Editing Digital permanence (section)

===Solid-state memory devices===
Digital computers, in particular, make use of two forms of [[computer memory|memory]] known as [[random-access memory|RAM]] or [[read-only memory|ROM]] and although the most common form today is RAM, designed to retain data while the computer is powered on, this was not always the case. Nor is ''active'' memory the only form used; ''passive'' memory devices are now in common use in digital cameras.  

* [[Magneti-core memory|Magnetic]], or ferrite core, data retention is dependent on the magnetic properties of iron and its compounds.
* [[Programmable read-only memory|PROM]], or ''programmable read-only memory'', stores data in a fixed form during the manufacturing process, with data retention dependent on the life expectancy of the device itself.
* [[EPROM]], or ''erasable programmable read-only memory'', is similar to PROM but can be cleared by exposure to [[ultraviolet]] light.
* [[EEPROM]], or ''electrically erasable programmable read-only memory'', is the format used by [[flash memory]] devices and can be erased and rewritten electronically.