ACKNOWLEDGEMENT

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 DEVICESThe 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 KEYBOARDKeyboard 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 MOUSEThe 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 DEVICESOUTPUT DEVICESThe The output unitoutput unit is responsible is responsible

for producing the output in for producing the output in user readable form. Various user readable form. Various output devices like output devices like monitormonitor ,printer , plotter,printer , plotter etc. etc. make the output of the make the output of the computercomputer..

M O M O N IN I T O T O R SR S MonitorMonitor is the most is the most common form of outcommon form of output from a computer.put from a computer. It displays informationIt displays information in a similar way to thatin a similar way to that shown on a television scshown on a television screen. The picture on areen. The picture on a monitor is made up of thousands of tiny monitor is made up of thousands of tiny

colored dots called colored dots called pixels. E.g. are :-pixels. E.g. are :-CATHODE RAY DISCHARGE TUBE(CRT).CATHODE RAY DISCHARGE TUBE(CRT).Etc.Etc.

1.CATHODE 1.CATHODE RAYRAY DISCHARGE DISCHARGE TUBETUBE

The The CRTCRT works in the same way as a works in the same way as a television - it contains an electron television - it contains an electron gun at the back of the glass gun at the back of the glass tube .This fires electrons at group of tube .This fires electrons at group of phosphor dots , which coats the inner phosphor dots , which coats the inner of the screen. When the electrons of the screen. When the electrons strike the phosphor dots they glow to strike the phosphor dots they glow to give the colours.give the colours.

2.LIQUID CRYSTAL DISPLAY2.LIQUID CRYSTAL DISPLAY (or (or "TFT" DISPLAY )"TFT" DISPLAY )

Liquid crystal isLiquid crystal is the the material used to create each material used to create each pixel pixel on the screenon the screen . The material has a special . The material has a special property - it can 'polarizeproperty - it can 'polarize ' light ' light depending on the depending on the electrical charge across itelectrical charge across it .This .This feature allows the feature allows the pixels topixels to bebe created .Each created .Each tiny cell of liquid crystal tiny cell of liquid crystal isis a pixel. TFT is the device a pixel. TFT is the device within each pixelwithin each pixel that that sets the charge .And sets the charge .And so sometimesso sometimes they are they are called "Liquid Crystalcalled "Liquid Crystal Display Display " referring to the " referring to the material they use or they are called "TFT material they use or they are called "TFT

Displays."Displays."

PPRRIINNTTEERRSSPrinters can broadly be divided into two Printers can broadly be divided into two

categories:-categories:- IMPACT PRINTERS:-IMPACT PRINTERS:-There is a mechanical There is a mechanical

contact between the print head and the contact between the print head and the paper. E.g :paper. E.g :Dot Matrix Printer.Dot Matrix Printer.

NON-IMPACT PRINTERS:-NON-IMPACT PRINTERS:-There isn’t any There isn’t any mechanical contact between the print mechanical contact between the print head and the paper. E.g: Laser printers, head and the paper. E.g: Laser printers, Thermal printers etc.Thermal printers etc.

DOT MATRIX DOT MATRIX PRINTERPRINTER

A dot matrix A dot matrix printer (DMP)printer (DMP) is the most is the most popular serial printer i.e., it printspopular serial printer i.e., it prints one one character at a time. In DMPs ,thecharacter at a time. In DMPs ,the printing head contains a verticalprinting head contains a vertical array array of pins . As the headof pins . As the head moves across moves across the the paper, selectedpaper, selected pins fire against pins fire against an an inked ribboninked ribbon to form a pattern of to form a pattern of dots dots on theon the paper . These days 24 pin paper . These days 24 pin DMPs DMPs areare also available in market offering also available in market offering moremore quality and more features. quality and more features.

1.ELECTRO-MAGNETIC 1.ELECTRO-MAGNETIC PRINTERS.PRINTERS.

By using By using magnetic recording techniquesmagnetic recording techniques , a , a magnetic image of what is to be printed canmagnetic image of what is to be printed can be be written on a drum surface. Thenwritten on a drum surface. Then this surface this surface is is

passed through magneticpassed through magnetic powder which powder which adheres to charged areas .Theadheres to charged areas .The powder is powder is pressed pressed onto paper .Speeds ofonto paper .Speeds of upto 250 upto 250

characters characters per second are obtainedper second are obtained in such in such systems.systems.

