Chapter 2, Topic 4

Question 1

Explain Secondary Memory

Answer 1

• Instructions and data are saved onto RAM, it will become full at some point. Instructions or data from RAM will need to be moved to secondary storage in order to make space for new instructions or data.
• Relatively slow memory that can be written to but is also non-volatile.
• Also known as persistent storage.
• Relatively high capacity to hold data compared to primary memory.

Question 2

Why secondary memory is necessary

Answer 2

• When computer starts up, RAM is empty so instructions from secondary memory need to be copied into RAM for computer system to run.
• If no secondary memory, only ROM could store programs and instructions. Since ROM cannot be over-written, computer can only perform fixed operations.

Question 3

Types of secondary memory

Answer 3

• Hard disk drive
• CD/DVD
• USB
• SD or CF card
• Zip disk
• Floppy disk
• Magnetic tape

Question 4

How HDD works

Answer 4

• Uses platters
• Platter divided into tracks
• Platter is spun
• Read write arm moves over platter
• Magnetic fields control magnetic dots of data
• Magnetic field determine binary value.

Question 5

Features of SSD

Answer 5

Non volatile
Uses NAND flash memory

Question 6

Differences between SSD and HDD

Answer 6

• SSD about 10 times more expensive per MB.
• HDD about 3 times more battery power.
• SSD generally no larger than 512 GB but HDD go up to 4 TB.
• SSD silent, HDD makes spinning disc sounds.
• Both very reliable forms of storage but HDD is more vulnerable to knocks because of moving parts.

Question 7

Why SSD is replacing HDD

Answer 7

• No moving parts
• Less power usage
• Smaller
• Faster
• Run cooler
• Run quieter