COMPUTER SYSTEM
OUTPUT DEVICES
Output unit consists of devices with the help of which we get the information from computer.
This unit is a link between computer and users.
Output devices translate the computer's output into the form understandable by users.
Monitors
Monitor commonly called as Visual Display Unit (VDU) is the main output device of a
computer. It forms images from tiny dots, called pixels, that are arranged in a rectangular
form. The sharpness of the image depends upon the number of the pixels.
There are two kinds of viewing screen used for monitors:
Cathode-Ray Tube (CRT)
Flat-Panel Display
Cathode-Ray Tube (CRT) Monitor
In the CRT, display is made up of small picture elements called pixels for short. 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 lines vertically.
There are some disadvantages of CRT:
Large in Size
High power consumption
Flat-Panel Display Monitor
The flat-panel display refers to a class of video devices that have reduced volume, weight and
power requirement compared to the CRT. You can hang them on walls or wear them on your
wrists. Current uses for flat-panel displays include calculators, video games, monitors, laptop
computer, graphics display.
The flat-panel display are divided into two categories:
Emissive Displays - The emissive displays are devices that convert electrical energy
into light. Examples 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)
Printers
Printer is the most important output device, which is used to print information on paper.
There are two types of printers:
Impact Printers
The printers that print the characters by striking against the ribbon and onto the paper, are
called impact printers.
Characteristics of Impact Printers are the following:
Very low consumable costs
Impact printers are very noisy
Useful for bulk printing due to low cost
There is physical contact with the paper to produce an image
These printers are of two types:
Character printers
Line printers
Character Printers:
Character Printers are printers, which print one character at a time.
These are of further two types:
Dot Matrix Printer (DMP)
Daisy Wheel
Dot Matrix Printer
In the market, one of the most popular printer is Dot Matrix Printer because of their ease of
printing features and economical price. Each character printed is in form of pattern of Dot's
and head consists of a Matrix of Pins of size(5*7, 7*9, 9*7 or 9*9) which comes out to form a
character that is why it is called Dot Matrix Printer.
OUTPUT DEVICES
Output unit consists of devices with the help of which we get the information from computer.
This unit is a link between computer and users.
Output devices translate the computer's output into the form understandable by users.
Monitors
Monitor commonly called as Visual Display Unit (VDU) is the main output device of a
computer. It forms images from tiny dots, called pixels, that are arranged in a rectangular
form. The sharpness of the image depends upon the number of the pixels.
There are two kinds of viewing screen used for monitors:
Cathode-Ray Tube (CRT)
Flat-Panel Display
Cathode-Ray Tube (CRT) Monitor
In the CRT, display is made up of small picture elements called pixels for short. 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 lines vertically.
There are some disadvantages of CRT:
Large in Size
High power consumption
Flat-Panel Display Monitor
The flat-panel display refers to a class of video devices that have reduced volume, weight and
power requirement compared to the CRT. You can hang them on walls or wear them on your
wrists. Current uses for flat-panel displays include calculators, video games, monitors, laptop
computer, graphics display.
The flat-panel display are divided into two categories:
Emissive Displays - The emissive displays are devices that convert electrical energy
into light. Examples 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)
Printers
Printer is the most important output device, which is used to print information on paper.
There are two types of printers:
Impact Printers
The printers that print the characters by striking against the ribbon and onto the paper, are
called impact printers.
Characteristics of Impact Printers are the following:
Very low consumable costs
Impact printers are very noisy
Useful for bulk printing due to low cost
There is physical contact with the paper to produce an image
These printers are of two types:
Character printers
Line printers
Character Printers:
Character Printers are printers, which print one character at a time.
These are of further two types:
Dot Matrix Printer (DMP)
Daisy Wheel
Dot Matrix Printer
In the market, one of the most popular printer is Dot Matrix Printer because of their ease of
printing features and economical price. Each character printed is in form of pattern of Dot's
and head consists of a Matrix of Pins of size(5*7, 7*9, 9*7 or 9*9) which comes out to form a
character that is why it is called Dot Matrix Printer.
