Unit 3 (IV term)
peripheral devices attached to EPOS (electronic point of sale) tills:
to look up prices using barcodes
barcode reader
to use the reflection of a light beam to read barcode labels
LCD (liquid crystal to output purchase details
display) screen
numeric keypads to input prices manually
swipe card plastic card with a magnetic strip running across it containing confidential data
swipe card reader to read bank cards
conventional cameras
rechargeable batteries
view-finder
digital cameras no film requiring chemical processing
to directly transfer pictures for editing
unwanted pictures can be deleted
data can be compressed
resolution is measured in pixels and given as two numbers, indicating how many pixels there
are across the image and how many going down the image
CCD to consist of photo-transistors (light-sensitive transistor - electronic switch)
(Charge-Coupled Device)
to create the pictures as a set of dots or pixels (picture elements)
memory cards solid state memory
flash cards electronic integrated circuits
to range from … to …
input devices to translate the information into a series of on and off electrical signals (bits)
bits are combined in specific series to represent letters, numbers, and signals
to have keys (controlled by the software) arranged in a similar layout to a typewriter
keyboard
to have a series of special keys to control sending information to the CPU
arrow keys move the cursor to any point in a document
cursor control input device used with a graphical user interface
mouse to operate by controlling the position of the cursor (in the shape of an arrow) on
the monitor
to have 2 or 3 button switches on top and a ball underneath that is rolled on a flat
surface
to be able to input a large amount of data quickly by moving a light beam across a
light pen barcode
to interpret and convert human writing into computer form
to convert the barcode into digital data that is usable by the computer
touch-sensitive screens/ to control the computer with the touch of a finger
displays/touch pads
to use a stylus and a special sensitive tablet to let users draw on the screen
graphics tablets
to be useful for graphics work and CAD (computer-aided design)
hand-held and desktop models
to copy graphic images into the computer
scanner to allow typewritten pages to be entered without retyping
to work by passing a beam of light across the original page
to sense the reflected light
to assemble the information into a data file that describes the images as rows of
tiny dots
to pass the file on to the computer
magnetic devices /optical devices / magneto-optical devices
fixed storage / removable storage
to transfer data to another computer
storage devices disk or tape drive moves the media past a read/write head that reads the data from
storage media and writes data to the storage media
the speed at which the drive moves the media past the read/write head
the capacity of the media
output devices
to require a matching type of display adapter in the system unit
to display and redisplay the computer's output / text characters
monitor to consume little power
flat-panel monitor
flat profile allows them to provide a full screen in a small folding unit
monochrome monitor to show one colour, generally white, green, or amber, on a dark background
graphics monitors
colour monitor
to display colour
do not consume light of their own, but consist instead of crystal molecules
LCD
The backlit LCDs are easier to read than the original LCDs, which were difficult to
(liquid crystal display) read in strong light.
EL (electroluminescent an improvement over LCDs because they actively emit light when electrically
screens) charged
gas-plasma screens use a gas that emits light in the presence of an electric current
gas-plasma gas-plasma displays cannot be battery-operated
must be plugged into a regular AC outlet
photo-quality colour printer
printer to print in colour
to create paper copies (hardcopies)
to use a series of dots to form a character
a low quality printer that prints by hammering pins on the paper to print an image
dot matrix printer made up of dots
The hammering action means that it can print on special multipart paper where a
number of copies are produced at the same time.
output quality can be relatively low
to spray small droplets of ink to create characters
ink jet printer
to produce a fine-quality print at an extremely high speed
a very high quality text and graphics printer that has a photosensitive drum that
laser printer deposits toner powder on the paper
to produce an exceptionally high-quality print at a very high speed
to move a piece of paper under a series of moving pens
to produce colour output by drawing with several different-coloured pens
plotter to use fine-point pens
the lines produced with a plotter can be very precise
to be used to produce line drawings: architectural drawings, maps, charts
input/output
to incorporate both input and output functions
devices
to send data from the computer out over telephone lines
to accept data over those same lines from other computers
to work by translating the electrical impulses of computer data into audible tones
modem to convert them back into electrical impulses (demodulation)
can be connected externally to the computer's serial port or mounted internally as
(modulator/demodulator) an expansion board
to link computers via phone
to access information from remote databases
to communicate in a variety of ways
