Computer Hardware: Input and Output Devices Explained, Study notes of Computer science

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Types of Keys on Keyboard The keys are categorised under the following groups

1. Alphanumeric Keys include the alphabet keys (A, B, C, ..., Z) and number keys (0, 1, 2, 3, ..., 9).
2. Numeric Keys are located at the right hand side of the keyboard. They consist of digits and mathematical operators.
3. Function Keys are the programmable keys, i.e. the programs can assign some specific actions. They are numbered from F1 to F12.
4. Cursor Control Keys include four direc- tional (left, right, up, down) arrow keys that are arranged in a inverted T formation between the alphanumeric and numeric keypad. Above the arrow keys there are four more keys to control the cursor. These are as follows (i) Home It is used to return the cursor to the beginning of the line or the beginning of a document. (ii) End It moves the cursor to the end of line. (iii) Page Up When it is pressed, the page view will be moved up one page and cursor goes to the back page. (iv) Page Down When it is pressed, the page view will be moved down one page and cursor goes to the next page.
5. Other Keys A keyboard contains some other keys such as follows (i) Control Key It performs a special operation with the combination of other keys. (ii) Enter Key It is used to finish an entry and begin the new entry in a document. Enter key is an alternative to press ok button. (ii) Shift Key Some keys on the keyboard like numeric keys have a symbol printed on their upper portion. Shift key is used to print these symbols. This key is also called combination key. (iii) Escape Key (Esc) It allows a user to cancel or abort operations, which are executing at present. It opens Start menu with the combination of Ctrl key.

(iv) Backspace Key It is used to erase anything typed. (v) Delete Key It is used to erase information from the computer’s memory and characters on the screen. (vi) Caps Lock Key It is used to type the alphabet in capital letters. It enables or disables all the letters from being typed in capital letters. When this key is enable, the alphabet would be in capital letters and when it is disabled, the alphabet would be in small letters. (vii) Num Lock Key It is used to enable and disable the numeric keypad. (viii) Windows Key It is used to open the Start menu. (ix) Spacebar Key It provides a space between two words. It is the longest key on the keyboard. (x) Tab Key It is used to move the cursor over to the right to a pre-set point. In Word document, tab is used to indent a paragraph.

n (^) QWERTY keyboard contains total 104 keys. n (^) Caps Lock and Num Lock keys are called as ‘toggle keys’ because when pressed, they toggle or change their status from one state to another. n (^) Shift, Ctrl and Alt keys are also known as modifier keys.

Pointing Devices

A pointing device is used to communicate with the computer by pointing to the locations on the monitor. Movements of the pointing device are echoed on the screen by movements of the pointer. Some commonly used pointing devices are mouse, trackball, joystick, light pen, touch screen, etc. which are described below :

Mouse It is a small handheld device having two buttons on its upper side and also has a small wheel between these buttons. It is a pointing device which provides a means to input data and commands in graphic form by selecting through moving an arrow called pointer on monitor.

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The mouse may be used to position the cursor on screen, move an object by dragging or select an object by clicking. Mouse was invented by Douglas Engelbart at Stanford Research Center in 1963.

There are three types of mouse as follows

(i) Wireless mouse (ii) Mechanical mouse (iii) Optical mouse

There are four actions of mouse as follows

1. Click or Left Click It selects an item on the screen.
2. Double Click It is used to open a document or program.
3. Right Click It displays a list of commands on the screen. Right clicking is used to access the properties of selected object.
4. Drag and Drop It is used to move an item on the screen.

Trackball It is another pointing device which is an alternative to a mouse. Trackball is also used to control cursor movements and actions on a computer screen. It is generally built in laptop, since there is no space for the mouse to move on the laptop. Trackball is used on CAD/CAM workstations and sometimes seen on computerised special purpose workstations such as radar consoles in an air-traffic control room and sonar equipment on a ship or submarine.

Joystick It is a device that moves in all directions and controls the movement of the cursor. Joysticks are used in flight simulators, CAD/ CAM system, etc.

A joystick is similar to a mouse except that the movement of cursor on screen stops working as soon as user stop moving the mouse. But with a joystick, the pointer continues moving in the previously pointing direction. Joystick allows movements in all directions (360°).

