2. Input and output devices Flashcards
What are ‘input devices’?
Hardware devices that allow data to be entered into a computer
What are the two types of input devices?
Manual input devices
Direct input devices
Manual input devices
Data is input into the computer by hand (people have to do most of the work).
Pointing devices
Used to control a cursor on a screen.
Mice:
Opening, closing, maximising and minimising programs and files
Moving, grouping and deleting files
Using applications
Touchpad:
Replacement of mouse
Same uses as mice
Tracker ball:
Same functions as mice
More comfortable to use than mice
Some arcade gaming machines use tracker ball’s to control gaming characters on screen.
Keyboard
Text, numbers and instructions
Used to input data into applications
Used to enter commands into the computer.
Keyboard
Text, numbers and instructions
Used to input data into applications
Used to enter commands into the computer.
Numeric keypads
Used to enter numbers into a computer system
- Used in: ATMs, telephones, chip and pin devices
Remote control
Used to control other devices using infrared signals
Home entertainment systems use remote controls: DVD / Blu-ray players, TV etc.
Industry uses remote controls to operate machinery that might be too dangerous to get near to: activating explosives in demolition.
Joysticks
Similar functions to mice and trackballs.
Can control characters or objects in video games
Can control industrial machinery
Used in simulators.
Touch screens
Input commands into a computer by pressing or touching buttons / icons on the screen.
Users can touch or press icons on the screen removes the need to use a mouse.
Mobile phones and PDAs use touch screens.
Interactive whiteboards in schools.
Scanners
Used to enter information on paper into a computer.
Reflects light off the hard copy in order to capture an analogue image of the document then converts it to digital format.
E.g. old photograph (analogue) -> scanner converts photo into digital data -> digital data can be stored on a computer.
Graphics tablet
Used by artists and designers to easily create and store digital graphics in a computer
Whatever is drawn onto tablet can be seen on a computer screen.
Allow designers to produce digital images much more accurately than if they were using a mouse.
Light pens
Used by directly drawing or selecting icons on a computer screen.
Works by: Picking up light from the computer screen + signaling to the computer exactly where light picked up
Microphones
Used to input analogue sounds into a digital computer.
Used in voice recognition software.
Used in gaming so that gamers can talk to each other.
Digital cameras
Store digital photographs on a memory card.
Built-in screen to allow for previewing
Capture video and sound
Exists in almost all modern mobile phones.
Web cameras
Used to conduct face-to-face conversations such as Skype.
Video-conferencing
Capture image and video content
Alternative to security cameras.
Direct input devices
Data is input into the computer directly by a machine / device.
Barcode readers
Reads and outputs printed barcodes to a computer.
- Used in supermarkets, stores
Advantages + disadvantages of barcode readers
ads:
- Quick & easy to change products price (all digital)
- Easy to get info on system (only have to scan)
- Automatic stock control.
- Very accurate->no typing
disads:
- Expensive(each item needs a barcode / computer technology / database needed)
- Can only read undamaged barcodes
- Barcodes can be swapped.
Optical mark readers (OMR)
Captures human-marked data
- Often used to read multiple choice examinations where students shade in areas they think are correct.
Advantages + disadvantages of OMR
ads:
- Very fast method of marking because it is automatic.
- Accurate because it automatically transfers data.
- Can save money from employing people
disads:
Forms need to be accurately designed.
Can only read shaded areas.
If forms are filled incorrectly, they cannot be read.
Magnetic ink character recognition (MCR)
Read information printed in a special ink, then convert it into form that computer can understand.
Write customer account numbers on cheques.
Advantages + disadvantages of MCR
ads:
- Cheques can be processed very quickly.
- Special ink characters cannot be changed, increases security.
- No manual inputs -> less errors.
disads:
Only limited characters can be read.
More expensive than other devices.
Magnetic Stripes Reader
Read magnetics stripes that are found on back of credit cards, loyalty cards etc.
Magnetic strips contain the user’s personal details such as account no, and name.
Advantages + disadvantages of magnetic stripes reader
ads:
- Simple for people to use.
