Keyboard...

keyboard is a one type of computer input device.

It is used to enter the text and any function into processor using press key.Its is primary used enter the text.

Keyboard is all individual key like,letter key,arrow key,special key and number key.

• Keyboard is a connect the computer system using the cable or wireless (WIFI).
• Keyboard is a same layout.letters,number,arrow and special are individual keys that is called character keys.
• Most widely used keyboard in English language is called qwerty is sequence first six letters top left. 

Key specified by:

• Enter and edit keys--enter,delete,insert,end.
• Modify key--control,shift,alter
• Navigation key--arrow key up,down,left,right.
• Lock key--caps lock

• Each software application in key is typically perform specific task.so,what are you doing in your computer system at that time.

Use of key:

Window key:this is a start menu of window and also use with any shortcut key.

scroll key:

           1.home:top of the page after press home.

           2.end:bottom of the page after press end.

           3.page up:up the page.

           4.page down:down the page.

ctrl key:this key are used for keyboard shortcut.hold the ctrl key with press any key, for example ctrl+a to use the select all.

alt key:its same as to ctrl.press the alt and tab together

tab key:move the cursor in next box

esc key:clear any text than you have type the text box.

menu key:click the right button of mouse.

number key:its use the typing.

Monitors...

The monitors works with a video card,located inside the computer case,to display image and text on the screen.

• Newer monitors usually have LCD (liquid crystal display) or LED (light emitting diode) display.
• These ca be made very thin,and they are often called flat-pannel display.
• Older monitors use the CRT display.
• CRT monitors are very large and havy weight.

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Monitor type: 

1.Digital monitor:

• The older monitor which use MDA ,CGA and EGA video standers are called digital monitor.
• The data describing the pixel colors are sent from the video adapter to the monitor in a series of digital signals which are stream of data bits. 

2.Analog Monitor:

• The analog type monitors use the VGA standers.
• The VGA standards allow transfer the color information from the video adapter to the monitor as analog signal.
• Analog monitor are support 256 different color.Whatsapp plus+

3.Multi-scanning monitor:

• These monitor can be connected to a wide variety of video board and they can be sued with analog or digital video adapter.
• They can switch auto or manual for working analog or digital monitor.
• They contain more sophisticated electronics circuit which gives more flexibility to work on different display standards.

CRT monitor:

• The pc monitor is a primary output devices which can display text and graphics on its CRT screen.
• The monitor contain a large vacuum tube that is similar to one found in a television (TV).
• The front part is tube where we seen the text and graphics and rear part contains electron guns which is surrounded by control circuit.
• The monochrome monitor contain single gun while color monitor contain three guns for emission of electron.if you want clansh of clans mod apk click

Flat panel display (FDP) monitor:

• FPD are thin, bright display output that are gaining a foothold on desktops as a replacement for traditional CRT monitor.
• The most obvious benefit is the much smaller amount of desk space required,because there is no big case housing the electron gun,nor a heavy glass front.
• Because they dont rely on transitory phosphors to create an image , they are free from flicker.
• FPD are also two to three times brighter than CRT screen.Since the screen is flat,this means that is no distored image at the edge of the view area,as there is with curved CRT monitor.
• FPD are generally easier on the eyes and dont require a "warm-up" period to reach full color saturation.
• FPD create an image made of pixel,just like their CRT counterparts , but they use different technology to accomplish that task.
• Several different type of FPD are available today,varying in cost,image quality.gbwhatsapp apk

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USB (Flash memory)...

USB stand for universal serial bus. It is develop in 1990 define the cable.It is also called flash memory.

• USB are connect Keyboards,mouse, printers and other portable media players are some examples of peripherals.device of usb.
• This is a nonvolatile and re writable memory that function like a RAM and a hard disk combine integrated with a USB interface.
• If power is lost,all data remaine in memory.
• Because of its high speed,durability ,and low voltage requirement,it is ideal for digital cameras,cell phone,printer,handheld computer ,pagers and audio record.
• USB flash drive are typically removable and re writable and physically.
• Now day external hard drive are used USB.

Five type of USB version:

1.USB 1.0 is introduce January 1996.

2.USB 1.1 is introduce august 1998.

3.USB 2.0 is introduce april 2000.

4.USB 3.0 is introduce november 2008.

5.USB 3.1 is introduce january 2013.

Optical disc drive...

An optical disc drive in a computer system allows you to use CD, DVD, and Blu-ray discs to listen a music or watch a movie etc... Most drives used are allow you to write data to a disc, so you can create your own data file or create back-up copy of important data and file.

These discs are read by light (optical) they should be referred to as an optical disc, not optical disk.

These functions are unique to optical support are:

• CD-ROM devices are most use to formatting pc.
• DVD devices directly attached optical media library devices
• LAN-local area network
• Virtual optical devices are use.

It is data read and write using laser.

 

Type of optical disc:

1.CD-ROM:

• Older type Optical Drives included the CD-ROM Drive which were only able to read compact disks (CDs). 
• There were also CD-R Drives which could also burn data 
• CD-RW compact disk which can be written to and erased many times.

2.DVA and Blueray

• Today a standard DVD Optical Drive and Blueray can read and write to compact disks, as well as disks. Some drives will let you read and write to Dual-layer & Triple-layer Disks. 
• You can also use Blu-ray Optical Drive which uses much very higher capacity disks than standard DVD and can proper image hold high definition films and high resolution video.  

Now days Popular software for burning an optical disk include Nero,free star and Roxio Creator.

