Overview of the Hard Disk Drive

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The hard disk uses an interface to communicate to communicate with the PC. There are two basic interfaces in use, ATA (formerly called IDE) and SCSI (pronounced "scuzzy"). By far the most common interface is ATA. SCSI is a faster, more expensive and slightly more difficult to set up.

Other common terms that also apply to hard disks are EIDE, ATA, SATA, PATA, Ultra and UDMA. These all apply to ATA drives and reflect improved standards in speed and performance. As of this writing, Ultra DMA/133 is the latest standard and simply reflects the overall performance of the interface.

There are several measurements by which hard disks can be compared. First is their capacity, currently measured in gigabytes (GB). Next is the interface used, such as UDMA/66 or UDMA/100. Third is their RPMs, two common speeds are 5400 RPMs and 7200 RPMs, faster is better. Others include their seek time (the time it takes to find a specific piece of data), access time ( the time it takes to begin retrieving the data) and transfer rate (how much data can be transferred per second.

Hard disk failures can be sudden and unexpected or they may give you some warning. Whenever you suspect that you may have a problem with your hard disk, IMMEDIATELY back up any critical files you have. You may back up data to floppies, a second hard disk, a CD burner, other computers on your network or even email files to yourself as attachments for later retrieval.

Hard disks are generally not repairable. When a drive fails you must replace it. Recovering data from a dead hard disk is possible. After you have installed a new hard disk, you may be able to access the "dead" drive as a second drive from which you can copy files. Otherwise, a file recovery specialist must be used. The cost for a specialist is high, often starting at $400 and possibly running into the thousands.

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