- Cards are inexpensive to make.
- Data on the card can be altered.
- Security is improved by PIN numbers.
disads:
- Limited storage for data.
- Data can be destroyed by strong magnetic fields.
- Not always secure because thieves can read the data on the card.
Biometric devices
Use fingerprint and retinal identification.
Identify at ATMs to withdraw cash, or register you at schools.
Devices capture the biometric data => then passed to a computer for processing and identification.
Advantages + disadvantages of biometric devices
ads:
- Security because only you can confirm your identity
- Convenient since no need for passwords.
disads:
Injuries can lead to false biometrics.
Expensive
Can be hacked
Optical character reader (OCR)
Consists of a scanner + special software
Lets us scan text on paper into a computer
Into computer, OCR software converts scanned text into a digital format
Advantages + disadvantages of OCR
ads:
- Fast way of entering hard-copy text into a computer
- Cheaper than paying an employee to manually re-type printed text into a computer
- Avoids typing errors as the process is automatic
disads:
The system can have difficulty reading handwriting
Not 100% accurate
Needs to be manually checked for errors -> time consuming
Chip and PIN reader
Used in debit cards (chip implanted)
- Compare stored info in the card and compare it to the PIN number typed in by user.
What are ‘output devies’?
hardware devices that allow information to be sent out of a computer system.
Temporary output
a computer monitor produces images on the screen that constantly refresh and change
Permanent output
a printer produces outputs as hard copies on paper.
CRT monitor
Stands for ‘cathode ray tube’
Old, bulky, heavy monitors
Becoming rare as TFT monitors are replacing them.
CRT monitor uses
Allows users to see outputs from the computer
- Used with light pens to allow drawings to be created on screen
Advantages + disadvantages of CRT monitor
ads:
- Can be used with light pens to create drawings on screen
- Larger range of colours than TFT monitors
- Screen angle is better than with TFTs
- Cheaper than TFT screens
disads:
Very large and bulky
Create a lot of heat
Screen glare makes viewing difficult
Need more power than TFTs to operate
TFT monitor
Stands for ‘thin film transistor’
Thin flat screened monitors that are commonly seen today
Most popular computer screens
TFT monitor uses
Used as screens in laptops, computer, mobile phones
Advantages + disadvantages of TFT monitor
ads:
- Lightweight so perfect for portable laptops
- Very thin and take up less space
- Produce much less glare than CRT
- Less power
- Emit less radiation
- Produce less heat
disads:
Images can appear unclear when viewed from an angle
Lower picture quality
Cannot be used with Light Pens yet
Laser printer
Produce high quality hard copy outputs
Use toner pressed on a page to produce printed documents
Can print large amounts of pages at a very quick rate
Work by using a laser beam to ‘draw’ onto a drum
Laser printer uses
Used in schools, businesses, offices
Advantages + disadvantages of laser printer
ads:
- Very fast at printing documents
- Toner cartridges last a long time
- Can handle high volumes of printing
- Very quiet
- Very high quality
- Reliable
- Cheaper to run than inkjets
disads:
- Environmentally unfriendly (produces ozone)
- More expensive to buy
- Colour laser printers are much more expensive to buy than inkjets
- Larger in size compared to other types of printers
Inkjet printer
Produce high quality hard copies on paper
Quality not as good as laser printers, but better than dot matrix
Have small amounts of internal memory (RAM) to store print jobs printing slow
Inkjet printer uses
Good where few printouts are needed
Ideal for single-page, very high quality
Often used to print photographs
Advantages + disadvantages of inkjet printer
ads:
Output is very high quality
Much cheaper to buy than laser printers
Smaller than laser printers so take up less space
Very quiet whilst printing
disads:
Slow printing rates
Ink cartridges don’t last long, not suitable for large print jobs
Expensive to run
Printouts can easily smudge if document not left to dry properly
Dot matrix printer
Slow, noisy and produce poor quality outputs
- Work by using a set of pins to press an inked ribbon against paper
Dot matrix uses
Very robust and can be used in noisy and dirty environments
Used in environments where print speed and noise is not an issue
Advantages + disadvantages of dot matrix printer
ads:
Work fine in dusty + dirty environments
Very cheap to buy and maintain
Good for continuous printing
disads:
Very noisy
Very slow
Very poor quality
Wide format printer / plotter
Two types: drum and flatbed
Are capable of printing on very large pieces of paper
High quality
Draw images on page using coloured pens
Plotter uses
Used to produce large, accurate drawings like:
Blueprints of buildings
Maps
Giant posters and adverts
Advantages + disadvantages of plotter
ads:
Can produce much larger printouts than other printers
Print quality is extremely high
Can ‘cut out’ designs for use in sign making