Light Pen It is a handheld electro-optical pointing device, which is used for making drawings, graphics and for menu selection. The pen contains a photocell in a small tube. It senses the light from the screen when it becomes closer and generates a pulse. It is used to especially in Personal Digital Assistants (PDA). It is very useful in identifying a specific location on the screen. However, it does not provide any information when it held over a blank part of the screen. Touch Screen It is an input device that accepts input when the user places a fingertip on the computer screen. Touch screens have an infrared beam that criss-cross the surface of screen. The ability to interact directly with a display typically indicates the presence of a touch screen. Touch screen is generally used in applications like ATM, hospitals, airline reservation, supermarkets, etc.

Barcode Reader It is an input device used for reading printed barcodes (Universal Product Code) available on product to be sold. A barcode reader emits a beam of light which reflects off the barcode image. A light sensitive detector in the barcode reader identifies the barcode image by recognising special bars at both the ends of the image. A perfect example of a barcode reader, use in a super market where barcode scanner reads the price of a product. A barcode is a machine readable representation of information in the form of stripes of dark and light ink.

Optical Mark Reader (OMR) OMR is also known as Optical Mark Recognition. It is the process of detecting the presence of intended marked responses. OMR is mainly used

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Trackball

Barcode Reader

Joystick

Barcode

(iii) Drum Scanners They are medium size scanners with a rolling drum. The sheet is fed through the scanners so that the drum rolls over the entire sheet to be scanned (just as the sheets are fed in a fax machine).

Microphone (Mic) We can send input to the computer through a special manual input device called microphone or mic. A mic converts the received sound into computer’s format, which is called Digitised Sound or Digital Audio.

To convert a voice into digital form, you need an additional hardware known as Sound Card. Sound is used most often in multimedia, where we can make our presentations more attractive using recorded narration, music or sound effects.

A microphone can be attached to a computer to record sound. Now-a-days, microphones are also being used with speech recognition software. This means that we do not have to type, rather just have to speak and the spoken words appear in our document.

Webcam (Web Camera) It is a video capturing device. Webcam is a digital camera attached to computers and can be used for video conferencing, online chatting, etc. A camera connected to a computer allows anyone, those are connected to the Internet, to view either a still picture or motion video of a user or other object.

Now-a-days, Webcams are either embedded into the display with laptop computers or connected via USB or firewire port or Wi-Fi to the computer.

PC Card

A PC card is a credit card size memory or I/O device that fits into a personal computer, usually

a notebook or laptop computer. Probably the most common use of a PC card is the tele- communications modem for notebook computers.

Output Devices An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing to the outside world. Some of the commonly used output devices are monitor, printers, plotter, speaker, headphones, projector etc. which are described below.

Monitor It is also known as Visual Display Unit (VDU). The monitor is provided along with the computer to view the display result. A monitor is of two kinds; monochrome display monitor and colour display monitor. A monochrome display monitor uses only one colour to display text and colour display monitor can display 256 colours at a time. An image on the monitor is created by a configuration of dots, also known as pixels. The refresh rate of monitor is measured in Hertz (Hz). The clarity of image depends on three factors which are as follows

1. Resolution of Screen Resolution refers to the number of pixels in horizontal and vertical directions. The resolution of monitor is higher when the pixels are closer together.
2. Dot Pitch It refers to the diagonal distance between two coloured pixels. The smaller the dot pitch, the better the resolution.
3. Refresh Rate It is the number by which per second. The higher the refresh rate, the more solid the image looks on the screen. The popular types of monitor are as follows
4. Cathode Ray Tube (CRT) It is a typical rectangular shaped monitor that you see on a desktop computer. The CRT works in a same way as a television. CRT has a vacuum tube. CRT works by moving an electron beam back and forth across the back of the screen. A screen covered with a fine layer of phosphorescent elements, called phosphores.

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Webcam with Computer (^) Webcam

Webcam

2. Liquid Crystal Display ( LCD) These screens are used in laptops and notebook sized PCs. A special type of liquid is sandwiched between two plates. It is a thin, flat and light weight screen made up of any number of color or monochrome pixels arranged in front of a light source.
3. Liquid/Light Emitted Diode (LED) It is an electronic device that emits light when electrical current is passed through it. LEDs usually produce red light, but today’s LEDs can produce RGB (Red, Green and Blue) light, and white light as well.
4. 3-D Monitor It is a television that conveys depth perception to the viewer. 3-D describes an image that provides the perception of length. When 3-D images are made interactive then user feels involved with the scene and this experience is called virtual reality.
5. Thin Film Transistor (TFT) TFT and Active-Matrix LCD (AMLCD) is a Liquid Crystal Display (LCD). With active-matrix displays, each pixel is controlled by one to four transistors that can make the screen faster, brighter, more colorful than passive-matrix and capable of being viewed at different angles. Because of this improved technology, active-matrix screens are often more expensive.

