Unit 17: Input and Output

Devices

INPUT DEVICE•Keyboard

A keyboard is typewriter keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches.

ADVANTAGE of keyboard, Reliable for data input of text and numbers. DISADVANTAGE of keyboard,

Users may be slow for not very accurate typists.

•Numeric Keypads A Numeric Keypad, numpad or tenkey

for short, is the small, palm-sized, seventeen key section of a computer keyboard, usually on the very far right.

ADVANTAGE of numeric keypads,Easier to use with just one hand. DISADVANTAGE of numeric keypads,As meaning of keys alter they can become difficult to use quickly.

• Pointing devices

A pointing device is an input interface (specifically a human interface device) that allows a user to input spatial (i.e., continuous and multi-dimensional) data to a computer.

ADVANTAGE of pointing devices, Move cursor around the screen faster than using keystrokes.

DISADVANTAGE of pointing devices, They are useless on command driven interfaces.

Touch pad

mouse

Tracker ball

• Remote Controls A remote control is a component of an

electronics device, most commonly a television set, used for operating the device wirelessly from a short line-of-sight distance.

ADVANTAGE of remote control,Each function can have its own

button makingthem very simple to use.

DISADVANTAGE of remote control,Only advanced models can be have the buttons reprogrammed so they cannot be used to control anything other than the device they were designed for.

• Joysticks 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.

ADVANTAGE of joysticks, Easy to learn to use.  Very simple design so they can be inexpensive.

DISADVANTAGE of joysticks, Control can be a bit crude as the directions in simple joysticks are limited to forward, backwards, left and right.  Better models offer diagonal movement or better. 

• Touch Screens A touch screen is an electronic visual

display that can detect the presence and location of a touch within the display area.

ADVANTAGE of touch screens,Big screen is ideal for web browsing, picture and movies.

DISADVANTAGE of touch screens,Big screen leads to low battery life.

• Magnetic Stripe Readers A magnetic stripe card is a type of

card capable of storing data by modifying the magnetism of tiny iron-based magnetic particles on a band of magnetic material on the card.

ADVANTAGE of magnetic stripe readers, Simple to use and cheap to produce. The data can be altered if necessary

DISADVANTAGE of magnetic stripe readers, Very limited storage capacity. Data easily destroyed by strong magnetic fields.

• Chip Readers

A smart card, chip card, or integrated circuit card (ICC), is any pocket-sized card with embedded integrated circuits.

ADVANTAGE of chip readers, It enables more data to be stored on the card and also enables the personal identification number (PIN) entered by the user to be checked against the information held in the chip.

DISADVANTAGE of chip readers, So easy to disappear.

• Scanners A device that optically scans images,

printed text, handwriting, or an object, and converts it to a digital image.

ADVANTAGE of scanners, Flat-bed scanners are very accurate and can produce images with a far higher resolution than a digital camera.

DISADVANTAGE of scanners, Can produce very large image files which need a lot of computer memory to view and edit.

• Digital camera A digital camera (or digicam) is a

camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor.

ADVANTAGE of digital cameras, No film is needed and there are no film developing costs.

DISADVANTAGE of digital cameras, Images often have to be compressed to avoid using up too much expensive memory.

• Microphones A microphone (pronounced as mic or

mike) is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal.

ADVANTAGE of microphones, Voice recognition software can be used to convert your voice into text or to control menu options on a phone system.

DISADVANTAGE of microphones, Voice commands can be difficult to recognize by the software.

• Sensor A device that measures a physical

quantity and converts it into a signal which can be read by an observer or by an instrument.

ADVANTAGE of sensor, Measurements are always taken at the right time.

DISADVANTAGE of sensor, Expensive when compared to traditional devices e.g. thermometers.

• Graphics Tablet A graphics tablet (or digitizing tablet,

graphics pad, drawing tablet is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper.

ADVANTAGE of graphics tablet, Direct input of user-preferred graphics into the computer.

DISADVANTAGE of graphics tablet, Configuration and compatibility can be an issue.

• MICR Magnetic Ink Character Recognition,

or MICR, is a character recognition technology used primarily by the banking industry to facilitate the processing of cheques.

