MICR :
MICR is an input device, which reads the characters printed using magnetic ink. Magnetic ink is a special type of ink containing iron oxide particles, which is used to write characters. MICRs are mostly used in banks for processing cheque. MICR reads the cheque by first magnetizing the magnetic characters printed on the cheque and then sensing the signal induced by each passing character under a reading head.
LASER PRINTER :
Laser printer uses a laser beam to produce and image on a drum, coated with photosensitive material. with this, certain parts of the drum surface get electrically changed and special ink (ink + developer) is sprinkled on the drum which sticks electrostatically to the charge area of the drum, forming the image. As the drum rotates the image is transferred onto the paper through a combination of heat and pressure (ie developer dry out and only ink remains there)
Print resolution ranges from 300 to 2400 dpi. So, laser printer produces extremely high quality text and graphics (including colors). they are expensive that other printers. the speed of laser printers can be up to 10-15 pages per minute.
SCANNER
Scanner is an input device that can be read text or illustration printed on paper and translates the information into a form that the computer can use. the resulting image (text or illustration) can be stored in a as bitmap or JPG (junction Photographic (Export) group), displayed on a screen, and manipulated by programs. User cannot directly edit text that has been scanned.
JOYSTICK
Joystick is also pointing device. It is used to move the cursor on a CRT screen. a joystick is a stick which has spherical ball at it's lower end as well as upper end. the lower spherical ball moves in socket. the joystick can be moved right or left, forward or backward. the electronic circuitry inside the joystick detects and measures the displacement of the joystick from it's central position; the information is sent to the processor. The joystick is used in playing games.
MODEM
MODEM (modulation-demodulation) is a device that allows a computer to transmit information over a telephone line. the modem translates between digital signal that the computer uses, and analog signals suitable for transmission over telephone lines. when transmitting the modem modulates the digital data onto a carrier signals on telephone line. when receiving the modem performs the reverse process and demodulates the data from carrier signal. It is mostly use in telecommunication/internet browsing.
TOUCH SCREEN
Touch Screen enable he user to select and option by pressing a specific part of the screen with finger. a matrix of beams covers the screen in the horizontal and vertical dimension. If the beams are interrupted by a finger then the position is determined by the interrupted beams. Touch screens are commonly used as tourist information terminals or shopping guides.
TRACKBALL
Trackballs is a pointing device that uses a ball to control cursor movement. the trackball is held stationary and the ball is manually rotated by hand in any direction. It does not require more space to use it. It is mostly used in portable computers.
DIGITAL CAMERA
Digital Camera is a portable handheld devices that capture images. the digital camera digitizes the image, compress it, and store it on a special memory card. the user can then copy information to a Pc, where images can be edited copied, printed, embedded in a document or transmitted to another user. Moving digital images from a digital camera to a computer is a simple process that uses standard cables, disk or even infrared networking capabilities. digital comers have become standard equipment for designers of all kinds.
PEN DRIVE
Pen Drive/Flash drive is the smallest device that can be used for storing data backup and file transfer etc. You have simply to plug your device into the USB 2.0 port of your computer and use it as well. they are portable and reliable. Usually very small you could put them into your pocket and taken with you anywhere you go. Beside you'll find sufficient memory for storing many computer programs, books, songs, texts etc. Generally flash drives are cheaper but the more capacity flash drive is more expensive.
The main advantage of flash drives is that they are not liable to scratching or erasing by magnets. You also have to make sure that the drive is write protect in order to prevent random erasures. If privacy is important, the drive should be able to be password protected.
The different size of flash drive are available in the market like 128 MB to 32 G.B. and more etc.
EXPANSION SLOTS
A slot or expansion slot is an engineered technique for adding new capabilities to the computer. Most of computers except portable contain slots for adding more memory, sound card graphics capabilities and support for special device. Nearly all the computers come with a collection of expansion slots. Actually they help to add new hardware capabilities in the future.
Expansion slots for PCs come into two sizes.
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Half size : Half size slots transfer 8 bit of data at a time, so it is call 8 bit slot.
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full size : full size lusts transfer 16 bit data so it call 16 bit slots.
MOUSE
A mouse is a pointing devise which is held in one had and moves across a flat surface. A mouse may have two or more buttons on the top and a ball at the bottom which rolls on a flat surface. the movement and directing of movement of mouse is detected by two rotating wheels on underside of the mouse. Each wheel is connected to shaft encoder which emits electrical pulses for every intermental movement of wheel.
When a user moves the mouse across a flat surface, the cursor on CRT screen also moves in the direction of mouse's movement. We can select menu, draw picture, edit text etc by pressing the mouse bottom.
They are
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Mechanical Mouse : It has a rubber o metal ball on it's underside able that can roll in all directions.
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Opto mechanical Mouse : It uses optical sensor to detect motion of ball.
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Optical Mouse : It uses a laser to detect mouse's movement.
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Wireless Mouse : It contains transmitter to send information to a receive itself connected to the computer. The wireless mouse is usable from 2m to 10m of the computer.
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