backing storage

In computing, memory outside the central processing unit (CPU) used to store programs and data that are not in current use. Backing storage must be nonvolatile – that is, its contents must not be lost when the power supply to the computer system is disconnected.

Backing storage uses either direct or serial access methods. Direct access means that particular files can be found without the need to read through all of the data, as with serial access. Data may be stored on (or written to) CD-ROM, floppy disk (both direct access), magnetic tape, or memory stick (serial access).