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Secondary Memory

                 Secondary memory is permanent in nature
                 and is not directly accessed by the CPU. It              The human brain can hold about
                 allows users to store data that may be easily        2.5 petabytes of information, equivalent

                 retrieved.  It is cheaper  as compared  to                 to a TV show being played for
                 primary memory.                                         approximately 342 years non stop.

                 Secondary memory devices are also called
                 secondary  storage devices. They  are
                 categorised into three types: Magnetic disk, Optical disc and Flash drive.


                                                   Secondary Memory




                   Magnetic Disk                        Optical Disc                        Flash Drive





                     Hard Disk       CD        DVD       Blu-ray Disc       Pen Drive       Memory Card         SSD



                 Magnetic Disk

                 A device, covered with a magnetic coating is called a magnetic disk. You can record and
                 erase data on a magnetic disk any number of times.

                 Hard Disk

                 The hard disk  consists  of one  or more  magnetic  disks.  Each
                 disk in the pack has top and bottom surfaces on which data
                 is recorded using magnetic head. It is permanently fixed in the
                 system unit. The most important function of the hard disk is to
                 store program files and data files.                                                Hard disk

                 Hard disks are available in a variety of sizes with storage capacities as high as 5 TB (Terabyte)
                 or even more. The CPU can access data stored on a hard disk much faster than other storage
                 devices.

                                           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. They
                                           offer  the convenience  of expanding  storage  capacity  without  the
                                           need for internal installation and are commonly used for backing up

                    External hard disk     data, transferring files, or increasing storage space on laptops and
                                           desktops.





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