3.5 Memory & Storage

Question 1

Primary storage

Answer 1

Storage inside the processor

Question 2

Random Access Memory (RAM)

Answer 2

1. Works by storing data as electrical charges
2. Volatile - charges disappear when electricity is switched off
3. CPU can access data in RAM very quickly
4. Read and write

Question 3

What does RAM store?

Answer 3

1. Operating systems
2. Running programs
3. Data currently being used

Question 4

Read-only Memory (ROM)

Answer 4

1. Small area of non-volatile memory

2. Read-only

Question 5

What does ROM store?

Answer 5

Computing boot up instructions (Bootstrap)

Question 6

Volatile memory

Answer 6

Memory that loses its contents when the electricity is turned off

Question 7

Secondary storage

Answer 7

Storage outside the processor

Question 8

Explain what is meant by off-line storage.

Answer 8

• it is non-volatile
• can be easily disconnected from the computer
• it is not directly accessed by the CPU
• suitable example eg. CD, DVD, USB flash memory

Question 9

Secondary storage

Magnetic storage - Hard Disk Drive (HDD) pros

Answer 9

1. Wired directly to processor, so access to HDD is quite fast (fast write speed)
2. Cheap
3. Vast storage capability, up to 2 TB or more

Question 10

Secondary storage

Magnetic storage - Hard Disk Drive (HDD) cons

Answer 10

1. Lots of mechanical parts
2. Not very durable
3. Internal hard drive is fixed inside a computer, so it is not portable
4. Makes spinning disc sounds

Question 11

Off-line storage

Magnetic storage - Portable hard disk / removable HDD

Answer 11

Must be plugged into the computer through a port (functions like a HDD)

Question 12

Off-line storage

Magnetic storage - Magnetic tape pros

Answer 12

1. Large capacity
2. Inexpensive
3. Does not take up much storage space

Question 13

Off-line storage

Magnetic storage - Magnetic tape cons

Answer 13

Slow to transfer data, because you need to wind through the whole reel of tape to get to the data you want

Question 14

Off-line storage

Optical storage - Why can a DVD store more data than a CD?

Answer 14

1. The pits are smaller

2. Read with a narrower laser spot (red laser light) than is used for a CD

Question 15

Off-line storage

Optical storage - Why can a Blu-ray disc store more data than a CD/DVD?

Answer 15

1. The pits are even smaller than that of a DVD

2. Read with an even narrower laser spot (blue laser light) than is used for a DVD

Question 16

Off-line storage

Optical storage - DVD-RAM

Answer 16

It has concentric tracks (instead of a single spiral track) allowing reading and writing to take place simultaneously

Question 17

Secondary storage

Solid state storage/flash memory - 6 Solid state drive (SSD) pros

Answer 17

1. Data access is fast (can replace a computer’s built-in HDD, because data is very close to the CPU)
2. Run quieter (no noisy fan)
3. Highly durable and reliable because no moving parts, so more suitable for portable computer/laptop
4. Run cooler
5. Less power consumption
6. Large storage for its size - therefore used in many mobile devices

Question 18

Secondary storage

Solid state storage/flash memory - Solid state drive (SSD) cons

Answer 18

Expensive

Question 19

Off-line storage

Solid state storage/flash memory - USB flash memory/ drive

Answer 19

1. A flash memory IC (integrated circuit) in a USB plug
2. Low cost
3. Portable and has no moving parts
4. Durable
5. Holds a lot of data for its size

Question 20

5 reasons for choosing magnetic storage over solid state storage

Answer 20

1. more read/write cycles over its lifetime / greater longevity
2. read/write speed is sufficient for most applications even though it is slower than solid-state
3. cheaper PER UNIT OF DATA stored
4. trusted technology as it has been traditionally used for many years
5. no requirement for portability