Computer storage
Optical storage
Optical storage includes
CD
CD-ROM
CD-R
CD-RW
DVD
DVD-ROM
DVD-R
DVD-RW
Compact disc (CD)
The main formats of CD are the following:
Compact disc read-only memory (CD-ROM)
Data is written only once to a compact disc but it can be replayed any number of
times.
Recordable CDs
A laser beam in a CD drive stores or burns data onto the surface of a CD and is also
used to read data from the disc.
Digital versatile disc (DVD)
A DVD is similar to a CD but can store a larger amount of data. The main formats of
DVD are the following:
Read-only DVD (DVD-ROM)
Data is written only once to a compact disc but it can be replayed any number of
times.
DVD-Recordable (DVD-R)
Data can be written to the disc once only. However, data can be read any number of
times.
High capacity optical storage media
Blu-ray disc (BD)
It is similar to CD and DVD media but its storage capacity is higher, for example, a
single layer Blu-ray disc can store 25GB and a double layer Blu-ray disc can store up
to 50GB of data.
Magnetic storage
Magnetic storage media includes the following:
Hard disk drive (HDD)
Internal hard disk drive
External hard disk drive
Network attached storage (NAS)
Magnetic tape
Hard disk drive (HDD)
A HDD is the main storage device in a computer and can be used for storing and
retrieving digital data. There are two categories of hard disk drive, one that is located
inside a computer and one that is located in a separate unit and can be connected to
a computer. Let’s investigate each type.
Internal hard disk drive
This type of HDD is located inside a computer. An additional hard disk drive can be
installed to most computers. It is also possible to remove an internal HDD and
replace it with a new one.
External hard disk drive
This is a portable type of HDD that works in the same way as an internal HDD but is
located in its own external unit which can be plugged into a computer.
Solid-state storage
Solid-state storage media includes the following:
Solid-state disk (SSD)
USB memory sticks
Memory cards/SD cards
Solid-state disk (SSD)
Data is stored directly onto microchips and there are no moving parts involved in
writing or reading data, unlike optical and magnetic storage – this explains the name
solid-state. It also ensures that the technology is more durable than the other two
types of storage. It is a form of flash memory and is non-volatile. It has become the
main internal storage for tablet computers.
Some users install a SSD into a computer as an addition to a magnetic HDD.
USB memory sticks
They are also known as USB flash drives, thumb drives and jump drives. They are
small and lightweight and have become widely used for backing-up digital data.
A memory stick can store (approximately) between:
51,200 documents (2GB) and 6,553,600 documents (256GB)
800 photos (2GB) and 101,920 photos (256GB)
281 videos (2GB) and 36,032 videos ( 256GB)
582 pieces of music (2Gb) and 74,496 pieces of music (256GB)
Memory cards/SD cards
This medium is also known as a flash memory card. There are also micro SD cards
available.
Memory cards can be used to store data on many portable devices such as, digital
cameras, audio players, mobile phones and video game devices.
