Transcript Slide 1

ACKNOWLEDG
EMENT
I AM VERY MUCH OBLIGED TOWARDS OUR COMPUTER
TEACHER " Mr. LOKESH" WHO ENCOURAGED US TO DO
THESE PRESENTATIONS
.
-by DEEPANITA and JYOTI
INPUT , OUTPUT AND
MEMORY DEVICES.
Data to be processed by a computer usually originate as written
documents . The data has to be first converted to a form which
can be read by an input unit of the computer .This form is called
as machine readable form .The data read by the input unit
,transformed to appropriate internal code and a stored in the
computers memory .The output unit transforms the internal
representation of data into a form readable by people.
INPUT DEVICES
The input unit is responsible for accepting the
input i.e. data and instructions from the user.
This work is accomplished with the help of
the input devices. Some of the input devices
are : 1.KEYBOARD
2.MOUSE3.MICROPHONE(mic)
THE KEYBOARD
Keyboard is a typewriter like
device which is used to type in
the letters , digits and
commands.A keyboard
contains a matrix of switches
(in which each switch has a
single code).
THE MOUSE
The mouse is a pointer
type device with a roller
on its base .Mouse
controls movement of
pointer (also called
mouse pointer).
THE MICROPHONE (mic)
A mic can converts the sound received
into computers format ,which is called
digitised sound or digital audio.A mic
can work if your computer has a
special hardware known as sound
card.
OUTPUT DEVICES
The output unit is responsible
for producing the output in
user readable form. Various
output devices like monitor
,printer , plotter etc. make
the output of the computer.
M O N IT O R S
Monitor is the most
common form of out
put from a computer.
It displays information
in a similar way to that
shown on a television sc
reen. The picture on a
monitor is made up of thousands of tiny
colored dots called pixels. E.g. are :CATHODE RAY DISCHARGE TUBE(CRT).
Etc.
1.CATHODE RAY
DISCHARGE TUBE
The CRT works in the same way as a
television - it contains an electron
gun at the back of the glass tube
.This fires electrons at group of
phosphor dots , which coats the
inner of the screen. When the
electrons strike the phosphor dots
they glow to give the colours.
2.LIQUID CRYSTAL DISPLAY (or
"TFT" DISPLAY )
Liquid crystal is the material used to create
each pixel on the screen . The material has a
special property - it can 'polarize ' light
depending on the electrical charge across it
.This feature allows the pixels to be created
.Each tiny cell of liquid crystal is a pixel. TFT is
the device within each pixel that sets the
charge .And so sometimes they are called
"Liquid Crystal Display " referring to the
material they use or they are called "TFT
Displays."
PRINTERS
Printers can broadly be divided into
two categories:IMPACT PRINTERS:-There is a
mechanical contact between the
print head and the paper. E.g :Dot
Matrix Printer.
NON-IMPACT PRINTERS:-There isn’t any
mechanical contact between the
print head and the paper. E.g: Laser
printers, Thermal printers etc.
DOT MATRIX PRINTER
A dot matrix printer (DMP) is the most
popular serial printer i.e., it prints one
character at a time. In DMPs ,the
printing head contains a vertical
array of pins . As the head moves
across the paper, selected pins fire
against an inked ribbon to form a
pattern of dots on the paper . These
days 24 pin DMPs are also available
in market offering more quality and
more features.
1.ELECTRO-MAGNETIC PRINTERS.
By using magnetic recording techniques , a
magnetic image of what is to be printed can
be written on a drum surface. Then this
surface is passed through magnetic powder
which adheres to charged areas .The powder
is pressed onto paper .Speeds of upto 250
characters per second are obtained in such
systems.
2.THERMAL PRINTERS
An electric pulse can be
converted to heat on selected
sections of a printing head or
on wires or on nibs. When this
heat is applied to heat
sensitive paper, a character is
printed .
3.ELETRO -STATIC PRINTERS
For electrostatic printers the paper is coated
with a non-conducting dielectric material
which holds charges when voltages are
applied with written "nibs " (heads ) .These
heads write dots on the paper as it passes
.Then the paper passes through a toner
which contains material with coloured
particles carrying an opposite charge to that
written by the nibs ;as a result , particles
adhere to the magnetized areas ,forming
printed characters.
4.INKJET PRINTERS
Some printers direct a high velocity stream of ink toward
the paper. This stream is
deflected, generally passing it
through an electrostatic field
such as that used to deflect
beams in oscilloscopes . In some
systems ,the ink stream is
broken into droplets by an
ultrasonic transducer.
