Page 28 - CA 165 ver 1.0 Class 9
P. 28

ROM
                  It stores a set of pre-defined instructions for the internal operations of a
                  computer. It is also referred as ‘non-volatile’ memory or ‘firmware’.

                  Once  the  user switches ‘ON’ the  computer,  the  computer  automatically
                  does a series of sequential tasks like POST (Power On Self Test), RAM Test,
                  etc. before the user starts his work.
                  The instructions for such predefined set of tasks are stored in the ROM. Such information on this memory
                  can only be read. There are different types of ROM like PROM, EPROM, EEPROM, Flash ROM. ROM helps
                  in starting or booting the system by executing the BIOS ( Basic Input Output System) commands.

                  BIOS pronounced as ‘Bye-ose’, is stored in ROM and it operates when the computer is switched ‘ON’. It
                  contains a set of essential softwares that test the setup of hardware devices during startup. It helps to
                  start the operating system and supports the transfer of data among the hardware devices.

                  Besides RAM and ROM, there are some other primary memories like the Cache or Buffer memory. Cache
                  Memory is a part of CPU and is used when there is swapping of information between the primary memory
                  and the ALU. Cache can be of two types:
                       Primary Cache: A primary cache is always located on the CPU. This cache is similar to register in
                  l
                       terms of size and access time.
                  l    Secondary Cache: A secondary cache is placed between the CPU and memory. This cache is slower
                       than primary cache in terms of access time but  bigger in size as compared to primary cache.

                  Secondary Memory/Auxiliary Memory

                  Secondary memory refers  to the permanent storage  of data.  During the operation  of computer, the
                  currently used data lies in the temporary memory. It may get lost, if the computer is suddenly switched
                  OFF. For such a purpose secondary memory is required, as it provides necessary backup and storage of
                  instruction or data that are permanent and can be retrieved back as and when required. It is also known
                  as backup memory. It has higher storage capacity than the primary storage/memory. There are various
                  types of secondary storage devices. Some of them are:

                  Magnetic Disks

                  Magnetic Disks are storage devices that are made up of magnetic coated material.
                                                                       Platter
                                                Spindle

                                                                             Head

                                                                                  Head Actuator Arm
                                       Actuator Axis
                                       & Pivot Screw


                                             Voice Coil                              Power Connector
                                              Actuator
                                                                                 Jumper Block
                                                                         Ide Connector On Printed
                                                                         Circuit Board (Interface)




                   26     Touchpad Computer Applications-IX
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