ADVANTAGE of MICR, The error rate for reading MICR characters is small as compared to other character recognition systems.

DISADVANTAGE OF MICR, MICR readers are expensive and capable of recognizing only MICR fronts written in a specific format.

• OMR Optical Mark Recognition (also called

Optical Mark Reading and OMR) is the process of capturing human-marked data from document forms such as surveys and tests.

ADVANTAGE of OMR,The user can only make marks and

cannotwrite any information.

DISADVANTAGE OF OMR, Document for mark reader are complicated to design.

• OCR A mechanical or electronic translation

of scanned images of handwritten, typewritten or printed text into machine-encoded text.

ADVANTAGE of OCR,Human-readable

DISADVANTAGE of OCR, Not accurate, because it first compares to a list then the one closest is chosen.

• Barcode Readers An electronic device for reading printed

barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones.

ADVANTAGE of barcode readers, Bar codes are a fast and reliable method of inputting data. They can be read even when they are on curved surfaces or upside down and the check digit that is included in the code makes it reasonably good at rejecting errors.

DISADVANTAGE of barcode readers, Input is limited to a number code.  An extra layer of packaging is needed for multi-pack goods because they need a different barcode to the one on the individual items.

• Video Cameras

A camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well

ADVANTAGE of video cameras, Makes video sequences available for editing by a computer.

DISADVANTAGE of video cameras, Video images take up a lot of main memory in a computer, or disk space.

• Webcams A video capture device that is

connected to a computer or computer network, often using a USB port or, if connected to a network, internet or Wi-Fi.

ADVANTAGE of webcams, Can record what is put into and taken out of a till, to deter theft.

DISADVANTAGE of webcams, Images can be poor quality.

• Light Pens A computer input device in the form

of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor.

ADVANTAGE of light pens, Easy to use.

DISADVANTAGE of light pens, Easily damaged.

Output devices

Monitor is an object intended to be used safely by more than one thread.

ADVANTAGE of CRT monitor Produce a very dark black and the highest contrast levels normally available.

DISADVANTAGE of CRT monitor They are large, heavy, and bulky. They consume a lot of electricity and produce a lot of heat.

Monitor (CRT)

& Contents mall developed by Guild Design Inc.

Monitor(TFT)Monitor is an object

intended to be used safely by more than one thread.

ADVANTAGE of TFT monitor smaller sized therefore consume less space.

DISADVANTAGE of TFT monitor Fewer glares produced and radiation is much less compared to CRT Monitors.

Projectors

Projectors are hardware device that enables an image, such as a computer screen, to be projected onto a flat surface.

Advantage of projectors Enables a lot of people to be able to see something even from a distance .

Disadvantage of projectors Image quality may not be as good when projected.

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Printers (laser)

A printer is a peripheral which produces a text and/or graphics) of documents stored in electronic form.

Advantage of laser printer color printing is possible , Print quality is good.

Disadvantage of laser prints emerge from the printer slightly wet and may need time to dry.

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Printers (ink jet)

A printer is a peripheral which produces a text and/or graphics) of documents stored in electronic form.

Advantage of ink jet printer are less expensive, you can do color printing with ink jet.

Disadvantage of ink jet printer the speed of printing is less if the cartridges got used they are very costly.

Printers (dot matrix)

A printer is a peripheral which produces a text and/or graphics) of documents stored in electronic form.

Advantage of dot matrix printer low purchase cost , Rugged and low repair cost.

Disadvantage of dot matrix printer Not all can do color, Color looks faded and streaky.

Plotters

A plotter is a computer printing device for printing vector graphics.

Advantage of plotter are that because they are a vector graphics printer, meaning they can only print lines and minimum curves, they are great for printing blueprints and maps.

Disadvantage of plotter they aren't designed for printing ordinary photographs so you would be disappointed with the quality if you tried.

Speakers

Speakers are hardware devices connected to a computer's sound card that outputs sounds generated by the card.

ADVANTAGE of speaker They're very simple to operate.

Disadvantage of speaker They can take up a fair amount of desk-space, compared to headphones.

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