RAM - Memory Technology Overview
by Jarred Walton on September 28, 2004 12:05 AM EST- Posted in
- Memory
Closing Thoughts
All the talk of latencies and timings will hopefully have helped everyone to realize that while the two major factors in overall performance of RAM are its bandwidth and the CAS latency, the other timings' impact can vary from being negligible to having a moderate influence on performance. Higher latencies can be overcome in many instances by improved bandwidth, provided that the system is designed with this goal - it is but one of the many design decisions that must be made, often years in advance. Demands are dependent on the application being used, of course, but in general, graphics-intensive operations demand a lot of bandwidth, office applications benefit more from latency, and games tend to want both.With the large number of memory types available, not to mention chipsets, it can be very difficult to understand how everything fits together. We will provide more detailed comparisons in part two of this series, where we will look at a variety of past, present and future memory technologies. Stay tuned!
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Lynx516 - Tuesday, September 28, 2004 - link
Your description of how SDRAM works is wrong. you do not bust down the rows as your artcle implys but instead it bursts along the columns.The whole column is sent imeadiatly but the other columns in the burst are not and are sent sequencially (idealy not quite the case if you want to interleave them).
Comparing Banks to set associativity is probably counter productive as most of your reader wont fully under stand how it works. And infact comparing banks to set associativity is a bad annalogy. A better one would be just to say taht the memmory space in the chip is split up into banks.
On top of this you have referred to a detailed comparsion of DRAM types. Even though there are many different types of DRAM most are not that interesting or used that much in PCs. I also assume that as you have said this you will not be talking about SRAM or RDRAM in forth coming articles which highlight the different approaches that can be taken when designing a memory sub system. (SRAM the low latency, high bandwidth but low density, RDRAM the serial approach)
I assume you are going to talk abit about how a memory controller works as they are one of the most complex components in a PC (more complex than the exectution core of a CPU) but you have not refered to any plans to talk about memory controller and how the type of memory you are using affects the design of a memory controller.
All in all a pretty confusingly written article. If you want a DRAM for beginners arstechnica have two good articles (though one is fairly old but atleast correctly and CLEARLY describes how SDRAM works).
Resh - Tuesday, September 28, 2004 - link
I really think that some diagrams would help, especially for novices like #10. Other than that, great article and hope to see the follow-ups soon.Modal - Tuesday, September 28, 2004 - link
Great article, thanks. I like these "this is how the pieces of your computer work" articles... very interesting stuff, but it's usually written in far too complicated a manner for a relative novice like me. This was quite readable and understandable however; nice work.danidentity - Tuesday, September 28, 2004 - link
This is one of the best articles I've seen at Anandtech in a long while, keep up the good work.deathwalker - Tuesday, September 28, 2004 - link
I..for one, would rather have 1 GB of CL 2.5 high quality memory than 512 MB of CL 2 high quality memory. I'm conviced that in this instance quantity wins out over speed.AlphaFox - Tuesday, September 28, 2004 - link
where are the pictures? ;)Pollock - Tuesday, September 28, 2004 - link
Excellent read!mino - Tuesday, September 28, 2004 - link
Sry for triple post but some major typpos:"1) buy generic memory until your budget could afford no more than 512M DDR400"
should be:
"1) buy generic memory until your budget could afford more than 512M DDR400"
and
"Goog"(ROFL) should be "Good"
onother -> another
Hope that's all ;)
mino - Tuesday, September 28, 2004 - link
OK, 3 rules ;) - I added 3rd after some thought.mino - Tuesday, September 28, 2004 - link
#2 You are missing one important point. That is, unless You can(want) afford at least 512M high quality RAM, it makes NO SENSE to buy 256M DDR400 CL2 since there are 2 basic rules:1) buy generic memory until your budget could afford no more than 512M DDR400
2) then spend some aditional money for brand memory
3) then go 1G and only at this point spent all additional money for better latencies and so on.
Also do remember that at many shops(here in Slovakia) there is 3 or 4 yrs warranty for generic memory(like A-DATA) and also if you have major problems with compatibility they will usually allow you to choose different brand/type for your board for no additional cost except price difference. Also in case the memory works fine with onother board.
Also Twinmos parts have 99month warranty (for price 10% higher than generic). That speaks for itself.
Except this little missing part of reality,
Goog work Jarred.