Page 23 - Viva ICSE Computer Studies 7 : E-book

Nowadays, external hard disks are also available, which are small in size and can be carried
anywhere easily.

Compact Disk

Compact disk (CD) is an optical storage device. A typical CD is 13 cm in
diameter. One CD can store 600–750 MB data on it. It can hold text, images,
sound, video clips, animated movies or their combinations. It is used for data
backup and to store software. Nowadays, we get two kinds of CDs.
• CD-R stands for compact disk-recordable. In this type of CD, data once written cannot be
changed or deleted, it can only be read.
• CD-RW stands for compact disk-rewritable. Data written on this CD can be erased.
New data can be written or recorded many times.

Digital Versatile Disk
Think and Discuss
Digital versatile disk (DVD) is also called
Which storage device(s) will
digital video disk. It is very similar to a you use to store three or more
CD but can store much more data. It is movies? Why?
an optical disk storage device used for
recording movies with high video and sound quality. Data can be recorded on a DVD on one or
both sides. Its capacity ranges from 4.7 to 8.5 GB.

Pen Drive

A pen drive is popularly known as fl ash drive. It is a small pen-like
storage device that can be attached outside a computer at a place
called USB port. Pen drive can store a large amount of data. Depending
on its capacity, it can store 1 GB, 2 GB or more data. It is used for
copying and moving data from one computer to another.

Blu-ray Disk

A blu-ray disk is similar to a CD or a DVD in appearance but it can hold up to
128 GB of data. Blu-ray disc is so called because a blue laser is used to read
the disk which allows information to be stored at a greater density than is
possible with red laser used for DVDs. This disk is mainly used for storing
high quality sound, games and movie.
Learn More

USB stands for Universal Serial Bus.
Computer Etiquette

All devices connected to a computer should be handled properly.

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