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Random Access Memory (RAM)

                  RAM is a temporary memory. The information stored in this
                  memory is lost when the computer is turned off. That’s why it is also
                  called volatile memory. It temporarily stores data and instructions

                  given by the user and also the results produced by the computer.

                  Types of RAM:                                                                        RAM
                  1.   Dynamic RAM (DRAM): It requires continuous power to refresh the data stored.

                  2.   Static RAM (SRAM): It also requires constant power to hold on to data, but it doesn’t
                     need to be continually refreshed the way DRAM does.
                      However, SRAM is significantly faster and uses less power than DRAM.

                                            Read Only Memory (ROM)

                                            Information stored in ROM is permanent in nature, i.e., it holds
                                            the data even if the system is switched off. It holds the starting

                                            instructions that are required to start a computer. It is also called
                    ROM
                                            non-volatile memory.
                  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 categorised
                  into three types: Magnetic disk, Optical disc and Flash drive.

                                                 Secondary Storage Devices




                         Magnetic Disk                    Optical Disc                    Flash Drive




                            Hard Disk           CD     DVD       Blu-Ray Disc      Pen Drive     Memory Card

                  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



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