<storage> (NVS, persistent storage, memory) A term describing
a storage device whose contents are preserved when its power
is off. Storage using magnetic media (e.g. magnetic disks,
magnetic tape or bubble memory) is normally non-volatile
by nature whereas semiconductor memories (static RAM and
especially dynamic RAM) are normally volatile but can be
made into non-volatile storage by having a (rechargable)
battery permanently connected.
Dynamic RAM is particularly volatile since it looses its
data, even if the power is still on, unless it is refreshed.
An acoustic delay line is a (very old) example of a volatile
storage device.
Other examples of non-volatile storage are EEPROM, CD-ROM,
paper tape and punched cards.
