Tuesday, October 14, 2008

Hard disk drive ABCs

The hard disk drive is the primary storage location where data is permanently stored. Below is an illustration of what the inside of the hard disk drive may look like. The four main components of a hard disk drive are the platters, head arm, chassis, and the head actuator.

The majority of computer hard disk drives are permanently stored in an internal drive bay at the front of the computer and are connected with one ATA / SCSI cable and power cable. Unlike other drives, the hard disk drive is the only drive that is not physically accessed by the user like the floppy disk drive or the CD-ROM drive.

Size information

The capacity of a computer hard disk drives and the files it contains can be confusing. Below is a listing of the standards in different size values. It is important to realize that not all manufacturers and developers use these values. For example, a manufacturer may consider a gigabyte as the value of a gibibyte.

Bit Value of 0 or 1
Nibble 4 Bits
Byte 8 Bits
Kilobit 1,000 bits
Kilobyte 1,000 bytes
Kibibit 1,024 bits
Kibibyte 1,024 bytes
Mebibit 1,048,576 bits
Mebibyte 1,048,576 bytes
Megabit 1,000,000 bits
Megabyte 1,000,000 bytes
Gibibit 1,073,741,824 bits
Gibibyte 1,073,741,824 bytes
Gigabyte 1,000,000,000 bytes
Gigabit 1,000,000,000 bits
Tebibit 1,099,511,627,776 bits
Tebibyte 1,099,511,627,776 bytes
Terabyte 1,000,000,000,000 bytes
Terabit 1,000,000,000,000 bits
Pebibit 1,125,899,906,842,624 bits
Pebibyte 1,125,899,906,842,624 bytes
Petabit 1,000,000,000,000,000 bits
Petabyte 1,000,000,000,000,000 bytes
Exabyte 1018 bytes
Exabit 1018 bits
Exbibit 260 bits
Exbibyte 260 bytes
Zettabyte 1021 bytes
Yottabyte 1024 bytes

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