Topic-7 Input Devices (Computer Fundamentals)

Keyboard
• It is the most common of all input devices.
• Microcomputers offer enhanced keyboards for easy entry of numbers.
• This is accomplished with a smaller group of keys known as a numeric
keypad at the right of the keyboard.
• These keys generally consist of the digits, a decimal point, a negative sign and
an ENTER key.
• This type of keyboard is ideal for accounting operations which require a
large volume of numbers to be entered.

Keyboard
• A keyboard generally utilize integrated circuits to perform essential functions,
such as determining binary code, to send to the CPU corresponding to each
depressed key, switching between shifted and non-shifted keys, repeating a
key code etc.
• The keyboard arrangement provided as standard on most keyboards is the
QWERTY arrangement, named for the six letters beginning at the top left of
the key board.

Keyboard
• This arrangement was chosen intentionally to slow expert typists, since they
type too fast to cause the keys on mechanical type writer to jam.
• Slowing down the typist was accomplished by scattering the mostly used
keys, making frequently used combinations of letters slower to type.
• The QWERTY keyboard has been in used for almost a century.

Reading Devices
• A character reader is capable of accepting printed or typed characters from source
documents and converting these data into a computer-acceptable code.
• The basic types of character readers are:
Magnetic-ink reader
Optical mark reader
Optical character reader
Hand written character reader
Smart cards etc.

Magnetic-ink Character reader
• Magnetic Ink Character Reader (MICR) can read data prerecorded on checks and deposit slips with
a special ferrite-impregnated ink.
• Magnetic ink character recognition readers are the primary tool used for check sorting,
processing and validation. When scanning a document such as a check, MICR readers magnetize
the ink and detect the MICR characters. The reader head of the device reads the characters.
• The magnetized characters can be read and interpreted by MICR equipment.
• Human involvement is minimal thus the potential for errors is small
• It is fast, automatic and reliable.
• However some human involvement is still required to encode the cheque amount in MICR
characters thus, some room for errors does remain.

Optical mark reader
• Optical mark reader (OMR) optically reads marks on carefully printed forms.
• Optical mark forms are relatively expensive, as they must be printed with
exact tolerances.
• The most popular use of such devices is optical readers for scoring
examinations in educational institutions.

Optical character reader
• Optical character reader (OCR) devices can convert data from source
documents to a machine-recognizable form.
• Applications of optical scanning include billing, insurance premium notices,
invoices etc.
• An OCR can reliably read and interpret script or handwriting.
• OCR are limited with respect to hand written characters and can only read
handwritten digits and some symbols.

Hand written character reader
• Data recorded by hands have dropped substantially over the last decades,
however quite a bit of data are still recorded this way.
• As OCR technology advanced, designers felt that it would be possible to
convert handwritten data into computer-usable form in much the same way
that typewritten data are.
• Devices with this capability are the most sophisticated and versatile of
the OCR devices.

Smart cards
• A smart card is small in size and to use it, the card is inserted into a special card-
reading terminal and then password is entered.
• The cards have microchips that can keep permanent records. Which are updated
each time the card is used.
• The transaction data stored on the card can later be read into the computer to
update the user’s bank records.
• Now a days smart card are used to pay bills. But merchandise, make phone calls
etc.

Pointing Devices
Mouse
• A mouse is a hand-movable device that controls the position of the cursor
on a screen.
• It has a box with buttons on the top and a ball on the bottom.
• The box is placed on a flat surface (mouse mat) with the user’s hand over it.
• It has become most popular pointing device for graphic interfaces by
windows.
• With the mouse one can control the PC by pointing to images.

Pointing Devices
Light Pen
• The earliest pointing device is the light pen.
• This device is placed close to a screen or monitor and turned on.
• A photo sensor inside light pen detects the scanning beam sweeping back
and forth across the screen.
• Light pens are used to select items from a list or menu displayed on the
screen and to draw graphic displays on the screen.

Pointing Devices
Digitizer Pad
• Digitizer pad looks like a graph pad with a pointer.
• If functions like a light pen on a display screen except that the pad is mounted
horizontally.
• As the pointer is moved on the pad, the corresponding point on the screen is
illuminated.
• The digitizer pad is useful in converting graphic input, such as charts, graphs
and blueprints into patterns that can be stored by the computer.

Pointing Devices
Joystick and Trackball
• Joysticks are used with video games for user input.
• These devices may also be used to move the cursor around a screen to facilitate
input to a graphical display.
• A trackball is similar in operation to the joystick.
• It uses a billiard-sized ball to position the cursor.
• Several keyboard manufacturers have integrated them directly into their
keyboards.

Pointing Devices
Touchscreen
• Touchscreen detects the tough of a human finger.
• One popular technique used to detect the touch of a finger utilizes infrared
light beams.
• In this technique, infrared light beams shine horizontally and vertically on the
face of the screen.
• A pointing finger interrupts both horizontal and vertical beams, pointing its
exact location.

Scanning Devices
Scanners
• Scanners allow a PC to convert a drawing or photograph into code that a
graphics or desktop publishing program can use to display the image on the
screen, to reproduce the image with a printer.
• A scanner can also convert printed text into editable text with the help of
optical character recognition software.

Scanning Devices
Bar code Reader
• A bar code reader is a device for scanning or reading a bar code.
• Bar code is printed code that consists of parallel bars of different width and
spacing.
• The application most commonly observed is the coding on food and the goods
that is read at the checkout counter and translated into a line of print on the
bill showing price and cost.
• The information is also used to update stock record and provide sales statistics.

Scanning Devices
Digital Camera
• A digital camera uses light-sensitive electronic technique instead of film to
capture images.
• Instead of a photo album, one can store picture in PC’s hard drive or in a
writable CD-ROM.
• Digital photography is not new, although most digitalized photos make their
way to disk via conventional photography scanners.
• Digital cameras that eliminates scanners already exists.

Other Input Devices
Punched card
• It serves as an input medium to automated computational devices.
• It has undergone little or no change, and most users have phased out and
replaced it with the more efficient data entry media.
• Among the punched card devices still is use is the punch card reader.

Other Input Devices
Voice input device
• Voice input device or voice recognition system converts spoken words into
electrical signals by comparing the electrical patterns by a speaker’s voice with a set
of prerecorded patterns.
• If a matching pattern is found, the computer accepts this pattern as a part of its
standard “vocabulary”
• The biggest problem with this technology are limitations on the size of the
computer’s vocabulary, pronunciation differences among individuals and the
computer’s inability to accept continuous speech.

Other Input Devices
Touch-tone device
• It has wide spread use in many developed nations.
• Touch-tone devices can be used to send data to a computer.
• Touch-tone devices are also used to run credit card checks in retail stores.
• After appropriate keys are touched, the device sends data over a phone line
to a central computer, which then checks the data against files and report
credit information back to the store.

Topic-7 Input Devices (Computer Fundamentals)

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