disads:
Print times are very slow
Very expensive to buy and maintain
Speakers
Connected directly to computer/are built into monitor
- Speakers are analogue
Speakers uses
Output sound from multimedia presentations
Home entertainment
Can be used by blind people to listen to words on the screen
Can be used play downloaded music files
Advantages + disadvantages of speakers
ads:
- Everyone in the room can hear the sound
- They can help blind people use a computer
disads:
Output from speakers can disturb people trying to work
High quality speakers can be expensive
Multimedia projector
Project whatever appears on computer monitor onto large screen so a lot of people can view it
Controlled using a remote control
Multimedia projector uses
Large scale advertising of new products
Home cinemas
Training presentations
Advantages + disadvantages of multimedia projectors
ads:
Many people to clearly view the same presentation
Enhance the viewer’s experience
disads:
Lower image quality compared to a computer screen
Expensive to buy
Cooling fans in the projector are noisy
Keyboards
Advantages
Enables fast entry of new text into a document
Well tried technology and well known method of entry
Most people find them easy to use
Easy to do verification check as data is entered, as it appears on the screen simultaneously
Disadvantages
Users with limited arm/wrist use can find keyboards hard to use
Entering data is slow when compared to direct data entry (e.g. Optical mark recognition)
They use up desk space as they are quite large
Concept Keyboard
Advantages
Enables fast data entry (there is no need to type in whole commands)
Waterproof, useful in a restaurant environment
They are tamperproof, preventing people from keying in information (which could corrupt the
system)
Mouse
Advantages
Faster to select an option by a mouse than a keyboard
Enables rapid navigation through applications and the internet
Mice are small and don’t take much area
Disadvantages
People with restricted hand/wrist movement can find it hard to operate a mouse
Easily damaged and can easily be clogged up with dirt
They are hard to use if there is no flat surface available
Touchpads
Advantages
Faster to select an option by a touchpad than a keyboard
Enables rapid navigation through applications and the internet
Since the touchpad is integrated into the laptop computer, there is no separate mouse, aiding portability
They can be used when no flat surfaces are available
Disadvantage
People with limited hand/wrist movement can find touchpads hard to use
It can be more difficult to control the pointer when compared to a mouse
They are more difficult when doing operations such as ‘drag and drop’
Joysticks
Advantages
Easier to navigate round a screen compared to a keyboard
Control is in three dimension
Disadvantages
More difficult to control the on-screen pointer with a joystick than with other devices such as mice
Touchscreens
Used for service tills e.g. petrol stations
Used where selections are made on a screen e.g. ATMs, public
information systems, airports and railway stations
Advantages
Enable faster entry of options than a keyboard or a mouse
Very easy to choose options
User friendly method for inputting data
They are tamperproof, preventing people from keying in information (which could corrupt the system)
Disadvantages
There is a limited number of options available
Using touchscreens often can lead to health problems e.g. (straining of arm muscles and RSI)
The screen can get very dirty with constant touching
Magnetic Stripe readers
Advantages
Data entry is fast compared with keying in using a keyboard or keypad
System is error free, no typing involved
Information is secure since there is no typing and the information can’t be read directly by a person
Can prevent access to restricted/secure areas
Magnetic stripes are unaffected by oil water and moisture
No moving parts therefore physically robust
Disadvantages
If the magnetic stripe is damaged the data is lost
Card needs to be in close contact with the reader
Since the information is not human readable, they need to find a way to show the information to the customer (e.g. hotel room number not printed on cards)
Scanners
Advantages
Images can be stored for editing at a later date
Scanners are much faster and more accurate than typing in documents again
It is possible to recover damaged documents and photographs by scanning them and then using appropriate software to produce an acceptable copy
Disadvantages
The quality can be limited depending on how good the scanner resolution is
Barcode readers
Advantages
Faster than keying in information, and fewer mistakes are made
Used as a way of recording data, can improve safety
Barcodes enable automatic stock control
Barcode scanning is a tried and trusted technology
When an item price is changed, only the central database needs to be updated, there is no need to change the prices individually on each item
Disadvantages
Barcode scanning is an expensive system to administer since every item in the shops needs a barcode and every barcode needs to be entered on the system.
