Page 16 - ModularV1.1 _c4_flipbook
P. 16

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
   11   12   13   14   15   16   17   18   19   20   21