2.2.THERTHERMALMAL PRINPRINTERSTERSAn electric pulse can be converted An electric pulse can be converted

to heat on selected sections of a to heat on selected sections of a printing head or on wires or on printing head or on wires or on nibs. When this heat is applied nibs. When this heat is applied to heat sensitive paper, a to heat sensitive paper, a character is printed .character is printed .

3.ELETRO -STATIC PRINTERSFor 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 PRINTERSSome 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. LASER5. LASER PRIPRINTERSNTERSThese printers These printers make usemake use of office copier of office copier

techtechnologies. The desired outputnologies. The desired output image is image is written on a copier drum with thewritten on a copier drum with the help of help of a a light beam controlled by alight beam controlled by acomputer . With computer . With this certain parts of thethis certain parts of the drum surface drum surface get get electrically chargedelectrically charged , then this , then this drum surface drum surface is exposedis exposed to the laser beam to the laser beam .These laser .These laser exposedexposed areas attract a toner areas attract a toner that forms that forms thethe image by attaching image by attaching itself ( toner ink )itself ( toner ink ) to to the laser generated the laser generated charges on the charges on the drumdrum .The toner is .The toner is then permanentlythen permanently fused fused on paper on paper with hot or pressure .with hot or pressure .

SPEAKERSSPEAKERS SpeakersSpeakers receive the sound in the form of receive the sound in the form of

electric current from the sound card electric current from the sound card and then convert it into sound format. and then convert it into sound format. The speakers that are attached to the The speakers that are attached to the computer are similar to the ones that computer are similar to the ones that are connected to a stereo .The only are connected to a stereo .The only difference is that the computer system's difference is that the computer system's speakers are usually smaller and they speakers are usually smaller and they contain their own small amplifier .contain their own small amplifier .

THETHE MEMORYMEMORY DEVICESDEVICES

An essential component of every computer An essential component of every computer is its memory.is its memory.

Memory is used for storing both instructions Memory is used for storing both instructions to be executed and datato be executed and data..

1.THE MAIN MEMORY ( THE PRIMARY 1.THE MAIN MEMORY ( THE PRIMARY MEMORY) :-MEMORY) :-

Broadly the main memory is classified into Broadly the main memory is classified into two parts :- two parts :-

RAM( Random access memory)RAM( Random access memory)ROM( Read only memory)ROM( Read only memory)

THETHE MAINMAIN MEMORYMEMORYRAM( Random access RAM( Random access

memory)memory)In the random access In the random access

memory the memory the memory cells can memory cells can be accessed for be accessed for more information more information transfer from any transfer from any desired random desired random action, thus the action, thus the name “random name “random access.”access.”

It is a volatile memoryIt is a volatile memory

ROM( READ ONLYROM( READ ONLY MEMORYMEMORY ))ROM is a memory that ROM is a memory that

performs the read performs the read operations only; it operations only; it does not have the does not have the write capability.write capability.

It is a non- volatile It is a non- volatile memory.memory.

TYPESTYPES OF OF RAMRAM ANDAND ROMROM

RAMRAM1.Dynamic RAM:-1.Dynamic RAM:- consists of a consists of a

transistor and a capacitor transistor and a capacitor that’s capable of storing an that’s capable of storing an electric charge.electric charge.

Types of DRAM:-Types of DRAM:-1.EDO DRAM 1.EDO DRAM 2.SDRAM ( Static DRAM)2.SDRAM ( Static DRAM)3.RDRAM( Rhombus DRAM)3.RDRAM( Rhombus DRAM)4.SDRAM( Double data rate)4.SDRAM( Double data rate)

2.Static RAM:-2.Static RAM:-need no special need no special regenerator circuits to retain regenerator circuits to retain the stored data, they are the stored data, they are volatile.volatile.

ROMROM1.1.Programmable ROM( PROM)Programmable ROM( PROM):-:-A ROM that can be A ROM that can be

programmed to record programmed to record information using a facility information using a facility known as PROM programmer.known as PROM programmer.

Types of PROM:-Types of PROM:-1.EPROM ( Erasable PROM)1.EPROM ( Erasable PROM)2.EEPROM( Electrically erasable 2.EEPROM( Electrically erasable

PROM)PROM)

RR AA MMIn the RAM the memory cells can be In the RAM the memory cells can be

accessed for information transfer accessed for information transfer from any desired random location. from any desired random location. That is , the process of locating a That is , the process of locating a word in memory is the same and word in memory is the same and requires an equal amount of requires an equal amount of memory , thus the name "Random memory , thus the name "Random Access ." Access ."