Printers

A printer prints information and data from the computer onto a paper. It can print documents in color as well as in black and white. The quality of a printer is determined by the clarity of a print.

The speed of a printer is measured in Characters Per Second (CPS), Lines Per Minute (LPM) and Pages Per Minute (PPM). Printer resolution is a numerical measure of print quality that is measured in Dots Per Inch (DPI).

Printers are divided into two basic categories

Impact Printers

This type of printer strikes paper and ribbon together to form a character, like a typewriter.

Impact printer can print a character or an entire line at a time. They use pins or hammers that pressed an inked ribbon against the paper. They are less expensive, fast and can make multiple copies with multipart paper. There are four types of impact printer

1. Dot Matrix Printer It forms characters using rows of pins which impact the ribbon on top of the paper therefore also called pin printers. Dot matrix printers print one character at a time. It prints characters and images as a pattern of dots. Many dot matrix printers are bi-directional, that is they can print the characters from either direction, i.e. left or right.
2. Daisy Wheel Printer In daisy wheel printers, characters are fully formed on the petals, like typewriter keys. These printers produce high resolution output and are more reliable than dot matrix.
3. Line Printer It is a high-speed printer capable of printing an entire line of text at once instead of one or more characters at a time. These are impact shaped character printers which print one line at a time. Print quality of line printer is not high.
4. Drum Printer An old line printer technology that uses formed character images around a cylindrical drum as its printing mechanism. When the desired character for the selected position rotated around the hammer line, the hammer hit the paper from behind and pushed it into the ribbon and onto the character. Non-Impact Printer This type of printer uses electrostatic chemicals and inkjet technologies. They do not hit or impact a ribbon to print. It can produce high quality graphics and often a wide variety of fonts than impact printers. There are following types of non-impact printer
5. Inkjet Printer It is a printer that places extremely small droplets of ink onto paper to create an image. It sprays ink onto paper to form characters and prints high quality text and graphics.

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parallel ports, Universal Serial Bus (USB), firewire ports, etc.

1. Parallel Port It is an interface for connecting eight or more data wires. The data flows through the eight wires simultaneously. They can transmit eight bits of data in parallel. As result, parallel ports provide high speed data transmission. Parallel port is used to connect printer to the computer.
2. Serial Port It transmits one bit of data through a single wire. Since, data is transmitted serially as single bit. It provides slow speed data transmission. It is used to connect external modems, plotters, barcode reader, etc.
3. Universal Serial Bus (USB) It is a common and popular external port available with computers. Normally, two to four USB ports are provided on a PC. USB also has the plug and play feature, which allows devices ready to be run. 4. Firewire It is used to connect audio and video multimedia devices like video camera. Firewire is an expensive technology used for large data movement. Hard disk drive and new DVD drives connect through firewire. It has data transfer rate of upto 400 MB/sec.

n (^) MP3 is an audio coding format for digital audio which uses a form of lossy data compression. n (^) The I/O devices that are attached, externally to the computer machine are also called peripheral devices. These are hardware. n (^) Speech recognition software can interpret voice data into words that can be understood by the computer. n (^) A dumb terminal is simply an output device that accepts data from the CPU.

1. Any component of the computer you can

see and touch is [IBPS Clerk 2015] (1) software (2) peripheral (3) storage (4) CPU (5) hardware

2. Which of the following is not a hardware?

[SSC FCI 2012] (1) Processor chip (2) Printer (3) Mouse (4) Java

3. A (n) …… device is any hardware component

that allows you to enter data and instructions into a computer? [SBI Clerk 2014] (1) interaction (2) input (3) communication (4) output (5) terminal

4. Computer gets …… with the help of mouse,

joystick or keyboard. (1) insert (2) delete (3) input (4) output

5. Computer keyboard is an example of

(1) memory device (2) input device (3) output device (4) Both ‘2’ and ‘3’

6. The most common method of entering text

and numerical data into a computer system is through the use of a [SBI PO 2015] (1) plotter (2) scanner (3) printer (4) keyboard (5) None of these

