Posted by
Hanafi Yahya
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HARD DRIVE
A Computer Hard Drive is a form of Computer memory used to permanently store files and programs. Computer Hard Drives can also be referred to as; Hard Disk Drive. When using Microsoft windows a hard disk drive is often referred to as the c-drive. Most PC Hard Drives are stored in a internal drive bay at the front of the computer. Hard drives are connected inside the computer using a ATA, SATA or SCSI cable and a power cord.
There are several types of Hard Drives; some are IDE, SATA and SCSI:
- IDE Hard Drive: (Also known as an ATA or PATA Hard Drive.) This is one of the most common drives used in computers. You can identify an IDE Hard Drive by having a 40 pin connector and a power connector.
- SATA Hard Drive: (Also Known as Serial ATA). Very similar to an IDE Hard Drive but uses a higher speed. You can identify an SATA Hard disk by having a smaller power connector than IDE.
- SCSI Hard Drive: SCSI Hard Drives are faster than IDE and SATA, but are more commonly used in servers due to higher cost. You can identify a SCSI Hard Disk at the connectors. (SCSI uses the same power connector as IDE.
- Platters: Aluminum, glass, or ceramic dishes coated with magnetic media. These dishes are used to store data and begin to rotate when the computer is turned on.
- Head Arm: (Also known as a “Actuator Arm”) The Head Arm is similar to the arm on a record player. It allows the Hard Disk Drive to move the read / write heads to the location where the information needs to be read or written to.
- Chassis: (Also known as the “Case”) A housing that helps protect and organize all components that make up the Hard Disk Drive.
- Head Actuator: An electronic device controlled by a motor that moves the Head Arm to locations where it is needed.
When looking to buy a hard drive you should be aware of some terms and specifications and what they mean:
Terms: | Example: | Definition: |
Brand- | Western Digital | Name of Company supplying HD |
Series- | Raptor | Category name within brand of HD |
Model- | WD1500ADFD | Model Number of HD |
interface- | SATA 1.5Gb/s | Cable connection between computer and HD |
Capacity- | 150GB | Size of HD storage |
RPM- | 10000 RPM | Speed at which data is transfered |
Cache- | 16MB | Small fast memory holding recently accessed data |
Average Seek Time- | 4.6ms | Time required for read/write heads to switch tracks |
Average Latency- | 2.99ms | Lapse of time between track switching and data access |
Average Write Time- | 5.2ms | Total time required to access data needed |
Form Factor- | 3.5" | Reference to size of disk diameters |
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