unit 2 - input output

magnetic stripe reader

device used to read the — of a card, which contains data

RFID

uses radio waves to identify and track special tags attached to objects

OCR

recognises typewritten or printed document and tanslates the images of the characters into digital text

OMR

recognising marks to select options to be captured for processing by a computer

CRT monitor ‘cathode ray tube’

allow users to instantly see outputs from the computer, also used with light pens to allow drawings to be created on screen

TFT/LCD monitor (‘thin film resistor’)

these are thin flat screened, monitors that are commonly seen today. They are used as screens in laptops and mobile phones

IPS/LCD monitor (liquid crystal display)

used for modern monitors and television sets. These are simply a development of the TFT monitors.

multimedia projector

Can be used for training presentations to allow the whole audience to see images from a single computer

laser printer

These produce high quality hard copy, use toner pressed on a page to produce printed documents. They can print large amounts of pages at a very quick rate.

inkjet printer

These are used to produce high quality hard copies. Although the quality of printouts is not as good as laser printers, it is far better than Dot Matrix printers

dot matrix printer

very robust and can be used in noisy and dirty environments. Can make ‘carbon copies’ of document using special ‘carbon paper’ underneath normal printer paper.

wide format printer

They are able to produce large scale projects which save time and money. They are often used for posters and banners.

actuator

a device that causes another machine or device to operate

differences and similarities between RFID and magnetic stripe

Data cannot be read by eye so more secure, Data can be re-written, RFID is contactless therefore has less wear and tear whereas magnetic is placed in reader RFID reads the data faster More data on RFID card

keyboard

used to input text, numbers and instructions into the computer, allows the user to type in command to the computer

keyboard advantages

fast entry if new data, easy use for most people

keyboard disadvantages

slow method of the data entry compared to direct entry deivces e.g. OMR, keyboards are quite large and takes up a lot of desk space

numeric keypad

used for ATMs and for chip and pin deivces when paying by credit/debit

numeric keypad advantages

faster than standard keyboards when entering numbers, they are portable

numeric keypad disadvantages

small keys can be difficult to use, sometimes the order of the keys isn’t intuitive

pointing devices

used to open, close, minimise software programs, can be used to group, move and delete files, edit images to change the size and position of an object

pointing deivces advantages

faster method of choosing options, quick to navigate through programs and the internet, doesnt take up a lot of desk space

pointing device disadvantages

needs flat surface, dirt can obstruct the sensor

remote control

used to control multimedia devices, used to remotely turn on/off devices, change the volume etc.

remote control advantages

can be used to operate from a distance, without a wire, can be safer to operate machinery from a distance

remote control disadvantages

signal can be blocked

joystick/wheel

used for computer games and simulators

joystick/wheel advantages

more realistic than a mouse for certain situations, easier than keyboard for navigating menus

joystick/wheel disadvantages

more difficult than a mouse to control a pointer

touch screen

used for self service tills, ATMs, interactive classrooms, public information systems

touch screen advantages

faster when choosing options than keyboard/mouse, easy to operate, user friendly and usually intuitive

touch screen disadvantages

options usually limited as user can’t do commands, can cause strain if used often, screen can become dirty, which reduces responsiveness

scanners advantages

faster and more accurate than typing documents again, recover damaged photographs by scanning and then using software

scanners disadvantages

quality can be limited, scanning is often slow, scanning multiple pages can be difficult

digital camera advantages

Easier to produce better photographs than traditional cameras, Faster to process and upload, rather than scanning , No need to develop or print film, Memory cards store many photographs

digital camera disadvantages

Need to know how to operate , Images often need to be compressed - reducing image quality, Can be bulky to carry, compared to a smartphone for example

microphone advantages

Faster to read than type text, with voice recognition software, Software can manipulate sound, Voice activated commands can improve safety, for example in cars

microphone disadvantages

Sound files can take up alot of storage, Voice recognition isn’t always accurate

sensors

can be used to measure temperature, light, pressure, sound, moisture and pH

sensors advantages

More accurate readings compared to humans, Readings are continuous, Systems can be automatic - no need for human interaction

sensors disadvantages

Faulty sensors give in inaccurate results, for example if they become dirty

light pen advantages

more accurate than touch screen to write/draw, portable, easy to use

light pen disadvantages

can lag when drawing quickly, doesnt work with all screens

magnetic stripe reader advantages

faster entry than typing, error free

magnetic stripe reader disadvantages

if the stripe gets damaged, the data is lost, needs close contact

chip and pin reader advantages

it is more secure than contactless cards as the PIN acts as a second security reader, it has a more robust system than magnetic stripe cards

chip and pin reader disadvantages

the PIN may be seen by someone whilst it is typed in

Radio frequency identification (RFID) reader advantages

no line of sight contact is needed, very robust and reliable technology, very fast read rate