7. Which key is also known as toggle keys?

(1) Caps lock (2) Num lock (3) ‘1’ and ‘2’ both (4) None of these

8. You can use the Tab key to [SBI Clerk 2013]

(1) move a cursor across the screen (2) indent a paragraph (3) move the cursor down the screen (4) Both ‘1’ and ‘2’ (5) None of the above

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9. To move to the beginning of a line of text,

press the ...... key. (1) Page up (2) Shift (3) Home (4) Enter

10. The …… key will launch the Start button.

(1) Esc (2) Shift (3) Window (4) Shortcut

11. Spacebar is used for

(1) giving space (2) deleting space (3) moving next line (4) All of these

12. In a keyboard, left-right-up-down set of

keys facilitates which among the following functions? [IBPS RRB PO Mains 2017] (1) Deleting Data or Modification (2) Page Scrolling to view a Document (3) Launching Start Menu (4) Initiating Search and Help (5) Controlling RAM or process execution

13. Shift, Ctrl, Alt are examples of which among

the following category? [IBPS RRB PO Mains 2017] (1) Modifier Keys (2) Primary Keys (3) Function Keys (4) Alternate Keys (5) Candidate Keys

14. Pointing device includes the following except

(1) mouse (2) joystick (3) trackball (4) keyboard

15. What type of device is a computer mouse?

[IBPS Clerk 2013] (1) Storage (2) Output (3) Input (4) Input/output (5) Software

16. Which of these is a pointing and draw

device? [IBPS PO 2012, IBPS Clerk 2013] (1) Mouse (2) Scanner (3) Printer (4) CD-ROM (5) Keyboard

17. First computer mouse was built by

[SSC CGL 2013] (1) Douglas Engelbart (2) William English (3) Oaniel Coogher (4) Robert Zawacki

18. Keyboard and …… are the examples of input

device. [SBI Clerk 2014] (1) monitor (2) modem (3) printer (4) mouse (5) CPU

19. Which is the best position for operating the

mouse? [IBPS Clerk 2011] (1) Tail away from the user (2) Tail towards the user (3) Tail facing the right (4) Tail facing the left (5) None of the above

20. Which button is called as middle button

used as third mouse button by pressing on it? [IBPS RRB PO Mains 2017] (1) right button (2) scroll wheel (3) touch bar (4) light bar (5) left button

21. Trackball is an example of a/an

[IBPS Clerk 2011] (1) programming device (2) pointing device (3) output device (4) software device (5) printing device

22. A joystick is primarily used to/for …….

[IBPS Clerk 2012, SBI PO 2013] (1) control sound on the screen (2) computer gaming (3) enter text (4) draw pictures (5) print text

23. A joystick allows movements in which angle?

(1) 30° (2) 60° (3) 90° (4) 360°

24. A device, which is used for making

drawings, graphics and for menu selection. (1) Keyboard (2) Mouse (3) Touch screen (4) Light Pen

25. .......... is generally used in applications like

ATM, hospitals, airline reservation etc. (1) Light pen (2) Touch screen (3) Joystick (4) Trackball

26. The pattern of printed lines on most

products are called [SBI Clerk 2009] (1) prices (2) OCR (3) scanners (4) barcodes (5) None of these

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44. After a picture has been taken with a digital

camera and processed appropriately, the actual print of the picture is considered as (1) data (2) output (3) input (4) the process

45. Using output device one can ………

[IBPS RRB PO Mains 2017] (1) View or Print Data (2) Modify Data (3) Store Data (4) Replicate Data (5) Enter Data

46. Which among the following is the smallest

unit in an image in a computer screen? [IBPS RRB PO Mains 2017] (1) Unit (2) Pixel (3) Array (4) Resolution (5) Clip

47. What type of device is a computer monitor?

[SBI Clerk 2014] (1) Software (2) Processing (3) Storage (4) Input (5) Output

48. Soft copy refers to ……. [IBPS Clerk 2013]

(1) printed output (2) digitizing (3) music sounds (4) screen output (5) None of these

49. The higher the resolution of a monitor, the

(1) larger the pixels [IBPS PO 2011] (2) less clear the screen is (3) further apart the pixels (4) closer together the pixels (5) None of the above

50. The most familiar output device for the

micro computers is (1) screen (2) TV (3) printer (4) monitor

51. The CRT is ……… in shape.

[RBI Grade B 2013, SBI PO 2011] (1) circular (2) rectangular (3) eclipse (4) conical (5) None of these

52. CRT has a [RBI Grade B 2013]

(1) hollow tube (2) vacuum tube (3) long tube (4) round tube (5) None of these

53. The rate at which scanning is repeated in a

CRT is called [SBI Clerk 2009] (1) refresh rate (2) resolution (3) pitch (4) bandwidth (5) None of these

54. …… provides hard copy output on paper.

