hard disk

A rigid magnetic disk fixed permanently within a drive unit and used for storing computer data. Hard disks generally offer more storage and quicker access to data than floppy disks do.

Unit that stores information (e.g., data files and programs) within the computer; also called fixed disk. Advantages of hard disks relative to diskettes are greater storage ability (e.g., 20-megabyte hard disk), speed, durability, and reliability. Hard disks are necessary when several application programs have to be readily available and applications are needed for substantial volumes of information. They are needed to take advantage of 16-bit, 32-bit, and 64-bit microprocessors requiring multiple functions and windowing abilities for high-access speed situations. Compared with floppy disks, however, hard disks cost more, are not as flexible, and are not interchangeable. Many hard disks are not removable from the CPU.

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