External Hardware Devices & Memory Storage Flashcards
(27 cards)
What is the purpose and use of a laser printer?
Prints documents as “hard” copies. Used in offices for large-volume printing. Alternative to inkjet printers (used at home for colourful logos, posters).
What is the operation of a laser printer?
Drum coated in negative static charge
Laser neutralises charge where black areas needed
Positively charged toner sticks to drum
Paper rolls over drum transferring toner
Heated rollers fuse toner to paper
What are Advantages and Disadvantages of a laser printer?
Advantages
✔ Cheap in long run, fast, suited to text, reliable, no wet pages, cheap paper
Disadvantages
❌ High initial cost, expensive to repair, lower graphic quality, needs colour model, high power use
What is the purpose and use of a barcode reader?
Used in supermarkets for item identification, retrieves price/description, updates stock, gathers statistics
What the operation of a barcode reader?
Laser shines at barcode
Moving mirror/user moves scanner
Black/white reflect different light
Light sensor converts to digital value
Converts reflection to numbers/characters
What are advantages and disadvantages of a barcode reader?
Advantages
✔ Fast, error-free input, stores lots of data
Q: Disadvantages
❌ Damaged barcode or dirty reader, needs proper hardware/software
How is the barcode reader connected to check digit?
Extra digit added via algorithm
Compared on scan to detect errors
If mismatch=error
If match=accepted
What is the purpose and use of a digital camera?
Captures and stores images digitally, used by professionals and consumers
What is the operation of a digital camera?
Light focused by lens onto CCD sensor
Each sensor = one pixel
ADC converts intensity to binary
Colour filter generates RGB values
Pixels stored as digital image
What are advantages and disadvantages of a digital camera?
Advantages
✔ Stores many images, easy to manipulate/share/print/view instantly
Disadvantages
❌ Requires editing skills, backup needed, initial cost, film still preferred for quality
How is a digital camera connected to Lossy/Lossless Compression and RLE?
Lossy: Reduces bit depth = smaller size, lower quality
Lossless: Algorithm removes redundant data without quality loss
RLE: Stores repeated pixels as value + count (e.g. 16455367 for 111111444445556666666)
What does RFID stand for?
Radio frequency identification
What is the use and purpose of RFID?
Wireless transfer between tag and reader, used in cards, hotel keys, supply chains, tracking animals/pets
What is the operation of a RFID?
Reader emits radio wave
Tag antenna picks it up, powers chip
Chip emits radio wave with data
Reader decodes it
What are advantages sand disadvantages of an RFID?
Advantages
✔ Secure, reads multiple tags, fast detection, automates data collection, read/write
Q: Disadvantages
❌ Hacking risk, larger tags, limited range, expensive setup, EMI interference
What is storage?
Holds data/instructions/info for future use
What is the volatility of Storage and Memory?
Storage = non-volatile (retains data when off)
Memory (RAM) = volatile (loses data when off)
What is Access time?
Time to deliver item from memory/storage to processor
What is the operation of a hard disk drive?
Magnetic platters + actuating arm + read/write head
Data on concentric tracks and sectors
Platter rotates at high speed
What is the capacity of a HDD?
500GB–5TB, increased via more platters or narrower tracks
What is a drawback of a HDD?
Susceptible to movement → not suitable for portable devices
What is the operation of an SSD?
NAND flash memory + controller
Uses floating gate transistors to trap charge
Data stored in pages → blocks
Page must be erased before writing new data
What are features of an SSD?
✔ No moving parts → faster than HDD
✔ Non-volatile
✔ Suitable for phones/tablets
What are different types of Optical disks?
CD: 700MB
DVD: 4.7GB–8.5GB
Blu-ray: 25GB–50GB
