Section 1 - Chapter 6: Storage Devices

Question 1

What is the need for secondary storage?

Answer 1

Can retain its contents when the computer power is turned off.

Question 2

Hard disk

Answer 2

A hard disk uses rigid rotating platters coated with a magnetic material. Ferrous particles on the disk are polarised to become either a north or south state. This represents 0 and 1. The disk is divided into tracks in concentric circles, and each track is subdivided into sectors. The disk spins very quickly at speeds up to 10,000 RPM. A head drive moves across the disk to access different tracks and sectors. Data is read from or written to the disk as it passes under the drive head.

Question 3

Advantages of hard disk

Answer 3

• High storage capacity
• Non volatile
• Cost effective
• Easily available

Question 4

Disadvantages of hard disk

Answer 4

• Less portable
• Low speed
• Gets damaged easily
• Noisy

Question 5

Optical disks

Answer 5

Comes in 3 different formats: read only, recordable and rewritable. An optical disk work by using a high powered laser to “burn” sections of its surface, making them less reflective. A laser at a lower power is used to read the disk by shining light onto the surface and a sensor is used to measure the amount of light that is reflected back.

Question 6

Advantages of optical disk

Answer 6

• Cheap
• Portable
• Easy to send through the post for distribution purposes.

Question 7

Disadvantage

Answer 7

• Can corrupt, damaged easily by excessive sunlight and scratches

Question 8

Solid State Drives

Answer 8

An SSD uses semiconductor chips instead of magnetic media to read and write data conversely.

Question 9

Advantage of SSD

Answer 9

• light and portable
• no moving parts; this makes them much more resistant to damage from movement
• high data transfer rates
• Consumes far less power
• Silent

Question 10

Disadvantage of SSD

Answer 10

• Cost
• Limited lifespan
• Voltage increases
• Capacity low

Question 11

RAM

Answer 11

Used to store programs and data that are currently being used. It is volatile, meaning all content is lost when the computer is switched off.

Question 12

ROM - Read Only Memory

Answer 12

Used to hold information that needs to be permanently in memory. It is non - volatile.

Question 13

Virtual Storage

Answer 13

Computer RAM may not be large enough to store program, so the hard disk is used as an extension of memory - called virtual memory.