5. LASER PRINTERS
These printers make use of office copier
technologies. The desired output image
is written on a copier drum with the help
of a light beam controlled by acomputer
. With this certain parts of the drum
surface get electrically charged , then
this drum surface is exposed to the laser
beam .These laser exposed areas attract
a toner that forms the image by
attaching itself ( toner ink ) to the laser
generated charges on the drum .The
toner is then permanently fused on
SPEAKERS
Speakers receive the sound in the form
of electric current from the sound
card and then convert it into sound
format. The speakers that are
attached to the computer are similar
to the ones that are connected to a
stereo .The only difference is that the
computer system's speakers are
usually smaller and they contain
their own small amplifier .
THE MEMORY DEVICES
An essential component of every
computer is its memory.
Memory is used for storing both
instructions to be executed and data.
1.THE MAIN MEMORY ( THE PRIMARY MEMORY)
:Broadly the main memory is classified
into two parts :RAM( Random access memory)
ROM( Read only memory)
THE MAIN MEMORY
RAM( Random access
memory)
In the random
access memory the
memory cells can
be accessed for
more information
transfer from any
desired random
action, thus the
name “random
access.”
It is a volatile
memory
ROM( READ ONLY
MEMORY )
ROM is a memory
that performs the
read operations
only; it does not
have the write
capability.
It is a non- volatile
memory.
TYPES OF RAM AND ROM
RAM
1.Dynamic RAM:- consists of a
transistor and a capacitor
that’s capable of storing an
electric charge.
Types of DRAM:1.EDO DRAM
2.SDRAM ( Static DRAM)
3.RDRAM( Rhombus DRAM)
4.SDRAM( Double data rate)
2.Static RAM:-need no special
regenerator circuits to
retain the stored data,
they are volatile.
ROM
1.Programmable ROM( PROM)
:-A ROM that can be
programmed to record
information using a facility
known as PROM
programmer.
Types of PROM:1.EPROM ( Erasable PROM)
2.EEPROM( Electrically
erasable PROM)
R A M
In the RAM the memory cells can
be accessed for information
transfer from any desired
random location. That is , the
process of locating a word in
memory is the same and
requires an equal amount of
memory , thus the name
"Random Access ."
D R A M (DYNAMIC RAM)
Dynamic RAM consists of a transistor and
capacitor that 's capable of storing an
electric charge . Depending on the
switch action of the transistor , the
capacitor either contains no charge ( 0bit) or does hold a charge (1-bit ). A
typical DRAM cell consists of only two
elements -a MOSFET ( Metal Oxide
Semiconductor Field Effect Transistor )
switch and a capacitor storing a bit
.Today's DRAM chips have access time
ranging from below 7 to 70
nanoseconds.
DRAM STORAGE DENSITY
A DRAM cell consists of only
one transistor and capacitor per
bit, it allows a DRAM chip to
pack a large number of cells
within the chip compared to
SRAM. Generally DRAM chips
are available with 128 bit or
256 bit densities or even more.
DRAM REFRESHING
The problem of a capacitor is that
it starts loosing the charge over a
period of time, and can retain data
for barely a thousandth of a
second. Even a read-attempt also
drains out the charge. Therefore, the
memory refresh the memory contents
as many as thousand times a second,
which is called memory refreshing.
TYPES OF DRAM
DRAM chips are available in various
designs. These are as given below :
1.EDO DRAM. Conventional DRAM
cells after each read operation
and requires refreshing time
before it can be read again . But
an EDO DRAM cell keeps its data
valid until it receives an
additional signal .
2.SYNCHRONOUS DRAM (SDRAM ). Because
of multiplexing ,EDO DRAM chips
cannot operate in lock –step with their
host microprocessors .
3.RAMBUS DRAM( RDRAM ) .The RDRAM
is fairly fast , and it has tried to address
some of the complex electrical and
physical problems involved with
memory .
4.DOUBLE DATA RATE ( DDR ) SDRAM
.Unlike SDRAM memory can do two
operations in each clock cycle ,there
doubling the memory bandwidth over
the corresponding single data rate
SDRAM.
STATIC RAM
Static RAM is also volatile but as they
are supplied with power , they need
no special regenerator circuits to
retain the stored data . The static
RAM consists eventually of internal
flip-flops that store the binary
information . The stored information
remains valid as long as power is
applied to the unit . Static RAMs take
up more space for a given storage
capacity than do dynamic RAMs .
Static RAMs are thus used in
specialized applications .
