The device through which can supply any form textual, audible, visual, graphic or mechanical data or instruction into the computer system or the channel through which computer receives the data is called input device. The most popular input devices area as follow:
Keyboard:
The most popular main computer input device that contain a series of switches each of which generates a series of different pulse codes so that the computer knows the one that was pressed. The most common input device which is used both for text based data input or instrcution into the computer. The keys are arranged in a similar way to a typewriter.
Keyboards usually have he following:
Qwerty- The most popular is the standard QWERTY keyboard. The newer keyboards can have a trackball built into the keyboard. This allow the user the convenience of a built in pointing device.
Mouse: - The pointing input device which generates a series of pulses by which the computer can tell the direction of mouse movement. This is often used to move a pointer on a screen, select a menu option or change and create different windows in a Graphical User Environment(GUI). A mouse has two or more buttons on top of it, the function of which depend upon the software being used.
Graphics Tablet: A graphics tablet is a kind of flat board on which a penis moved.The pen holds a magnet and underneath the tablet is a fine grid of wires. Movements of the pen cause disturbance in the electrical pulses in the wires and the co-ordinates of the pen can be detected.It is used for example , in sophisticated computer art packages and video-editing systems for special effects.
Light Pen: A light pen is a pointing device shaped in a pen and is connected to a VDU. The tip of the light pen contains a light-sensitive element which, when placed against the scree, detects the light form the screen enabling the computer to identify the location of the pen on the screen. Light pens have the advantage of 'drawing' directly onto the screen, but this can become uncomfortable, and they are not as accurate as diziting tablets.
Optical Mark Recognition (or Mark Sensing): This uses the techniques described to detect black marks on white paper.A common application is in examinations where multiple choice papers have several boxes; candidates mark the box corresponding to the correct answer usually with a soft pencil. The forms are an example of pre-printed stationery; some information is already printed on the form.
Optical Character Recognition (OCR): The principle of using reflected light is also applied to scanners, fax machines and optical character recognition. The scanner passes a beam of light over a page and measures the reflected light. This gives a two-dimensional pattern of light and dark, which can be represented by 1's and 0's. When you have the characters or drawings converted to a binary pattern then you can send them as a string of electrical pulses to a fax machine or import them into a computer program. With ORC, you can try to match the binary patterns stored in the computer's memory and each recognized character is then assigned its standard code (ASCII usually).
Magnetic Ink Character Recognition (MICR): The "funny-looking" numbers at the bottom of the cheque are encoded in magnetic ink for use with MICR readers at the bank. Some banking systems prefer MICR because of the increased reading speed and extra security against forgery compared to OCR. However MICR is much more expensive than OCR. When the cheque is received by the bank, the amonut has to be encoded in the blank space on the right before the cheque is processed.
Sensor : The sensor are used to collect data when processes are automated, such as car washes, automatic washing machines, heating control in buildings, and petrol delivery in modern petrol station.These processes may be controlled with microprocessor applications rather than general purpose computers.
Digital Cameras: These are becoming increasingly common, with near photographic quality and prices are now comparable to good quality conventional cameras. They can be used with a monitor for applications like video conferencing or simply to take photographs to display on a web page. Usually some form of data compression is used when storing and transmitting photographic images to save space and decrease transmission time. A common standard is JPEG.
Keyboard:
The most popular main computer input device that contain a series of switches each of which generates a series of different pulse codes so that the computer knows the one that was pressed. The most common input device which is used both for text based data input or instrcution into the computer. The keys are arranged in a similar way to a typewriter.
Keyboards usually have he following:
- Keys for the letters of the alphabet.
- Keys for punctuation symbols.
- Numbered keys or a numeric keypad (or both).
- Keys to move the typing cursor and other text controls, such as Tab, Insert, Delete, Backspace, Enter, and so on.
- Keys which change he function of other keys, such as Shift, Caps Lock, Alt, and Ctrl.
- Function keys numbered from F1 to F12.
Qwerty- The most popular is the standard QWERTY keyboard. The newer keyboards can have a trackball built into the keyboard. This allow the user the convenience of a built in pointing device.
- 83-key PC and XT keyboard
- 84-key AT keyboard
- 101-key enhanced windows keyboard
Mouse: - The pointing input device which generates a series of pulses by which the computer can tell the direction of mouse movement. This is often used to move a pointer on a screen, select a menu option or change and create different windows in a Graphical User Environment(GUI). A mouse has two or more buttons on top of it, the function of which depend upon the software being used.
Graphics Tablet: A graphics tablet is a kind of flat board on which a penis moved.The pen holds a magnet and underneath the tablet is a fine grid of wires. Movements of the pen cause disturbance in the electrical pulses in the wires and the co-ordinates of the pen can be detected.It is used for example , in sophisticated computer art packages and video-editing systems for special effects.
Light Pen: A light pen is a pointing device shaped in a pen and is connected to a VDU. The tip of the light pen contains a light-sensitive element which, when placed against the scree, detects the light form the screen enabling the computer to identify the location of the pen on the screen. Light pens have the advantage of 'drawing' directly onto the screen, but this can become uncomfortable, and they are not as accurate as diziting tablets.
Optical Mark Recognition (or Mark Sensing): This uses the techniques described to detect black marks on white paper.A common application is in examinations where multiple choice papers have several boxes; candidates mark the box corresponding to the correct answer usually with a soft pencil. The forms are an example of pre-printed stationery; some information is already printed on the form.
Optical Character Recognition (OCR): The principle of using reflected light is also applied to scanners, fax machines and optical character recognition. The scanner passes a beam of light over a page and measures the reflected light. This gives a two-dimensional pattern of light and dark, which can be represented by 1's and 0's. When you have the characters or drawings converted to a binary pattern then you can send them as a string of electrical pulses to a fax machine or import them into a computer program. With ORC, you can try to match the binary patterns stored in the computer's memory and each recognized character is then assigned its standard code (ASCII usually).
Magnetic Ink Character Recognition (MICR): The "funny-looking" numbers at the bottom of the cheque are encoded in magnetic ink for use with MICR readers at the bank. Some banking systems prefer MICR because of the increased reading speed and extra security against forgery compared to OCR. However MICR is much more expensive than OCR. When the cheque is received by the bank, the amonut has to be encoded in the blank space on the right before the cheque is processed.
Sensor : The sensor are used to collect data when processes are automated, such as car washes, automatic washing machines, heating control in buildings, and petrol delivery in modern petrol station.These processes may be controlled with microprocessor applications rather than general purpose computers.
Digital Cameras: These are becoming increasingly common, with near photographic quality and prices are now comparable to good quality conventional cameras. They can be used with a monitor for applications like video conferencing or simply to take photographs to display on a web page. Usually some form of data compression is used when storing and transmitting photographic images to save space and decrease transmission time. A common standard is JPEG.