Also there is a need to invest in the
computer technology together with staff training, which can all be expensive
The system is not fool proof- barcode can be swapped around on items
OMR Devices
Advantages
A very fast way of inputting results of a survey
Since there is no typing, it is more accurate than keying in data
OMR is more accurate than OCR
Disadvantages
Forms need to be carefully designed to make sure that the marks/shadings are correctly positioned to gather accurate information
There can be problems if forms aren’t filled correctly, sometimes they have to be checked manually
before being read by an OMR, this is both time consuming and expensive
MICR Device
Used to process cheques in banking operations – cheque is
read using a batch processing method
Advantages
MICR offers great security than OCR since the oriented characters cannot be altered
There is no manual input, thus errors are reduced
If somebody writes over the magnetic ink characters it can still be read
Disadvantages
Only certain characters can be read and the number of different characters is very limited
It is a more expensive method than other methods used for direct data entry
Digital Cameras
Advantages
Easier to produce better quality photographs than with a tradition camera
Easier and faster to upload photographs to a computer
There is no need to develop film and print out photographs (saves paper and no longer needs the chemicals to produce photographs from films)
Easy to delete an image from the memory if it’s not satisfactory
The memory card can store several hundred photographs
Disadvantages
The camera user needs to be computer literate to use the camera properly
There is some artistry lost since clever software corrects errors in the photographs
The resolution is not yet as good as traditional cameras
Images often need to be compressed to reduce the amount of memory used
It is possible to fill up computer memory very quickly with several photos of the same subject(in order to find the perfect snap shot)
Webcams
Advantages
Can be left on constantly and activated when required
Allow people to keep in contact with each other without the need to travel, particularly useful for disabled or elderly people
Disadvantages
Webcams have limited features and the picture is often of poor quality
They need to be connected to a computer
Microphone
Advantages
Faster to read in text than to type it using a keyboard
Possible to manipulate sound in real time using special software
If used in a voice activation system, this has the advantage of improving safety
Disadvantage
Sound files can use up a lot of computer memory
Voice recognition software isn’t as accurate as typing in manually
Sensors - examples:
Temperature
Pressure
Light
Sound
Humidity/moisture
pH
Advantages
Readings by sensors are more accurate than taken by humans
Readings are continuous, there is no break in monitoring
Because it is a continuous process any necessary action or warning will be initiated immediately
The system can be automatic, removing the need for human intervention, this is particularly important if the process is hazardous
Disadvantages
Faulty sensors can give spurious results
Graphics Tablets
Advantages
It is possible to modify drawings before they are input
They offer an accurate method of drawing
Disadvantages
They are more expensive than other pointing devices
Light Pens - used fro:
selecting objects on CRT screens
and for drawing on screens e.g. with a (CAD package)
Advantages
Light pens are more accurate than touchscreens
They are small, so can be used where space is an issue
They are easy to use
Disadvantages
There are problems with lag when drawing on screens
Only work with CRT monitors at the moment
They are not very accurate when drawing
What are output devices?
