Zusammenfassung der Ressource
Input and Output Devices
- Input Devices
- Keyboards
- Used to enter user created text in applications. For
example creation of a letter using a word processor.
Often called a QWERTY keyboard if the letters are
arranged so that the first 6 letters from the top left are
QWERTY. The arrangement of the rest of the keyboard
depends upon the part of the world it is sold. Advantages
and disadvantages • Most people know how to use it so
specialist training not required • Cheap • Easily collects
dust and dirt so not suitable for dirty environments
• Requires significant desktop space
- Numeric Keypad
- Either found as a separate section of a standard desktop PC keyboard or as
a completely separate input device in applications only requiring numeric
data to be entered. Examples of numeric keypads are found on • Bank ATM
machines • PIN PADS for entering a Personal Identification Number when
using a bank card to pay in a shop Advantages and disadvantages • Rapid
operation for experienced users • Smaller footprint so good in working
environments with reduced space such as an EFTPOS terminal • Only allows
numeric data to be entered
- Mouse
- A pointing device used to control a pointer or
curser. Used to select items on a GUI (Graphical
User Interface) e.g. clicking on an icon to run a
program. Advantages and disadvantages • May de
difficult to use by people with physical disabilities
• Requires desktop space to use • Picks up dust and
dirt easily - ball may become stuck • Most people
know how to use it
- Touch Pad
- Commonly found on laptop computers. It has the
same functionality as a mouse. Cursor is controlled
by the movement of a finger over a sensitive pad.
Advantages and disadvantages • Does not require
desktop space to useful in reduced space
applications • A sealed unit so less problems with
malfunction due to dust and dirt • Can take time to
become familiar with its operation
- Tracker ball
- Same functionality as a mouse. Cursor controlled my
moving a ball with fingers or palm. The ball protrudes
from the top of the device. Advantages and disadvantages
• Not common and needs time to become aquainted with
its operation • Easier to use by people with physical
disabilities
- Remote Control
- Device used to control the operation of devices
such as • T.V's • Video Recorders and players • DVD
Recorders and players • Satellite decoders/
receivers • Music Systems • Multimedia Projectors
Advantages and disadvantages • Makes it easier to
control device without having to be right next to it
• Often small and portable so easily lost
- Joystick
- Device used to control movement on a screen in
applications such as flight simulators, driving
simulators and computer games. Advantages and
disadvantages • Allows simulators to be more
realistic e.g. flight simulators
- Touch Screen
- Touch sensitive screen that enables a user to select from a
limited list of items. Used in applications such as
Point-Of-Sale terminals, tourist information kiosks and
systems to find out about public transport. Advantages and
disadvantages • Combines output device (screen) with input
device so reduced space requirements • Operators will
require training to use it effectively • Less prone to
malfunction due to dust and dirt.
- Magnetic Stripe Reader
- Device to read the magnetic stripe on the back of bank
cards and some types of identification cards for security
systems. Found in bank ATM machines, EFTPOS
terminals in supermarkets and entry systems for secure
locations. Advantages and disadvantages • Easy
operation by untrained users • Can become unusable by
too much dust and dirt
- Chip Reader
- Device used to read the chip found on bank cards. Used in shops to pay for purchases.
Similar applications as magnetic stripes and magnetic stripe readers but more recent
technology. Advantages and disadvantages • Secure way of storing banking and personal
data • Easy operation for untrained user • Less common than magnetic strip readers so
may not always be available
- PIN Pad
- A numeric keypad used together with magnetic stripe readers and chip readers to confirm the
person is the rightful owner of the card by typing in a PIN (4 digit Personal Identification Number).
Advantages and disadvantages • Easy operation for untrained user • Small footprint on shop
counters • Enable PIN entry without others seeing what is typed
- Scanner
- Used to convert hard copy documents into digital form to allow it to be stored on a computer.
Advantages and disadvantages • Allows rapid entry of images and text into a digital form for storage
on a computer • Can be used with OCR to enter large amounts of text data rapidly • Expensive and
may require extra software to be useable
- Digital Camera
- Camera which captures an image on a light sensitive digital sensor (also called a CCD or Charge
Coupled Device) instead of a piece of film. The image id captured in a digital form that can be sent
directly to a computer. Advantages and disadvantages • Reduced cost of processing and buying film
• More expensive than comparable film camera • Easy to upload images to a computer • Often more
compact than a comparable film camera • Less chance of dust and dirt entering as it does not need
to be opened to change film
- Microphone
- Used to record audio such as voice for input into a computer
- Sensors
- Devices that respond to a certain physical property and convert it into
an electrical signal. Can be connected to a computer often via an
analogue to digital converter. Examples of the physical properties that
can be sensed and the applications in which they are found include
• Temperature o Automatic washing machines o Automatic cookers
o Air conditioning controllers o Central heating controllers
o Computer-controlled greenhouses o Monitoring and recording
scientific experiments o Environmental monitoring and recording
• Pressure o Burglar alarms o Automatic washing machines o Robotics
o Production-line control o Monitoring and recording scientific
experiments o Environmental monitoring and recording • Light
o Computer-controlled greenhouses o Burglar alarms o Robotics
o Production-line control o Monitoring and recording scientific
experiments o Environmental monitoring and recording
- Graphics Tablet
- Device used to convert free-hand drawings into digital form
that can be sent to a computer. Consists of a flat surface that
detects the movement of a pen and sends this data to the
computer.
- MICR
- Stands for Magnetic Ink Character Recognition. Device used to
read the special magnetic ink that banks use to print details on
the bottom of a cheque. The magnetic ink is used to record the
persons bank account number and branch sort code. This
enables to cheque to be machine readable and speeds up the
processing of cheques compared to manual input by an
operator. The characters printed with magnetic ink are also
human readable.
