
already have an onboard on their motherboard.
4. Mother Board:
The target circuit board
found inside the computer. Without it, a computer is just a metal box. The
motherboard contains all the remaining items in this table; for all practical
purposes.
5. Microprocessor:
A group of computer
chips or integrated circuits (ICs) that, when working together, manage and
control the computer system. This set includes the CPU and other chips that
control the flow of data throughout the system.
STORAGE DEVICES
1. Floppy Disk:
A floppy disk is a type
of data storage that is composed of a disk of thin, flexible (floppy) magnetic
storage medium encased in a square or rectangular plastic shell. Floppy disks
are read and written by a floppy disk drive. Floppy disks are a dying and being
replaced by the optical and flash drives. Many new computers do not come with
floppy drives any more but there are a lot of older ones with floppy drives
lying around. While floppy disks are very cheap the amount of storage on them
compared to the amount of storage for the price of flash drives makes floppy
disks unreasonable to use.
2. CD (Compact Disc):
CDs are the most common
type of removable media. They are inexpensive but also have short life-span.
There are a few different kinds of CDs. CD-ROM which stands for Compact Disc
Read Only Memory are popularly used to distribute computer software although
any type of data can be stored on them. CD-R is another variation which can
only be written to once but can be read many times. CD-RW (rewritable) can be
written to more than once as well as read more than once. Some other types of
CDs which are not as popular include Super Audio CD (SADC),
Video
Compact Discs (VCD), Super Video Compact Discs (SVCD), Photo CD, Picture CD,
CD-I and Enhanced CD.
CD-ROM Drive:
There are two types of
devices in a computer that use CDs: CD-ROM drive and a CD writer. The CD-ROM
drive used for reading a CD. The CD writer drive can read and write a CD. CD writers
are much more popular are new computers than a CD-ROM drive. Both kinds of CD
drives are called optical disc drives because the use a laser light or
electromagnetic waves to read or write data to or from a CD.
3. DVD:
DVDs
(Digital Versatile Discs) are another popular optical disc storage media
format. The main uses for DVDs are video and data storage. Most DVDs are of the
same dimensions as compact discs. Just like CDs there are many different
variations. DVD-ROM has data which can only be read and not written. DVD-R and DVD+R can be written once and then
function as a DVD-ROM. DVD-RAM, DVD-RW or DVD+RW hold data that can be erased
and re-written multiple times. DVD-Video and DVD-Audio discs respectively refer
to properly formatted and structured video and audio content. The devices that
use DVDs are very similar to the devices that use CDs. There is a DVD-ROM drive
as well a DVD writer that work the same
way as a CD-ROM drive and CD writer. There is also a DVD-RAM drive that reads
and writes to the DVD-RAM variation of DVD.
4. Blu-ray:
Blu-ray is a newer optical
disc storage media format. Its main uses are high-definition video and data
storage. The disc has the same dimensions as a CD or DVD. The term ‘Blu-ray’
comes from the blue laser used to read and write to the disc. The Blu-ray discs
can store much more data then CDs or DVDs. A dual layer Blu-ray disc can store
up to 50GB, almost six times the capacity of a dual layer DVD (WOW!). Blu-ray
discs have similar devices used to read them and write to them as CDs have. A
BD-ROM drive can only read a Blu-ray disc and a BD writer can read and write a
Blu-ray disc.
5. Hard Disk Drive:
A hard disk drive (HDD)
is a non-volatile storage device which stores digitally encoded data on rapidly
rotating platters with magnetic surfaces. Just about every new computer comes
with a hard disk these days unless it comes with a new solid-state drive.
Typical desktop hard disk drives store between 120 and 400GB , rotate at 7,200
rpm and have a media transfer rate of 1 GB or higher. Hard disk drives are
accessed over one of a number of bus types, including parallel ATA (also called
IDE), Serial ATA (SATA), SCSI, Serial Attached SCSI and Fiber Channel.
6.
Solid-State
Drive:
A solid-state drive (SSD)
is a data storage device that uses solid-state memory to store persistent data.
An SSD emulates a hard disk drive thus easily replacing it in any application.
SSDs have begun to appear in laptops because they can be smaller than HHDs. SSD
are currently more expensive per unit of capacity than HHDs which is why they
have not caught on so quickly.
7.
Disk
Array Controller:
A disk array controller
is a device which manage the physical disk drives and presents them to the
computer as logical units. It almost always implements hardware RAID. RAID
(Redundant Array of Independent Drives) is a technology that employs the
simultaneous use of two or more hard disk drives to achieve greater levels of
performance, reliability, and/or larger data volume sizes. A disk array
controller also provides additional disk cache.
8.
Flash
Drives:
A flash drive is a data storage
device that uses flash memory for storage purposes. Typical in design, flash
drives are light-weight and small in design and are hence easily portable.
Flash drives operate from the power supplied by a computer’s USB port (the port
in which they are plugged in). the data on it can be erased and re-programmed
as per the user’s requirements. It only has a specific number of erase and
write cycles that it can withstand, after which it creates a tendency to lose
out on the stored information. Memory cards and USB flash drives are some modes
of this type of memory storage. Low cost, minimal power consumption and
portable features make flash drives extremely desirable and popular in modern
times.
SOFTWARE OF COMPUTERS
1.
Software:
Computer
software is the set of programs that makes the hardware perform a set of tasks
in particular order. Hardware and software are complimentary to each other.
Both have to work together to produce meaningful results. Computer software is
classified into two broad categories; system software and application software.
a.
System
Software:
System software consists of a
group of programs that control the operations of a computer equipment including
functions like managing memory, managing peripherals, loading, storing and is an
interface between the application programs and the computer. MS DOS
(Microsoft’s Disk Operating System), UNIX are examples o system software.
