Hard Disk / Drives

A hard disk is a magnetic storage device for digital data.

Most personal computers contain an internal hard disk that can store large amounts of data, often hundreds of Gigabytes.

A hard disk is made up of a number of rotating platters mounted on a spindle which housed in a metal casing. On each side of a platter there is a read/write head.

Digital data is written to the disk be means of the 'head' that is flying far less than a hairs' breadth above each platter. The head is fed with data from an electronic circuit also housed inside the metal casing.

Digital data is read off the disk by the same head and electronics.

Typical Hard disk sizes range from 40Gb to 1000Gbytes. They spin at about 7200rpm, sometimes more.

Hard drives are now also popular as an 'external hard drive'. The drive is housed in its own casing and is connected to the computer through an USB port. Some need an additional power supply whilst others are powered directly off the USB port. They are used for backup and archiving as even DVDs are often too small to store the vast amount of data we seem to collect these days in the form of music, films and family photos.

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