28 Great Lessons You Can Learn From Input Devices.
A computer is a data-processing system that coverts input (data) into output (information). A computer must be able to accept data. Input devices are hardware devices used to provide data to the computer. The selection of devices depends on the application for which the computer is being used.
The keyboard
The keyboard is the most common and the most important input device. Entering data using a keyboard is called manual data entry. A keyboard normally has 104 keys. Alphabet keys are used to enter alphabetic data. A numeric keypad is used to enter numeric data. Special keys give instructions to the computer. Folding keyboards use less space. The keys on Braille keyboards are embossed with Braille characters to help visually-impaired people.
Pointing devices
Pointing devices allow users to indicate the function to be performed, by controlling the movement of a pointer on the screen.
The mouse
The electronic mouse is used to point at objects on the screen and give commands. A mechanical mouse has two or three buttons and a scroll wheel on top. It has a ball on the bottom and is attached by a cord to the system unit. As it is moved across a smooth surface, the ball rotates and moves the pointer. Pressing a button lets us select an icon or a menu. An optical mouse has no rotating ball and can be used on any flat surface. It puts less pressure on the palm and is more precise in positioning the pointer on the screen. A cordless mouse does not need a cord.
The touch pad
A touch pad is a small, flat surface with buttons around the edge. Moving a stylus or a finger across the pad moves the cursor. The buttons work like mouse buttons. Touch pads are used in laptops and desktop PCs.
The touch screen
A touch screen is used both as an input device and an output device. It consists of a touch-sensitive screen covered with a plastic layer. Users select and enter data by touching points on the screen.
The joystick
A joystick consists of a vertical lever mounted on a base. Moving the lever in different directions moves the cursor. Joysticks are used in games, flight simulation programs, and for controlling robots.
The light pen
A light pen looks like a normal pen connected to a computer. It is used to select items on the screen. It can also be moved by hand over a pad to enter drawings into the computer.
Digitizing devices
Digitizing devices convert manually-produced data into a digital form.
The graphics tablet
A graphics tablet is a board covered by a touch-sensitive membrane. A stylus is a pointer while a puck is a mouse-like device. The stylus and puck are used to draw directly on the tablet. Graphics tablets are used to make maps and drawings.
The digital notepad
A digital notepad is shaped like a regular notepad. Using a regular pen instead of a stylus or puck, the user can take notes and make drawings on the pad. It is used by students and people in business to record notes.
Scanning devices
Scanning devices are input devices that store large quantities of data in the form of images when they are run across the surface of the data.
The optical scanner
An optical scanner converts printed or handwritten text, diagrams, and photographs into a digital form and transfers them directly to the computer. The digital image can be displayed on the monitor, modified, printed, and stored for later use. A portable scanner is a hand-held device. It is dragged carefully over the image to scan it and convert it into a digital form. A flatbed scanner is larger in size. It consists of a glass pane and a cover.
The card reader
A card reader reads a magnetic stripe on a plastic card. Magnetic stripes hold information to allow a computer to identify the owner of the card. Credit cards, debit cards, personal identity cards, and travel tickets use magnetic stripes. A smart card has an embedded microchip. It can store more data than a magnetic stripe (around 8000 characters). Laser cards can store over 2 million characters.
The point-of-sale (POS) terminal
A point of sale is a place in a shop where customers pay for goods. A point-of-sale terminal is an input device used at a point of sale to obtain details of purchased items and send them to a computer. It consists of a reader that scans bar codes and prices. It displays the information on a small monitor. A small printer then prints a receipt.
The bar-code reader
A bar code is a series of black and white lines of varying thickness. It helps a central computer identify an item with the help of a bar code number. The product’s name, description, and latest price are stored on the computer. The bar code identifies the product, its country of origin, and its manufacturer. A check digit helps to make sure that the bar code is read correctly. Several POS terminals are connected to a central computer.
A bar-code reader is connected to each POS terminal. As the reader is run across the bar code, the details are sent to the central computer. The computer matches the bar code with product and price information and sends it back to the POS terminal. The details are displayed on the LCD of the POS terminal, printed on a receipt, and recorded on the central computer.
The fingerprint reader
A fingerprint reader is used to identify people. A computer stores the fingerprints of several people. When a person places a finger on the reader, the fingerprint is scanned and sent to the computer. The computer checks if the fingerprint matches any one of those stored on the computer.
Character and mark recognition devices
Character and mark recognition devices can recognize special characters and marks.
The MICR Scanner
MICR full form: “Magnetic Ink Character Recognition”
MICR is used to read special characters printed at the bottom of cheques. These characters are printed in special magnetized ink. The MICR scanner reads a large number of cheques quickly. Another important advantage of using magnetic ink is that it is not spoiled easily. Hence, the chances of data getting corrupted are very remote.
The OMR Reader
OMR full form: Optical Mark Recognition
OMR is also called mark sensing. An OMR reader senses the absence or presence of a mark, such as a pencil mark. OMR is used in multiple-choice tests and to read lottery tickets.
OCR Reader
OCR full form: “Optical Character Recognition”
OCR uses pre-printed characters that are read by a light source and changed into a code. A common OCR reader is the hand-held wand. OCR readers are used to read utility bills, price tags, and airline tickets.
Image-capturing devices
Image-capturing devices are used to transfer graphical data to a computer.
The digital camera
A digital camera captures still images. Images are recorded digitally on a disk or in the memory of the camera. No film is needed. Pictures can be taken and viewed immediately. They can be uploaded and saved on a computer.
The digital video camera
A digital video camera records digital video clips instead of still images. These video files can also be uploaded and saved on a computer.
The webcam
A webcam is connected directly to a computer and set up in a fixed position. It feeds video or still pictures to a web site.
Audio-based input systems
Audio-based input systems provide oral data and instructions to a computer.
Voice recognition systems
Voice recognition systems are used to give oral commands to a computer. A microphone is used to dictate text or give commands. These systems are used by surgeons, pilots, and drivers, whose hands are usually occupied.
(MIDI)
Midi Full Form: “Musical Instrument Digital Interface”
MIDI helps connect electronic musical instruments to a computer. Music played is input directly to a computer and stored digitally. Keyboards and guitars are common MIDI instruments.
Sensors
A sensor measures changes in temperature, pressure, and light and sends them to a computer. The computer analyzes the readings. If they exceed a normal range, the computer sends a signal to operate a device, such as a heater or an alarm.
Summary: Conclusion
- Input devices are used to provide data to the computer.
- The keyboard is used to type data. Different keys are used to enter data in different forms.
- Pointing devices allow users to indicate the function to be performed, by controlling the movement of a pointer on the screen.
- The mouse, touch pad, touch screen, joystick, and light pen are common pointing devices.
- Digitizing devices convert manually-produced data into a digital form.
- The graphics tablet and digital notepad are common digitizing devices.
- Scanning devices can store large quantities of data in the form of images.
- The optical scanner, card reader, bar-code reader, and fingerprint reader are common scanning devices.
- Image-capturing devices are used to transfer graphical data to a computer.
- The digital camera, digital video camera, and webcam are common image-capturing devices.
- Audio-based input systems provide sound-based data and instructions to a computer.
- Voice recognition systems and Musical Instrument Digital Interface (MIDI) are used to enter sound-based data to a computer.
- A sensor measures changes in temperature, pressure, and light and sends them to a computer for analysis and action.