Physical hardware
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What is a barcode?
A barcode is a sequence of parallel black and white bars with varied width and spacing that encodes binary information Sometimes a check digit is added to the end of the barcode for validation
What are QR codes? How are they different from regular barcodes?
Two-dimensional barcodes They have a higher storage capacity QR codes are read using images, not lasers
What does RFID stand for and what is its purpose?
RFID (radio frequency identification) allows data to be transmitted wirelessly over radio waves.
What are the two parts to an RFID system?
Tag Reader
What is in a passive RFID tag?
chip, which contains a small amount of memory antenna
Advantage of RFID over barcodes or digital cameras
The use of radio signals means that the system does not require a line of sight between the tag and the reader
What is a passive RFID tag? Range?
An RFID tag that doesn’t contain a power supply The device is powered by radio energy transmitted by the reader Range of up to 1m
What is an active RFID tag? Range?
An RFID tag that has a small battery within the tag The tag will transmit its identifier at regular intervals Range of up to 200mq
What type of storage are Hard Disk Drives?
Magnetic storage
What are the parts of a HDD?
at least one metal platter a spindle which spins the platter a read-write head on an actuator arm
Give pros of a HDD:
High read-write access speed (but slower than SSD) Greater Capacity than SSD … at a lower cost per GB than SSD Reliable and don’t degrade over time
Give cons of HDDs:
Not as portable as CD/DVD/USB memory sticks HDDs are more likely to fail as they are made up of lots of moving parts HDD’s are fragile (bumps and knocks damage disk) Slower access speeds than SSDs (slow seek time)
What type of storage are Solid State Drives?
solid state storage / NAND flash memory
Give pros of SSDs compared with HDDs:
Faster than HDD No moving parts means it is more robust than HDD No moving parts means it uses less power than HDD No moving parts means it is quieter than HDD
When is an SSD suitable?
When files need to be read or changed frequently (e.g. in a server) Or when the system needs to be portable
Give cons of SSDs compared with HDDs:
The number of times SSD devices can be written to is limited (hence unsuitable for long term archiving of data) Higher cost per GB than HDD
What kind of storage do optical drives use?
Optical storage (e.g. CD, DVD, BluRay)
Name optical discs (e.g. CD)
Compact Disc (CD) Digital Versatile Disc (DVD) Blu-ray Disc
Name the types of optical drive (e.g. ROM):
ROM (read only) R (recordable) Can be written onto once. Good for archiving data RW (rewritable) Has a chemical dye layer on top of the reflective layer The chemical dyes allow the burning process to be reversed
Give pros of optical discs:
Extremely light and portable … so they are good for media distribution Relatively cheap (for lower storage capacities) Reliable (unless scratched)
Give cons of optical drive: 3 points.
Any 3 from: 1. Data can be ruined if disc is scratched 2. Lower capacity than HDD and SSD 3. Slow seek time