Difference Between SRAM and DRAM
SRAM vs DRAM
There are two types of Random Access Memory or RAM, each has its own advantages and disadvantages compared to the other. SRAM (Static RAM) and DRAM (Dynamic RAM) holds data but in a different ways. DRAM requires the data to be refreshed periodically in order to retain the data. SRAM does not need to be refreshed as the transistors inside would continue to hold the data as long as the power supply is not cut off. This behavior leads to a few advantages, not the least of which is the much faster speed that data can be written and read.
The additional circuitry and timing needed to introduce the refresh creates some complications that makes DRAM memory slower and less desirable than SRAM. One complication is the much higher power used by DRAM memory, this difference is very significant in battery powered devices. SRAM modules are also much simpler compared to DRAM, which makes it easier for most people to create an interface to access the memory. This makes it easier to work with for hobbyists and even for prototyping.
Structurally, SRAM needs a lot more transistors in order to store a certain amount of memory. A DRAM module only needs a transistor and a capacitor for every bit of data where SRAM needs 6 transistors. Because the number of transistors in a memory module determine its capacity, a DRAM module can have almost 6 times more capacity with a similar transistor count to an SRAM module. This ultimately boils down to price, which is what most buyers are really concerned with.
Because of its lower price, DRAM has become the mainstream in computer main memory despite being slower and more power hungry compared to SRAM. SRAM memory is still used in a lot of devices where speed is more crucial than capacity. The most prominent use of SRAM is in the cache memory of processors where speed is very essential, and the low power consumption translates to less heat that needs to be dissipated. Even hard drives, optical drives, and other devices that needs cache memory or buffers use SRAM modules.
Summary:
1. SRAM is static while DRAM is dynamic
2. SRAM is faster compared to DRAM
3. SRAM consumes less power than DRAM
4. SRAM uses more transistors per bit of memory compared to DRAM
5. SRAM is more expensive than DRAM
6. Cheaper DRAM is used in main memory while SRAM is commonly used in cache memory
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thank you very much…..
content is unique…..
It would have been so much better if the author included basic metrics for comparison purpose. For example what is the cost per GB of SRAM and DRAM. And most importantly, exactly how much faster is SRAM over DRAM. I think that the majorrity of the people who endup on this page come here to find out the performance difference. If anyone knows that then please add the info to this article
NO BUT UR ASIAN
According to another website I visited SRAM is about 6 times faster than DRAM.
Ajaz, considering it is clearly stated that SRAM is often used for CPU cache and DRAM for system memory, it’s trivial to realize the speed difference.
On a modern CPU, Cache latencies are in the 1ns to 15ns range (depending on the cache level) with bandwidth between 500GB/s and 1TB/s. Part of the low latency is due to the near CPU location of cache memory, but SRAM system memory is still in the 20-40ns range.
DRAM on the other hand is in the 60-100ns range with 20-40GB/s speeds and a multitude of additional delays in both latency and bandwidth, due to the refresh cycles etc.
the point about the power consumption is wrong if one considers power consumption per die,its the other way
tanks
great summary
Thanks, Helped me a lot.
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I like the Summary 🙂
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me 2
thnks a lot it helpd
Thanks alot for all summary and explanation because i get a more knowledge.
The point “SRAM consumes less power than DRAM” is wrong
What are the Characteristics of memory systems?
I think the “power consumption” comparison needs to be reviewed. Very nice article though.
thanks, for knowledege.
very usefull article
According to jp hayes Wcb/mcgraw hill publication. Sram ic’s consumer more power than dram
check it out
Consumes
SRAM will retain information as long as the power supply is not cut off, what about DRAM? Does DRAM have the capability to save information due to the refreshment process it goes through?
Steve: DRAM’s refresh circuit needs power supply as it is typically made of inverters.
Exactly what I needed to know. Thank you.
has been a good one, liked it
good summary
Thanx man
good and very nice
thanks useful and nice
I’m a little confused as to what “internal memory” is in smart phones. According to this article and comments, SRAM and DRAM need power for them to retain that memory. In other readings it says ROM is only used for the OS and other system files on phones. So is “internal memory” actually ROM, SRAM, DRAM or something else? I believe it is DRAM that has the ability to keep it’s memory without needing electricity. Anybody know the answer?
@Brad,
In this context, memory is the short term, temporary keeping of information. Sort of a scratch pad which is not meant for anything to be kept beyond the current operations being performed.
Stuff that is kept for the future is not considered memory, but instead terms like storage are used (hard drive and such).
So in your phone, it has RAM (memory, as in the above article) which runs the programs/APPs and when you close the APP, what was in memory is usually discarded. Anything needing to be saved, is put into storage. That storage is frequently described as FLASH, but sometimes called things like EEPROM or SSD which are related technology.
Those little memory cards used in digital cameras use the same flash technology as USB drives, and that is what is in your phone as storage. Storage is usually too slow for a program to run, so your phone has RAM for temporary execution and storage for saving things long term.
Thank you for this nice explanation!
Thankyou this website is very usefull
summary is too good.
Nice way but give difference in two parts
i liek this articl very nicee
Interesting.helped me in my exam Question 🙂
Anyone know about similarities of SRAM and DRAM or Application of Volatile Memory
Nice information…
Summary is so easy to understand.
But the contact is not clear…
This is very helpful to me for my self study….THANK U
Great explanation.
Thanks for provide me this information about ram.
thank for this
how can difference based on memory refresh