Friday, February 13, 2009

Dynamic RAM

Dynamic RAM or DRAM uses memory cell for its working.It uses MOS transistor and capacitor for storing the bits.In this way each bit requires only one transistor resulting in more compact memory than SRAM.Sometimes it is possible that charge stored in the capacitor starts leaking due to which loss of data takes place.To prevent such type of loss of data,each cell must be regularly charged or refreshed.In general,a typical DRAM cell's minimum refresh rate is once every 16.25 microseconds.For this the DRAM is designed in such a way that whenever any data read takes place it refreshes the word's cell.In particular.accessing a DRAM word results in the word's data being stored in a buffer and then being written back to the word's cell.If we talk about accessing speed of DRAM then it is slower than SRAM.

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