Changes

[[Dynamic random access memory]] (DRAM) is the majority in computers.  Modern computers use several types of DRAM. Before 2002, most computers used single data rate (SDR) RAM.  Most computers made since then use either double data rate (DDR), DDR2, DDR3, or [[:en:DDR4_SDRAM|DDR4]] RAM.  The later types allow stored data to be moved and used more quickly, so that the computer's processor can keep working quickly without having to wait for data as long or as often.  

[[Dynamic random access memory]] (DRAM) is the majority in computers.  Modern computers use several types of DRAM. Before 2002, most computers used single data rate (SDR) RAM.  Most computers made since then use either double data rate (DDR), DDR2, DDR3, or [[:en:DDR4_SDRAM|DDR4]] RAM.  The later types allow stored data to be moved and used more quickly, so that the computer's processor can keep working quickly without having to wait for data as long or as often.  

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.

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.

[[Static RAM]] (SRAM) needs power to keep its data, but does not need the computer to be active. Some SRAM chips are battery-backed. This type has a built-in [[battery]] to make sure no data is lost if the computer is turned off. Some computers have a little SRAM and mostly DRAM.

[[Static RAM]] (SRAM) needs power to keep its data, but does not need the computer to be active. Some SRAM chips are battery-backed. This type has a built-in [[battery]] to make sure no data is lost if the computer is turned off. Some computers have a little SRAM and mostly DRAM.

RAM is usually used to store information of running programs inside computers. RAM may also be used for different things.

RAM is usually used to store information of running programs inside computers. RAM may also be used for different things.

== Virtual Memory ==

== Virtual Memory ==

Using virtual memory, a computer can combine permanent storage with RAM to create a bigger pool of storage. This is useful when the RAM does not have enough space to store any more information. The extra data is then placed in the permanent storage instead of the RAM. The method has a limitation which is that permanent storage is often slower than RAM, which can slow down a computer.

Using [[virtual memory]], a computer can combine permanent storage with RAM to create a bigger pool of storage. This is useful when the RAM does not have enough space to store any more information. The extra data is then placed in the permanent storage instead of the RAM. The method has a limitation which is that permanent storage is often slower than RAM, which can slow down a computer.

== RAM disk ==

== RAM disk ==

A computer can use a part of the RAM to store permanent files. This is called a RAM disk. When the computer is turned on, files are copied to the RAM disk. This allows the files to open faster because RAM is faster than permanent storage. When the computer is turned off, the information on the RAM disk is lost, which is why the files need to exist on permanent storage as well.

A computer can use a part of the RAM to store permanent files. This is called a RAM disk. When the computer is turned on, files are copied to the RAM disk. This allows the files to open faster because RAM is faster than permanent storage. When the computer is turned off, the information on the RAM disk is lost, which is why the files need to exist on permanent storage as well.

Random-access-memory (RAM) is not to be confused with Ram as in the male [[Domestic sheep|sheep]].

Random-access-memory (RAM) is not to be confused with Ram as in the male [[Domestic sheep|sheep]].

== Random-access MemoryDifferent Types Of RAM Media ==

== Random-access Memory Media ==

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<gallery widths='160px' heights='100%' mode='traditional' caption=''>

File:Electronic Memory.jpg|A 64 bit memory chip die, the SP95 Phase 2 Buffer Memory produced at IBM mid 60s, versus [[Magnetic-core memory|memory core iron rings]]

File:Electronic Memory.jpg|A 64 bit memory chip die, the SP95 Phase 2 Buffer Memory produced at IBM mid 60s, versus [[Magnetic-core memory|memory core iron rings]]

File:Early SSA accounting operations.jpg|These IBM [[tabulating machine]]s from the mid-1930s used [[mechanical counter]]s to store information.

File:Early SSA accounting operations.jpg|These IBM [[tabulating machine]]s from the mid-1930s used [[mechanical counter]]s to store information.

File:Bundesarchiv Bild 183-1989-0406-022, VEB Carl Zeiss Jena, 1-Megabit-Chip.jpg|1-[[megabit]] (Mbit) chip, one of the last models developed by [[Carl Zeiss AG|VEB Carl Zeiss Jena]] in 1989

File:Bundesarchiv Bild 183-1989-0406-022, VEB Carl Zeiss Jena, 1-Megabit-Chip.jpg|CMOS 1-[[megabit]] (Mbit) DRAM chip, one of the last models developed by [[Carl Zeiss AG|VEB Carl Zeiss Jena]] in 1989

File:SRAM Cell (6 Transistors).svg|Circuit diagram of an SRAM cell, built with six MOSFETs. The bulk connection of all transistors is to ground, but is not shown from simplicity.

File:SRAM Cell (6 Transistors).svg|Circuit diagram of an SRAM cell, built with six MOSFETs. The bulk connection of all transistors is to ground, but is not shown from simplicity.