- OMR
- Stands for Optical Mark Recognition. Relies on a specifically designed
paper form that has certain regions where a mark can be placed by a
person using a pen or pencil. The presence of the mark on the page has a
meaning based on the position of the mark which is understood by the
software on the computer. The system does not recognise actual
characters such as letters or numbers.
- OCR
- Stands for Optical Character Recognition. A device to enable a
computer to recognise written or printed characters. Used
together with a scanner it enables a page of text to be scanned
and entered into a computer as editable text (for use in a word
processor) instead of just an image of the text that cannot be
changed.
- Barcode Reader
- A barcode is a series of black lines on a white background
used to identify products. Each number is represented by a
line with a different thickness. The barcode reader passes a
beam of light over the barcode to detect the lines and their
thickness and converts this into a number. Used in
supermarkets at EPOS terminals to connect a product being
purchased with the correct price stored in the supermarkets
database.
- Video Cameras
- A digital video camera works in a similar way to a
digital still camera but enables moving images to
be captured as a series of still digital images.
- Web Cams
- Often mounted on a computer or built into the screen of
laptop computers. It enable to capture of moving images in
the same way as a video camera.
- Light Pen
- Used to control the movement of a
cursor or to select items from a
screen in situations where space is
limited so the use of a mouse or
graphics tablet would be difficult
- Output Devices
- CRT Monitor
- These monitors are easy to identify as
they have large bulky backs behind a
glass screen. They used to be the most
common monitors for use with desktop
computers. These days other Monitor
types have become cheaper and so CRT
monitors are not commonly seen
except in old equipment. Advantages
and disadvantages • Cheap to buy
• Produces good colours • Large
footprint so takes up lots of desktop
space. • Very heavy compared to other
monitor types • Screen is generally
convex and this makes output at the
edges slightly distorted.
- TFT Monitor
- These are the most common type of computer monitor at
present. They use LCD technology which requires backlighting
to enable the image to be seen. Advantages and disadvantages
• Thinner and lighter then CRT monitors making them suitable
for portable products • The back lighting does not evenly light
the screen causing dark and light patches • Narrow viewing
angle - Picture quality changes as the viewer moves around.
- Projector
- Computer screens are too small to show something to an
audience. Multimedia projectors plug into computers and the
normal image on the display is projected onto a large screen.
Advantages and disadvantages • Allows larger numbers of
people to see what is on the computer display • Bulb lifetime is
limited and bulbs are expensive to replace • Often require
significant distance between screen and projector so require
large rooms to work
- Laser Printers
- Laser printers are the main types of printers found in
offices and businesses. They produce high quality printouts
of both text and graphics and can produce both colour and
grey scale output. Advantages and disadvantages • More
expensive to buy a laser printer than an inkjet printer • Less
expensive to print per page than an inkjet printer. • Produce
very high quality output
- Plotters
- Also called a 'plotter' these are used to printout line drawings in situations like architects or
engineering diagrams. There are two types • Flat-bed plotters - The paper lies on flat surface and
pens are moved across the surface to draw diagrams • Drum-plotters - The paper is on a roll and as it
unrolls pens draw on it. Advantages and disadvantages • Can work on very large paper sizes
• Produce very high quality line drawings • Very large and so take up lots of office space • Very
expensive top buy the plotter • Pen plotters have mostly been replaced by very large inkjet printers
in most situations
- Speakers
- Enable a computer to output sounds as long as there is a sound card fitted into the computer.
Advantages and disadvantages • Enable to users to hear sounds - useful for feedback for visually
impaired people • Enables computers to be used a multimedia devices such as in video playback with
sound • Require desktop space
- Motors
- Allows a computer to make other equipment move such as microwaves, washing machines and
robots. Advantages and disadvantages • Enables computers to control automated equipment.
• Requires additional equipment like D2A converters to enable computers to control motors
- Buzzers
- Buzzers enable feedback to users such as alarms for microwaves once they have finished.
Advantages and disadvantages • Enables computers to give audible feedback if the user is not able to
see the device. • Noise can be intrusive in situations where low noise levels are important
- Lights
- Found in computer controlled greenhouses, street lighting and traffic lights. Advantages and
disadvantages • Improve the productivity of the greenhouse by maximising the amount of light for
the plants. • Makes driving safer by automatically turning on when it is dark
- Heaters
- Used in computer controlled
greenhouses. In colder climates and
at night the computer can turn the
heater on to maintain the optimum
temperature for the plants growth.
Advantages and disadvantages
• Improve the productivity of the
greenhouse by maximising the
temperature for the plants.
• Enables the growth of plants which
would not grow in colder climates
• Excessive use of heaters and lights
to grow non-native plants
contributes to atmospheric warming
- Inkjet Printer
- Inkjet printers produce a printout by emitting
small drops of ink onto paper. They are not
impact printers. Inkjet printers are very common
for home printing requirements. Advantages and
disadvantages • Produce high quality printouts in
colour • Cheap to purchase the printer initially
• Quieter than impact printers such as dot-matrix
• High ink costs per page • Printouts may not be
touch-dry when first produced so will smudge if
not handled carefully
- Dot Matrix Printer
- Dot-matrix printers are impact printers. They work by striking the page with small
pins coated in ink at the tip. They used to popular in home printing applications but
have now been mostly replaced by inkjet printers. Their main use is in printing
multi-part forms which require the impact to imprint the character through to the
last page. Advantages and disadvantages • Very fast for printing text • Can print
onto multi-part forms because they use impact to work (the other types of printer
mentioned are non-impact). • Very noisy so not suitable for offices due to noise
pollution. • Still popular in warehouses, or similar, where noise is less of an issue
and multi-part form use is still common. • Produce very poor image quality only
really suitable for text