Editing Computer memory (section)

=== Volatile memory ===
[[File:Kinds-of-RAM.JPG|thumb|Various memory modules containing different types of DRAM (from top to bottom): DDR SDRAM, SDRAM, EDO DRAM, and FPM DRAM]]
{{Main|Volatile memory}}

Volatile memory is computer memory that requires power to maintain the stored information. Most modern [[semiconductor]] volatile memory is either [[static RAM]] (SRAM) or [[dynamic RAM]] (DRAM).{{efn|Other volatile memory technologies that have attempted to compete or replace SRAM and DRAM include [[Z-RAM]] and [[A-RAM]].}} DRAM dominates for desktop system memory. SRAM is used for [[CPU cache]]. SRAM is also found in small [[embedded system]]s requiring little memory.

SRAM retains its contents as long as the power is connected and may use a simpler interface, but [[Static random-access memory#Design|commonly uses six transistors per bit]]. Dynamic RAM is more complicated for interfacing and control, needing regular refresh cycles to prevent losing its contents, but uses only one transistor and one capacitor per bit, allowing it to reach much higher densities and much cheaper per-bit costs.<ref name=":1" /><ref name="HC" /><ref name=":2" />