Chapter 3.2 A - Input devices FINAL BOARDS Flashcards
What is a barcode
a series of dark and light parallel lines of varying thickness
What happens after the barcode is read (supermarket)
The barcode is looked up in stock database
When the barcode number is found, the stock item record is looked up
The price and other stock item details are sent back to the checkout or the POS
the number of stock items in the record is reduced by 1 each time the barcode is read
this new value for number of stock is written back to the stock item record
the number of stock items is compared to the re-order level; if it is less than or equal to this value, more stock items are automatically ordered
once an order for more stock items is generated, a flag is added to the record to stop re-ordering every time the stock item barcode is read
when new stock items arrive, the stock levels are updated in the database.
What is a key field
how does it relate to a barcode
the field that uniquely identifies a record in a file
barcode acts as a key field for items in a supermarket
What is the POS
point of sales terminal
Advantages of barcodes (managers)
Automatic stock control
More up-to-date sales information and sales trends
Much faster and easier to change prices on stock items
Advantages of barcodes (customer)
Faster checkout queues
Errors in billing are reduced
An itemized bill is given to the customer
What is a QR code
a matrix of dark and light squares which represent data
Full form of QR
Quick Response
How can a QR code be read
QR code apps and smart phone cameras
Common uses of QR codes
Advertising
Restaurant menus
Storing boarding passes of flights and trains
Advantages of QR code compared to Bar code
More information
Few errors - QR Codes have a built in error checking systems. This helps guard against badly printed, damaged QR codes
Easy to read - don’t need a laser or an led light source
Disadvantages of QR codes
Can be used to transfer malicious codes. It is very easy to embed malicious code into a QR code. This code could be a virus, etc.
What is the process of transferring malicious codes through a QR code called
Attaging
What is a Frame QR code
a type of QR code that includes a space for advertising
What colour system do most cameras use
24-bit RGB Colour system - 3 primary colours, each get 8 bits.
What does the number of pixels in the picture determine
size of the file used to store the photograph
What does the quality of the image (camera) depend on
Recording device (how good the camera lens is and how good the sensor array is)
Number of pixels used (the more pixels used, the better the image)
Levels of light and how the image is stored (JPEG, raw file, png, etc)
What is a DAC (full form and def)
Digital to analogue converter - device that converts digital data into electric currents
What is a virtual keyboard
an onscreen keyboard which uses the features of the touch screen to emulate a physical keyboard
How does an ergonomic keyboard tackle RSI
these have the keys arranged differently
They are also designed to give more support to the wrists and hands when doing a lot of typing.
What is RSI (full form and def)
repetitive strain injury - pain felt in the muscles,
nerves and tendons caused by a repetitive action (for
example
What does a microphone do
Converts sound waves into an electric current. The current is then converted to a digital format so that the computer can process/store it
What is the nature of the current gen by the microphone
analogue
What is a CMOS (full form and func)
complementary metal oxide semiconductor - a chip that generates an electric current when light falls on its surface
What is a DSP (optical mouse)
digital signal processor - a processor that calculates, the coordinates of a pointing device based on the pulses of electricity received
Why an optical mouse is better than a mechanical mouse
No moving parts - more durable
Dirt can’t get trapped in any of the mechanical components
No special surfaces are required
Advantages of wired connections over Bluetooth and wireless (mouse)
No signal loss - consistent pathway
Cheaper to operate - no need to buy batteries over and over again
What is a 2D scanner
Most common form of scanners that are used to input hard copy (paper) documents
What is an OCR (full form and function)
Optical character recognition - Technology that can convert hard copy text or images into a digital format such as a text file that is to be stored in a computer memory
What is a 3D scanner
Scan solid objects and produce a three-dimensional image.
Take images on several different points along the X, Y and Z coordinates.
Where can the images from a 3D scanner be used to design and create
CAD - computer aided design which is a software used to create drawings
What is a application of a 3D scanner
Computed tomographic scanners.
What does a CT scanner do
used to create a 3D image of a solid object
What is a touchscreen
Allows the user to select or manipulate a screen image using the touch of a finger or stylus
3 Types of touchscreen
resistive
Capacitive
Infrared
Two types of capacitive screens
Surface
Projective
Surfaces that can control a surface capacitive screen
bare fingers
stylus
surfaces that can control a projective capacitive screen
bare fingers
stylus
thin surgical or cotton gloves
What other facilities does a projective capacitive screen allow for
Multi-touch
Advantages of capacitive screens compared to others
Better img quality comp to resistive
Durable
Projective allow multi touch
Disadvantages of capacititive screens comapred to others
Surface capacitive screens only work with bare fingers or stylus
This screen is sensitive to electromagnetic radiation
What is an infrared touch screen
Infrared touch screens use a glass screen with an array of sensors and infrared transmitters
Advantages of infrared touch screens comp to others
Multi-touch
good durability
operability isn’t affected by a scratched or cracked screen
Disadv of infrared touch screens comp to others
Screen is sensitive to water and moisture
Accidental activation can take place if beams are broken by any other objects or are disturbed in someway.
Could be sensitive to light interferance
What is a resistive touch screen
made up of two layers of electrically resistive material with a voltage applied across them
Adv of resistive touch screens comp to others
Good resistance to dust and water
Can be used by bare fingers, stylus and gloved hands
Disadv of resisitive touch screens comp to others
Low touch sensitivity
Doesn’t allow multi-touch
Poor visibility in strong sunlight
Vulnerable to scratches on the screen
What control cameras
an embedded system
What does the embedded system in cameras control?
» adjust the shutter speed
» focus the image automatically
» operate the flash gun automatically
» adjust the size of the image
» remove ‘red eye’ when the flash gun has been used
How are 2D scanners used in airports
two-dimensional photograph in the passport is scanned and stored as a JPEG image.
Picture of passengers face is taken via a camera
Key characteristics of face are compared using face recog/detection software
What are the key characteristics of faces that are compared in 2D scanner airport application
» distance between the eyes
» width of the nose
» shape of the cheek bones
» length of the jaw line
» shape of the eyebrows
Use and full forms of
CT
MRI
SPECT
computerised tomography - X-ray
MRI - magnetic resonance images - Radio frequencies
single photon emission computer tomography - gamma rays
