Random access memory
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Random access memory (or simply RAM) is the memory or information storage in a computer that is used to store running programs and data for the programs. Data (information) in the RAM can be read and written quickly in any order. Normally, the random access memory is in the form of computer chips. Usually, the contents of RAM are accessible faster than other types of information storage but are lost every time the computer is turned off.
Different types of RAM [change]
There are several types of RAM used in modern computers. Before 2002, most computers used single data rate (SDR) RAM. Most computers made since use either double data rate (DDR), DDR2, or DDR3 RAM. DDR2 allows stored data to be moved and used more quickly than DDR, so that the computer's processor can keep working quickly without having to wait for data as long or as often, and DDR3 technology works even faster.
Different kinds of RAM usually will not work together in the same computer. Most computers can only use one kind of RAM. Some can use a small number of different kinds. Different kinds of RAM often have differently shaped connectors. This limits which RAM chips a particular computer model can use.
One type of RAM is battery-backed RAM. This is a RAM chip with a built-in battery. This is to make sure that no data is lost if the computer is turned off.
Other kinds of memory [change]
Information that the computer always needs, that does not often change, is normally kept in read-only memory (ROM), which does not lose its contents when the computer is turned off. Such items include the BIOS (Basic Input/Output System), which stores the most basic commands for the computer, telling it how it should start up. The BIOS also tells the computer how to input and output information. The BIOS can be compared to the part of your brain that tells your heart how to beat. This is an important part.