Chapter Output devices

OUTPUT DEVICES

The main function of an output device id to convert the binary information inside computer in numbers and words so as to be easily understood by the user.Whatever we input the data, it is processed and comes in front of us in special format which is called output.To showing this output there are a number of output there are a number of output devices available like Monitor, Printers etc .Some of them are described below:

MONITORS (VISUAL DISPLAY UNIT)

Monitors is a output devices also called visual display unit.This device displays data or informations while getting input and also displays the data or information after getting processed in the CPU.

A cathode ray tube is used in most of the monitors (in early times) now a days LCD is in use.Its memory unit receives the code in binary form and then form the result.

The formation of images and pictures is controlled by a video controller. The video controller and memory are together termed as the display adapter. Controller and memory are together termed as the display adapter.

Display adapter is used to display alphabetical data while it is in the text mode.

In the graphic mode, the display screen is divided into thousands of picture elements.These picture elements are called ‘pixels’.The number of pixels on the screen decides the resolution of the monitor.There are two types of monitors mainly used:
(i) VGA Monochrome
(ii) VGA Colour

VGA MONOCHROME

Monochrome monitor are often called black and white monitor. It shows text and objects in black and white only. VGA means Video Graphic Adapter.

VGA COLOUR

VGA Colour monitor is colour monitor with high resolution.It displays text and object in several colour ranging from 16 to over millions in number.

PRINTER

Result from a computer can be provided on a sheet of paper using the devices known as printer.There are many types of printers.Some of them are:

(i) Line Printer : Line printers print entire line at once.Line printers have normally 132 print positions. A character can be printed in any of the print position. The lines of data are printed at a rate of 300 to 3000 lines per minute.

(ii) Dot Matrix Printer : This type of printers prints one character at a time, with an array of pins moving across a line. Characters to be printed are sent one at a time from the memory to the printer.

A dot-matirx printer can print graphics and letters in different fonts. It can print upto 300 characters per second. But now high speed printers are also available which can print 500 characters per second.

(iii) Inkjet Printer : These types of printers spray jets of ink towards the paper. It is very cheap in price but its printing cost is high.

(iv) Laser Printer : Laser printer is the most advanced printer. It is a combination of micro electronics, laser beam technology and photocopying technology.
A laser beam sensitizes selected areas on a print page. The laser exposed area magnetizes a toner that attaches itself to the laser generated changes to the drum. Heat or pressure constantly fuses the toner on the paper.
A laser printer can print upto 10-12 pages per minute.

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