01 c] List any three input and three output devices of a computer and explain one each.
Answer:-
Input Devices:-
Keyboard:
- Every computer supports a keyboard – either a physical or touchscreen.
- The keyboard has a QWERTY layout and contains a large number of symbols.
- Each letter, numeral, or symbol is known as a character, which represents the smallest piece of information.
- Each character has a unique value called the ASCII (American Standard Code for Information Interchange) value.
Pointing Devices:
- GUI (Graphical User Interfaces) like windows needs a pointing device to control the movement of a cursor on the screen.
- This is implemented as a mouse on a desktop and a touchpad on a laptop. The earliest form has a rotating ball and two buttons.
- The left button is used for selecting (by clicking once) and executing (by clicking twice).
- The right button is used to check and change attributes.
- The optical mouse uses infrared laser/LED, the wireless mouse uses radio frequency technology.
Scanner:
- A scanner is a device that creates a digital image of a document by optically scanning it.
- The flatbed scanner doesn’t exceed more than A4 size. It is operated by using special software.
- The document to be scanned is placed on a glass plate covered by a lid.
- Modern scanners have an OCR (Optical Character Recognition) facility which extracts the text as a stream of characters i.e. converting image file to text file and MICR (Magnetic Ink Character Recognition) reads the codes using handheld barcode readers.
Output Devices:-
Monitor:
- The monitor is an integral part of the computer which displays both text and graphics.
- The performance is measured in terms of image quality, resolution, and energy consumption.
CRT (Cathode Ray Tube) Monitors:
- The CRT monitors have a rarefied tube containing three electron guns.
- The guns emit electrons to create images.
- They usually have a resolution of 640*840 pixels.
- They are large, heavy, energy-efficient, and produce a lot of heat.
LCD (Liquid Crystal Display) Monitors:
- The image is formed by applying a voltage to crystals.
- The backlight is provided by fluorescent light.
- They consume less power, generate less heat, and have an increased life span.
Impact Printers:
- It produces the hard copy of the output.
- The impact printers are old and noisy. But, still, the dot-matrix printer is in usage.
Dot-Matrix Printer:
- The print head of the dot-matrix printer has either 9 or 24 pins.
- When the pins fire against the ribbon, an impression is created on the paper.
- The speed is 300 cps and doesn’t produce high-quality output.
- It can produce multiple copies.
Daisy-wheel Printer:
- It employs a wheel with separate characters distributed along its outer edge.
- The wheels can be changed to obtain a different set of fonts.
Line Printer:
- For heavy printing, the line printer is used. It uses a print chain containing the characters.
- Hammers strike the paper to print and it rotates at the speed of 1200 lpm.
- It is also noisy and is of low quality.