Computer Applications: Secondary Level: Unit-2: Input Devices, Output Devices

Bar code Readers (BCR)

Scanner tag Reader is a gadget utilized for perusing bar coded information (information as light and dim lines). Bar coded information is for the most part utilized in naming merchandise, numbering the books, and so on. It very well might be a handheld scanner or might be implanted in a fixed scanner. Scanner tag Reader examines a standardized tag picture, changes over it into an alphanumeric worth, which is then taken care of to the PC that the bar code is associated with.

Voice Recognition

Voice or speaker acknowledgment is the capacity of a machine or program to get and decipher transcription or to comprehend and do spoken orders. Voice acknowledgment has acquired unmistakable quality and use with the ascent of AI and smart colleagues, like Amazon’s Alexa, Apple’s Siri and Microsoft’s Cortana. Voice acknowledgment frameworks empower shoppers to collaborate with innovation just by addressing it, empowering sans hands solicitations, updates and other straightforward errands. Voice acknowledgment is a PC programming project or equipment gadget with the capacity to disentangle the human voice.

Light Pen

Light pen is a pointing gadget like a pen. It is utilized to choose a showed menu thing or draw pictures on the screen. It comprises of a photocell and an optical framework set in a little cylinder. At the point when the tip of a light pen is moved over the screen and the pen button is squeezed, its photocell detecting component distinguishes the screen area and conveys the relating message to the CPU.


Microphone is an information gadget to enter sound that is then put away in a computerized structure. The mouthpiece is utilized for different applications, for example, adding sound to an interactive media show or for blending music.

Touch Screen

A touch screen is a presentation gadget that permits the client to cooperate with a PC by utilizing their finger. They can be very helpful as an option in contrast to a mouse or console for exploring a graphical UI (GUI). Contact screens are utilized on different gadgets, for example, PC and PC screens, PDAs, tablets, sales registers, and data booths. Some touch screens utilize a network of infrared pillars to detect the presence of a finger as opposed to using contact delicate information.

2.5. Output Devices

Following are a portion of the significant result gadgets utilized in a PC.
  • Monitors
  • Graphic Plotter
  • Printer


Monitor, normally called as Visual Display Unit (VDU), are the fundamental result gadget of a PC. It structures pictures from small specks, called pixels that are organized in a rectangular structure. The sharpness of the picture relies on the quantity of pixels.
There Are Two Sorts Of Review Screen Utilized For Monitor.
  • Cathode-Ray Tube (CRT)
  • Flat-Panel Display

Cathode-Ray Tube (CRT) Monitor

The CRT show is comprised of little picture components called pixels. The more modest the pixels, the better the picture clearness or goal. It takes more than one enlightened pixel to frame an entire person, for example, the letter ‘e’ in the word help. There are a few hindrances of CRT Large in Size and High power utilization.

Flat Panel Display Monitor

The Flat-Panel show alludes to a class of video gadgets that have decreased volume, weight and power necessity in contrast with the CRT. You can balance them on walls or wear them on your wrists. Current purposes of flat-panel board shows incorporate mini-computers, computer games, screens, PC, designs show. The flat-panel board show is partitioned into two classes
  • Emissive Displays− Emissive showcases are gadgets that convert electrical energy into light. For instance, plasma board and LED (Light-Emitting Diodes).
  • Non-Emissive Displays− Non-emissive showcases utilize optical impacts to change over daylight or light from another source into designs. For instance, LCD (Liquid-Crystal Device).

Characteristics Of A Screen

Following are the qualities of a screen:
a) Size: The main part of a screen is its size. Screen sizes are estimated in askew inches, the separation starting with one corner then onto the next inverse corner slantingly.
b) Resolution: The goal of a screen demonstrates how thickness the pixels are stuffed. Pixel is short for picture component. A pixel is a solitary point in a realistic picture.
c) Band Width: how much information that can be sent in a decent measure of time.
d) Refresh Rate: Display screens should be invigorate all the time. The invigorate rate decides how often each seconds the screen is to be red drawn. The revive pace of a screen is estimated in Hertz.
e) Interlacing: It is a strategy wherein as opposed to checking the picture each line in turn, it filters on the other hand for example substitute lines are examined at each pass.

