Sir Sadiq s computer notes for class IX. Chapter no 3. Input/Output Devices

Transcription

1 12

2 Q: What are Input Devices? Ans: Input Devices: Input devices are physical equipment that read or translate data consisting of alphabets, numbers or other symbols into electronic impulses, which can be understood by the computer. The purpose of input devices is to pass information into the memory unit of the CPU and convert the characters into binary patterns. There are different types of Input Devices used to transfer data in the computer. E.g. Keyboard, Mouse, Trackball, Joystick, Scanner etc. Q: What are the parts (division) of Keyboard? Or Write a note on Keyboard. Ans: Keyboard: A keyboard is a primary input device used to feed information and algorithm directly into a computer. It consists of a set of keys, which uses the same key arrangement as the mechanical and electronic typewriter keyboards. The standard arrangement of alphabetic keys is known as QWERTY keyboard. A standard keyboard includes about 100 or 104 keys and each key sends a different signal to the CPU. These keys are divided into five different groups. These groups are: 1. The alphabet keys (Aa to Zz) 2. Numeric Keys (0 to 9) 3. Function Keys (F1 to F12) 4. Screen navigation and editing keys (Cursor keys, Home, End, Page up and Page down keys) 5. Special function keys (Enter, Caps Lock, Shift etc) Q: What are standard alphanumeric keys? Ans: Alphanumeric keys: An alphanumeric keypad is a main part of a keyboard that contains both numbers and letters. By using this keypad the letters (a-z, A-Z), the numbers (0 9), symbols (!@#$%^&*()_+-=[]{},~etc) may be typed. Many of these characters are typed by holding shift key. Any type of data can be entered through this keypad. 13

3 Q: What is numeric keypad? Ans: Numeric Keypad: The Numeric keypad is located on the right Side of keyboard. When Num lock key is pressed then the numbers on numeric keypad can be used. These keys are used to input numeric data only. It looks like a simple calculator which includes number keys from 0 to 9 digits. Q: What are function keys? Ans: Function Keys: These are twelve keys marked as F1 to F12 located at the top of the keyboard. All of these keys have pre-defined meanings which provided to a programmer to attach special functions to each key depend on the application software. These keys are used to input commands without typing the long commands. These keys perform different functions in different programs. Fr example F1 key is a help key in most of the program. Q: What is screen navigation and editing keys? Ans: Screen Navigation keys: These keys are provided to move cursor around in the screen. Most keyboards include the following cursor movement keys: Arrow keys (left, right, up, down), Home and end keys (to moves the cursor to the beginning of the line and to the end of line), Page up and page down keys (to make the cursor jump page by page). Q: What is the use of enter key? Ans: Enter key: Enter key tells the computer that an instruction is completed or to transfer a written instruction or data into the ALU. Enter key is also used to move the cursor to the next line by adding one-line space when we want to start a new paragraph. 14

4 Q: Write about Mouse. Ans: Mouse: The mouse is an alternate input device normally called a pointing device. It is used to move a pointer on the computer screen in order to point to a place on a display screen and to select one or more actions to be taken from that position. The mouse is an integral part of the Graphical User Interface (GUI) of any personal computer. The mouse apparently got its name by being about the same size and shape as a toy mouse. A mouse has two or three buttons in the front. The left button is used most frequently. We use mouse for selecting, clicking, dragging and dropping. Q: Write about Track ball? Ans: Track Ball: A track ball is an input device. The function of a track ball is same as mouse. We use a trackball by rolling the ball with our palm or fingers in the direction we want the pointer to go. The user spins the ball with fingers to move the pointer on the screen. The advantage of trackballs over mouse is that the trackball is stationary so it does not require much space to use it. Q: Write about Joystick. Ans: Joystick: A Joystick is a hand-held stick like the joystick in an aero plane, which is used as a pointing device. Joysticks are used mostly for computer or video games, but they are also used occasionally for CAD/CAM systems and other applications. The joystick is just like a vertical handle that is gripped by hands. This handle is used to move an object on screen in any direction. Q: Write about light pen. Ans: Light pen: Light pen is a pointing input device that contains a photo detector or light source, and that allows interaction with a computer through a specially designed monitor / display screen. It is usually used for engineering designing. A light pen is similar to a mouse, except that with a light pen we can move the pointer and select objects on the display screen by directly pointing to the objects with the pen. 15

5 Q: Write about digital camera. Ans: Digital camera: A digital camera is another hand-held, portable input device that takes pictures as input. Normal cameras capture picture on a special coated film, while digital camera capture imaged electronically without the need of a film. The digital camera stores then snapshots in its memory then user can copy them into a computer. These images can be edited, printed or copied in a document etc. Most digital cameras have abilities to increase their capacity by accepting additional memory. Q: Write about scanner. Ans: Scanner: Scanner is an input device that reads images or text and converts the data into digital signals, which can be directly fed and stored in computer. Graphical scanners read photos or other images into the computer and digitize them, producing bitmapped graphics files. The scanner saves an image of the graphic as a file on the computer. Scanner usually comes with software such as Adobe Photoshop product. Some most common types of scanners are follows: 1. Hand-held scanners 2. Flatbed scanners 3. Sheet-fed scanners Q: What is output? Or what are output devices? Ans: Output Devices: The data processed according to instructions is called meaningful information. Meaningful information is the result of work done by the CPU. It is either shown on the screen or printed on a sheet of paper. This result is known as output. The output can be shown on output devices. The output devices convert computer signals into a form to be understood by human or devices. Some of the output devices are monitor, printer, plotters, output on microfilm etc. Q: Write a note on Monitor. Ans: Monitor: It is also called a display screen. The monitor usually refers to the entire box. It is a device that displays text and graphics generated by a computer. In the future flat-screen LCD (Liquid Crystal Display) panels are likely to completely replace today s bulky cathode ray tube (CRT). The basic two types of monitors are: 16