Radio frequency identification (RFID) reader disadvantages

tag collision may occur, as they use radio waves, they are easy to jam/interrupt, easy to hack into the signal, rfid is more expensive than a comparable barcode system.

OMR advantages

very fast way of inputting survey results, it is more accurate because there is no human intervention, more accurate than OCR methods

OMR disadvantages

designing the forms can be complicated to ensure the marks are correctly positioned, if there are problems, they need to be manually checked, which can be time consuming

OCR advantages

it is much faster data entry system than manual typing, no human intervention so its error free

OCR disadvantages

system has difficulty in reading different handwriting, not a very accurate technique

barcode reader advantages

much faster than manually keying in data, allow automatic stock control, they are a tried and trusted technology

barcode reader disadvantages

relatively expensive system to administer, barcodes may be swapped between items, can be more easily damage than rfid tags or magnetic stripes

QR code scanner advantages

hold much more information than normal barcode, fewer errors than with barcodes, QR codes are easier to read, It is possible to encrypt QR codes.

QR code reader disadvantages

more then one QR format is available. QR codes can be used to transmit malicious data

Cathode ray tube (CRT) monitors advantages

unlike LCDs it can be seen at a wider range of angles, allow the use of light pens

Cathode ray tube (CRT) monitors disadvantages

they are very heavy and bulky, they run very hot and can cause fires if left unattended, they use a lot more power than LCDs. their flickering can lead to headaches, image burn in is a common issue

LCD advantages

very efficient and have low power consumption, lightweight devices, screens can be made in various sizes, no flickering images, very sharp image resolution

LCD disadvantages

color contrast from different angles are inconsistent, motion blur is a common issue, has lower contrast than CRT monitors

touch screens advantages

they don’t need additional input devices, they are very interactive and have many functions, they add a high tech feel to devices and interfaces

touch screen disadvantages

they tend to get dirty with frequent use, frequent use results in straining of arm muscles etc, if large amounts of data are input/output, they aren’t very accurate and the interface isn’t very fast

multimedia projector advantages

more people can watch, avoids the need for several networked computers

multimedia projector disadvantages

images can be fuzzy, expensive to buy, set up can be complicated

laser printer advantages

printing is fast, they can handle very large print jobs, quality is consistently high, toner cartridges last for a long time

laser printer disadvantages

they are only considerably fast if several copies are being made, colored — printers are expensive to run

inkjet printer advantages

high quality output, cheaper than laser printes, very lightweight,

laser printer disadvantages

slow output if many copies are needed, cant do large print jobs, printing can smudge if user isnt careful, can be expensive if used a lot

dot matrix printers advantages

can be used in varying environments unlike laser/inkjet printers, very cheap to run and maintain, good for continuous printing

dot matrix printer disadvantages

very noisy, initial cost is more than an inkjet printer, very slow and poor quality printing

plotter advantages

very high quality output, can produce large drawings very accurately, can print on a variety of materials

plotter disadvantages

very slow printing, expensive equipmet to purchase initially, takes up a lot of space compared to a printer

3d printer advantages

manufacturing objects has become much easier, even though the initial cost is high it is still cheaper, customisable designs

3d printer disadvantages

potential to make counterfeit items, could lead to manufacture of dangerous items, job loss potential, very expensive

speaker advantages

can be heard by alot of people at a time, ranges of sizes and power output, immersive audio, helps people with disabilities

speaker disadvantages

speaker output can disturb other people in the area, varying sound quality, expenisve for higher quality output

actuators advantages

precise movement, programmable, allow automatic control of many devices, allow remote operation of many devices, they are relatively inexpensive devices

actuators

controls motors, pumps, switches etc

actuator disadvantages

requires power, potential mechanical wear, requires DAC (digital data to analogue data)