1.1.3 Input, output and storage

What are input devices?

#peripherals used to provide data and control signals to a computer system

What is a bacrode?

#a means of representing data in a machine-readable form.

How do barcodes represent data?

#Traditional barcodes represent data by using a set of parallel lines of varied width and spacing.

What is a check digit?

#An extra digit or character added to the end of a long code

Whatis a type of barcode reader

Laser scanner

What do QR codes do?

#QR codes are typically used to provide a link to a particular page on a website, or to provide a link to an email or app that holds data

How much can QR codes store?

#A QR code can store up to 7,089 numbers or 4,296 characters.

What factors must be taken into account when purchasing a device?

• #

• Cost

• Speed

• Accuracy

• Reliability

What is a biometric?

#a physical characteristic such as fingerprints, facial images, irises, and voice.

What is biometric spoofing?

#A term used to describe a method of fooling biometric scanners.

Why is biometric spoofing seen as the most secure method of authentication?

#Iris recognition is one of the most secure forms of authentication, because the iris is well protected by the cornea.

Fingerprints can be damaged by cuts, and are easier to spoof as it is fairly easy to obtain copies.

What are the different types of sensors?

#accelerometers, gyroscopes, magnetometers, GPS receivers, barometers, thermometer proximity sensors, and ambient light sensors.

How do sensors work?

#The analogue signal is converted to digital form (for processing) by an analogue to digital converter (ADC).

How do digital cameras work?

#

• When you take a picture on a digital camera, you open a shutter to allow light to enter the camera through the lens.

• The lens focuses the light onto an image sensor, which is an array of millions of photosites (light-sensitive elements). The 'picture' is thus broken up into millions of pixels.

• The photosites measure only the intensity of the light. To determine the colour of each pixel, a 'Bayer filter' is used.

How is the colour of each pixel determined using a Bayer filter?

#The photosites measure only the intensity of the light. To determine the colour of each pixel, a 'Bayer filter' is used. This sits above the image sensor and provides an array of red, green, and blue filters, one for each photosite. There are twice as many green filters (as red and blue filters), as this matches the colour sensitivity of the human eye.

What are the two types of digital sensors?

#CCD (charge-coupled device) and CMOS (complementary metal-oxide semiconductor).

Which of the two types of digital sensors is better and why?

• The more expensive CCD sensors produce higher-quality images.

• However, CMOS systems use less energy, so are more popular on mobile phones and other devices that use a lot of power.

What does RFID(radio frequency identification allow for?

#RFID (radio frequency identification) allows data to be transmitted wirelessly over radio waves.

What are the two types of RFID system?

#There are two parts to an RFID system: a tag and a reader.

What are the features of RFID tags?

• #

• RFID tags are made up of an antenna, for receiving and transmitting the radio frequency signals, and a chip, which processes the signals.

• Each tag has a unique identifier and will often store some additional data in a non-volatile memory cell.

How are RFID tags used?

• #

• Tiny sticky labels → hidden in products.

• Plastic enclosures → attached to items for sale.

• ID cards → open doors, car park barriers (employees, students).

• Library & transport cards → book loans, bus/train payments.

• Warehouses & factories → track goods on production lines.

• Animal tracking:

  • Farm animals → monitor movement.

  • Pets → microchip (SIM-card size) inserted under neck skin, scanned with handheld reader for ID.

What are the two types of RFID tags?

• #

• Read-only: Fixed data (e.g., ID number).

• Read-write: Data can be updated.

• Active

• Passive

What are the features of passive RFID tags?

#

• No battery – powered by the reader’s radio signal.

• Antenna in the tag collects energy from the reader to activate the chip.

• Short range: usually up to 1 metre; some need the reader very close to the tag.

What are the features of Active tags?

• #

• Have a small battery inside the tag.

• Automatically transmit their ID at regular intervals.

• Long range: up to 200 metres, depending on battery power.

Where are active tags used?

