Magnetic and Optical Storage Devices

Magnetic and Optical Storage Devices

How they works

What is Storage means in Computer?

• In digital computing, data is represented by Bits

• Storage means storing the on/off state

• https://www.tinkercad.com/things/8BtgLiyfAbH-4-bit-storage

In computer we can represent everything in bits

Numbers, Characters, Pictures, Sound, Video and more...

Storage media physically stores data bit by bit

i.e. Storing the state of physically

Magnetic Storage

• Magnets have two polarity, North and South

• Each bit on magnetic medium is a very small magnetized region, either in S or N, representing 0 or 1

• Read: using sensor to detect the polarity of that "dot"

• Write: use electromagnet to magnetize the region

Hard Disk Drive

Data is stored on the disk(s) of HDD

The read/write head will move in and out of the circle while the disk spin to reach the data.

Open Ended

By looking at the construction of HDD, do you think HDD allows fast random access of data compare to magnetic tape? Explain why.

This is also magnetic storage

Optical Storage

Optical Storage Media

• Data is stored as pits and land

• Read: Laser shine on the region and a sensor detects if it is reflected (land) or not (pit)

• Write: Laser burns on the surface to form the pits (that's why CD-ROM writing program is called CD Burner)

• Since the pits is formed by burning, optical disc are usually Read Only or Write Once

How much data?

The size of each dot governs how much data you can store

Blu-Ray is smallest among the three and can store at least 25GB of Data, compare to DVD and CD, which is about 4.7GB and 600MB respectively

Solid State

• No mechanical moving parts

• Data stored on the ICs

• Most portable compare to others

Multiple Select

Which of the followings are Solid State Storage?

• Memory in iPhone

• Memory Card in Digital Camera

• USB Flash Drive

• Nintendo Switch Storage

Open Ended

Evaluate the Access Speed of Solid State Drive, compare to magnetic and optical, by discussing the difference in their design.

Exit questions

Multiple Select

Check all the correct answers:

• Solid State is fast in access since there is no mechanical moving parts

• Laser is used to burn pits on magnetic storage

• Laser is reflected on optical media and read by sensor

• Both Magnetic and Optical devices requires a moving head to read and write data

• Data is stored as bits in storage media