1.3.4 Optical Storage & Properties

Question 1

How Optical Storage Works - Storing a bit

Answer 1

Each 1 or 0 (value of a bit) is represented as a microscopic hole (called a pit) or a flat surface (called a land) on the surface of the disk.

Question 2

How Optical Storage Works - Accessing data

Answer 2

A laser is shone on the disk surface.
If the laser hits a land, it will be reflected into a sensor.
If the laser hits a pit, then it will be reflected elsewhere.
These can be used to represent our 1 and 0.

Question 3

Properties of Optical Media - Great Reliability

Answer 3

Optical media is:
Waterproof.
Shockproof.
This makes it ideal for portability (transporting).

Question 4

Properties of Optical Media - Low Cost

Answer 4

Optical media is very cheap per-gigabyte (GB).

Question 5

Properties of Optical Media - Good Capacity

Answer 5

Each disk has a low capacity.
Disks are small and fairly cheap. So it can be easy to gain a high capacity of storage by buying multiple disks.

Question 6

Properties of Optical Media - Low Speed

Answer 6

Because the parts in the optical media drive have to move to find the right bit of data on the disk, access times can be quite slow.
Writing to a disk can also be a very slow process.