Video Standard

It will be baffling in the event that you get another screen and, figure out you can’t associate it to your PC! Your PC needs to send data to your screen so you can see it. The exact way it does that, and through what sort of link, is the video standard utilized. Four distinct norms are broadly utilized. Each has unsatisfactory. Your PC will ordinarily have from 1 to 3 of those choices accessible to you. They only sometimes offer each of the four guidelines. Your screen will most likely proposition 2 or 3 choices. At times your PC probably won’t have the sort of standard utilized by your screen, particularly in the event that you are adding a subsequent screen.


The most established standard is VGA. It represents Video Graphics Array and was presented by IBM in 1987. It has been improved from that point forward to take into consideration more pixels and better execution. This is an Analog showcase standard, so cabling, and distance can corrupt the nature of the result. All things considered, screens will be more appealing utilizing a computerized norm.


A Super Video Graphics Array (SVGA) screen is a result gadget which utilizes the SVGA standard. SVGA is a video-show standard sort created by the Video Electronics Standards Association (VESA) for IBM PC viable PCs (PCs).


XGA (Extended Graphics Array) is a high-goal video show mode that gives screen pixel goal of 1,024 by 768 of every 256 tones or 640 by 480 in high (16-bit) variety. The XGA standard is utilized in work area and PCs well as in projection frameworks.


Printer is a result gadget, which is utilized to print data on paper.
There are two sorts of printers-
  • Influence Printers
  • Non-Impact Printers

Influence Printers

Influence printers print the characters by striking them on the strip, which is then pushed on the paper.
Attributes of Impact Printers are the accompanying −
  • Exceptionally low consumable expenses
  • Exceptionally boisterous  Useful for mass printing because of minimal expense
  • There is actual contact with the paper to deliver a picture
These printers are of two kinds −
  • Character printers
  • Line printers

Character Printers

Character printers are the printers which print each person in turn.
These are additionally isolated into two sorts:
  • Dot Matrix Printer(DMP)
  • Daisy Wheel

Dot Matrix Printer

On the lookout, one of the most well known printers is Dot Matrix Printer. These printers are famous on account of their simplicity of printing and conservative cost. Each character printed is as example of dabs and head comprises of a Matrix of Pins of size (5*7, 7*9, 9*7 or 9*9) which emerge to frame a person which is the reason it is called Dot Matrix Printer.


  • Modest
  • Generally Used
  • Other language characters can be printe


  • Slow Speed
  • Low quality

Daisy Wheel

Head is lying on a haggle relating to characters are like petals of Daisy (bloom) which is the reason it is called Daisy Wheel Printer. These printers are by and large utilized for word-handling in workplaces that require a couple of letters to be sent to a great extent with exceptionally decent quality.


  • More solid than DMP
  • Better quality
  • Textual styles of character can be effectively different


  • More slow than DMP
  • Uproarious
  • More costly than DMP

Line Printers

Line printers are the printers which print each line in turn.
These are of two sorts
  • Drum Printer
  • Chain Printer

Drum Printer

This printer resembles a drum in shape subsequently it is called drum printer. The outer layer of the drum is partitioned into various tracks. All out tracks are equivalent to the size of the paper, for example for a paper width of 132 characters, drum will have 132 tracks. A person set is embellished on the track. Different person sets accessible in the market are 48 person set, 64 and 96 characters set. One turn of drum prints one line. Drum printers are quick in speed and can print 300 to 2000 lines each moment.


  • Exceptionally high velocity


  • Over the top expensive
  • Characters Fonts can’t be changed

Chain Printer

In this printer, a chain of character sets is utilized, subsequently it is called Chain Printer. A standard person set might have 48, 64, or 96 characters.


  • Character text styles can without much of a stretch be changed.
  • Various dialects can be utilized with a similar printer.


  • Uproarious
Non-influence Printers
Non-influence printers print the characters without utilizing the lace. These printers print a total page at a time, thus they are likewise called as Page Printers.
These printers are of two sorts
  • Laser Printers
  • Inkjet Printers
Attributes of Non-influence Printers
  • Quicker than influence printers
  • They are not boisterous
  • Top caliber
  • Upholds numerous textual styles and different person size

Laser Printers

These are non-influence page printers. They use laser lights to create the dabs expected to shape the characters to be imprinted on a page.


  • Extremely fast
  • Extremely great result
  • Great illustrations quality

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