Input and Output Devices: Computer Awareness Notes

Mentor for Bank Exams
Input and Output Devices: Computer Awareness Notes
We interact with computers in several ways. e.g., we type in a keyboard, swipe a screen, use the mouse to click and browse. A computer receives information from all these devices we use. Such devices are called input devices.
Input device is a peripheral (piece of computer hardware equipment) used to provide data and control signals to a computer. Examples of input devices include Keyboard, Mouse, Scanners, Trackpad and Joystick.
A) Keyboard
A computer keyboard is a typewriter-style device which uses an arrangement of buttons or keys to act as mechanical levers or electronic switches.
The most popular type is the QWERTY design, which is based on typewriter keyboards.
i) Alphabet Keys: The alphabet keys are lined in QWERTY type Aa-Zz
ii) Function Keys: The function keys are lined along the top of the keyboard and labeled F1 through F12.
iii) Control Keys: A Control key is a modifier key which, when pressed in conjunction with another key, performs a special operation (for example, Ctrl+C); similar to the Shift key, the Control key rarely performs any function when pressed by itself.
B) Mouse
Used to move or position a cursor on a computer screen. It is a pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows for fine control of a graphical user interface.
Physically, a mouse consists of an object held in one’s hand, with one or more buttons. Mice often also feature other elements, such as touch surfaces and “wheels”, which enable additional control and dimensional input.
i) Typical Mouse Buttons: Three-button scroll mouse has become the de facto standard. Users most commonly employ the second button to invoke a contextual menu in the computer’s software user interface, which contains options specifically tailored to the interface element over which the mouse cursor currently sits.
By default, the primary mouse button (used for clicking the pointed/selected object) sits located on the left-hand side of the mouse
ii) Mechanical Mouse: The ball mouse has two freely rotating rollers. They are located 90 degrees apart. One roller detects the forward-backward motion of the mouse and other the left-right motion.
iii) Optical Mouse: Optical mice rely entirely on one or more light-emitting diodes (LEDs) and an imaging array of photodiodes to detect movement relative to the underlying surface
iv) Mouse with Scroll Wheel: A scroll wheel is a hard plastic or rubbery wheel on a mouse that is perpendicular to the mouse surface. It is normally located between the left and right mouse buttons. It is used, as the name suggests, for scrolling.
C) Trackpad
A touchpad or trackpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user’s fingers to a relative position on the operating system that is outputted to the screen. Touchpads are a common feature of laptop computers. They are available in the following types:
i) Resistive: A resistive touchpad allows the users to use equipment to touch the screen or application. Resistive touchpads, however, don’t allow the user to use his fingers to activate the touchpad capability.
ii) Electromagnetic: The electromagnetic touchpad works much like the resistive touchpad. This touchpad is also operated by an instrument. The instrument is different than a stylist used in resistive touchpads because the electromagnetic touchpad is operated by a light pen.
iii) Capacitive: The capacitive touch pad is highly preferred over resistive and electromagnetic touchpads. Capacitive touchpads may be used for public access to Internet, guiding systems or cell phones.
D) Joystick
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer.
E) Scanner
A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources for computer editing and display. Scanners come in hand-held, feed-in, and flatbed types and for scanning black-and-white only, or colour.
After a computer performs its function, it interacts with us through several ways. e.g., it displays information in a monitor or prints a page in the printer.
An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by a computer to a human (in most cases). Output devices convert the electronically generated information into human-readable form.
Examples of output devices are Display/Monitor, Speaker, Printer and Projectors.
A) Display/Monitor
A display device is an output device for presentation of information in visual or tactile form.
i) CRT (Cathode Ray TubE): A cathode ray tube (CRT) is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface. Most desktop computer displays make use of CRTs.
ii) LED (Light-Emitting DiodE): Light-emitting diode (LED) computer monitors do not use cold-cathode technology and fluorescent technology. Instead, light diodes illuminate the screen in one of two different ways, or a combination of both.
iii) LCD (Liquid-Crystal Display): A liquid-crystal display better known as (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.
iv) Tactic Display: A tactile electronic display is a kind of display device that presents information in tactile form. The two most popular kinds of tactile electronic displays.
B) Speaker
The computer speakers are one of the most common output devices used with computer systems. They receive audio input from the computer’s sound card and produce audio output in the form of sound waves. The computer speakers have an internal amplifier which allows you to increase the volume or amplitude of the sound.
C) Printer
A 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. Printer types are given below:
i) Dot Matrix: Dot matrix printing is a type of computer printing which uses a print head that moves back-and-forth, or in an up-and-down motion, on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like the print mechanism on a typewriter.
ii) Inkjet: Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper, plastic, or other substrates. Inkjet printers are the most commonly used type of printer, and range from small inexpensive consumer models to expensive professional machines
iii) Bubble Jet: Bubble-jet printers use special heating elements to prepare the ink. Bubble-jet printers use serial printing process.
iv) Laser: A laser printer is a printer for computers. It uses LED-technology to get small particles of toner from a cartridge onto paper.
v) Plotters: The plotter is a computer printer for printing vector graphics. In the past, plotters were used in applications such as computer-aided design, though they have generally been replaced with wide-format conventional printers. A plotter gives a hard copy of the output. It draws pictures on a paper using a pen.
D) Projector
The projector is a device that projects computer output onto a white or plane screen that is wall, ceiling or tripod mounted. It is widely used in auditoriums and classrooms for instruction and slide presentations.
Screen Capture/Display Resolution Measurement
DPI: Dots Per Inch
PPI: Pixels Per Inch
PPCM: Pixels Per Centimeter
Display Devices/Technologies
CRT: Cathode Ray Tube
HDTV: High Definition Television
LCD: Liquid Crystal Display
LED: Light Emitting Diode
OLED: Organic Light-Emitting Diode
Ports and Other Concepts
A port serves as an interface between the computer and other computers or peripheral devices. Ports are parts of a computer that can be used to connect other input/output and memory devices to it.
Different types of devices require different types of ports. Ports enable information to flow from our towards a computer.
A) A serial port is used to connect a computer to a printer or mouse
B) A parallel port is used to connect a computer to a monitor
A) Serial Port
A serial port is a general-purpose interface that can be used for almost any type of device, including modems, mice, and printers.
Serial Port in a Computer is the one with the symbol IOIOI
Male and Female Connectors and Wire for Serial Port
B) Parallel Port
A parallel port is a type of interface found on computers (personal and otherwisE) for connecting peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port.
The picture below shows the image of a Parallel and Serial Port in an old Laptop
Scanning and Data Interfacing Technologies/Measurements
OCR: Optical Character Recognition
MICR Code: Magnetic Ink Character Recognition Code
QR Code: Quick Response Code
MIDI: Musical Instrument Digital Interface
HSSI: High-Speed Serial Interface
HDMI: High-Definition Multimedia Interface
IOPS: Input/Output Operations Per Second
USB: Universal Serial Bus