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Secondary Memory
This memory is permanent in nature and is not directly accessed by the CPU. It allows
users to store data that may be easily retrieved. It is cheaper as compared to primary
memory. Secondary memory devices are also called secondary storage devices. They
are divided in three categories: Magnetic Disks, Optical Discs and Flash Drives.
Magnetic Disk
A device such as a hard disk is covered with a magnetic coating. You can record
and erase data on a magnetic disk any number of times.
✶ Hard Disk: It consists of one or more magnetic disks called
platters. It is permanently fixed in the CPU box. It comes
in a variety of sizes with storage capacities as high as 5 TB
(TeraByte) or even more.
✶ External hard disks: Are also available. They are the hard Hard disk
disks that can be connected to any computer with the help of a USB port.
Optical Disc
An optical disc is an electronic data storage medium that can be written onto and
read using a low-powered laser beam.
✶ Compact Disc (CD): The CD drive reads
information stored on a compact disc (CD). CD
is an external storage device. It can hold up to
700 MB of data. A CD is read or written on by a
CD drive that is fitted in the CPU box. The types
of CDs are CD-ROM, CD-RW and CD-R.
CD DVD
✶ Digital Versatile or Video Disc (DVD): DVDs are now widely-used to store
data. A DVD is similar to a CD.
Flash Drive
Flash Drive is a small portable data storage device integrated with a USB (Universal
Serial Bus) connector.
✶ Pen Drive: Pen drive is a storage device that can store a large amount of data.
It is connected to a computer using a USB port.
It can be carried in your pocket easily. Pen drive
has a storage capacity of up to 1 TB.
✶ Memory Card: It is commonly known as
multimedia memory card. It is very small in size
usually 1–1.5 inches. These are used in mobile Pen drive Memory card
phones and digital cameras. You need to have card reader to read stored data on
memory card.
14 Modular (Ver. 1.1)-IV

