Dynamic RAM, DRAM Memory Technology Tutorial


DRAM (Dynamic Random Access Memory) is an operational memory that is a working area of ​​the CPU. During the operation, active programs and data are stored here. Memory is a temporary data storage, and so before turning off the computer or pressing the reset button all the changes should be saved to permanent memory device, it is usually a hard disk. Since the reference to the data stored in the memory does not depend on the order of their arrangement, the memory device is also called random access memory.

DRAM Structure

The main feature of DRAM is a dynamic storage. This makes it possible to repeatedly write information into memory, but there is a need always to update the data. Actually overwriting takes place every 15 microseconds. There is also a static random access (or cache) memory (SRAM) which does not require constant data updates. These two functions work only when the computer is switched on. RAM is a set of chips connected to the system board. As the characteristics of these chips are quite different, they must be compatible with the system for proper operation.

Nowadays, DRAM is one of the most widely used computer memories. The main advantage of this type of memory is extremely dense packing of cells, allowing you to create a large memory capacity, and the device itself takes up very little space. Each cell is a micro capacitor which holds charges. The main problem of this memory is the need constantly to regenerate the capacitor charge not to lose to data. The built-in-controller with the rate of recovery in 15 microseconds responds for updates and saving of data. In modern computers, operating at microwave frequencies, the regeneration process takes no more than 1% of CPU time. Therefore, it makes no sense to increase the time between cycles – it does not affect significantly on the operation, but as a consequence, it may lead to data loss in main memory.

DRAM Technology History

In 1834 Charles Babbage began developing the analytical engine. One of the important parts of this machine he called a store, this part was implied for the storage of intermediate results of calculations. These data were stored on magnetic drums, then on magnetic core memory.

Magnetic RAM was invented in 1947 and was used until the mid-1970s. It became a widespread type of random access memory.

In 1968 Robert Dennard invented dynamic random access memory (DRAM). His invention significantly increased memory density, and as a consequence its operating speed.

In 1969 Intel presented its first chip memory technology. The first product became SRAM (64 bit). The great SRAM advantage was that it didn’t require additional replacement, i.e. it could store data till it worked and there was no leak of data.

Then Honeywell, the owner of mainframe computer firm who was the first to present a PC for small business, addressed the Intel if they could create a dynamic random access memory chip. And soon DRAM became the main semiconductor technology driver. Produced on the basis of bipolar processing, it required few transistors for a process cell. And this fact made it rapid.

During the next decade DRAM became as “currency” of semi conducted business that was so important for computer industry, calculators, videogames.

In early 1970s the Intel designed DRAM IC (1102). But it had a lot of problems and it made the company develop a new DRAM technology with more reliable operation. As a result, a new device called the Intel 1103 appeared in late 1970s.

The time went on and in 1973 MOSTEK presented their MK4096 with a 4k capacity. This device had a multiplexed row and column addresses lines approach that enabled the memories to fit into packages with fewer pins. And this approach was a great advantage than in its turn let the MOSTEK DRAM technology gain ¾ of the world market share.

Taking into account all the written above, there are some advantages and disadvantages of DRAM. They are the following:



Low cost per bit

The structure of memory cell is simple enough


Manufacturing process is complex

Data needs refreshing

Volatile memory

Operational speed is relatively slow

As you see, DRAM memory is a very important component in electronics and computer technology. The DRAM memory is suitable for many processors and computer applications. In light of the evidence, DRAM memory chips are widespread and produced in large quantities and used in a number of new applications.

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