Hard Disk Drive

A Hard Disk Drive (HDD), commonly referred to as a hard drive, hard disk, or fixed disk drive, is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk. Early HDDs had removable media; however, an HDD today is typically a sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media.

Originally, the term "hard" was temporary slang, substituting "hard" for "rigid", before these drives had an established and universally-agreed-upon name. A HDD is a rigid-disk drive although it is rarely referred to as such. By way of comparison, a floppy drive (more formally, a diskette drive) has a disc that is flexible. Some time ago, IBM's internal company term for a HDD was "file".

HDDs (introduced in 1956 as data storage for an IBM accounting computer) were originally developed for use with general purpose computers; see History of hard disk drives.

In the 21st century, applications for HDDs have expanded to include digital video recorders, digital audio players, personal digital assistants, digital cameras and video game consoles. In 2005 the first mobile phones to include HDDs were introduced by Samsung and Nokia. The need for large-scale, reliable storage, independent of a particular device, led to the introduction of configurations such as RAID arrays, network attached storage (NAS) systems and storage area network (SAN) systems that provide efficient and reliable access to large volumes of data. Note that although not immediately recognizable as a computer, all the aforementioned applications are actually embedded computing devices of some sort.


Types of Hard Disk

• IDE or Integrated Drive Electronics - The IDE hard disk is until know the most used hard disk in computers but in the future the SATA hard disks will be used more and more. A IDE hard disk is later renamed to ATA, and then later to PATA (Parallel Advanced Technology Attachment, to distinguish it from the new Serial ATA). This means Parallel ATA and can transmit data on a normal speed and is a bit slower then the SATA hard disks. You can recognize a IDE hard disk at the connector. It has a 40 pins connector and it has quite a big power connector.

• SATA or Serial Advanced Technology Attachment - A SATA hard disk works the same as an IDE hard drive but this type has a higher speed than the IDE hard disk. Also the connectors are a bit different then the IDE hard disk. You can recognize a SATA hard disk at the connector and it has a smaller power connector then the IDE hard disk. This hard disk is more and more used and probably it will replace the IDE hard disks.

• SCSI or Small Computer System Interface - SCSI hard disks are much faster then the IDE or SATA hard disks. SCSI hard disks are mostly used for professional systems which need fast data access. These types of hard disks are often not used in home situations because they are more expensive then a IDE or SATA hard disk and in a home situation you don’t need that high speed. Mostly these hard disks are used in servers. You can recognize a SCSI hard disk at the connector and it has the same power connector then the IDE hard disk.

• USB or Universal Serial Bus - This type of data storage medium is not installed in the computer but it can be attached to it using the USB interface. This is an external hard disk, also called a portable data storage device. This type of hard disk can be useful if you have a laptop with a small hard disk inside, you can use a USB hard disk to store your data on. These hard disks are a bit slower then the IDE or SATA hard disks. The speed also depends on the type of USB interface you attach it to. There are USB 1.1 interfaces and USB 2.0. Be sure you attach it to a USB 2.0 interface to let the hard disk work faster.

• FireWire - A FireWire hard disk works the same as a USB hard disk and is also an External hard disk. The only difference is that a USB hard disk is attached to the computer using the USB interface and a FireWire hard disk uses the FireWire interface. A FireWire hard disk is also a bit faster than a USB hard disk. But your computer has to have a FireWire interface and not every computer has such interface where a USB interface is almost on every computer.

Sources:
Wikipedia
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