Hard Drives

Primary storage for any computer system is actually made of one or more aluminum or glass platters, which is then coated with a ferromagnetic material.  Hard drives are either fixed disks—where the coated platters are permanently on the drive.  Almost all PC’s have internal hard drives installed in them.  Hard drives are non-volatile storage device which stores data on a magnetic platters.  Standard desktop hard drives start at 40GB, 80GB, 160GB to even 500GB rotating at 7200 revolutions per minute (rpm).

Mobile and laptop hard disk drive are physically smaller and slower than desktop hard drives, around 5400 rpm.  Hard drives are accessed in a number of bus types SCSI, EIDE,  Serial Advanced Technology Attachment(SATA), Parallel Advanced Technology Attachment (PATA), IEEE 1394 and USB.

ATA hard drives has its own data controller thereby minimizing data rate problems.  The only disadvantage with ATA drives was the master and slave configuration.  SATA drives entirely eliminate the master/slave setups totally by putting each disk its own channel.  FireWire/IEEE 1394 and USB 1.0/USB 2.0 hard disk drives are external units having ATA or SCSI disk with easy expansion ports usually found at the rear for effective expansion and transportability.  Most of these type of  hard drives have the ability to easily daisy-chain each other.


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