#Active RFID devices are commonplace in shops, where battery-powered tags are secured onto items. The tags are deactivated or removed when the goods are paid for. A reader is situated at the shop's exit and an alarm is triggered if it detects an active tag when a customer leaves the shop.

How is barcode read using a barcode reader

#

• To read the code, a light from a laser illuminates the barcode.

• More light is reflected from the white areas than from the black bars.

• The reflected light is captured by one or more photoelectric cells that generate a set of electrical pulses that correspond to the black and white stripes in the barcode.

What are output devices?

#peripherals that reproduce or display data and information from a computer system

What are common output devices

#Speakers, Inkjet printers, Laser printers, Plotters, 3D printers, Display screens

How is print resolution measured?

#Print resolution is measured in dots per inch (dpi), and a resolution of at least 300 dpi is needed for photo-quality images.

What are impact printers?

#Printers that work by producing characters by striking paper

Where are impact printers used?

#They were once commonplace and useful for printing on multipart stationery (where the sheets are carbonated to produce two or more copies).

What are the advantages and disadvantages of impact printers?

#Impact printers are noisy, and it is quite rare to find them in today's office environments.

• Faster, cheaper printers make it easy to produce multiple copies by selecting more than one copy, or by photocopying an original.

What are ink jet printers?

#Non- impact printers that use liquid ink to produce black-and-white or colour prints

What are the advantages and disadvantages of inkjet printers?

• #

• This type of printer can cost anything from tens to hundreds of pounds depending on factors such as speed, quality, and paper handling capability.

• High-end inkjet printers can often handle specialist paper and print at very high resolutions.

• iquid ink produces richer colours, making this type of printer the most suitable for printing photo-quality images.

Where are inkjet printers used?

#They are also preferred by photographers and for print studios because of their superior colour production and paper handling capabilities.

Where are laser printers used?

#Laser printers are frequently used in the workplace.

What are the advantages of laser printers?

#-Laser printers do not use liquid ink. Instead, they use powdered ink called 'toner

-Are usually faster than inkjet printers. High-specification laser printers are capable of producing 200 pages per minute.

-Powdered ink is cheaper than liquid ink, and lasts longer.

What are the disadvantages of laser printers?

#

• The toner cartridges are quite large and colour printers (which have four separate toner cartridges) can be bulky and take up a lot of room.

• Other laser printer consumables such as the drum will need to be replaced from time to time

• Comparison sites often quote a cost per page to allow disparate printers to be compared.

• The quality of laser-printed output is generally very good for text, but not so good for photo-quality images, as it is difficult to produce deep, rich colours.

What is a plotter?

#A device that uses one or more pens to draw an image.

How do plotters work?

#Pens are lifted or applied to the paper as required, to produce a very precise drawing.

What are other features and uses of plotters?

Plotters are often large devices that can handle very wide paper, sometimes on a drum to allow repeated layers to be printed.

Plotters are commonplace in engineering and architectural practices.

How do 3D printers work?

#3D printers use filament,(normally plastic-based resin), which is heated and printed layer (slice) by layer to form a solid object.

How are 3D printers used?

#bioprinters — to make living body parts.

What are the types of computer screen displays?

#LCD screens, LED displays and OLED displays

What are the features of LCD screens (Liquid crysal display)

#

• Found in offices and on standard desktop and laptop computers

• Low cost

What are the features of LED displays? (Light emitting diode)?

• Use less power than LCD

• Cheaper

• More environmentally friendly to run

What are the features of OLED displays? (Organic Light emitting diode)?

#

• Lighter

• more flexible than LED displays, so are a good option for mobile devices such as phones and tables

What is the resolution for print resolution?

#Dots per inch (dpi)

What resolution is required for photo-qulaity images?

#at least 300 dpi

How do impact printers work?

#Impact printers produce characters by striking the paper

Where are impact printers used?

#They were once commonplace and useful for printing on multipart stationery

What are the disadvantages of impact printers?

#Noisy

What are inkjet printers?

#Inkjet printers are non-impact printers that use liquid ink to produce black-and-white or colour prints