READ ONLY MEMORY (ROM)
A ROM is a memory unit that
performs the read operation
only ; it does not have a write
capability .This implies that
the binary information stored
in a ROM is made permanent
during the hardware
production. It has a nonvolatile memory.
TYPES OF ROM(
Read Only Memory )
1.PROM (Programmable read only
memory ) is a ROM that can be
programmed to record
information using a facility known
as PROM- programmer .
2. ERASABLE READ
ONLY
MEMORY(EPROM )
It is another type of ROM that can
be erased and the chip can be
reprogrammed to record different
information using a special PROM
–program facility .
3.ELECTRICALLY ERASABLE
PROM
This type of ROM can be
programmed and erased by
electrical signals . It does not
require exposure to UV –light to
erase its contents as EPROM
memory does , and provides an
easy means to load and store
temporary or permanent
information in a form of ROM
memory.
OTHER MEMORY DEVICES
1.CACHE MEMORY:-The cache memory is a
high speed memory available inside CPU
in order to speed up access to data and
instructions stored in RAM memory.
2.SECONDARYN MEMORY DEVICES:Some most common storage devices are:*hard disks
*floppy disks
*CD ROMs
*DVDs
FLOPPY DISKS
The floppy disks are one of the
oldest type of portable
storage devices still in use .
These disks enables one to
transfer small files between
computers and also store
data /information as back
up.
HARD DISKS
The hard disk memories
store information on one
or more circular patterns
which are continuously
spinning. These rotating
disks are coated with a
magnetic material and
stacked with space
between them.
CDs( COMPACT DISKS)
The compact disks or CDs are optical
media.
The CDs are relatively cheap and have a
storage capacity of up to 700Mb.There
are three main types of CDs:1.CD-ROM:-used to store only data and not
information.
2.CD-R:-data can be recorded once and
can’t be erased.
3.CD-RW:-erasable disk so user can use a
multiple of times.
DVDs
DVD is an optical
storage device that
looks same as a
compact disks but is
able to write them
only once .
They are of three
types:1.DVD-ROM
2.DVD-R
3.DVD-RW
SIDES
LAYERS
STORAGE
CAPACIT
Y
1
1
4.7GB
1
2
8.5GB
2
1
9.4GB
2
2
17GB
PORTS
Ports are used to connect
external devices to the
computer .They are
connecting points of various
devices to the
computer.There exists
various devices to the
computer.
1.SERIAL PORTS
As the name suggests ,the serial ports transfers
data serially a bit at a time. As a result , the
serial port needs only wire to transmit 8 bits .
The disadvantage is that it takes 8 times
longer to transmit a byte . Also , it is necessary
to send a start bit before each byte of data , a
stop bit after the byte to mark the end of byte
and a parity bit to help check the integrity of
data serial ports come in the form of 9 -pin or
25- pin male connector .
2.PARALLELPORTS
Parallel ports can send or receive a
byte ( 8- bit) at a time . Unlike the
serial ports , these 8- bits are
transmitted parallel to each
other . Parallel ports come in the
form of 25-pin female connector.
Parallel ports are popularly used
to connect printer , scanner , CD
writer , zip drive , etc.
3.USB( UNIVERSAL SERIAL BUS
) PORTS
To spare the user botheration of 8 pin , 25- pin , male, female
connectors , the USB has been
designed . It gives you a single
,standardized , easy -to - use way
to connect a variety of devices to a
computer . These devices include
printers , scanners , mice , joystick
, digital camera , web cameras,
etc.
4.AGP PORTS
The AGP( Accelerated Graphics
Port) port is used to connect to
graphic card that provides highspeed video performance
typically required in games and
multimedia applications.
5.INFRARED PORTS
An IR port is a port , which sends and
receives infrared signals from other
devices . In this special form of
radio transmission , a focused ray
of light in the infrared frequency
spectrum , measured in terahertz ,
or trillions of hertz ( cycles per
second ) , is modulated with
information and send from a
transmitter to a receiver over a
relatively short distance.
6.BLUETOOTH
Bluetooth is a telecommunications
industry specification that
describe how mobile phones ,
computers and personal digital
assistants ( PDAs) can be easily
interconnected using a short range wireless connection.
7.PS-2 PORT
The PS/2 standard , introduced by IBM
in 1987 , stands for personal system
/2.A PS/2 port is an electronic
receptacle plug found on computers
.It accepts a PS/2 cable with a mini DIN connector , and is most often
used to plug in a keyboard or mouse
.The PS/2 port is female while the
mini -DIN cable is male .The
connector is small with a diameter of