1)How does a hard disk work ?


•  A Hard Disk : one or more platters and their associated read-write heads.


•  Hard Disk Platter : a flat, rigid disk made of aluminum or glass and coated with magnetic iron oxide particles. Both sides of it are used for data storage. Besides, Each platter has the same number of tracks, and a track location that cuts across all platters is called cylinder.


•  Read-write Head : movies in and out from the center of the disk o locate data. All read-write heads are attached to a single access arm , so they cannot move independently.


2 ) Controller


•  A circuit board of a hard disk mechanism which positions the disk and read-write heads to locate data.


•  Popular drive controllers :
- Ultra ATA ( AT attachment )
- EIDE ( enhanced integrated drive electronics )
- SCSI ( small computer system interface )


3 ) Storage technology


•  It used on many PCs transfers data from a disk, through the controller, to the processor, and finally to RAM before it is actually processed.

•  Types of storage technology :
- DMA ( direct memory access )
- UDMA ( ultra DMA )