Optical storage uses light to read data stored on optical discs or memory cards. Common optical storage devices include CDs, DVDs, Blu-Ray discs, HD DVDs, USB flash drives, memory cards, and smart cards. CDs hold around 800MB of read-only data, while DVDs and Blu-Ray discs can hold significantly more data up to 50GB in writable formats, using laser light of different wavelengths to read small pits in the disc's surface. Flash memory cards and drives store data electronically in non-volatile memory.

1. OPTICAL STORAGE
By Yohniki Gordon

2. WHAT IS OPTICAL STORAGE
•Optical storage is data that is stored on
optical readable medium. Light is used to aid
the device in reading the data that stored.
Optical storage devices range from CD-ROMs
which was established in 1982 to Flash drives
which were introduced in 1999. The latest
optical storage to date is the Blu Ray Disc.

3. READ-ONLY OPTICAL DISCS
• Compact Disc – CDs have
Read-Only Memory that can
hold around 800MB of data.
The data cannot be edited or
deleted once its added to
the disc so therefore it cannot
be deleted ‘accidentally’.
CDs are non-volatile.

4. •Digital Versatile Disc
(DVD) – DVDs gave
Random-Access
Memory. They can hold
up to a total of 4.7GB of
data. There are also
dual-layer DVDs that
can hold up to twice
that amount.

5. • Blu-Ray - Blu-Ray discs are a
recent replacement of
DVDs. These disc can hold
from 25 – 50GB of data. A
dual-layer can hold up
100GB. Blu-Ray disc are
consider random-access
devices. The ‘Blu’ in Blu-ray is
of a fact that the light in the
laser is blue instead of red.
Blue light has a shorter
wave-length than red light

6. •HD DVD – High-densityDVD (HD-
DVD) disc can hold around15GB of
data (a dual-layer HD-DVD can hold
twice that)HD-DVDs are random-
accessdevices. HD-DVD can be used
in the same ways asDVD-ROM but,
since they can holdmore data, they
are used to store very high-quality,
high-definition(HD)videos.

7. •USB Memory Stick –
Memory sticks ( thumb
drive), since invented
has made many other
forms of portable
storage become
obsolete such as CDs
and DVDs. The popular
question asked is “why
burn a CD or DVD when
you can easily copy the
files onto a flash drive?”
USB memory sticks are

8. • Memory card - Many of
the devices used today
require memory cards
to store data such as
cameras. Memory cards
are compact and non-
volatile. One of most
common formats of
memory card are SD
Cards. Some phones
also have extra internal
memory card to store
data so don’t have to
depend on memory

9. • Smart Card - Many credit
cards (e.g. ‘chip-and-pin’
cards), door entry cards,
satellite TV cards, etc. have
replaced the very limited
storage of the magnetic
strip (the dark strip on the
back of older cards)
with flash memory. This is
more reliable and has a
much larger storage
capacity.
Cards with flash memory

10. WHAT HAVE YOU LEARNT?
1)What would you consider the sim card in
your phone?
2)What is the max capacity of a Blu-Ray Disc?
3)What is used to read the data off a Optical
Disc?
4)What is the meaning of RAM?
5) Are flash drives volatile or non-valatine?

11. THE END