[SBI Clerk 2015] (1) Mouse (2) Keyboard (3) LCD monitor (4) Scanner (5) Printer

55. Printer is an example of [SBI Clerk 2014]

(1) output device (2) input device (3) processing device (4) storage device (5) None of these

56. What are the units used to count the speed

of a printer? [IBPS Clerk 2013] (1) CPM (2) DPI (3) PPM (4) BIT (5) None of these

57. …… printer cannot print more than one

characters at a time. [SSC CHSL 2013] (1) Line (2) Daisy wheel (3) Laser (4) Dot matrix

58. Speed of line printer is limited by the speed

of [IBPS PO 2012, Clerk 2013] (1) paper movements (2) cartridge used (3) length of paper (4) All of these (5) None of these

59. An example of peripheral equipment is

(1) printer (2) CPU (3) spreadsheet (4) microcomputer

60. Dot matrix is a type of

(1) tape (2) printer (3) disk (4) bus (5) None of these

61. Dot matrix printer is

(1) unidirectional (2) bi-directional (3) sequential (4) random

62. The impact printers are

(1) dot matrix (2) drum (3) inkjet (4) Both ‘1’ and ‘2’

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63. Drum printer is an example of

(1) input (2) output (3) processing (4) storage

64. The example of non-impact printers are

[RBI Grade B 2013] (1) Laser-Dot matrix (2) Inkjet-Laser (3) Inkjet-Dot matrix (4) Dot matrix (5) None of these

65. Line printer speed is specified in terms of

(1) LPM (Lines Per Minute) [RBI Grade B 2013] (2) CPM (Characters Per Minute) (3) DPM (4) Any of the above (5) None of the above

66. In laser printers, printing is achieved by

deflecting laser beam on to …… surface of a drum. [SBI PO, IBPS Clerk 2011, 2013] (1) magnetised (2) photosensitive (3) magnetic (4) Either ‘1’ or ‘2’ (5) None of these

67. Which of the following printers, are you

sure, will not to use if your objective is to print on multi carbon forms? (1) Daisy wheel (2) Dot matrix (3) Laser (4) Thermal

68. Laser printers belong to

(1) line printer (2) page printer (3) band printer (4) dot matrix printer

69. Which of the following produces high

quality output? (1) Impact printer (2) Non-impact printer (3) Plotter (4) Both ‘1’ and ‘2’

70. Resolution of laser printer is specified in

terms of (1) DPI (2) LPM (3) CPM (4) PPM

71. A hard copy would prepared on a

[SBI Clerk 2013] (1) line printer (2) dot matrix printer (3) plotter (4) type writer terminal (5) All of these

72. All of the following are examples of input

device except (1) scanner (2) mouse (3) keyboard (4) printer

73. It is used to produce large drawings or

images such as construction plans, blueprints for mechnanical object etc. (1) Printer (2) Plotter (3) MICR (4) OCR

74. What type of devices are computer speakers

or headphones? [IBPS Clerk 2015, SBI Clerk 2012] (1) Input (2) Input/Output (3) Software (4) Storage (5) Output

75. Which of the following devices is used to

give input as well as to display output? (1) Tourch screen (2) Headsets (3) Facsimile (4) Audio cards (5) All of these

76. The transfer of data from a CPU to

peripheral devices of computer is achieved through [SSC CGL 2012] (1) interfaces (2) buffer memory (3) modems (4) I/O ports

77. A parallel port is most often used by a

[SSC CPO 2011] (1) printer (2) monitor (3) mouse (4) external storage device

78. …… ports provide slow speed data

transmission. (1) Serial (2) Parallel (3) Firewire (4) USB

79. Which is not an item of hardware?

[IBPS Clerk 2013] (1) An MP3 file (2) A keyboard (3) A mouse (4) Printer (5) None of these

80. USB in data cables stands for

(1) Unicode Smart Bus [IBPS Clerk 2014] (2) Universal Structural Bus (3) Unicode Serial Bus (4) Universal Smart Bus (5) Universal Serial Bus