What is DRAM (Dynamic Random Access Memory)? How Does it Work? (2024)

What is DRAM (Dynamic Random Access Memory)? How Does it Work? (1)


  • Alexander S. Gillis,Technical Writer and Editor

What is DRAM (dynamic random access memory)?

DRAM (dynamic random access memory) is a type of semiconductor memory that is typically used for the data or program code needed by a computer processor to function.

DRAM is a common type of random access memory (RAM) that is used in PCs, workstations and servers. Random access allows the PC processor to access any part of the memory directly rather than having to proceed sequentially from a starting place. RAM is located close to a computer's processor and enables faster access to data than storage media such as hard disk drives and solid-state drives.

How does DRAM work?

Memory is made of bits of data or program code that are arranged in a two-dimensional grid. DRAM will store bits of data in what's called a storage or memory cell, consisting of a capacitor and a transistor. The storage cells are typically organized in a rectangular configuration.

When a charge is sent through a column, the transistor at the column is activated. A DRAM storage cell is dynamic, meaning that it needs to be refreshed or given a new electronic charge every few milliseconds to compensate for charge leaks from the capacitor.

The memory cells will work with other circuits that can identify rows and columns, track the refresh process, instruct a cell whether or not to accept a charge and read or restore data from a cell.

DRAM is one option of semiconductor memory that a system designer can use when building a computer. Alternative memory choices include static RAM (SRAM), electrically erasable programmable read-only memory, NOR flash and NAND flash. Many systems use more than one type of memory.

Types of DRAM

There are many types of DRAM that a device can use. Some examples are the following:

  • Synchronous DRAM (SDRAM) syncs memory speeds with CPU clock speeds, letting the memory controller know the CPU clock cycle. This enables the CPU to perform more instructions at a time.
  • Rambus DRAM was more widely used in the early 2000s for graphics cards.
  • Double Data Rate SDRAM (DDR SDRAM) almost doubles the bandwidth in data rate of SDRAM by using double pinning. This process allows for data to transfer on rising and falling edges of a clock signal. It has been available in different iterations over time, including DDR2 SDRAM, DDR3 SDRAM and DDR4 SDRAM.
  • Fast Page Mode DRAM gives higher performance than other DRAM types through focusing on fast page access.
  • Extended Data Out DRAM improves the time to read from memory on microprocessors, such as Intel Pentium.

Major DRAM manufacturers include Kingston Technology, Micron, Samsung and SK Hynix.

Types of DRAM packages

There are two main types of DRAM packaging: single inline memory module (SIMM) and dual inline memory module (DIMM). Single inline memory module packaging is considered obsolete now and was used in the 1980s to 1990s. SIMMs came in 30 and 72 pin sets and typically had 32-bit data transfer rates. DIMMs, on the other hand, are commonly used now and have pins on both sides of the chip. DIMMs commonly have 168 pin connectors -- or more -- and support a 64-bit data transfer rate.

DRAM package types for DIMMs are set as different integrated circuit architectures. Some of these are the following:

  • Unbuffered DIMMs are commonly used on desktops and laptops. These cost less and run faster but are less stable.
  • Registered DIMMs are commonly used with servers. These are more stable and reduce strain on a CPU's memory controller.
  • Fully Buffered DIMMs are used in larger memory systems. These are more reliable since they can improve error detection methods and maintain signal integrity.
What is DRAM (Dynamic Random Access Memory)? How Does it Work? (2)


The main advantages of DRAM include the following:

  • Its design is simple, only requiring one transistor.
  • The cost is low in comparison to alternative types of memory, such as SRAM.
  • It provides higher density levels.
  • More data can be stored using DRAM.
  • Memory can be refreshed and deleted while a program is running.


The main disadvantages of DRAM include the following:

  • Memory is volatile.
  • Power consumption is high relative to other options.
  • Manufacturing is complex.
  • Data in storage cells needs to be refreshed.
  • It is slower than SRAM.


DRAM is a successor to SRAM. Memory designers reduced the number of elements per bit and eliminated differential bit lines to save chip area in order to create DRAM. As a result, DRAM is less expensive to produce than SRAM.

But SRAM retains some advantages over DRAM. SRAM does not need to be refreshed because it operates on the principle of switching the current flow in one of two directions rather than holding a charge in place within a storage cell. SRAM is generally used for cache memory, which can be accessed quicker than DRAM.

SRAM is capable of byte-level reads/writes and is faster at reads/writes than DRAM. DRAM writes data at the byte level and reads at the multiple-byte page level.

Power differences vary based on whether the system is in active or sleep mode. DRAM requires less power than SRAM in an active state, but SRAM consumes considerably less power than DRAM does while in sleep mode.


One of the first uses of DRAM was in a Toshiba calculator in 1965 -- using a capacitive form of DRAM that was made from bipolar memory cells. That same year, IBM created a 16-bit silicon memory chip.

