My External Hard Disk Not Reading?

The process of reading and writing to a hard or floppy disk is done with what?

• Answer:

  The actual read and write process is done via the read/write heads. The head is a very small coil of wire with a tidy metal core in the centre, the coil is coated in plastic and mounted on the end of a thin metal arm. The arm moves the coil across the disk between the inner and outer track to access different parts of the disk surface. Floppy disks have just one recording surface, Hard disks save several recording surfaces, usually two or four but on large drives may be up to 16. Each surface has its own read/write head, all the heads move at the same time as all the arms are driven by one actuator which moves them around. With floppy disks the heads usually just touch the disk surface. Hard drives spin much faster and the heads skim just off the surface, separation is maintained by a cushion of air created by the design of the plastic head body - it works a little like an aircraft wing.