Hard disk drive (HDD)...

• Some time that is called hard drive, HD or HDD and this is a non volatile memory.
• HDD is a permanent data and information are store and retrieve.
• HDD is connect and power connection is power supply unit(PSU).
• The magnetic storage hard drive is based on a more than 40 year old technology and still is being improved repidly.
• Hard disk continue to shrink in size, gain increased storage capacity and increased transfer speed. whatsapp apk download
• The development has been tremendous during the last 10 year.
• The only the storage capacity is not decide the one hard disk is good than other one.the other factore requires for choosing good hard disk.the following factor needs to closely watch when we choose the hard disk. game killer

Structure of hard disk:

1.Disk platters:

• All hard disk consist of thin platters with a magnetic coating.They rotate quite fast inside a metal container.
• Data are written and read/write heads,which are designed to ride on a microscopic cushion of air,without touching the power.They register bits from the magnetic coating.

2.Spindle motor:

• The disk platters are connected to one central spindle,which is directly connected to the main spindle motor.Most of the spindle motor is located at the bottom of the drive.
• Spindle motor gives circular rotation to the platters for read/write operation on specific location.
• This motor work on a feedback loop to automatically adjust the disk rotation speed.

3.Read/Write head:

• The arms, which guide the movement of the read/write head , move in and out. These heads do not require clening or any other maintenance, as the floppy drive head.
• Because these head do not touch the disk surface insted it float a distance above the disk suface during the read/write process.

4.Head actuator mechanism:

• To moving read/write head disk drive on the platters referred as head actuator mechanism.
• There are to type:

          1.Stepper motor actuator 

          2.Voice coil actuator

5.Sides or head:

• Drive with three platters one read and write on six sides.
• If the drive is servo based than one side may be used;for the servo information and only 5 usable sides will be available.

6.Track:

• Each side of the hard disk drive platters surface is divided into concentric circles called tracks.
• These track are not visible marks on the disk surface instead these are magnetic infomation written during the formating of the hard disk drive.
• Each track is identified by its number.

7.Cylinder:

• The hard disk having more than one platter makes virtually a cylinder like structure on smae tracks of different platter.
• The data is store cylinder by cylinder on the disk.

8.Sector:

• The tracks are dividing futher, which called the sector.
• During the formatting of the hard disk,the formatting program divides the disk surface into different sector by writing magnetic platter on the disk surface.

Type of hard disk drive (HDD):

1.SCSI (Small computer system interface)

2.IDE (Integrated drive electronics) or PATA (Paralled advanced technology attachment)

          a)ATA IDE

          b)XTA IDE

          c)MCA IDE

          d)EIDE

3.SATA (Serial advance technology attachment)

4.RAID (Redundant array of independent drive)

5.USB (Universal serial bus)

RAM (Random Access Memory)...

• RAM is a temporary storage device.it is also called volatile memory.
• It is a inside the CPU and store the data and program.
• RAM is a one integrated  circuit that allow the store data and program.When you system is shout down than memory clean.

• RAM is a random access memory and is the basic kind of internal memory.
• RAM is called "random access" because the processor or computer can use any location or data in main memory.
• RAM has been made from reed relays ,transistors,integrated circuit ,magnetic core, or anything that can hold and store binary value.
• Most morden RAM is made from integrated circuits.

Main two categories of RAM:

1.SRAM:

2.DRAM:

1.SRAM:

• SRAM stand for static random access memory.
• Static RAM is called static because when power is immediately off than information and data is store and hold any location.
• Magnetic core and reed relays are example of static memory.
• SRAM is also used the cache memory and and fast execute or access.
• SRAM is a very expensive.
• SRAM is a no need to refresh because it is auto refresh.
• SRAM is size is very large.

2.DRAM:

• DRAM stand for dynamic random access memory.
• DRAM is called dynamic because when power is off than loss the all data and file.
• Transistors and integrated circuit are example of dynamic memory.
• It is possible to battry backup for device.
• It is a very slow to compare to SRAM.
• DRAM is a need to manual refresh.
• DRAM is used to ram.
• DRAM is a less expensive.
• Less size compare to SRAM. 

Type of RAM: 

• DIP (Dual inline memory);
• SIPP (Single inline pinned package)
• SIMM (Single inline memory module) 
• DIMM (dual inline memory module)
• SRAM (Static random access memory)
• DRAM (Dynamic random access memory)
• SLDRAM (Synchronous link DRAM)

 

  

ROM (read only memory)...

ROM (read only memory)

• ROM is read only memory it is also random access , but only for read.
• ROM is typically used to store thing that will never change for the life of the computer , such as low level portion of an operating system.
• computer almost always contain a small amount of read only memory that hold instruction for starting up the computer.
• it is non_volatin which means once you turn off the computer the information is still there.

 Main three type of ROM:

1.PROM (programmable):Using the program

2.EPROM (erasable programmable):first erased and reprogrammed.

3.EEPROM (electrically erasable programmable):using electrical lesser.

1.PROM (Programmable read only memory):

A PROM is a memory and it is  data can be written only once.

Once a program has been written onto a PROM , its remain there forever.
PROM is manufactured as blank memory.

2.EPROM (Erasable programmable read only memory):

EPROM is a one type of PROM that can be erased by exposing it to ultraviolate light.

once it is erased,its can be reprogrammed.

3.EEPROM (Electrically Erasable programmable read only memory):

EEPROM is a same as the flash memory. 
This make memory faster.

It is also called flash EEPROM.