However, at this time, the bipolar DRAM that was in use could not compete against magnetic-core memory. This stayed true of DRAM until the invention of the metal-oxide-semiconductor field-effect transistor (MOSFET), which led to the metal-oxide-semiconductor DRAM (MOS DRAM). The patent for MOS DRAM was granted in 1968. 1969 saw Intel develop DRAM that used a three-transistor cell.

Intel improved on its DRAM product with Intel 1103 in 1970, seeing commercial use. MOS memory began to make more of a market presence compared to magnetic-core memory around this time.

1973 also saw the invention of Mostek MK4096, a 4-kilobit DRAM. This was the first DRAM that incorporated multiplexed row and column address lines. Mostek MK4096 could fit into small packages with a small pin count, since it halved the number of address lines required.

In 1992, Samsung developed SDRAM, which had a capacity of 16 megabits.

This was last updated in March 2024

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What is DRAM (Dynamic Random Access Memory)? How Does it Work? (2024)


What is DRAM (Dynamic Random Access Memory)? How Does it Work? ›

Dynamic Random Access Memory, or DRAM, is a semiconductor memory that is normally used as the main memory of a computer . DRAM is a type of Random Access Memory (RAM) and is volatile memory, meaning it loses the stored data when the power is removed. DRAM stores the data in a charge on a transistor and capacitor pair.

What is DRAM and how does it work? ›

What does DRAM do? All RAM types, including DRAM, are a volatile memory that stores bits of data in transistors. This memory is located closer to your processor, too, so your computer can easily and quickly access it for all the processes you do.

What is Random Access Memory and how does it work? ›

What Is RAM? RAM is a common computing acronym that stands for random-access memory. Sometimes it's called PC memory or just memory. In essence, RAM is your computer or laptop's short-term memory. It's where the data is stored that your computer processor needs to run your applications and open your files.

What is a DRAM used for? ›

While pharmaceuticals are measured nowadays exclusively in metric units, fluid drams are still used to measure the capacity of pill containers. Dram is used informally to mean a small amount of liquor, especially Scotch whisky.

What is the main function of DRAM? ›

DRAM is widely used in digital electronics where low-cost and high-capacity memory is required. One of the largest applications for DRAM is the main memory (called the “RAM”) in modern computers and graphics cards (where the “main memory” is called the graphics memory).

Why is DRAM so important? ›

DRAM is essential because it allows your computer to run efficiently by providing quick access to essential data that your processor needs to operate at peak performance. Without DRAM, your processor would have to look through much slower storage mediums like hard drives or solid-state drives every time it needed data.

What is the example of DRAM? ›

DRAM, or Dynamic RAM, is the most widely used RAM that consumers deal with. DDR3 is an example of DRAM. SRAM, or static RAM, offers better performance than DRAM because DRAM needs to be refreshed periodically when in use, while SRAM does not.

Where is DRAM memory used? ›

DRAM chips are widely used in digital electronics where low-cost and high-capacity computer memory is required. One of the largest applications for DRAM is the main memory (colloquially called the "RAM") in modern computers and graphics cards (where the "main memory" is called the graphics memory).

What is the difference between RAM and DRAM memory? ›

Fast speed: One major benefit to using DRAM is that it offers faster speeds than other types of RAM. This means that your computer will be able to process data much more quickly than if you were using a slower type of RAM.

Who uses the DRAM? ›

The Armenian dram (Armenian: դրամ; sign: ֏; abbreviation: դր.; ISO code: AMD) is the currency of Armenia. It was historically subdivided into 100 luma (լումա). The Central Bank of Armenia is responsible for issuance and circulation of dram banknotes and coins, as well as implementing the monetary policy of Armenia.

What is the fastest type of memory technology? ›

Cache memory is the fastest memory on the system, required to keep up with the CPU as it fetches and executes instructions. The data most frequently used by the CPU is stored in cache memory.

What is the difference between DIMM and DRAM? ›

DIMM is a module containing one or several Random Access Memory (RAM) or Dynamic RAM (DRAM) chips on a long, thin strip of printed circuit board with pins that connect it directly to the computer motherboard. A DIMM (of DDR2 or DDR3 sockets) typically has a 240-pin connector and supports 64/72-bit data transfer.

Why does DRAM need to be refreshed? ›

DRAM cells leak charge over time, causing stored data lost. To prevent this situation, DRAM cells require recharge periodically. These recharge operations are also known as DRAM refresh. There are two important parameters for DRAM refresh, refresh interval (tREFI) and refresh cycle time (tRFC).

Does DRAM make a big difference? ›

The DRAM helps the SSD to manage the intricacies of NAND flash writes. DRAM also helps SSDs communicate with processors through a protocol that was designed around HDDs, which are altogether different from NAND flash.

How does DRAM work on SSD? ›

The DRAM served as cache for writing data to the drive, and for storing the mapping tables that keep record of the location of the data on the SSD to allow access to the data. For years, it became the standard to continue to push the limits and gain better performance from SSDs using DRAM.

Can you read in a DRAM? ›

Generally speaking, no, you can't read in a dream because the parts of your brain that process language are inactive while you sleep. That said, people who study language, like poets and writers, may be among the rare few who can read or write in dreams.

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