Dynamic random-access memory: Difference between revisions

Revision as of 22:46, 14 December 2002

Revision as of 13:13, 28 January 2003

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[[pl:DRAM]]

'''DRAM''' is a type of [[random access memory]] that stores each [[bit]] of data in a separate [[capacitor]]. The amount of electric charge stored in the capacitor determines whether the bit is considered 1 or 0. As leakage causes the charge on a capacitor to decay, the capacitorsinformation mustgets belost refreshedeventually, periodicallyunless bythe specialisedcharge [[refreshis logic]]refreshed periodically. This puts DRAM in the class of ''volatile'' memory devices.

[[Refresh logic]] is commonly used with DRAMs to automate the periodic refresh. This makes the circuit more complicated, but the advantagedrawback is usually outweighed by the fact that capacitors are cheap and small, so high-density, low-power memory chips can be made using this technology. The alternative to DRAM is [[Static Random Access Memory|SRAM]].

An important feature of DRAMs is called ''address multiplexing''. This technique splits the address in half and feeds each half in turn to the chip on the same set of pins. Therefore a DRAM needs only half as many address pins as an SRAM of the same capacity, allowing it to be produced in a smaller, cheaper package.