3.3 data storage and compression

Question 1

.what is primary storage

Answer 1

• directly accessed by CPU

Question 2

what is ROM

Answer 2

• small piece of memory located on motherboard
• contains startup instructions for computer
• non volatile

Question 3

features of RAM

Answer 3

• volatile (contents lost if RAM turned off)
• used to store data, files
• can be written to / read from
• contents of the memory can be changed

Question 4

when is RAM used

Answer 4

• when it needs to store and access data (immediately)
• that is actively being used/processed by user

Question 5

advantages of virtual memory

Answer 5

• can be larger than physical memory provided in RAM
• avoid need to install/upgrade RAM (expensive)
• system wastes no storage on unwanted/unused data

Question 6

why do you need primary storage

Answer 6

• access time faster than secondary
• quicker FDE cycle

Question 7

what is ROM

Answer 7

• small memory chip located on computers motherboard
• primary storage that holds first instructions computer needs to start up (bootstrap)
• contains BIOS
• non-volatile
• read-only

Question 8

features of ROM

Answer 8

• non volatile (contents remain even when ROM turned off)
• used to store start-up instructions (BIOS)
• data/contents of ROM can only be read, cannot be changed

Question 9

what is secondary storage

Answer 9

not directly accessed by CPU, necessary for more permanent storage of data

Question 10

examples of secondary storage devices

Answer 10

• hard disk drives (HDD)
• solid-state drive (SSD)
• CD/DVD
• blu-ray disks
• USB flash memory
• cloud storage

Question 11

how does magnetic storage work

Answer 11

• data stored in digital format on magnetic surface of disk (platter)
• number of read/write head can access all surfaces of disk
• each platter will have 2 surfaces used to store data
• data stored on surfaces in sectors and tracks

Question 12

example of magnetic storage

Answer 12

hard disk drive

Question 13

advantages of magnetic storage

Answer 13

• cheap
• fast
• hold large amounts of data

Question 14

how does optical storage work

Answer 14

• use laser to create and read pits (low) and lands (high)
• land reflect, pits scatter. detected by light sensor

Question 15

DVD/CD vs blu-ray

Answer 15

• BR stores more

Question 16

examples of optical storage

Answer 16

• compact disks (CDs)
• digital versatile disks (DVDs)
• blu-ray disks

Question 17

features of optical storage

Answer 17

• low storage
• slow access to data

Question 18

how does solid-state storage work

Answer 18

• use NAND or NOR technology
• transistors used as control gates and floating gates
• state of transistors represent binary

Question 19

types of solid state storage

Answer 19

• solid state drives (SSDs)
• memory cards
• USB flash drives

Question 20

advantages of SSD

Answer 20

• no moving parts: more durable
• lower power consumption
• fast data access

Question 21

disadvantages of SSD

Answer 21

• bad longevity

Question 22

when is virtual memory used

Answer 22

• computer doesn’t have enough RAM to store all data & programs currently in use
• problem with memory management, system has high chance of crashing

Question 23

how does virtual memory work

Answer 23

• pages of data transferred between RAM and virtual memory (paging in/out)
• when data needed again, must first be copied back into RAM. v slow

Question 24

what is cloud storage

Answer 24

• data stored remotely on servers
• require internet connection to access data

Question 25

cloud vs local storage

Answer 25

• cloud can access from any computer, but require internet
• local fully under users control
• local always faster to access
• cloud can have unauthorised access
• cloud greater ability to increase capacity

Question 26

Diagram for virtual memory

Answer 26