Hardware devices that allow data to be output from a computer
Some hold data temporarily e.g. a monitor
Some produce permanent output in the form of a hardcopy e.g. a printer
CRT Monitors
Advantages
Produce higher quality images than TFT monitors
Angle of viewing is better than a TFT monitor
They work with light pens in CAD and CAM applications (Computer Aided Design/Manufacturing)
Disadvantages
Tend to be heavy, weight hazard if not supported properly
Run very hot, can cause fires if left unattended – especially if they are old
Consume more power than TFT monitors
They can flicker, this leads to headaches and eyesight problems with prolonged use
TFT Monitors
Advantages
Lightweight, so no weight hazards like CRT monitors
Less glare produced than in CRT monitors; also emit less radiation
Consume much less power and generate less heat than CRT monitors
Disadvantages
Angle of viewing is critical, image appears unclear if viewed slightly from the side
The definition is sometimes not as good as CRT monitors
They cannot yet be used with light pens, so cannot be used in CAD
Laser Printers
Advantages
Printing is fast for high volumes, slightly faster than inkjet if only a few pages are to be printed
Can handle very large print jobs
Quality is consistently high
Toner cartridges last for a long time; laser printers can be a cost effective option if colour outputs are not required
Disadvantages
Expensive to buy
Only really fast if several copies are being made
Colour laser printers tend to be expensive to run since four cartridges are needed as well as diffuser kits, etc.
Produce ozone and volatile organic compounds because of their printing method and type of toner/ink
used
Inkjet Printers
Advantages
High quality output
Cheaper to buy than laser printers
Very lightweight and take up little space (small footprint)
Do not produce ozone and volatile organic compounds, unlike laser printers
Disadvantages
Output is slow if several copies needed – there is little buffer capacity to store the pages
The ink cartridges run out too quickly to be used for large print jobs
Printing can smudge if the user is not careful
Can be expensive to run if they are used a lot – original ink cartridges are expensive
3D Inkjet Printers
A new type of printer that produces solid 3D models using modified inkjet technology called tomography
Very thin layers of fine powder (plaster, resin, starch) are bonded together as a 3D model is slowly built up
Items produced are known as prototypes
Advantages
Save a lot of money, other methods of making prototypes are very time consuming and expensive
The powders used can often be ground up and reused
Physical scale models are produced with working parts, which gives a better idea of how the end product will look
Disadvantages
Expensive to buy
Slow at producing their output
End product is sometimes a little rough, often further work needs to be done
Dot Matrix Printers
A type of impact printer
A print head made up of a matrix of pins presses against an inked ribbon
Advantages
Can be used in environments which would be a problem for laser and inkjet printers – dusty, dirty or moist atmospheres
Carbon copies or multi-part outputs can be produced
Very cheap to run and maintain
Easy to use if continuous stationary is required e.g. long print jobs such as wage slips
Disadvantages
Very noisy – not good in an office environment
Cost more than an inkjet printer to buy
Very slow
Printing is of poor quality
Graph Plotters
Used to produce large drawings e.g. blueprints of buildings; are often used with CAD applications
Advantages
Can produce huge printouts
Print quality is extremely high
Disadvantages
Slow in operation
Expensive to buy and maintain
Speakers
Advantages
Usually long lasting and durable (if operated within their intended power levels)
Often provided with the computer/laptop although these may not be the best quality
Disadvantages
Can take up a lot of desk space, compared to headphones
Can distract people around you, everyone can hear what you are playing
May not be able to hear the full sound spectrum, this requires multiple speakers
Multimedia Projectors
Used for training presentations ( allows the whole audience to see the images from a computer)
Also used for advertising presentations (shown at exhibitions, shopping malls etc.)
Home cinema systems (projecting the images from a DVD or television) use multimedia projectors
Advantages
Enables many people to see a presentation rather than all of them crowded around a small computer
screen
Avoids the need for several networked computers e.g. when looking at a video clip on the internet, everybody can see the video on the large screen rather than logging on to a number of computers
Disadvantages
Images can sometimes be fuzzy
Expensive to buy
Setting up projectors can be a little difficult
Control Devices: a type of output device
Used to control processes when combined with sensor input devices
Actuators:
Transducers that are used to take signals from a computer and convert them into some form of motion e.g. operating motors, pumps, switches and valves
Digital signals are sent from the computer to an actuator
Motors:
Turned on or off by the actuator
Buzzers:
Switched on or off by the actuator
Lights:
The actuator is connected to the switch that turns the lights on or off
Heaters:
Actuators are connected to switches which turn the heater on or off
What is the definition of an input device?
