Hard Disk

   The most commonly used device to storedata in the computer is the hard disk. This is fixed as a closed unit inside the computer.

                 There are different capacities in hard disk according to your requirment.

         In hard disk, data are stored in platters and there can be several platters ina hard disk. All these platters are fixed on one  spildle. All these are rotated together in the same speed whilw a resd / write head fixed in each platters separateley to read  and write.

                   The speed of the hard disk is  measured using its access time. This access time taken a vert small value andits measured in milliseconds (thousand unit per second)