RAM
From PHWiki
RAM is an abbreviation for random access memory. RAM is very fast to access and write randomly.
RAM is often used as a synonym for the working memory of a computer or other device.
Types of RAM
Dynamic RAM or DRAM is the cheaper type of memory. Each cell is based on a capacitor, which acts as a cup to hold a charge. Reading a word of data drains the cups in that word; the DRAM chip then "refreshes" the data in that word by refilling the capacitors with charge. A "refresh" also happens upon write. However, capacitors are leaky, and they must be refreshed continually. In less expensive DRAMs, this refreshing process draws a significant amount of current.
Static RAM or SRAM is a more expensive type of memory that can be faster. Each cell contains a flip-flop, or four to six transistors wired in an "echo chamber" configuration. It holds data as long as at least a small trickle of current continues to flow; this low power consumption at idle makes it attractive for persistent data storage. See also SRAM.
