Storage media

Question 1

Three types of storage

Answer 1

• primary storage
• secondary storage
• off-line storage

Question 2

Primary storage

Answer 2

Computer’s internal storage. Storage where the data are held ready for processing. The capacity is quite small. Separated into RAM and ROM.

Question 3

RAM

Answer 3

Random access memory. Is volatile chip. Used in normal operations after starting up and loading the operating system.

Question 4

ROM

Answer 4

Read only memory. Is non-volatile chip. Used to start up and loading the operating system.

Question 5

EPROM

Answer 5

Erasable programmable read-only memory

Can be erased by UV light and than rewritten with a process that needs higher than usual voltage applied.

Question 6

EEPROM

Answer 6

Electrically erasable programmable read-only memory
Allows entire content to be electrically erased and then rewritten electrically, so it doesn’t need to be removed form computer.

Question 7

Volatile

Answer 7

Requires constant source of power. If power is lost, data on a chip will be lost also.

Question 8

Non-volatile

Answer 8

Doesn’t require a constant source of power. When power is lost, a chip will keep all information stored.

Question 9

Secondary storage

Answer 9

Software and data also need to be kept for future use. They can be held in secondary storage, until they are erased or rewritten.

Question 10

The CPU in a computer can only access data when…

Answer 10

it is being held in the RAM. So programs, data and operating system must first be transferred into RAM from secondary storage.

Question 11

Key features of primary storage

Answer 11

• directly accessible by the processor
• temporarily stores data
• fixed within a computer
• can be read or rewritten instantly

Question 12

Key features secondary storage

Answer 12

• data first has to be transferred into RAM
• permanently stores data till erased
• slower to read data and write them
• large storage
• some devices are removable

Question 13

Three types of secondary storage

Answer 13

• magnetic
• optical
• solid-state storage

Question 14

Magnetic storage

Answer 14

Read, write and erase data by using electromagnets and magnetic fields to control tiny magnetic dots of data. Either tape based or disk based.

Question 15

Disk-based magnetic storage

Answer 15

Consists of several disks known as platters. It can be made from metal or glass. They have magnetised coating on which the data dots are stored. The platters are spinning an the data are read or written, by heads.

Question 16

Optical storage

Answer 16

Read data by shining a laser beam onto the surface of plastic disks. Coated with aluminium to make them reflective. Data is written by using a laser to make pits.

Question 17

Pit

Answer 17

An indention on the surface of an optical disk, used to represent data.

Question 18

Land

Answer 18

The raised surface on the surface between pits on an optical disk.

Question 19

Burning

Answer 19

The process of recording data onto an optical disk. Laser burns the pits into the disk surface.

Question 20

Blu-ray disk

Answer 20

Use a blue-violet laser that operates at a shorter wavelength. This gives more precision when writing or reading the disk. The data can be packed even closer together than DVD.

Question 21

Compact disk (CD)

Answer 21

An early, but still used, optical medium.

Question 22

Digital versatile disk (DVD)

Answer 22

A later, higher capacity optical medium. Use higher frequency laser, this allows the pits to be packed tightly, so more data can be stored.

Question 23

Blue-ray and DVD can have more…

Answer 23

than one reflective layer on which data can be stored.

Question 24

Types of optical media:

Answer 24

• ROM
• R
• RW

Question 25

ROM optical media

Answer 25

Read only. The data is already burned onto the disk by a manufacture or other user. Can be only read.

Question 26

-R optical media

Answer 26

The disk is initially empty of data. The data can be written only once. Once written a data can be only read.

Question 27

-RW optical media

Answer 27

The disk is initially empty of data. It can be written to and read from repeatedly. This disk has a reflective surface that have pits burned in. By using a higher power laser, the pits can be erased, which returns the disk to a blank state.

Question 28

Solid-state storage (SSD)

Answer 28

Has no moving parts. Instead, high speed flash memory is used to store data.

Question 29

Examples of SSD

Answer 29

USB RAM sticks

Solid-state hard drives

Question 30

SD card

Answer 30

Solid-state cars used to store and transfer data.

Question 31

Tre performance of solid-state devices

Answer 31

They are quite small in size, but their data transfer rate is much quicker than other types of storage. Can be written to and read from many times.

Question 32

Uses of SSD

Answer 32

• physically small size, makes them useful as portable storage device
• can be rewritten many times

Question 33

Off-line storage

Answer 33

Any non-volatile storage device that is disconnected or removed from computer. E.g. USB, DVD, CD….

Question 34

Factors when choosing an appropriate secondary device:

Answer 34

• capacity
• transfer speed
• portability-how easily the medium can be transported
• durability-how resistant the medium is to data loss and damage
• cost