System Software consists
of a group of programs that control the operations of a computer equipment
including functions like managing memory, managing peripherals, loading,
storing and is an interface between the application programs and the computer.
MS DOS, UNIX are examples of system software.
b.
Application
Software:
Software that can
perform a specific task for the user, such as word processing, accounting,
budgeting or payroll, fall under the category of application software. Word
processors, spreadsheets, database management systems are all examples of
general purpose application software.
Types of application software
are:
·
Word
processing software: The main purpose of this software
is to produce documents. Ms-Word Pad, Notepad and some other text editors are
some of the examples of word processing software.
·
Database
software: Database is a collection of related data. The
purpose of this software is to organize and manage data. The advantage of this
software is that you can change way data is stored and displayed. MS access,
dBase, FoxPro, Paradox and Oracle are some of the examples of database
software.
·
Spreadsheet
software: The spreadsheet software is used to maintain
budget, financial statements, grade sheets and sales records. The purpose of
this software is organizing numbers. It also allows the users to perform simple
or complex calculations on the numbers entered in rows and columns. Ms-Excel is
one of the example of spreadsheet software.
·
Presentation
software: This software is used to display the
information in the form of slide show. The three main functions of presentation
software is editing that allows insertion and formatting of text, including
graphics in the text and executing the slide shows. The best example for this
type of application software is Microsoft Power Point.
·
Multimedia
software: Media players and real players are the examples
of multimedia software. This software will allow the user to create audio and
videos. The different forms of multimedia software are audio converters,
players, burners, video encoders and decoders.
TYPES OF MEMORIES
1. Primary Memory:
Primary Memory (also
called main memory) is used for immediate access of data by the processor.
While primary memory storage demonstrate faster processing ability, it is
costly and hence is not largely used for data storage. Most computer systems
around the world use primary memory only for bootstrapping and related purpose
and use secondary memory devices for personal data storage purpose.
Primary Memory can be
divided into two types – Random Access Memory(RAM) and Read Only Memory(ROM).
RAM retains its contents as long as the power supply is on. A RAM chip is used
as primary memory in most computers today. However, older computers (in the
’80s) used ROM devices (floppy disks, magnetic tapes, paper clips or punches;
but more prominently floppy disks) as primary memory mechanism..
i.
Random
Access Memory (RAM):
RAM is a memory scheme
within the computer system responsible for storing data on a temporary basis,
so that it can be promptly accessed by the processor as and when needed. It is
volatile in nature, which means that data will be erased once supply to the
storage device is turned off. RAM stores data randomly and the processor
accesses these data typically loaded from the computer’s hard disc and includes
data related to the operating system and certain applications. When the system
is switches off, the RAM loses all stored information. The data remains stored
on secondary storage though and can be retained when the system is running
again. Some of the earliest computers used delay-line format of computer
storage. Most modern computers use an embedded RAM circuitry motherboard which
reads data in bursts. So, modern RAM devices are not random memory devices as
such; they are burst memory access devices, but the term RAM has stuck in
everyday usage.
There are primarily two forms
of RAMS:
a.
Static RAM (SRAM)
b.
Dynamic RAM (DRAM)
a. Static RAM: The
most expensive of the lot, SRAM uses bi-stable latching circuitry to store one
bit each and hence is faster than its counterpart. Its high price prevents it
from being widely used in everyday computing machines, but many modern machines
use SRAM as the processor’s cache register.
b. Dynamic RAM: Widely
used in modern computers as primary memory, DRSM is slower than SRAM, but id
inexpensive due to its one transistor-one capacitor paired assembly of memory
storage.
ii.
Read
Only Memory (ROM):
ROM is a permanent from
of storage. ROM stays active regardless of whether power supply to it is turned
on or off. In spite of this, ROM was used (in rare cases is still used) as the
primary device for most computers back in the ’80s. this was because ROM
devices do not allow data stored on them to be modified. As the name itself
suggests, data can modified. This made it an ideal choice as bootable devices,
for old computers, programmable interpreters and portable OS files carrier. The
system programs stored on a ROM device could never be altered and hence, stayed
secure for use.
PROM (Programmable Read Only
Memory): A PROM is a memory chip on which you can store
a program. But once the PROM has been used, you cannot wipe it clean and use it
to store something else. Like ROMs, PROMs are non-volatile.
EPROM (Erasable Programmable
Read Only Memory): An EPROM is a special type of PROM
that can be erased by exposing it to ultraviolet light.
EEPROM (Electrically Erasable
Programmable Read Only Memory): An EEPROM is a
special type of PROM can be erased by exposing it to an electrical charge.
2. Secondary Memory:
Secondary Memory is
available on mass storage devices for permanent data storage. Data stored on a
secondary device is retained even when it is not supplied any power. This data
can be transported in most cases and looks and appears the same on any machine,
irrespective of where the data was first copied onto the secondary storage
device.
Unlike primary memory,
secondary is not directly accessible by the computer. When a computer needs to
run or execute an application stored in secondary memory, it first brings it to
primary memory storage for a while, to control and carry out its execution.
Once execution of the application is done, the processor releases the
application and restores its control and memory data with the secondary memory
device.
·
Punching Devices
·
Magnetic Tape
·
Floppy Disk
·
Optical Discs (CD/DVD)
·
Hard Disk Drives
·
Flash Drives
3. Cache Memory:
Cache is a type of RAM
which was originally implemented as a temporary storage mechanism to assist
redirection to previously manipulated data by the user or the machine.
Eventually, the concept of cache has evolved to become a temporary as well as
permanent form of storage for the computer, as well as for individual
applications. Most individual applications these days maintain their own cache
which can be accessed by the processor, as well as the user and can be
maintained for as long as required without any risk of losing the data.
