2. A computer system needs to communicate with its external environment its
user). The Input/output devices provide this capability to a computer system.
they are also known as peripheral devices, because they surround a computer's
cpu and memory.
INPUT OUTPUT DEVICES
4. INPUT DEVICE
Input devices are used to enter data from outside
world into primary storage & output devices supply
the result of processing from primary storage to
users.
Input device is any peripheral (piece of computer
h/w equipment) used to provide data & control
signals to an information processing system.
Input/output devices make up the h/w interface
between a computer .
5. THE MOST COMMON INPUT DEVICES A R E
FOLLOW ING .
Keyboard
Mouse
6. KEYBOARD
• The keyboard is the main input device for computers. For instance,
boot up a computer without a keyboard and it stops, warning the
user that no keyboard is attached.
• The keyboard is the only tool available at the command prompt, so it
is a necessity for a computer.
• It is also used in almost every application like spreadsheets, email,
word processing documents and coding.
8. MOUSE
Mouse is most popular pointing device. It is a very famous cursor-
control device having a small palm size box with around ball at its base
which senses the movement of mouse and sends corresponding signals to
CPU when the mouse buttons are pressed.
Generally it has two buttons called left and right button and a wheel is
present between the buttons.
Mouse can be used to control the position of cursor on screen, but it
cannot be used to enter text into the computer.
10. Output device
An output device is any piece of computer hardware equipment used to
communicate the results of data processing carried out by an information
processing system (such as a computer) to the outside world.
In computing, input/output, or I/O, refers to the communication between an
information processing system (such as a computer), and the outside world.
Inputs are the signals or data sent to the system, and outputs are the signals
or data sent by the system to the outside.
12. MONITOR
A Monitor or Display (sometimes called a visual display unit) is an
electronic visual display for computers.
The monitor comprises the display device, circuitry, and an enclosure.
The display device in modern monitors is typically a thin film transistor liquid
crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray
tube about as deep as the screen size.
13. TYPES OF MONITOR
Tow basic types of monitors are used with micro
computers, which are as follows:
Cathode-Ray Tube(CRT)
Thin Film Transistor (TFT)/Flat Panel Display
14. CRT:
Cathode-Ray Tube:
(CRT) Monitor The CRT display is made up of small picture
elements called pixels.
The smaller the pixels, the better the image clarity, or resolution. It takes more than
one illuminated pixel to form whole character, such as the letter 'e' in the word help. A
finite number of characters can be displayed on a screen at once. The screen can be
divided into a series of character boxes fixed location on the screen where a standard
character can be placed. Most screens are capable of displaying 80 characters of data
horizontally and 25 line There are some disadvantages of CRT Large in Size High power
consumption
15. TFT:
Flat-Panel Display Monitor The flat-panel display refers to a class of video devices that have
reduced volume, weight and power requirement in comparison to the CRT.
You can hang them on walls or wear them on your wrists.
Current uses of flat-panel displays include calculators, video games, monitors, laptop
computer, graphics display.
The flat-panel display is divided into two categories Emissive Displays - The emissive
displays are devices that convert electrical energy into light.
Example are plasma panel and LED(Light-Emitting Diodes).
Non-Emissive Displays - The Non-emissive displays use optical effects to convert sunlight
or light from some other source into graphics patterns. Example is LCD(Liquid-Crystal Device).
16. PRINTER
After a document is created on the computer, it can be sent to a
printer for a hard copy (printout).
Some printers offer special features such as coloured and large page
formats Some of the most commonly used printers are:
Laser Printer
Ink Jet Printer
Dot Matrix Printer
Line Printer
17. LASER PRINTER
Laser Printer: A laser printer produces high quality print that one
normally finds in publishing.
It is extremely fast andquiet. Moreover, the operation of a laser printer
is easy with automatic paper loading and no smudging or messing up
ofink ribbons.
The fastest laser printer Laser Printer Basics of Computer :: 9 can
print up to 200 pages per minute inmonochrome (black and white) and up
to 100 pages per minute in colour.
18. INK-JET PRINTER
Ink-jet Printer: An ink-jet printer creates an image directly on paper by spraying
ink through as many as 64 tiny nozzles Although the image it produces is not
generally quite as sharp as the output of a laser printer, the quality of ink-jet images
is still high.
In general, ink-jet printer offers an excellent middle ground between dot matrix
and laser printer Like laser printer, an ink-jet printer is quiet and convenient, but not
particularly fast.
Typically, an ink-jet printer is more expensive than a dot-matrix printer, but
costs only half as much as a laser printer.
19. DOT MATRIX PRINTER:
Dot Matrix Printer: The dot matrix printer was very popular at one
point of time.
It is a very versatile and inexpensiveoutput device.
In dot matrix printer the print head physically "hits" the paper through
the ribbon and produces text (orimages) by combinations of dots; hence
the name dot matrix printer.
Its speed is measured in characters per second(CPS). Although it is less
expensive, it is louder, slower and produces lower print quality.
