Hard Disks

Types of Magnetic Disks

Storage: Magnetic Disks

Of the various types of Auxiliary Storage, the types used most often involve some type of magnetic disk. These come in various sizes and materials, as we shall see. This method uses magnetism to store the data on a magnetic surface.

Advantages:

high storage capacity reliable gives direct access to data

A drive spins the disk very quickly underneath a read/write head, which does what its name says. It reads data from a disk and writes data to a disk. (A name that actually makes sense!)

Credit: Western Digital

A hard disk consists of 1 or more metal platters which are sealed inside a case. The metal is one which is magnetic. The hard disk is usually installed inside the computer's case, though there are removable and cartridge types, also.
Technically the hard drive is what controls the motion of the hard disks which contain the data. But most people use "hard disk" and "hard drive" interchangeably. They don't make that mistake for floppy disks and floppy drives, described below. It is clearer with floppies that the drive and the disk are separate things.

Diskette / Floppy Disk (extinct?)

Both sizes are seem to be extinct in work places. The only remaining flocks of such disks are hiding among the dust balls in back storage closets, waiting for someone to decide what to do with them.

Sizes:

5¼" (really ancient stuff)

3½" (just horribly old)

Both sizes are made of mylar with an oxide coating. The oxide provides the magnetic quality for the disk. The "floppy" part is what is inside the diskette covers - a very floppy piece of plastic (i.e. the mylar).

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