Memory Storage Media

Question 1

primary storage

Answer 1

main memory inside a computer
directly accessed by CPU
e.g. ROM, RAM, Cache

Question 2

secondary storage

Answer 2

non-volatile(persistent) memory
accessed by device that is part of computer system - not directly accessed by CPU
e.g. HDD, SDD

Question 3

off-line storage

Answer 3

non-volatile memory
isn’t permanently connected to computer(can be removed from system)
e.g. DVD, Blu-ray, CD, USB

Question 4

ROM

Answer 4

Read only memory

stores boot program/BIOS
used to boot up computer when it is switched on
non-volatile - contents are stored when power is turned off
fixed size
contents never change(read only)

Question 5

RAM

Answer 5

random access memory

used to store data or programs/instructions that are currently in use
volatile- contents lost when power switches off
easily expandable
contents change frequently

Question 6

Virtual memory

Answer 6

section of hard disk
stores items in RAM that are currently not being used
allows more programs and data to be loaded when RAM is full

Question 7

Adding more RAM

Answer 7

more memory for programs and data to be loaded into
CPU can multitask more programs
programs may run faster due to less use of virtual memory

Question 8

Cache memory

Answer 8

temporary storage area between CPU and RAM

store frequently used instructions and data

Question 9

2 advantages of cache memory

Answer 9

faster to access- data doesn’t need to be fetched from RAM

uses faster SRAM

Question 10

1 disadvantage of cache memory

Answer 10

more expensive

Question 11

DRAM

Answer 11

dynamic ram

capacitators hold bits of information(0 and 1)
transistors act as a switch to read/change capacitors value

Question 12

2 advantages of DRAM

Answer 12

less expensive

higher storage capacity

Question 13

1 disadvantage of DRAM

Answer 13

needs to be constantly refreshed/charged so values aren’t lost

Question 14

SRAM

Answer 14

static ram

uses ‘flip flops’ which hold each bit of memory
used when speed is essential e.g. memory cache

Question 15

3 advantage of SRAM

Answer 15

doesn’t need to be constantly refreshed
faster
consumes less power

Question 16

Magnetic tape

Answer 16

magnetic storage
serial access medium
has to be read starting at beginning of tape
used for ‘cold storage’
- storing large volumes of data offline which will seldom be accessed

Question 17

Advantages of magnetic tape

Answer 17

large capacity
doesn’t take up much storage space
cost-effective for large volumes of data

Question 18

Hard disk drive

Answer 18

1. data is stored on magnetic surface of several disks that spin at many thousand times a second
2. Each disk has two surfaces which can be used to store data
3. disk contains concentric circles called tracks(which are divided into sectors)
4. disk heads that are mounted on mechanical arms read and write the data

Question 19

Flash memory

Answer 19

non-volatile
no moving parts
type of EEPROM
stores data by controlling electrons
used in phones, cameras and computers

Question 20

EEPROM

Answer 20

electronically-erasable-programmable read-only memory

Question 21

How flash memory stores data

Answer 21

1. flashes an electrical current through a barrier
2. electrons pass from source to the drain, and some are trapped between, on the floating gate
3. this gate effect continues whether there is no electricity, and so storage remains when power is removed

Question 22

How data is created on hard disk drive

Answer 22

by magnetising fine ferrous particles on the disk

north and south polarities represent 0s and 1s

Question 23

5 advantages of flash memory

Answer 23

uses NAND chips
- majority of solid-state storage devices use NAND technology
cheaper than EEPROM
quieter than HDD
more potable than HDD
much quicker access time than HDD

Question 24

3 disadvantages of flash memory

Answer 24

slower than EEPROM
only allows blocks of data to be read or erased
more expensive than HDD

Question 25

3 advantages of EEPROM

Answer 25

faster than flash memory
used when smaller amounts of storage/speed is needed and not re-written often
allows data to be read or erased in single bytes at a time

Question 26

2 disadvantages of EEPROM

Answer 26

more expensive than flash

uses NOR chips

Question 27

Solid state drive

Answer 27

no moving parts

uses non-volatile flash memory

Question 28

5 advantages of SSD

Answer 28

uses less battery power
smaller and lighter
faster at loading and copying files
reliable
silent- no moving parts

Question 29

3 disadvantages of SSD

Answer 29

10x more expensive than HDD per MB
smaller capacity
less longevity for read/write functions

Question 30

3 advantages of HDD

Answer 30

10 x cheaper than SSD per MB
larger capacity than SSD
greater longevity for read/write functions

Question 31

5 disadvantages of HDD

Answer 31

use 3x more battery power
less portable
slower
more vulnerable to knocks because of moving parts
makes spinning disc noises

Question 32

Optical storage

Answer 32

CDs and DVDs

thin layer of metal alloy or light-sensitive organic dye is used to store data
data is stores as pits and lands burnt into a single spiral track circulating outwards from centre

Question 33

Reading optical storage

Answer 33

1. red lasers shine onto surface of disc(read and write)
2. disc is rotated at constant speed
3. as laser beam passes over pits and lands, the level of reflection is measured
4. 0s and 1s can be derived from whether if there is reflection or not

Question 34

advantage of DVD

Answer 34

1. larger capacity
   - uses dual layering(two individual recording layers)
   - shorter laser wavelength(more data can be stored on surface)

Question 35

CD-R, DVD+R, DVD-R

Answer 35

recordable
write once(or fill over time) and then can only be read
laser heats up dye layer and changes its transparency

Question 36

CD-RW, DVD-RW, DVD+RW

Answer 36

re-writeable

written to and read many times
uses a special alloy that can change between two states when heated

Question 37

CD-ROM, DVD-ROM

Answer 37

read only
mass-produced by pressing
data written to them before they are sold

Question 38

DVD-RAM

Answer 38

have concentric tracks rather than one spiral track
allows numerous simultaneous read and write operations(using red laser)
greater longevity(ideal for archiving)

Question 39

Blu-ray

Answer 39

single spiral track
blue laser is used to carry out read and write operations
single polycarbonate layer

Question 40

3 advantages of Blu-ray

Answer 40

smaller wavelength than DVD(pits and lands can be much smaller)
much larger storage capacity
faster transfer rate

Question 41

3 advantages of optical storage

Answer 41

no moving parts, so not sensitive to movement
small and portable
cheap

Question 42

3 disadvantages of optical storage

Answer 42

tend to be smaller capacity
easily damaged/scratched
slow write speeds