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Dynamic random-access memory facts for kids

Kids Encyclopedia Facts

Dynamic random access memory, often called DRAM, is the most common type of RAM used in computers. Think of RAM as your computer's short-term memory, where it keeps information it needs right now.

DRAM is called "dynamic" because it needs constant attention to remember things. If it's not refreshed all the time, it will forget the data it's holding. Because DRAM loses its data when the power is turned off, it's known as "volatile" memory. This word comes from a Latin word meaning "flying" or "fleeting."

Refreshing DRAM means the computer quickly reads the data from the DRAM and then immediately writes it back again. This happens many times every second.

DRAM is built from millions of tiny parts called capacitors. Each capacitor is like a tiny bucket that can hold a small electric charge, representing a piece of data (like a 1 or a 0). Next to each capacitor is a transistor, which acts like a gate, letting energy in and out. These tiny capacitors slowly lose their charge. If the DRAM isn't refreshed often enough, a capacitor might lose too much energy, causing a 1 to accidentally become a 0, and the data gets lost or mixed up.

DRAM vs. SRAM: What's the Difference?

DRAM is often compared to another type of memory called SRAM, which stands for Static RAM. Both are types of RAM, but they work a bit differently.

  • SRAM can hold data as long as it has power, without needing to be refreshed constantly.
  • SRAM can also be faster than DRAM.
  • However, SRAM is much more expensive to make than DRAM.
  • Also, SRAM uses more electricity and can get hotter faster than DRAM.

Both DRAM and SRAM lose all their data when the computer is turned off. This is different from non-volatile random-access memory, which can remember things even without power.

Images for kids

  • MT4C1024-HD

    A close-up picture of a chip from a Micron Technology MT4C1024 DRAM, made in 1994. It could store 1 megabit of data, which is 128 kilobytes.

  • NeXTcube motherboard

    The main circuit board (motherboard) of a NeXTcube computer from 1990. You can see the 64 MiB main memory DRAM chips at the top left and 256 KiB of VRAM (video memory) at the bottom right.

  • Square array of mosfet cells read

    How a simple 4x4 DRAM array works when reading data.

  • DRAM cell field (details)

    The basic parts of a DRAM cell array.

  • Square array of mosfet cells write

    How data is written to a DRAM cell.

  • DRAM self-aligned storage node locations

    Modern DRAM designs use "self-aligned storage nodes" to make them easier to build.

  • Pair32mbEDO-DRAMdimms

    Two 32 MB EDO DRAM memory sticks.

  • SAMSUNG@DDR-SDRAM@64MBit@K4D62323HA-QC60 Stack-DSC03539-DSC03556 - ZS-DMap

    A close-up of a Samsung DDR-SDRAM 64MBit chip.

  • Sapphire Ultimate HD 4670 512MB - Qimonda HYB18H512321BF-10-93577

    A 512 MBit Qimonda GDDR3 SDRAM chip, often used in graphics cards.

  • SAMSUNG@QDDR3-SDRAM@256MBit@K5J55323QF-GC16 Stack-DSC01340-DSC01367 - ZS-retouched

    What's inside a Samsung GDDR3 256 MBit chip.

  • Olivetti JP90 - Toshiba TC518129CFWL-80 on controller-8514

    A 1 Mbit high-speed CMOS pseudo static RAM chip, made by Toshiba.

See also

Kids robot.svg In Spanish: DRAM para niños

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