DD RR AA MM (DYNAMIC RAM)(DYNAMIC RAM)

Dynamic RAM consists of a transistor and Dynamic RAM consists of a transistor and capacitor that 's capable of storing an capacitor that 's capable of storing an electric charge . Depending on the switch electric charge . Depending on the switch action of the transistor , the capacitor action of the transistor , the capacitor either contains no charge ( 0-bit) or does either contains no charge ( 0-bit) or does hold a charge (1-bit ). A typical DRAM cell hold a charge (1-bit ). A typical DRAM cell consists of only two elements -a MOSFET consists of only two elements -a MOSFET ( Metal Oxide Semiconductor Field Effect ( Metal Oxide Semiconductor Field Effect Transistor ) switch and a capacitor storing Transistor ) switch and a capacitor storing a bit .Today's DRAM chips have access a bit .Today's DRAM chips have access time ranging from below 7 to 70 time ranging from below 7 to 70 nanoseconds.nanoseconds.

DRAM STORAGE DENSITYDRAM STORAGE DENSITY

A DRAM cell consists of only one A DRAM cell consists of only one transistor and capacitor per bit, it transistor and capacitor per bit, it allows a DRAM chip to pack a large allows a DRAM chip to pack a large number of cells within the chip number of cells within the chip compared to SRAM. Generally DRAM compared to SRAM. Generally DRAM chips are available with 128 bit or chips are available with 128 bit or 256 bit densities or even more.256 bit densities or even more.

DRAM REFRESHINGDRAM REFRESHING

The problem of a capacitor is that it The problem of a capacitor is that it starts loosing the charge over a period starts loosing the charge over a period of time, and can retain data for barely a of time, and can retain data for barely a thousandth of a second. Even a read-thousandth of a second. Even a read-attempt also drains out the charge. attempt also drains out the charge. Therefore, the memory refresh the Therefore, the memory refresh the memory contents as many as thousand memory contents as many as thousand times a second, which is called memory times a second, which is called memory refreshing.refreshing.

TYPES OF DRAMTYPES OF DRAM

DRAM chips are available in various DRAM chips are available in various designs. These are as given below : designs. These are as given below : 1.EDO DRAM. Conventional 1.EDO DRAM. Conventional DRAM cells after each read DRAM cells after each read operation and requires refreshing operation and requires refreshing time before it can be read again . But time before it can be read again . But an EDO DRAM cell keeps its data an EDO DRAM cell keeps its data valid until it receives an additional valid until it receives an additional signal .signal .

2.SYNCHRONOUS DRAM (SDRAM ).2.SYNCHRONOUS DRAM (SDRAM ). Because Because of multiplexing ,EDO DRAM chips cannot of multiplexing ,EDO DRAM chips cannot operate in lock –step with their host operate in lock –step with their host microprocessors .microprocessors . 3.RAMBUS DRAM( RDRAM ) .3.RAMBUS DRAM( RDRAM ) .The RDRAM is The RDRAM is fairly fast , and it has tried to address fairly fast , and it has tried to address some of the complex electrical and some of the complex electrical and physical problems involved with physical problems involved with memory .memory . 4.DOUBLE DATA RATE ( DDR ) 4.DOUBLE DATA RATE ( DDR ) SDRAM .SDRAM .Unlike SDRAM memory can do Unlike SDRAM memory can do two operations in each clock cycle ,there two operations in each clock cycle ,there doubling the memory bandwidth over the doubling the memory bandwidth over the corresponding single data rate SDRAM.corresponding single data rate SDRAM.

STATIC RAMSTATIC RAMStatic RAM is also volatile but as they Static RAM is also volatile but as they

are supplied with power , they need no are supplied with power , they need no special regenerator circuits to retain special regenerator circuits to retain the stored data . The static RAM the stored data . The static RAM consists eventually of internal flip-flops consists eventually of internal flip-flops that store the binary information . The that store the binary information . The stored information remains valid as stored information remains valid as long as power is applied to the unit . long as power is applied to the unit . Static RAMs take up more space for a Static RAMs take up more space for a given storage capacity than do given storage capacity than do dynamic RAMs . Static RAMs are thus dynamic RAMs . Static RAMs are thus used in specialized applications . used in specialized applications .

READ ONLY MEMORY (ROM)READ ONLY MEMORY (ROM)

A ROM is a memory unit that performs A ROM is a memory unit that performs the read operation only ; it does not the read operation only ; it does not have a write capability .This implies have a write capability .This implies that the binary information stored in that the binary information stored in a ROM is made permanent during the a ROM is made permanent during the hardware production. It has a non-hardware production. It has a non-volatile memory.volatile memory.

