Memory - Volatilty / Permanent


When the power is removed, the memory device (storage media) is considered:

  • volatile memory if the data vanishes
  • permanent (non-volatile) memory if the data remain stored

When the data is stored on a volatile device, the data is said to be volatile


Non-volatile / Permanent memory

The data will retain the stored information even if it is not constantly supplied with electric power. It is suitable for long-term storage of information. Nowadays used for most of secondary, tertiary, and off-line storage. In 1950s and 1960s, it was also used for primary storage, in the form of magnetic core memory.


Volatile memory

Requires constant power to maintain the stored information. The fastest memory technologies of today are volatile ones (not a universal rule). Since primary storage is required to be very fast, it predominantly uses volatile memory.


  • Processor registers – fastest possible access (usually 1 CPU cycle), only hundreds of bytes in size
  • the main memory system RAM and controller cards

Documentation / Reference

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