external hardware

Question 1

SSD principles

Answer 1

Uses NAND flash memory, data stored in floating gate transistors that store charge
Can’t read/write individual bits so instead data is read in pages/blocks
Can use multiple level cells that store 2 bits

Question 2

RFID Tags Principles

Answer 2

Reader sends radio waves out to antenna of the RFID tag
RFID tag is energised
Transponder sends the data signal back
Reader receives the signal

Question 3

CCD Barcode Reader Principles

Answer 3

CCD measures ambient light reflected from bar code
Black areas reflect less than the lighter areas
CCD converts this into an electrical signal
Image analysis software used to process and determine the value encoded in the barcode.
Check digit to validate entry

Question 4

Photodiode Barcode Reader Principles

Answer 4

Light is shone at barcode, which is reflected back
Black areas reflect less
Photo-diode measures amount of reflected light, which is converted to an electrical signal
Reflection analysed to determine value encoded
Data sent as binary codes
Check digit to validate entry

Question 5

Laser Printer Principles

Answer 5

Print drum coated in negative charge
Printer generates bitmap of page, lasers reverses charge on the drum in the exact image of the bitmap
Charged drum picks up toner and toner is transferred to the paper
Toner bonds with paper by heat rollers/pressure

Question 6

Inkjet Printer Principles

Answer 6

Heater behind ink reservoir is warmed
Ink droplets are favourited
Electricity applied to the piezoelectric crystal which deforms the shape
Fires the ink out
Colours created by mixing different spots together

Question 7

CD-R Principles

Answer 7

A high powered laser makes sections of pits.
Low powered laser is used to read it back. Measures pits and lands where 1s and 0s are indicated.
Data stored on a continuous spiral track

Question 8

HDD Principles

Answer 8

Binary digits shown by magnetising spots on disk
Disk is made of tracks (concentric circles)
Driver head moves out to the track whilst disk is spinning at high speed
Data read/written as correct sector passes under the driver head

Question 9

Digital Camera Principles

Answer 9

Lens focuses photons onto the CCD device
Uses ADC to convert light intensity to binary value
Larger the pixels, the larger the quality level
Firmware processes data to tidy it up, colour filter applied
Image is stored as a group of pixels

Question 10

SSD vs HDD

Answer 10

SSD uses less power
SSD has faster read/write times
SSD is a noiseless operation
HDD is cheaper per GB
HDDs have been used for a long time so greater confidence about it