6th Class Computers Science Basics of Computer Output Device

     Output Device

The output devices are peripherals that receive machine understandable output in the form of binary code from the processor and convert it into user understandable form. The following are the output devices:  

   Monitor

As we have already studied in the previous classes that "a device, on which images are generated by the computer's video adapter is known as monitor". Here the monitor is connected by the video adaptor by a cable. Basically monitor contains two types of screen, color screen and monochromic screen. Monitor that generally displays 256 colors from a selections of 256,000 choices are called color screen whereas the monitor which displays only a single color is known as monochrome which display any multimedia object or text graphics in a single color usually black, white, green or amber. (See Figure 6.1.10)  

  Display devices

A number of display devices are available, which generally vary from one to the other on the basis of several key factors, may be their physical design or a display technology.  

 These display devices are commonly categorized as:

• LCD (Liquid Crystal Display)
• CRT (Cathode Ray Tube)
• TFT (Thin Film Transistor)  

  Liquid Crystal Display

The LCD (Liquid Crystal Display) is one of the devices which is generally used for numerical indicators, such as in digital watches, calculators and in many others. Basically these types of display devices are very useful in those devices which are battery powered devices because they require a very small amount of current. Now a day, LCD display is widely used for the text and graphics output after some modifications.  

  Cathode Ray Tube

The CRT is a display device which is used in mostly television and computer display screen. Generally the CRT (Cathode Ray Tube) refers technically to an electronic vacuum tube applying beam of electrons.  

   Thin Film Transistor

The TFT (Thin Film Transistor) is one of the popular technologies in the field of electronics now a day. Many companies have adopted this technology to enhance the color screen. This technology is also known as Active Matrix.  

  Printer

Printer is one of the primaries output devices which are used to create a hard copy of any of the soft copy weather it may be a text or any picture. Generally it is one of the useful and convenient methods for delivering information using printed character. Printer s classified into two categories. (See Figure 6.1.11)    

  Impact Printer

Impact printers are those printers which basically prints through striking characters against ribbons or the ink pads so that impression should be on the paper and thus known as the impact printers. Generally these printers are having a mechanical contact between the paper and the printer head such as character printer and the line printer. Daisy wheel printer and Dot Matrix printer are the example of Impact printer  

 Non Impact Printer

Those printers which are using a thermal, magnetic or laser technology are generally known as non-impact printers, such as Ink Jet printer. Electromagnetic printer, thermal printer and Laser printers. the first laser printer was developed by Xerox Corporation in 1971. It uses laser ream and an electro photographic drum to develop images on paper. The quality of printing by laser printer is high. Inkjet printer was developed by Canon. It places vary small droplets of ink onto a paper to create an image. The diameter of dots is between 50 to 60 microns.

 Monitor is an output device which is used to display the output. Which of the following types of monitor uses Active Matrix technology?

(A) LCD                                                                

(B) CRT

(C) TFT                                                                 

(D) Both A and C

(E) None of these  

Answer: (d)

Explanation

Correct Option:

(D) LCD and TFT are based on Active Matrix technology.

Incorrect Options:

(A) LCD is used for numerical indicator and based on active matrix technology.

(B) CRT is based on vacuum tube.

(C) TFT is based on Active Matrix technology.  

  Which one of the following types of monitors uses vacuum tube for applying a focused beam of electrons?

(A) LCD                                                                

(B) CRT

(C) TFT                                                                 

(D) All of these

(E) None of these  

Answer: (b)

Explanation

Correct Option:

(B) CRT refers technically to an electronic vacuum tube applying a focused beam of electrons.

Incorrect Options:

(A) LCD is used for numerical indicator and based on active matrix technology.

(C) TFT is based on Active Matrix technology.    

 Printer is an output device that gives the hard copy of your program output. The output may be text or picture. They are of two types. Impact printer and Non Impact printer. Which one of the following is an example of Impact printer?

(A) Thermal printer                                        

(B) Daisy wheel printer

(C) Laser printer                                              

(D) All of these

(E) None of these  

Answer: (b)

Explanation

Correct Option:

(B) Daisy wheel printer is an impact printer.

Incorrect Options:

(A) Thermal printer is a non impact printer.

(C) Laser printer is a non impact printer.

(D) Is incorrect

(E) Is incorrect    

• The first computer printer was invented by Charles Babbage.
• The latest monitors will switch to a power-saving mode if no video-input signal is received.  

• Mouse: Mouse is a type of input device which basically contains two buttons one at right and another is on the left.
• Light Pen: It works similarly as of mouse but it's basically used to point out for particular task.
• Barcode Reader: It is an optical input device that is used to read the values or quantities printed on the products in the form of vertical bars known as bar code.
• TFT (Thin Film Transistor): lt is a popular technology in the field of electronics now a day.  

• Micro Computer is a computer whose CPU (Central Processing Unit) is a microprocessor.
• The history of computer starts with the birth of abacus.
• First generation computers used machine language.
• The fifth generation computers are based on an artificial intelligence.
• Joystick is mainly used for playing Video Games.
• Handheld scanners works like a manual device.
• In 1822 Babbage started to design an automatic mechanical machine called difference engine
• Second generation computers basically used two types of devices which were transistors and magnetic core and were used for memory storage.
• The process of writing computer programs is called computer programming.
• Flowchart is a technique that allows you to represent computer program graphically.
• Optical mouse is much advanced comparison to the other mouse. It responds very fast and precisely than any other mouse.  

    Abbreviations

USB                        -              Universal Serial Bus

CAD                       -              Computer Aided Designing

UNIVAC                 -              Universal Automatic Computer