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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.
                                                                                                 Hard disk
            ✶  External Hard Disks are also available. They are the hard
               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 to and
            read using a low powered laser beam.



                                                   ✶   Compact Disc (CD): The CD drive fitted in the
                                                       CPU box, reads information stored on a compact
                                                       disc (CD). CD is an external storage device. It
                                                       can hold upto 700 MB of data.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. It’s storage capacity is 4.7 GB.

            Flash Drive

            The Flash Drive is a small portable data storage device.

            ✶  Pen Drive: Pen drive is a storage device which can store a large amount of data.
               It is connected to a computer using a USB (Universal Serial Bus) port. It can
               be carried in your pocket easily. Pen drive has
               storage capacity of upto 1 TB.

            ✶  Memory Card:  It  is  commonly  known  as
               multimedia memory card. It is very small in size.
               It is used in mobile phones and digital cameras.
               You need to have a card reader to read stored                   Pen drive         Memory card
               data on memory card. It has a storage capacity up to 2 TB.


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