Memory & Storage - 1.2.1

Question 1

What is RAM?

Answer 1

Random Access Memory
Main memory in a computer where data, files and programs are stored while being used
When a computer system boots up the OS is copied from the secondary storage to the RAM
When software applications, documents and files are opened they are copied from the secondary storage to the RAM

Question 2

Features of RAM (4):

Answer 2

Volatile memory - temporary, requires power to retain
Reads & writes
Easily upgradable
Faster than secondary storage but slower than cache

Question 3

What is ROM?

Answer 3

Read Only Memory
Built into the motherboard, contains all the instructions for a computer to start up (BIOS)
As soon as computer starts CPU reads instructions from ROM

Question 4

Features of ROM (3):

Answer 4

Non-volatile memory
Only read
Can’t change the information on it

Question 5

What is virtual memory?

Answer 5

Used when RAM is full so data is moved to a location secondary storage called virtual memory for more space.
When data is needed again it needs to be moved back to RAM which is quite a slow process
Risk of hard disk thrashing

Question 6

What is primary storage?

Answer 6

Memory that the CPU can easily access, e.g. registers, cache, ROM, RAM
Mostly volatile, fast at reading/writing

Question 7

What is secondary storage?

Answer 7

Where all data is stored when not in use
Non volatile, read/ write speeds are much slower
Magnetic, optical & solid state

Question 8

Why do we need secondary storage?

Answer 8

It is non-volatile and long-term so if the computer switches off nothing is lost unlike with RAM.

Question 9

How does solid state roughly work?

Answer 9

By trapping electrons between two plates. Can be written and overwritten like RAM.

Question 10

Benefits of solid state (4):

Answer 10

Non volatile - contents are retained if computer switches off
No moving parts - so produces less heat and therefore components last longer
Also is more portable without moving parts
Faster than HDD

Question 11

Drawbacks of solid state (2):

Answer 11

Expensive
Short life span

Question 12

Examples of solid state:

Answer 12

Flash drives
SSD Laptops/computers

Question 13

How do magnetic devices work (6 steps)?

Answer 13

Uses magnetic fields to magnetise tiny individual sections of a metal spinning disk.
Each tiny section represents one bit.
A magnetised section represents a binary ‘1’ and a demagnetised section represents a binary ‘0’.
As the disk is spinning, a read/write head moves across its surface.
To write data, the head magnetises or demagnetises a section of the disk that is spinning under it.
To read data, the head makes a note of whether the section is magnetised or not.

Question 14

Types of magnetic (2):

Answer 14

HDD Laptops/computers
Tape

Question 15

Benefits (2) & Drawbacks (2) of HDD laptops/desktops:

Answer 15

Cheap for amount of storage
Large storage

Shock damage
Not good with magnets - strong magnetic field could erase the data

Question 16

Benefits (1) & drawbacks (3) of tape:

Answer 16

Huge storage

Very slow
Sequential access - must read everything in the order of the file to get to wanted part
Also not good with magnets

Question 17

How do optical devices work?

Answer 17

Uses a laser to scan the surface of a spinning disc with tracks and lands which change how the light is reflected from the laser

Question 18

Benefits (2) & drawbacks (2) of CD’s:

Answer 18

Cheap to mass produce
Long life span as it’s plastic

Slow
Easily damaged

Question 19

Which has the fastest and slowest read/write speed?

Answer 19

Fastest - SSD
Slowest - optical disc

Question 20

Which has the cheapest and most expensive cost per GB?

Answer 20

Cheapest - magnetic tape
Priciest - SSD

Question 21

Which has the lowest and highest capacity?

Answer 21

Lowest - optical disc
Highest - tape