When you save data or install programs on your computer, the information is typically written to your hard disk. The hard disk is a spindle of magnetic disks, called platters, that record and store information. Because the data is stored magnetically, information recorded to the hard disk remains intact after you turn your computer off. This is an important distinction between the hard disk and RAM, or memory, which is reset when the computer’s power is turned off.
Basic of hard disk
Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called “fixed disks” or “Winchesters“. They later became known as “hard disks” to distinguish them from “floppy disks.”
How hard disks work
Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies. Hard disks store digital information in a relatively permanent form. Every desktop computers and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them. You can even find VCR-type devices and ccorders that use hard disks instead of tape. These billions of hard disks do one thing well — they store changing digital information in a relatively permanent form. They give computers the ability to remember things when the power goes out.
At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magneticrecording techniques described in How Tape Recorders Work. Hard disks and cassette tapes also share the major benefits of magnetic storage — the magnetic medium can be easily erased and rewritten, and it will “remember” the magnetic flux patterns stored onto the medium for many years.
Benefits of Hard disk
- In a hard disk, the magnetic recording material is layered onto a high-precision aluminum or glass disk. The hard-disk platter is then polished to mirror-type smoothness.
- you can move to any point on the surface of the disk almost instantly.
- The read/write head “flies” over the disk, never actually touching it.
- A hard-disk platter can spin underneath its head at speeds up to 3,000 inches per second.
- The information on a hard disk is stored in extremely small magnetic domains compared to a cassette tape’s. But it size of these domains is made possible by the precision of the platter and the speed of the medium.
A present hard disk is able to store an information in a small space. A hard disk can also access any of its information in a fraction of a second.