TYPES TYPES OF OF ROMROM( Read ( Read Only Only Memory )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 DISKSThe 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 DISKSThe 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.

CDsCDs( COMPACT ( COMPACT DISKS)DISKS)

The compact disks or CDs are optical media.The compact disks or CDs are optical media.The CDs are relatively cheap and have a The CDs are relatively cheap and have a

storage capacity of up to 700Mb.There are storage capacity of up to 700Mb.There are three main types of CDs:-three main types of CDs:-

1.CD-ROM:-1.CD-ROM:-used to store only data and not used to store only data and not informationinformation..

2.CD-R:-2.CD-R:-data can be recorded once and data can be recorded once and can’t be erased.can’t be erased.

3.CD-RW:-3.CD-RW:-erasable disk so user can use a erasable disk so user can use a multiple of times. multiple of times.

DVDsDVDsDVDDVD is an optical is an optical

storage device that storage device that looks same as a looks same as a compact disks but is compact disks but is able to write them able to write them only once .only once .

They are of three types:-They are of three types:-

1.DVD-ROM1.DVD-ROM

2.DVD-R2.DVD-R

3.DVD-RW3.DVD-RW

SIDESSIDES LAYERSLAYERS STORAGESTORAGECAPACITYCAPACITY

11 11 4.7GB4.7GB

11 22 8.5GB8.5GB

22 11 9.4GB9.4GB

22 22 17GB17GB

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 PORTS1.SERIAL PORTSAs the name suggests ,the serial ports transfers As the name suggests ,the serial ports transfers

data serially a bit at a time. As a result , the data serially a bit at a time. As a result , the serial port needs only wire to transmit 8 bits . serial port needs only wire to transmit 8 bits . The disadvantage is that it takes 8 times longer The disadvantage is that it takes 8 times longer to transmit a byte . Also , it is necessary to send a to transmit a byte . Also , it is necessary to send a start bit before each byte of data , astart bit before each byte of data , a stop bit after stop bit after the byte to mark the end of byte and a parity bit the byte to mark the end of byte and a parity bit to help check the integrity of data serial ports to help check the integrity of data serial ports come in the form of 9 -pin or 25- pin male come in the form of 9 -pin or 25- pin male connector .connector .

2.PARALLELPORTSParallel 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.USB3.USB( UNIVERSAL ( UNIVERSAL SERIAL BUS )SERIAL BUS ) PORTSPORTS

To spare the user botheration of 8 -To spare the user botheration of 8 -pin , 25- pin , male, female pin , 25- pin , male, female connectors , the USB has been connectors , the USB has been designed . It gives you a designed . It gives you a single ,standardized , easy -to - single ,standardized , easy -to - use way to connect a variety of use way to connect a variety of devices to a computer . These devices to a computer . These devices include printers , devices include printers , scanners scanners , mice , joystick , digital , mice , joystick , digital camera , web cameras, etc.camera , web cameras, etc.

4.AGP PORTS

The AGP( Accelerated Graphics Port) port is used to connect to graphic card that provides high-speed video performance typically required in games and multimedia applications.

5.INF5.INFRARRARED ED POPORTSRTS An IR port is a port , which sends andAn IR port is a port , which sends and

receives infrared signals fromreceives infrared signals from other other devices . In this special form of radio devices . In this special form of radio transmission , a focusedtransmission , a focused ray of light ray of light in the infrared frequency spectrum , in the infrared frequency spectrum , measured inmeasured in terahertz , or trillions of terahertz , or trillions of hertz ( cycles per second ) , is hertz ( cycles per second ) , is modulatedmodulated with information and send with information and send from a transmitter to a receiver over from a transmitter to a receiver over aa relatively short distance.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-27.PS-2 PORTPORTThe PS/2 standard , introduced by IBM in The PS/2 standard , introduced by IBM in

1987 , stands for personal system /2.A 1987 , stands for personal system /2.A PS/2 port is an electronic receptacle PS/2 port is an electronic receptacle plug found on computers .plug found on computers .It accepts a It accepts a PS/2 cable with a mini - DIN connector , PS/2 cable with a mini - DIN connector , and is most often used to plug in a and is most often used to plug in a keyboard or mousekeyboard or mouse .The PS/2 port is .The PS/2 port is female while the mini -DIN cable is female while the mini -DIN cable is male .The connector is small with a male .The connector is small with a diameter of about 1/3 inch.diameter of about 1/3 inch.