6 1. CRT monitors, which is similar to the television screen and also works in the same way. It uses a large vacuum tube called Cathode Ray Tube (CRT). 2. Flat-Panel Display (Liquid Crystal Display or LCD), which is usually used with portable computers but now have become very popular with the desktop computers too. In terms of color capabilities, all the monitors fall into three classes: 1. Monochrome: Monochrome monitors actually display two colors, one for the background and one for the foreground. The color can be black and white, green and black, or amber and black. 2. Gray-Scale: A gray-scale monitor is a special type of monochrome monitor capable of displaying different shades of gray. 3. Color: color monitors can display anywhere from 16 to over 1 million different colors. Colors are sometimes called RGB (Red, Green and Blue) monitors. Q: What is printer? Write about it. Ans: Printer: Printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. There are many different types of printers. In terms of the technology utilized, printers fall into basic two categories: a) Impact printers b) Non-impact Printers. a) Impact printers: Impact printers include all printers that work by striking an ink ribbon. Daisy wheel, dot matrix, and line printers are impact printers. Impact printers are much noisier than other printers. b) Non-Impact printers: Non-Impact printers include laser printers, ink-jet printers etc. They are quiet and speedy printers. Non-Impact printers form characters and images without making physical contact between printing mechanism and papers. Q: Write a note on Plotter. Ans: Plotter: A plotter is an output device for printing high quality drawings. It helps us in getting graphical or pictorial representation of information. Plotter is used 17

7 where fine work is involved like drawing graphs that requires a great deal of accuracy. It is generally used by architects and engineers. It is usually used for drawings or taking large posters. Plotters can be of two types: Pen plotters and Electrostatic plotters. Pen plotters have an ink pen attached to draw the images, and electrostatic plotters work similarly to a laser printer. Pen plotters are further divided into two types: Drum plotters and Flatbed plotter. Q: Write a short note on Drum plotters and Flatbed plotters. OR Types of a plotter. Ans: Drum plotters: A drum plotter consists of a solid cylindrical drum that has embossed characters in bands on its upper surface. This drum rotates at a high speed. The speed of drum plotter is form 300 lines per minute to 2000 lines per minute. In drum plotters, the pen is moved in a single axis track and the paper itself moves on a cylindrical drum to add the other axis or dimension. Flatbed plotters: It is a plotter in which the paper is fixed on a flat surface and pens are moved to draw the image. This plotter can use several different color pens to draw with. The size of the plot is limited only by the size of the plotter s bed. Q: What is soft copy and what is hard copy? Or Write the difference between softcopy and Hardcopy? Ans: Softcopy: Screen output is known as softcopy because it is intangible and temporary. Or The output displayed on the monitor is called soft copy. We cannot touch it. It is editable. Hardcopy: Paper output is known as hardcopy because it is tangible and can be permanent. Or The output displayed on the paper is called hard copy. We can touch it. It is a non-editable. Q: Which device is used as an input device as well as output device? Or write about dual devices. Ans: Dual Devices: Dual devices are devices that are input and output devices at the same time e.g. disk drive and CD writer. Disk drive is a peripheral device that read or writes that disks. Similarly, CD writer can write on compact disk. When these devices are used to read some data from it, they fall in the category of input devices, while during writing data onto the disk they will be considered as output devices. 18

8 Differences Soft copy and Hard copy Soft Copy The output produced by the computer on display screen or is in audio or voice form is called soft copy. Soft copy is intangible. (It cannot be touched copy) It is temporary copy. It is an editable copy. Monitor and speaker are commonly used soft copy producing device. Hard Copy The output produced by the computer on paper or other material like transparency etc is known as hard copy. Hard copy is tangible. (It can be touched copy) It is permanent copy. It is non-editable copy. Printers and plotters are commonly used hard copy producing devices. Impact printer and Non-impact printer Impact printer An impact printer forms characters or imaged by striking a mechanism such as print hammer or wheel on a linked ribbon against the paper. They are noisy printers. Images or documents produce by the impact printer is not of good quality. They are not very speedy. Dot-matrix, daisy wheel, drum printer are the examples of impact printer. Non-impact printer The non-impact printers form characters and images without making physical contact between printing mechanism and paper. They are quiet printers. Images or documents produce by the non-impact printer is of good quality. They are speedy. Thermal, inkjet, laser printers are the example of non-impact printer. Sir Sadiq s Computer Notes for Class IX. Composed by: Sir Sadiq smsadiqnoori@gmail.com 19