Memory refresh

Memory refresh is the process of periodically reading information from an area of computer memory, and immediately rewriting the read information to the same area without modification, for the purpose of preserving the information. Memory refresh is required in semiconductor dynamic random access memory, the most widely used type of computer memory, and in fact is the defining characteristic of this class of memory. In a DRAM chip, each bit of memory data is stored as the presence or absence of an electric charge on a small capacitor on the chip. As time passes, the charges in the memory cells leak away, so without refresh the stored data would eventually be lost.

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