Hardware that allows data to be entered into a computer.
How many types of input devices are there?
2 - manual input devices and direct input devices.
What is the definition of a manual input device?
A device that allows data to be entered into a computer by hand.
Give 5 examples of manual input devices.
keyboard, numeric keyboard, pointing devices, remote control, joystick, touch screen, scanner, graphics tablet, light pen, microphone, digital camera, web camera
What are keyboards used for?
To enter data into applications e.g. word processing applications such as Word.
To use enter commands e.g. keyboard short cuts such as CTRL + P to print.
What are the advantages of using a keyboard?
Enables fast entry of text into documents.
Very easy to use (you just press the keys)
Information instantly appears on the screen so you can check quickly that what you entered is correct.
What are the disadvantages of using a keyboard?
People with wrist or hand problems can find a keyboard painful to use.
Keyboards are quite large and can take up a lot of desk space.
Entering data is slow compared with other methods.
What are numeric keypads used for?
Entering numbers into a computer system.
Some numeric keypads allow you to enter simple text and symbols.
Uses of numeric keypads include: ATM machines, telephones, chip and pin devices.
What are the advantages of using a numeric keypad?
Faster than using a QWERTY keyboard.
They are small so they can fit easily on smaller devices e.g. a phone
What are the disadvantages of using a numeric keypad?
People with large hands can find them hard to use.
Difficult to enter text information.
What are pointing devices?
Pieces of hardware that are used to control a pointer or curser on a screen.
Frequently used with GUI
Used to input commands by selecting icons
What are the 3 main types of pointing devices?
Mouse
Touchpad
Trackerball
How many types of mice are there?
2
ball mouse - uses a ball under the mouse to detect movement
optical mouse - uses reflected light to detect movement
What are the uses of a mouse?
opening, closing, maximising and minimising programmes and files
Moving, grouping and deleting files
Selecting icons and moving them around the page
Editing images
What are the advantages of using a mouse?
Faster to select icons
Very easy to move pointer
Small and don’t take up much space
What are the disadvantages of using a mouse?
People with wrist problems may find them painful to use
Dirt can affect accuracy
Need a flat surface to work on
What are touchpads used for?
Replacement for a mouse - especially in laptops
What are the advantages of using a touchpad?
easier than using a keyboard
built into laptops
can be used even when there is no flat surface
don’t get clogged with dirt
What are the disadvantages of using a touchpad?
more difficult to control than a mouse
can be painful to use for people with wrist problems
drop and drag can be more difficult to perform
What are trackerballs?
similar to mice but the ball is on the top of the device rather than the bottom
What are the uses of trackerballs?
Used as an alternative to a mouse
Used in arcade gaming machines
What are the advantages of trackerballs?
People with wrist problems can still use them
More accurate than touchpads
Can be used when no flat surface is available
No limit on ball travel
What are the disadvantages of trackerballs?
More expensive than mice
More difficult to learn how to use than a mouse
What are remote controls used for?
Controlling other devices using infra-red signals e.g.
changing the tv channel
increasing/decreasing volume on a music player
selecting a different chapter on a dvd player
operating cranes with heavy
activating explosives in demolition
operating robot arms in hazardous chemical plants
What are the advantages of using remote controls?
Devices can be operated without having to go up to them - helpful for people with disabilities
Can operate devices in unsafe environments
What are the disadvantages of using remote controls?
People with limited hand movement can find them difficult to use
The infra red signal between remote and device can become blocked
What is the function of a joystick?
To control a pointer on a screen (similar to a mouse)
What are the uses of a joystick?
To control a pointer on a screen -
the handle moves the pointer
the buttons allow us to select or ‘click stuff’
What are joysticks used for?
video games
industrial machinery
simulators
